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14 pages, 682 KB  
Article
In Vitro Screening of Antibacterial Efficacy of Moringa oleifera and Thymus vulgaris Methanolic Extracts Against Different Escherichia coli Strains and Their In Vivo Effects Against E. coli-Induced Infection in Broiler Chickens
by Majid Ali, Naila Chand, Sarzamin Khan, Rifat Ullah Khan, Babar Maqbool, Shabana Naz, Ala Abudabos, Abdul Hafeez and Ibrahim A. Alhidary
Vet. Sci. 2025, 12(10), 957; https://doi.org/10.3390/vetsci12100957 - 6 Oct 2025
Abstract
This study evaluated the antibacterial efficacy and growth-promoting potential of Moringa oleifera and Thymus vulgaris methanolic extracts in broiler chickens challenged with Escherichia coli O78. In vitro antibacterial screening using agar well diffusion and disc diffusion assays revealed that ciprofloxacin exhibited the strongest [...] Read more.
This study evaluated the antibacterial efficacy and growth-promoting potential of Moringa oleifera and Thymus vulgaris methanolic extracts in broiler chickens challenged with Escherichia coli O78. In vitro antibacterial screening using agar well diffusion and disc diffusion assays revealed that ciprofloxacin exhibited the strongest inhibitory effect, followed by tetracycline and enrofloxacin, whereas among plant extracts, T. vulgaris was more effective than M. oleifera. The optimal combination (M100T150; 100 mg M. oleifera + 150 mg T. vulgaris) produced the largest inhibition zones against E. coli strains. For the in vivo trial, 540 Ross-308 broiler chicks were distributed into six treatment groups in a completely randomized design and reared for 42 days. Parameters assessed included growth performance, carcass traits, gut pH, ileal microbial counts, and intestinal histomorphology. Results showed that E. coli challenge significantly reduced feed intake, weight gain, carcass yield, and villus integrity while increasing FCR and E. coli counts (p < 0.05). Addition of plant extracts, particularly M100T150, significantly improved weight gain, FCR, Broiler Performance Efficiency Factor (BPEF), and Broiler Farm Economy Index (BFEI) compared to the positive control (p < 0.05). Extracts reduced duodenal and jejunal pH (p < 0.001), suppressed E. coli counts (p = 0.003), and enhanced Lactobacillus populations (p = 0.0004). Histological analysis revealed that extract-supplemented groups had greater villus height and surface area with shallower crypts than the positive control, indicating restoration of gut integrity. These findings suggest that methanolic extracts of M. oleifera and T. vulgaris, particularly in combination, can serve as natural alternatives to antibiotics in broiler production under pathogenic challenge. Full article
(This article belongs to the Special Issue Nutritional Health of Monogastric Animals)
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24 pages, 1249 KB  
Systematic Review
Evaluation of Factors Affecting Fluoride Release from Fluoride Varnishes: A Systematic Review
by Maciej Dobrzyński, Agnieszka Kotela, Sylwia Klimas, Zuzanna Majchrzak, Julia Kensy, Marzena Laszczyńska, Mateusz Michalak, Zbigniew Rybak, Magdalena Fast and Jacek Matys
Materials 2025, 18(19), 4603; https://doi.org/10.3390/ma18194603 - 4 Oct 2025
Abstract
Introduction: Fluoride varnishes are widely used in caries prevention, but the rate and duration of fluoride ion release differ depending on material composition and environmental factors. Objectives: This systematic review synthesized evidence from in vitro studies on human teeth to identify key factors [...] Read more.
Introduction: Fluoride varnishes are widely used in caries prevention, but the rate and duration of fluoride ion release differ depending on material composition and environmental factors. Objectives: This systematic review synthesized evidence from in vitro studies on human teeth to identify key factors influencing fluoride release. Methods: A systematic literature search was conducted in July 2025 in PubMed, Scopus, Web of Science, Embase, and the Cochrane Library using the terms “fluoride release” AND “varnish” in titles and abstracts. Study selection followed PRISMA 2020 guidelines, predefined eligibility criteria, and was structured according to the PICO framework. Of 484 retrieved records, 15 studies met the inclusion criteria and were analyzed qualitatively. Results: The primary outcome was the magnitude and duration of fluoride release from varnishes. Most studies reported peak release within the first 24 h, followed by a marked decline, although some formulations (e.g., Clinpro XT and Duraphat) maintained more stable long-term release. Substantial methodological heterogeneity was observed across studies, including differences in sample type, storage medium, pH, temperature, and measurement protocols, which influenced fluoride release dynamics. Reported secondary outcomes included enamel remineralization, changes in surface properties, and antibacterial activity, with bioactive additives such as CPP–ACP and TCP enhancing preventive effects. Acidic conditions consistently increased fluoride release. Conclusions: The magnitude and persistence of fluoride release from varnishes depend on both intrinsic material properties and external environmental conditions. Bioactive additives may prolong fluoride availability and provide additional preventive benefits. Full article
(This article belongs to the Special Issue Advanced Dental Materials: From Design to Application, Third Edition)
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22 pages, 543 KB  
Review
Carbon Dots as Multifunctional Nanomaterials: A Review on Antimicrobial Activities and Fluorescence-Based Microbial Detection
by Andreas Romulo, Steven Suryoprabowo, Raden Haryo Bimo Setiarto and Yahui Guo
Molecules 2025, 30(19), 3969; https://doi.org/10.3390/molecules30193969 - 3 Oct 2025
Abstract
The increasing prevalence of antimicrobial resistance and the persistent challenge of infectious diseases highlight the critical necessity for novel approaches that integrate pathogen management with swift detection methods. Carbon dots (CDs) are a versatile class of fluorescent nanomaterials that have garnered increasing attention [...] Read more.
The increasing prevalence of antimicrobial resistance and the persistent challenge of infectious diseases highlight the critical necessity for novel approaches that integrate pathogen management with swift detection methods. Carbon dots (CDs) are a versatile class of fluorescent nanomaterials that have garnered increasing attention owing to their tunable surface chemistry, strong photoluminescence, high stability, and biocompatibility. Recent studies demonstrate that CDs possess broad-spectrum antibacterial and antifungal activities via multiple mechanisms, including the generation of reactive oxygen species, disruption of membranes, inhibition of biofilms, and synergistic interactions with conventional antimicrobials. The performance is significantly affected by precursor selection, heteroatom doping, and surface functionalization, with minimum inhibitory concentrations reported to range from highly potent at the microgram level to moderate at elevated concentrations. The intrinsic fluorescence of CDs, in addition to their antimicrobial activity, facilitates their use as sensitive and selective probes for microbial detection, allowing for rapid and real-time monitoring in biomedical, food safety, and environmental settings. This review summarizes recent advancements in the antimicrobial properties of carbon dots (CDs) and their fluorescence-based applications in microbial detection. It emphasizes their theranostic potential and future prospects as multifunctional nanomaterials for combating infectious diseases and ensuring microbial safety. Full article
(This article belongs to the Section Food Chemistry)
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17 pages, 1818 KB  
Article
pH-Sensitive Release of Functionalized Chiral Carbon Dots from PLGA Coatings on Titanium Alloys for Biomedical Applications
by Roberto López-Muñoz, Pascale Chevallier, Francesco Copes, Rafik Naccache and Diego Mantovani
Polymers 2025, 17(19), 2667; https://doi.org/10.3390/polym17192667 - 2 Oct 2025
Abstract
Titanium and its alloys are the most widely used metallic materials for bone contact implants. However, despite advances in implant technology, these alloys are still susceptible to post-operative clinical complications such as inflammation, which is often joined by infections and biofilm formation. A [...] Read more.
Titanium and its alloys are the most widely used metallic materials for bone contact implants. However, despite advances in implant technology, these alloys are still susceptible to post-operative clinical complications such as inflammation, which is often joined by infections and biofilm formation. A number of coatings were studied to overcome the drawbacks of these complications, but the controlled release of bioactive molecules over the first few days and the adhesion of the coating to the substrate remain recognized challenges. Carbon dots and the antibacterial potential of chiral carbon dots (CCDs) were recently reported, and their chirality was identified as a major contribution to the bactericidal effect. This study aimed to achieve a stimuli-responsive medium-term controlled release for up to one month. Two types of chiral carbon dots (CCDs) with distinct functional groups were incorporated into a stable and adherent biodegradable polymer coating, i.e., poly(lactic-co-glycolic acid) (PLGA). To enhance the coating adhesion, the titanium alloy surfaces were pre-treated and activated. The wettability, morphology, and surface composition of the coatings were characterized by contact angle, profilometry, SEM, and XPS, respectively. Coating degradation, adhesion, and CCDs release were studied at physiological pH (7.4) and at an acidic pH characteristic of an inflammatory site (pH 3.0) for up to one month. Their biological performances and blood compatibility were assessed as well. Degradation studies conducted over 28 days revealed a slow mass loss of approximately 10%, with maximum release rates for CCDs-OH and CCDs-NH2 of 67% and 45% at pH 7.4, respectively. At pH 3.0 an inverse trend was observed with 49% and 59% maximum release after 28 days. Furthermore, the coatings did not exhibit any cytotoxic and hemolytic effects. These findings demonstrate the potential of this approach to providing titanium implants with pH-sensitive controlled release of bioactive CCDs lasting up to one month, which could address key challenges in implant-associated complications. Full article
(This article belongs to the Special Issue Smart and Functional Biopolymers)
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20 pages, 6891 KB  
Article
Influence of TiO2 Nanoparticle Concentration on Micro-Arc Oxidized Calcium–Phosphate Coatings: Corrosion Resistance and Biological Response
by Ainur Zhassulan, Bauyrzhan Rakhadilov, Daryn Baizhan, Aidar Kengesbekov, Dauir Kakimzhanov and Nazira Musataeva
Coatings 2025, 15(10), 1142; https://doi.org/10.3390/coatings15101142 - 2 Oct 2025
Abstract
Titanium and its alloys are widely used in biomedical implants due to their favorable mechanical properties and corrosion resistance; however, their natural surface lacks sufficient bioactivity and antibacterial performance. Micro-arc oxidation is a promising approach to producing bioactive coatings, and the incorporation of [...] Read more.
Titanium and its alloys are widely used in biomedical implants due to their favorable mechanical properties and corrosion resistance; however, their natural surface lacks sufficient bioactivity and antibacterial performance. Micro-arc oxidation is a promising approach to producing bioactive coatings, and the incorporation of nanoparticles such as TiO2 may further improve their functionality. This study aimed to determine the optimal TiO2 nanoparticle concentration in the micro-arc oxidation electrolyte that ensures coating stability and biological safety. Calcium–phosphate coatings were fabricated on commercially pure titanium using micro-arc oxidation with two TiO2 concentrations: 0.5 wt.% (MAO 1) and 1 wt.% (MAO 2). Surface morphology, porosity, and phase composition were analyzed by scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction. Corrosion resistance was evaluated via potentiodynamic polarization in NaCl and Ringer’s solutions, while biocompatibility was assessed in vitro using HOS human osteosarcoma cells and MTT assays. Increasing the TiO2 content to 1% decreased coating porosity (13.7% vs. 26.3% for MAO 1), enhanced corrosion protection, and reduced the friction coefficient compared to bare titanium. However, MAO 2 exhibited high cytotoxicity (81% cell death) and partial structural degradation in the biological medium. MAO 1 maintained integrity and showed no toxic effects (3% cell death). These results suggest that 0.5% TiO2 is the optimal concentration, providing a balance between corrosion resistance, mechanical stability, and biocompatibility, supporting the development of safer implant coatings. Full article
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18 pages, 3573 KB  
Systematic Review
Effects of Implant Silver Coatings on Bone Formation in Animal Models: A Systematic Review and Meta-Analysis
by Ali Alenezi
J. Funct. Biomater. 2025, 16(10), 369; https://doi.org/10.3390/jfb16100369 - 1 Oct 2025
Abstract
Background/Objective: Clinical statistics show that bacterial infection is a major driver of implant failure. To enhance antibacterial performance, some metallic elements, such as silver (Ag), zinc (Zn), and copper (Cu), are commonly used to modify the titanium surface. Despite the promising antibacterial performance [...] Read more.
Background/Objective: Clinical statistics show that bacterial infection is a major driver of implant failure. To enhance antibacterial performance, some metallic elements, such as silver (Ag), zinc (Zn), and copper (Cu), are commonly used to modify the titanium surface. Despite the promising antibacterial performance of Ag, concerns persist regarding dose-dependent cytotoxicity, systemic accumulation, and potential effects on local bone metabolism. This review aimed to investigate the effects of incorporating or coating titanium (Ti) implant surfaces with Ag on bone formation around implants. Methods: A search was undertaken using three main databases (PubMed, Web of Science, and Scopus). The search was limited to studies published within the last 20 years that involved animal experiments using endosseous implants coated with or incorporating Ag. Meta-analyses were performed for bone-to-implant contact (BIC), bone formation (BA), and bone volume (BV/TV) around the implant in control and test groups. The compared groups were subjected to similar implant surface treatments aside from the presence of silver in the test group. Results: Sixteen studies met the inclusion criteria in this study and were included. The analysis of BIC values revealed a statistically significant overall effect in favor of silver-coated implants (Z = 2.01, p = 0.04), along with 95% confidence intervals (CIs). The BA analysis found no significant difference between silver-coated and control implants (Z = 1.09, p = 0.28). The BV/TV analysis also showed no statistically significant overall difference (Z = 0.35, p = 0.73). Conclusions: In animal models, silver-coated Ti implants improve bone–implant contact without altering peri-implant bone volume metrics. Full article
(This article belongs to the Special Issue Biomaterials Applied in Dental Sciences)
36 pages, 8611 KB  
Article
Multifunctional Electrospun Materials from Poly(Vinyl Alcohol)/Chitosan and Polylactide Incorporating Rosmarinic Acid and Lidocaine with Antioxidant and Antimicrobial Properties
by Milena Ignatova, Dilyana Paneva, Selin Kyuchyuk, Nevena Manolova, Iliya Rashkov, Milena Mourdjeva and Nadya Markova
Polymers 2025, 17(19), 2657; https://doi.org/10.3390/polym17192657 - 30 Sep 2025
Abstract
Novel multifunctional fibrous materials were prepared by simultaneous dual spinneret electrospinning of two separate solutions differing in composition. This technique allowed for the preparation of materials built of two types of fibers: fibers from poly(vinyl alcohol) (PVA), chitosan (Ch), and rosmarinic acid (RA), [...] Read more.
Novel multifunctional fibrous materials were prepared by simultaneous dual spinneret electrospinning of two separate solutions differing in composition. This technique allowed for the preparation of materials built of two types of fibers: fibers from poly(vinyl alcohol) (PVA), chitosan (Ch), and rosmarinic acid (RA), and poly(L-lactide) (PLA) fibers containing lidocaine hydrochloride (LHC). Confocal laser scanning microscopy (CLSM) analyses showed that both types of fibers are present on the surface and in the bulk of the new materials. The presence of all components and some interactions between them were proven by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. RA and LHC were in an amorphous state in the fibers, and their presence affected the temperature characteristics and the crystallinity, as detected by differential scanning calorimetry (DSC) and X-ray diffraction analyses (XRD). The presence of PVA/Ch/RA fibers enabled the hydrophilization of the surface of the multifunctional fibrous materials (the water contact angle value was 0°). The newly developed materials demonstrated adequate mechanical properties, making them suitable for use in wound dressing applications. The RA-containing fibrous mats possessed high radical-scavenging activity (ca. 93%), and the combining with LHC led to an enhancement of this effect (ca. 98.5%). RA-containing fibrous mats killed all the pathogenic bacteria S. aureus and E. coli and decreased the titer of fungi C. albicans by ca. 0.4 log for a contact time of 24 h. Therefore, the new materials are prospective as antibacterial and atraumatic functional wound dressings, as systems for local drug delivery, and in medical skincare. Full article
(This article belongs to the Special Issue Electrospinning of Polymer Systems)
26 pages, 2250 KB  
Article
The Quality and Bioactive Properties of Mulberry Wine Under Different Fermentation Conditions
by Jiajun Li, Huiming Zhang and Tieyan Jin
Foods 2025, 14(19), 3393; https://doi.org/10.3390/foods14193393 - 30 Sep 2025
Abstract
This study systematically investigated the effects of key fermentation parameters—initial sugar content (24–28 °Brix), temperature (15–20 °C), and yeast inoculation rate (0.04–0.12%)—on the quality, volatile aroma characteristics, antioxidant capacity, and bioactive properties of mulberry wine. Through a combination of single-factor experiments and response [...] Read more.
This study systematically investigated the effects of key fermentation parameters—initial sugar content (24–28 °Brix), temperature (15–20 °C), and yeast inoculation rate (0.04–0.12%)—on the quality, volatile aroma characteristics, antioxidant capacity, and bioactive properties of mulberry wine. Through a combination of single-factor experiments and response surface methodology (RSM), optimal fermentation conditions were determined as follows: initial sugar content of 25 °Brix, temperature of 18 °C, and yeast inoculation rate of 0.08%. Under these conditions, the resulting wine exhibited superior sensory characteristics, enhanced antioxidant activity (total phenolic content, DPPH and ABTS radical scavenging capacity, and FRAP), and significantly higher levels of key aroma compounds (e.g., ethyl acetate, phenethyl alcohol) compared to unfermented mulberry juice. Furthermore, the wine exhibited dose-dependent inhibition of proliferation in HepG2 and HT29 cells with IC50 values of 0.82 mg/mL and 1.05 mg/mL, respectively, and demonstrated selective antibacterial activity against Escherichia coli and Staphylococcus aureus. These findings provide a scientific basis for optimizing the production of mulberry wine with enhanced sensory qualities and functional properties, highlighting its potential as a health-promoting fermented beverage. Full article
(This article belongs to the Section Drinks and Liquid Nutrition)
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27 pages, 2749 KB  
Article
Biogenic TiO2–ZnO Nanocoatings: A Sustainable Strategy for Visible-Light Self-Sterilizing Surfaces in Healthcare
by Ali Jabbar Abd Al-Hussain Alkawaz, Maryam Sabah Naser and Ali Jalil Obaid
Micro 2025, 5(4), 45; https://doi.org/10.3390/micro5040045 - 30 Sep 2025
Abstract
Introduction: Hospital-acquired infections remain a significant healthcare concern due to the persistence of pathogens such as Staphylococcus aureus and Escherichia coli on frequently touched surfaces. Conventional TiO2 coatings are limited to UV activation, which restricts their application under normal indoor light. Combining [...] Read more.
Introduction: Hospital-acquired infections remain a significant healthcare concern due to the persistence of pathogens such as Staphylococcus aureus and Escherichia coli on frequently touched surfaces. Conventional TiO2 coatings are limited to UV activation, which restricts their application under normal indoor light. Combining TiO2 with ZnO and employing green synthesis methods may overcome these limitations. Methodology: Biogenic TiO2 and ZnO nanoparticles were synthesized using Bacillus subtilis under mild aqueous conditions. The nanoparticles were characterized by SEM, XRD, UV-Vis, and FTIR, confirming nanoscale size, crystalline phases, and organic capping. A multilayer TiO2/ZnO coating was fabricated on glass substrates through layer-by-layer deposition. Antibacterial activity was tested against S. aureus and E. coli using disk diffusion, direct contact assays, ROS quantification (FOX assay), and scavenger experiments. Statistical significance was evaluated using ANOVA. Results: The TiO2/ZnO multilayer exhibited superior antibacterial activity under visible light, with inhibition zones of ~15 mm (S. aureus) and ~12 mm (E. coli), significantly outperforming single-component coatings. Direct contact assays confirmed strong bactericidal effects, while scavenger tests verified ROS-mediated mechanisms. FOX assays detected elevated H2O2 generation, correlating with antibacterial performance. Discussion: Synergistic effects of band-gap narrowing, Zn2+ release, and ROS generation enhanced visible-light photocatalysis. The multilayer structure improved light absorption and charge separation, providing higher antimicrobial efficacy than individual oxides. Conclusion: Biogenic TiO2/ZnO multilayers represent a sustainable, visible-light-activated antimicrobial strategy with strong potential for reducing nosocomial infections on hospital surfaces and surgical instruments. Future studies should assess long-term durability and clinical safety. Full article
(This article belongs to the Topic Antimicrobial Agents and Nanomaterials—2nd Edition)
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21 pages, 4240 KB  
Article
Development and Characterization of Effective Hemostatic Composites Based on Polyvinyl Alcohol/Kaolinite/Chitosan
by Aruzhan Alimbek, Bayansulu Otegenova, Zhanar Bekissanova, Balzhan Savdenbekova, Nailya Ibragimova, Renata Nemkayeva, Myroslav Sprynskyy and Alyiya Ospanova
Polymers 2025, 17(19), 2637; https://doi.org/10.3390/polym17192637 - 30 Sep 2025
Abstract
In this study, hemolytically safe and antibacterial polyvinyl alcohol/kaolinite/chitosan (PVA/KAO/CS) hydrogels were obtained using the freeze–thaw method. The structure of the chemical bonds present in the developed hydrogels was investigated by Fourier transform infrared spectroscopy (FTIR). Scanning electron microscopy (SEM) and optical microscopy [...] Read more.
In this study, hemolytically safe and antibacterial polyvinyl alcohol/kaolinite/chitosan (PVA/KAO/CS) hydrogels were obtained using the freeze–thaw method. The structure of the chemical bonds present in the developed hydrogels was investigated by Fourier transform infrared spectroscopy (FTIR). Scanning electron microscopy (SEM) and optical microscopy study results showed the morphological and structural characteristics of the hydrogels’ surface. The thermal stability and phase transitions of the obtained hydrogel samples were determined by thermogravimetric analysis (TGA). Porosity, swelling, gel fractions, and mechanical properties were also examined. Biomedical properties of the samples were evaluated using in vitro and in vivo tests such as hemolytic activity, inhibition of protein denaturation, antimicrobial activity, and hemostatic activity. The obtained hydrogels demonstrated safe hemolytic activity, pronounced hemostatic activity, the ability to prevent thermal denaturation of albumin, as well as antimicrobial activity against Gram-positive bacteria Staphylococcus aureus ATCC BAA-39 and Streptococcus pyogenes ATCC 19615 and Gram-negative bacteria Pseudomonas aeruginosa ATCC 9027 and Escherichia coli ATCC 8739. All the obtained characteristics confirmed the promising biomedical applications of the obtained hydrogels. Full article
(This article belongs to the Section Polymer Composites and Nanocomposites)
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15 pages, 803 KB  
Article
Mechanical and Antimicrobial Evaluation of Chitosan-Coated Elastomeric Orthodontic Modules
by Lucía Gabriela Beltrán-Novelo, Fernando Javier Aguilar-Pérez, Myriam Angélica De La Garza-Ramos, Arturo Abraham Cienfuegos-Sarmiento, José Rubén Herrera-Atoche, Martha Gabriela Chuc-Gamboa, Jacqueline Adelina Rodríguez-Chávez and Juan Valerio Cauich-Rodríguez
Dent. J. 2025, 13(10), 447; https://doi.org/10.3390/dj13100447 - 29 Sep 2025
Abstract
Background/Objectives: Orthodontic appliances disrupt oral biofilm homeostasis, leading to an increase in plaque and disease risk. Elastomeric modules (EMs) promote bacterial growth due to their material composition. Surface coatings have been developed to reduce bacterial colonization. We evaluated the mechanical, antimicrobial, and [...] Read more.
Background/Objectives: Orthodontic appliances disrupt oral biofilm homeostasis, leading to an increase in plaque and disease risk. Elastomeric modules (EMs) promote bacterial growth due to their material composition. Surface coatings have been developed to reduce bacterial colonization. We evaluated the mechanical, antimicrobial, and cell viability properties of a chitosan coating for EMs. Methods: EMs were coated with chitosan (CS) and chitosan-glutaraldehyde (CS-GTA) to assess antimicrobial and cell viability. Uncoated EMs were used as a control. These surface-coated modules were characterized and analyzed with Fourier transform infrared (FTIR) and Raman spectroscopy, and tensile testing. Antibacterial activity was assessed by colony-forming units (CFU) counts after incubation. Cell viability was tested with gingival fibroblasts using the MTT assay. ANOVA, Tukey, Kolmogorov–Smirnov, and Kruskal–Wallis tests were used for statistical analysis. Results: Raman spectra of the chitosan coatings showed characteristic molecular vibration bands. ANOVA revealed a significant difference in mechanical properties between the materials and between the control and the CS-GTA groups, confirmed by the Tukey post hoc test. No significant difference was observed between the groups in the Yield Stress test. All the coated groups showed reduced CFU counts in the antibacterial assay. The average cell viability of the coated groups was 85% and 89%. Conclusions: We synthesized CS and GTA-cross-linked chitosan coatings. The coatings did not affect the mechanical properties of the elastomeric modules. The chitosan and glutaraldehyde-cross-linked CS coatings inhibited bacterial growth. No significant differences were observed in antibacterial activity between the CS and the GTA-crosslinked chitosan coatings. Full article
36 pages, 20275 KB  
Article
Development and Physico-Chemical and Antibacterial Characterization of Chromium-Doped Hydroxyapatite in a Chitosan Matrix Coating
by Daniela Predoi, Carmen Steluta Ciobanu, Simona Liliana Iconaru, Roxana Alexandra Petre, Krzysztof Rokosz, Steinar Raaen and Mihai Valentin Predoi
Polymers 2025, 17(19), 2633; https://doi.org/10.3390/polym17192633 - 29 Sep 2025
Abstract
Chromium-doped hydroxyapatite (7CrHAp) and chromium-doped hydroxyapatite in chitosan matrix (7CrHAp-CH) coatings were synthesized in order to address the need for biomaterials with improved physico-chemical and biological properties for biomedical applications. Both chromium-doped hydroxyapatite (7CrHAp) and chromium-doped hydroxyapatite in chitosan matrix (7CrHAp-CH) coatings could [...] Read more.
Chromium-doped hydroxyapatite (7CrHAp) and chromium-doped hydroxyapatite in chitosan matrix (7CrHAp-CH) coatings were synthesized in order to address the need for biomaterials with improved physico-chemical and biological properties for biomedical applications. Both chromium-doped hydroxyapatite (7CrHAp) and chromium-doped hydroxyapatite in chitosan matrix (7CrHAp-CH) coatings could represent promising materials for biomedical applications due to their superior properties. This study aims to evaluate the physico-chemical and in vitro biological properties of 7CrHAp and 7CrHAp-CH coatings to determine the impact of chitosan incorporation on the physico-chemical and biological features. The results reported in this study indicate that addition of chitosan improves surface uniformity and biological properties, highlighting their potential for uses in biomedical applications. In this study, coatings of chromium-doped hydroxyapatite (7CrHAp, with xCr = 0.07) and its composite variant embedded in a chitosan matrix (7CrHAp-CH) were systematically analyzed using a suite of characterization techniques: X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and metallographic microscopy (MM). The results of the XRD analysis revealed that the average crystal size was 19.63 nm for 7CrHAp and 16.29 nm for 7CrHAp-CH, indicating a decrease in crystallite size upon CH incorporation. The films were synthesized via the dip coating method using stable suspensions, whose stability was assessed through ultrasonic measurements (double-distilled water serving as the reference medium). The values obtained for the stability parameter were 2.59·10−6 s−1 for 7CrHAp, 8.64·10−7 s−1 for 7CrHAp-CH, and 3.14·10−7 s−1 for chitosan (CH). These data underline that all samples are stable: CH is extremely stable, followed by 7CrHAp-CH (very stable) and 7CrHAp (stable). The in vitro biocompatibility of the 7CrHAp and 7CrHAp-CH coatings was evaluated with the aid of the MG63 cell line. The cytotoxic potential of these coatings towards MG63 cells was quantified using the MTT assay after 24 and 48 h of incubation. Our results highlight that both 7CrHAp and 7CrHAp-CH coatings exhibit high biocompatibility with MG63 cells, maintaining cell viability above 90% at both incubation times, thus supporting osteoblast-like cell proliferation. Furthermore, the antimicrobial efficacy of both 7CrHAp and 7CrHAp-CH samples was evaluated in vitro against the Pseudomonas aeruginosa 27853 ATCC (P. aeruginosa) reference strain. The in vitro antibacterial activity of the 7CrHAp and 7CrHAp-CH coatings was further evaluated against Pseudomonas aeruginosa 27853 ATCC (P. aeruginosa), Escherichia coli ATCC 25922 (E. coli) and Staphylococcus aureus ATCC 25923 (S. aureus) reference strains. In addition, atomic force microscopy (AFM) analysis was also used to investigate the ability of P. aeruginosa, E. coli and S. aureus cells to adhere and to develop colonies on the surfaces of the 7CrHAp and 7CrHAp-CH coatings. The results from the biological assays indicate that both coatings exhibit promising antibacterial properties, highlighting their potential for being used in biomedical applications, particularly in the development of novel antimicrobial devices. Full article
(This article belongs to the Special Issue Polysaccharides: Synthesis, Properties and Applications)
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22 pages, 5662 KB  
Article
Physical Vapor Deposited TiN and TiAlN on Biomedical β-Type Ti-29Nb-13Ta-4.6Zr: Microstructural Characteristics, Surface Hardness Enhancement, and Antibacterial Activity
by Hakan Yilmazer
Coatings 2025, 15(10), 1126; https://doi.org/10.3390/coatings15101126 - 29 Sep 2025
Abstract
Beta (β)-type Ti-29Nb-13Ta-4.6Zr (TNTZ) alloys combine low modulus with biocompatibility but require improved surface properties for long-term implantation. This study aimed to enhance the surface mechanical strength and antibacterial performance of TNTZ by applying TiN and TiAlN coatings via PVD. Notably, TiAlN was [...] Read more.
Beta (β)-type Ti-29Nb-13Ta-4.6Zr (TNTZ) alloys combine low modulus with biocompatibility but require improved surface properties for long-term implantation. This study aimed to enhance the surface mechanical strength and antibacterial performance of TNTZ by applying TiN and TiAlN coatings via PVD. Notably, TiAlN was deposited on TNTZ for the first time, enabling a direct side-by-side comparison with TiN under identical deposition conditions. Dense TiN (~1.06 μm) and TiAlN (~1.73 μm) coatings were deposited onto solution-treated TNTZ and characterized by X-ray diffraction, scanning probe microscopy, Vickers microhardness, Rockwell indentation test (VDI 3198), static water contact angle measurements, and a Kirby–Bauer disk-diffusion antibacterial assay against Escherichia coli (E. coli). Both coatings formed face-centered cubic (FCC) structures with smooth interfaces (Ra ≤ 5.3 nm) while preserving the single-phase β matrix of the substrate. The hardness increased from 192 HV (uncoated) to 1059 HV (TiN) and 1468 HV (TiAlN), and the adhesion quality was rated as HF2 and HF1, respectively. The surface wettability changed from hydrophilic (48°) to moderately hydrophobic (82°) with TiN and highly hydrophobic (103°) with TiAlN. Similarly, the diameter of the no-growth zones increased to 18.02 mm (TiN) and 19.09 mm (TiAlN) compared to 17.65 mm for uncoated TNTZ. The findings indicate that TiAlN, in particular, provided improved hardness, adhesion, and hydrophobicity. Preliminary bacteriostatic screening under diffusion conditions suggested a modest relative antibacterial response, though the effect was not statistically significant between coated and uncoated TNTZ. Statistical analysis confirmed no significant difference between the groups (p > 0.05), indicating that only a preliminary bacteriostatic trend— rather than a definitive antibacterial effect—was observed. Both nitride coatings strengthened TNTZ without compromising its structural integrity, making TiAlN-coated TNTZ a promising candidate for next-generation orthopedic implants. Full article
(This article belongs to the Special Issue Films and Coatings with Biomedical Applications)
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25 pages, 3491 KB  
Article
Selective Targeting and Enhanced Photodynamic Inactivation of Methicillin-Resistant Staphylococcus aureus (MRSA) by a Decacationic Vancomycin–Mesochlorin Conjugate
by He Yin, Xiaojing Liu, Min Wang, Ying Wang, Tianhong Dai and Long Y. Chiang
Antibiotics 2025, 14(10), 978; https://doi.org/10.3390/antibiotics14100978 - 28 Sep 2025
Abstract
Background/Objectives: Covalent conjugation of an antibiotic vancomycin (VCM) moiety and a photosensitizing mesochlorin (mChlPd) unit into one molecular entity may present the potential to produce the combinatorial effect of both antibacterial photodynamic therapeutic (aPDT) and antibiotic activities. Our recent [...] Read more.
Background/Objectives: Covalent conjugation of an antibiotic vancomycin (VCM) moiety and a photosensitizing mesochlorin (mChlPd) unit into one molecular entity may present the potential to produce the combinatorial effect of both antibacterial photodynamic therapeutic (aPDT) and antibiotic activities. Our recent study indicated that a short linkage of <4 (C−C/or C−N) bond distances between these two moieties resulted in significant steric hindrance due to the bulky VCM, which greatly reduces the accessibility of the agent to the cell surface of methicillin-resistant Staphylococcus aureus (MRSA). The observed aPDT efficacy was found to be minimal. Here, we report that the revision of this linkage, via an EG10 unit using identical synthetic procedures, was able to resolve the issue. Methods: Accordingly, the corresponding combinatorial aPDT−antibiotic compound, consisting of two covalently bonded quaternary ammonium pentacationic arms on the mesochlorin chromophore core, designated as VCMe-mChlPd-N10+ (LC40e+), was prepared for applications in antibacterial photodynamic inactivation (aPDI) activity. It was selected to investigate its enhanced binding and targeting ability to the surface of Gram-positive MRSA cells. Subsequent antibacterial photodynamic therapeutic (aPDT) activity to inactivate MRSA was investigated to substantiate the corresponding cell-surface binding effect on the efficacy of aPDT. Results: We found that the covalent combination of 10 positive charges and an MRSA-targeting vancomycin (VCM) moiety in a conjugated structure, functioning as an antibiotic–decacationic photosensitizing agent (Abx-dcPS), was capable of largely improving the MRSA cell-targeting efficiency. Importantly, variation in the chain length of the oligo(ethylene glycol) linker of VCMe-mChlPd-N10+, which was sufficiently long enough to properly separate the photoactive mesochlorin ring moiety from the VCM moiety within the molecular structure, resulted in significantly enhanced aPDT activity. The new conjugate provided nearly complete eradication (>6.5-log10 colony-forming units (CFU) reduction) of MRSA cells in vitro. The aPDT efficacy followed the order Abx-dcPS (combinatorial decacationic) > dcPS (decacationic) >> nPS (nonionic). This order was also verified by the relative physical binding trend of these PSs using either nPS-, dcPS-, or Abx-dcPS-pretreated and pre-fixed MRSA cells in investigations of fluorescent confocal microscopy, UV–vis fluorescence spectroscopy, and transmission electron microscopy (TEM). Conclusions: Furthermore, the molecular conjugate of Abx-dcPS may provide covalent co-delivery of two drug components concurrently, which might also serve as an effective antibiotic agent after aPDT and potentially prevent the reoccurrence of MRSA-induced infection. Full article
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19 pages, 8475 KB  
Article
Synergistic Antimicrobial Effects of Baicalin Combined with Kanamycin Against MRSA: Underlying Mechanisms and Diminished Colonization on Lettuce
by Xin Meng, Zhiyun Yu, Chao Ning, Mingtong Sun, Mengna Kang and Haiyong Guo
Pharmaceuticals 2025, 18(10), 1458; https://doi.org/10.3390/ph18101458 - 28 Sep 2025
Abstract
Background: The treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections is extremely challenging due to its antibiotic resistance, and the combination of plant active ingredients with antibiotics represents a potential strategy to address this issue. Methods: We determined the combinatorial relationship between baicalin (BA) [...] Read more.
Background: The treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections is extremely challenging due to its antibiotic resistance, and the combination of plant active ingredients with antibiotics represents a potential strategy to address this issue. Methods: We determined the combinatorial relationship between baicalin (BA) and kanamycin (KM) using the checkerboard dilution method. The antibacterial activity of the baicalin–kanamycin (BA/KM) combination was evaluated through growth curve determination assays and scanning electron microscopy (SEM). The effects of the BA/KM combination on the cell membrane and cell wall of MRSA were analyzed using reactive oxygen species (ROS) detection assays, intracellular protein leakage experiments, alkaline phosphatase (AKP) activity assays, laser scanning confocal microscopy (LSCM) observations, and molecular docking simulations. The antibiofilm activity and related mechanisms of the BA/KM combination were elucidated via crystal violet staining, MTT assay, phenol-sulfuric acid method, congo red staining, staphyloxanthin determination assays, and quantitative real-time polymerase chain reaction (qPCR). The safety of the BA/KM combination was assessed through hemolytic activity analysis, and its anti-MRSA efficacy was evaluated on lettuce. Results: BA/KM combination showed a synergistic antibacterial effect on MRSA USA300. Mechanistic studies revealed that BA may interact with amino acid residues of peptidoglycan synthetase PBP2a to hinder peptidoglycan synthesis, thereby facilitating KM penetration through the cell wall. Subsequently, BA binds to amino acid residues of the membrane transporter NorA, leading to disruption of cell membrane homeostasis and enhancing KM’s ability to induce intracellular ROS accumulation in MRSA. Furthermore, the BA/KM combination reduced MRSA biofilm formation by 77.85% and decreased the metabolic activity of biofilm cells by 42.93% through inhibiting the synthesis of biofilm components EPS and PIA. Additionally, this combination suppressed the synthesis of staphyloxanthin and downregulated the expression of agrA and agrC genes. When 1/8 MIC BA was combined with 1/4 MIC KM, the count of MRSA on lettuce surfaces was reduced by 0.88 log CFU/cm2, an effect comparable to that of 0.2% (v/v) hydrogen peroxide. Conclusions: According to these findings, the BA/KM combination may offer a promising option for enhancing antibacterial efficacy through synergism, reducing antibiotic usage concentrations, and limiting MRSA transmission in fresh agricultural products. Full article
(This article belongs to the Section Biopharmaceuticals)
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