Search Results (196)

The widespread phase-out of long-chain per- and poly-fluoroalkyl substances (PFASs) has created an urgent need for durable, fluorine-free water-repellent finishes that match the performance of legacy chemistries while minimising environmental impact. Here, the performance of an eco-friendly hybrid organic–inorganic treatment obtained by the in situ hydrolysis–condensation of triethoxy(octyl)silane (OS) in an amino-terminated polydimethylsiloxane (APT-PDMS) aqueous dispersion was investigated. The sol was applied to plain-weave cotton and polyester by a pad-dry-cure process and benchmarked against a commercial fluorinated finish. Morphology and chemistry were characterised by SEM–EDS, ATR-FTIR, and Raman spectroscopy; wettability was assessed by static contact angle, ISO 4920 spray ratings, and AATCC 193 water/alcohol repellence; and durability, handle, and breathability were evaluated through repeated laundering, bending stiffness, and water-vapour transmission rate measurements. The silica/PDMS coating formed a uniform, strongly adherent nanostructured layer conferring static contact angles of 130° on cotton and 145° on polyester. After five ISO 105-C10 wash cycles, the treated fabrics still displayed a spray rating of 5/5 and AATCC 193 grade 7, outperforming or equalling the fluorinated control, while causing ≤5% loss of water-vapour permeability and only a marginal increase in bending stiffness. These results demonstrate that the proposed one-step, water-borne sol–gel process affords a sustainable, industrially scalable route to high-performance, durable, water-repellent finishes for both natural and synthetic textiles, offering a viable alternative to PFAS-based chemistry for outdoor apparel and technical applications. Full article

Cellulose acetate butyrate (CAB) and cellulose acetate propionate (CAP) are biobased materials that are insoluble in water and present a potential alternative to fossil-based plastics. Solvent removal-induced in situ matrices are gaining attention as an innovative dosage form for localized drug delivery for periodontitis therapy. This study aims to develop levofloxacin hemihydrate (Lh)-loaded in situ matrices formed through solvent removal, incorporating various molecular weights (MWs) and concentrations of CAB and CAP. Increased MWs and higher concentrations of these cellulosic esters significantly improved formulation viscosity and injection force, contributing to enhanced phase inversion and greater matrix toughness. Microscopic analysis of interfacial phase changes revealed progressive thickening of the matrix over time, which was influenced by polymer concentration and limited solvent movement. The transformed matrices with high MW CAP and elevated CAB content demonstrated prolonged drug release, predominantly following first-order kinetics, suggesting drug dissolution and diffusion through the scaffold structure. CAB-based in situ matrices containing 15% and 20% polymer exhibited low viscosities suitable for injection, along with optimal gel formation for maintaining their shape, and adhered effectively to periodontal pockets. These matrices provided extended Lh release for up to 120 h and inhibited the growth of periodontopathic bacteria for over 15 days. Therefore, the developed Lh-loaded in situ matrices show promise as an effective treatment for periodontitis, warranting further research to explore their therapeutic potential. Full article

Nasal drug delivery faces numerous challenges related to the ineffectiveness of most nasal formulations without a mucoadhesive nature, prolonging residence time on the nasal mucosa. Another challenge is the low administrable dosage strength, which can be solved via nano-encapsulation techniques, including the utilization of polymeric micelles. In this study, gellan gum–cellulose derivative complex in situ gelling matrices were formulated to test their effect on the colloidal characteristics of polymeric micelles, their respective rheological behavior, and nasal applicability. It has been proven that these complex matrices can form gels upon contact with nasal fluid without disrupting the micellar structure. Changes in the drug release and permeation profile have been shown in a concentration-dependent manner to hinder the burst-like drug release profile of polymeric micelles. Formulations show concentration- and composition-dependent mucoadhesive features under nasal conditions. Most of the hydrogels possess a soft gel characteristic, making them suitable for nasal administration. In conclusion, this descriptive study provides useful insights for conscious, nasal dosage form design. Full article

Long-acting injectable (LAI) formulations have revolutionized veterinary pharmaceuticals by improving patient compliance, minimizing dosage frequency, and improving therapeutic efficacy. These formulations utilize advanced drug delivery technologies, including microspheres, liposomes, oil solutions/suspensions, in situ-forming gels, and implants to achieve extended drug release. Biodegradable polymers such as poly(lactic-co-glycolic acid) (PLGA), and polycaprolactone (PCL) have been approved by the USFDA and are widely employed in the development of various LAIs, offering controlled drug release and minimizing the side effects. Various classes of veterinary medicines, including non-steroidal anti-inflammatory drugs (NSAIDs), antibiotics, and reproductive hormones, have been successfully formulated as LAIs. Some remarkable LAI products, such as ProHeart^® (moxidectin), Excede^® (ceftiofur), and POSILACTM (recombinant bovine somatotropin), show clinical relevance and commercial success. This review provides comprehensive information on the formulation strategies currently being used and the emerging technologies in LAIs for veterinary purposes. Additionally, challenges in characterization, in vitro testing, in vitro in vivo correlation (IVIVC), and safety concerns regarding biocompatibility are discussed, along with the prospects for next-generation LAIs. Continued advancement in the field of LAI in veterinary medicine is essential for improving animal health. Full article

New 3D printing aerogel materials are environmentally friendly and could be used in environmental protection and biomedical fields. There is significant research interest in 3D printing cellulose-based aerogels since cellulose materials are biocompatible and are abundant in nature. The gel-like nature of the cellulose water suspension is suitable for 3D printing; however, the complexity and resolution of the geometry of aerogels are quite limited, mainly due to the inks’ low viscosity that fails to maintain the integrity of the shape after printing. To address this limitation, a carefully optimized formulation incorporating three key ingredients, i.e., nanofibrils (TEMPO-CNFs), 2,2,6,6-tetramethyl-1-piperidinyloxy modified cellulose nanocrystals (TEMPO-CNC), and sodium carboxymethyl cellulose (CMC), is utilized to enhance the viscosity and structural stability of the ink. This combination of cellulose derivatives utilizes the electrostatic repulsive forces between the negatively charged components to form a stable and uniformly distributed suspension of cellulose materials. Our ink formulations improve printability and shape retention during 3D printing and are optimal for DIW printing. We print by employing an all cellulose-based composite ink using a modified direct ink writing (DIW) 3D printing method, plus an in situ freezing stage to form a layer-by-layer structure, and then follow a freeze-drying process to obtain the well-aligned aerogels. We have investigated the rheological properties of the ink formulation by varying the concentration of these three cellulose materials. The obtained aerogels exhibit highly ordered microstructures in which the micropores are well-aligned along the freezing direction. This study demonstrates a strategy for overcoming the challenges of 3D printing cellulose-based aerogels by formulating a stable composite ink, optimizing its rheological properties, and employing a modified DIW printing process with in situ freezing, resulting in highly ordered, structurally robust aerogels with aligned microporous architectures. Full article

Aqueous gel-casting provides a cost-effective and scalable approach for synthesizing nano-spherical Co₃O₄ powders, enabling precise control over particle morphology. In this study, Co₃O₄ powders were prepared using this method and evaluated as a catalyst precursor for the hydrolysis of sodium borohydride (NaBH₄). The effects of the monomer (acrylamide, AM)-to-metal molar ratio and initiator content (ammonium persulphate, APS) on particle size and catalytic performance were systematically explored. X-ray diffraction (XRD) analysis confirmed the formation of the Co₃O₄ phase at 400 °C, while transmission electron microscopy (TEM) images revealed particle sizes ranging from 16 to 85 nm, with higher AM and APS concentrations promoting finer particles. The optimized catalyst achieved a high hydrogen generation rate (HGR) of 28.13 L min⁻¹·cat.⁻¹, demonstrating excellent catalytic activity. Moreover, in situ-formed cobalt boride, derived from Co₃O₄ calcined at 600 °C for 2 h, exhibited an activation energy of 51.81 kJ mol⁻¹, comparable to Ru-based catalysts. This study underscores the aqueous gel-casting technique as a promising strategy for synthesizing efficient and low-cost hydrogen generation catalysts, offering an alternative to noble metal-based materials. Full article

Foam and hydrogel profile control are commonly utilized water-blocking and profile modification techniques in oil fields. This study integrates a foam system with a gel system, employing an organic titanium crosslinking agent to crosslink polyvinyl alcohol, thereby forming a gel system. Concurrently, a gas-evolving agent is incorporated into the system to induce in situ foaming, thereby creating an environmentally benign foam gel system. The fundamental constituents of this system comprise 2 wt% to 5 wt% polyvinyl alcohol, 2 wt% to 4 wt% crosslinker, and 0.3 wt% to 0.9 wt% gas-generating agent. By varying the amounts of each component, the strength grade, gelation time, and foaming volume of the foam gel can be effectively adjusted. The results of the temperature resistance performance evaluation indicate that within the temperature range of 80 °C to 130 °C, the gelation performance of the foam gel is stable and good. At 90 °C, the foam gel can remain stable for 340 days with minimal strength variation. The plugging experiments indicate that the formulated foam gel system exhibits superior injectability and can effectively seal the sand-filled tube model, achieving a blocking efficiency of up to 96.36%. Full article

Biodiesel was produced via transesterification of canola oil in the presence of a silica xerogel catalyst with deposited gold nanoparticles. The silica-gold catalyst was produced in situ, where gold metal was added to a sodium silicate solution; subsequently, gold nanoparticles were synthesised within the solution. The sodium silicate-gold nanoparticles solution was then turned into a silica-gold gel at pH 8.7 and later dried to form silica-gold nanoparticles xerogel. The produced silica-gold nanoparticles xerogel was characterised by X-ray diffraction (XRD), X-ray fluorescence (XRF), transition electron microscopy (TEM), and nitrogen physisorption. The gel had a silica content of 91.6 wt% and a sodium content of 6.4 wt%, with the added gold content being 99.5% retained. The biodiesel produced in the presence of silica-gold nanoparticles xerogel was characterised by gas chromatography-mass spectroscopy (GC-MS) and its physical properties, such as density, kinematic viscosity, flash point, pour point, and cloud point, were also determined. The silica-gold nanoparticles xerogel catalyst remained solid throughout its usage without leaching into the reaction medium. The produced biodiesel contained mostly monounsaturated fatty acid methyl esters and had a yield of 99.2% at optimum reaction conditions. Full article

The growing need for sustainable biotechnological solutions to address environmental challenges, such as climate change and resource depletion, has intensified interest in microbial-based production systems. Synthetic biofilms, which mimic natural microbial consortia, offer a promising platform for optimizing complex metabolic processes that can convert renewable feedstocks into valuable chemicals. In this context, understanding and harnessing the interactions between co-immobilized microorganisms are critical for advancing bioprocesses that contribute to circular bioeconomy goals. In this study, we investigated the viability and metabolic activity of Clostridium carboxidivorans and Clostridium kluyveri within a synthetic, dual-layered biofilm composed of agar hydrogel. This setup compartmentalized each bacterial species. Embedding the bacteria in a structured biofilm offers numerous opportunities for bioproduction, but the inability to monitor cell growth or movement within the immobilization matrix limits process insights. To address this, we adapted a fluorescence in situ hybridization (FISH) protocol, enabling precise, species-specific visualization of bacterial distribution and growth within the gel matrix. Batch processes with the dual-layered biofilm in anaerobic flasks, designed with a metabolic advantage for C. kluyveri, revealed distinct growth dynamics. C. kluyveri exhibited significant metabolic activity, forming clusters at low initial cell concentrations and converting ethanol and acetate into 1-butyrate and 1-hexanoate, indicating viability and cell growth. C. carboxidivorans remained evenly distributed without significant growth or product formation, suggesting that while the cells were viable, they were not metabolically active under the experimental conditions. Both bacterial species were confined to their respective compartments throughout the process, with C. kluyveri showing enhanced substrate conversion at higher initial cell densities in the hydrogel. The pH drop throughout the batch experiment likely contributed to incomplete substrate consumption, particularly for C. kluyveri, which thrives within a narrow pH range. These findings highlight synthetic biofilms as a promising platform for optimizing microbial interactions and improving bioprocess efficiency, especially in applications involving complex metabolic exchanges between co-immobilized microorganisms. Further research will focus on applying conditions to support the growth and metabolic activity of C. carboxidivorans to explore spatial dynamics of bacterial migration and cooperative relationships in the synthetic biofilm. Full article

Bioactive metal and metal oxide-based nanocomposite hydrogels exhibit significant antibacterial properties by interacting with microbial DNA and preventing bacterial replication. They offer potential applications as coating materials for human or animal skin injuries to prevent microbial growth and promote healing. In this study, silver nanoparticles (AgNPs) were synthesized using a chemical reduction method and incorporated into a polymer network to fabricate silver nanocomposite hydrogels (AgNCHGs) through a simple free radical polymerization method. N-isopropylacrylamide (NIPA), which has lower critical solution temperature (LCST) at about body temperature, or acrylamide (AAm) was used as the main monomer, while one or more ionic co-monomers, such as acrylic acid (AAc) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS), were incorporated to obtain AgNCHGs. AgNPs were introduced into the hydrogel network via three different approaches. In the first method, the synthesized hydrogel was immersed in a silver nitrate (AgNO₃) solution and reduced in situ using sodium borohydride (NaBH₄) as a reducing agent. The second method involved mixing AgNO₃ with gel precursors before reduction with NaBH₄ to form AgNPs within the hydrogel. The final approach synthesized the AgNCHGs directly in a dispersion of pre-fabricated AgNPs. The incorporation of AgNPs in different AgNCHGs was confirmed through various characterization techniques. Varying temperature and pH conditions can trigger the release of bioactive AgNPs from the hydrogels. Furthermore, the antimicrobial and wound-healing properties of the AgNCHGs were evaluated against bacteria and fungi, demonstrating their potential in biomedical applications. In addition, AgNCHGs exhibit excellent electrical conductivity. The electrical conductivity of the hydrogels can be finely tuned by adjusting the concentration of AgNPs, making these materials promising candidates for energy, sensor, and stretchable electronics applications. This study presents facile synthesis methods of AgNCHGs, which integrate bioactivity, wound healing, and electrical conductivity in the same matrix, addressing a significant challenge in designing multifunctional hydrogels for next-generation technologies. Full article

Efficient and sustainable catalytic processes are crucial for advancing green chemical manufacturing. Here, we describe the synthesis of novel silver artificial metalloenzymes in colloidal form in aqueous media and room temperature. The strategy is based on the in situ generation of silver nanoparticles by a genetically modified Geobacillus thermocatenulatus lipase (GTL) in the active site as an inducer and scaffold protein, producing an enzyme–Ag bioconjugate. Using a structural analysis of the formation of silver nanoparticles by XRD and UV spectra, we found the formation of Ag₂O species with nanoparticles of around 11 nm average diameter size. Gel filtration chromatography demonstrated the presence of single protein molecules in the bioconjugates, although silver nanoparticles were initially formed by cysteine coordination in the active site but later were formed in other parts of the protein (five AgNPs per molecules, which is in concordance with the UV size). The enzyme structure was altered after nanoparticle formation and Ag-S interaction, which was observed in fluorescence analysis. This new enzyme showed reductive activity against p-nitrophenol to p-amino and a high conversion > 99% in the reduction of acetophenone to phenylethanol, although the enantioselective was quite moderate but higher in water that in the presence of co-solvents. Finally, oxidase-like activity was evaluated in the direct oxidation of phenylethanol to acetophenone in water, obtained at around a 23% yield of ketone after 60 h. Full article

Cellulose acetate butyrate is a biodegradable cellulose ester bioplastic produced from plentiful natural plant-based resources. Solvent-exchange-induced in situ gels are particularly promising for periodontitis therapy, as this dosage form allows for the direct delivery of high concentrations of antimicrobial agents to the localized periodontal pocket. This study developed an in situ gel for periodontitis treatment, incorporating a combination of metronidazole and doxycycline hyclate, with cellulose acetate butyrate serving as the matrix-forming agent. Consequently, assessments were conducted on the physicochemical properties, gel formation, drug permeation, drug release, morphological topography, and antimicrobial activities of the formulation. The formulation demonstrated an increased slope characteristic of Newtonian flow at higher bioplastic concentrations. The adequate polymer concentration facilitated swift phase inversion, resulting in robust, solid-like matrices. The mechanical characteristics of the transformed in situ gel typically exhibit an upward trend as the polymer concentration increased. The utilization of sodium fluorescein and Nile red as fluorescent probes effectively tracked the interfacial solvent–aqueous movement during the phase inversion of in situ gels, confirming that the cellulose acetate butyrate matrix delayed the solvent exchange process. The initial burst release of metronidazole and doxycycline hyclate was minimized, achieving a sustained release profile over 7 days in in situ gels containing 25% and 40% cellulose acetate butyrate, primarily governed by a diffusion-controlled release mechanism. Metronidazole showed higher permeation through the porcine buccal membrane, while doxycycline hyclate exhibited greater tissue accumulation, both influenced by polymer concentration. The more highly concentrated polymeric in situ gel formed a uniformly porous structure. Metronidazole and doxycycline hyclate-loaded in situ gels showed synergistic antibacterial effects against S. aureus and P. gingivalis. Over time, the more highly concentrated polymeric in situ gel showed superior retention of antibacterial efficacy due to its denser cellulose acetate butyrate matrix, which modulated drug release and enhanced synergistic effects, making it a promising injectable treatment for periodontitis, particularly against P. gingivalis. Full article

The study investigates the development and characterization of dual-loaded niosomes incorporated into ion-sensitive in situ gel as a potential drug delivery platform for ophthalmic application. Cannabidiol (CBD) and epigallocatechin-3-gallate (EGCG) simultaneously loaded niosomes were prepared via the thin film hydration (TFH) method followed by pulsatile sonication and were subjected to comprehensive physicochemical evaluation. The optimal composition was included in a gellan gum-based in situ gel, and the antimicrobial activity, in vitro toxicity in a suitable corneal epithelial model (HaCaT cell line), and antioxidant potential of the hybrid system were further assessed. Dual-loaded niosomes based on Span 60, Tween 60, and cholesterol (3.5:3.5:3 mol/mol) were characterized by appropriate size (250 nm), high entrapment efficiency values for both compounds (85% for CBD and 50% for EGCG) and sustained release profiles. The developed hybrid in situ gel exhibited suitable rheological characteristics to enhance the residence time on the ocular surface. The conducted microbiological studies reveal superior inhibition of methicillin-resistant Staphylococcus aureus (MRSA) adhesion by means of the niosomal in situ gel compared to the blank gel and untreated control. Regarding the antioxidant potential, the dual loading of CBD and EGCG in niosomes enhances their protective properties, and the inclusion of niosomes in gel form preserves these effects. The obtained outcomes indicate the developed niosomal in situ gel as a promising drug delivery platform in ophthalmology. Full article

FmocFF (9-fluorenyl methoxycarbonyl-phenylalanine) is an extensively studied low-molecular-weight hydrogel. Although there have been numerous studies on FmocFF hydrogel, its potential to form organogels has not been well explored. In this work, we systematically explore the organogels of FmocFF in a wide range of organic solvents. FmocFF is found to be a robust organogeltor, and the subsequent organogels exhibit diverse gelmorphic behavior exhibiting various degrees of crystallinity and morphology depending on the solvent used. The mechanical strength of the organogels is evaluated using rheology. A novel technique, in situ SHG microscopy, is introduced to study the gel structure in its native state. In addition to the solvent–solute interactions that are typically used to predict gelmorphic behavior, we observed indications that the degree of crystallinity also plays a significant role in determining the mechanical properties and structure of FmocFF organogels. Full article

Hydrogels have emerged as promising biomaterials due to their excellent performance; however, their biocompatibility, biodegradability, and absorbability still require improvement to support a broader range of medical applications. This paper presents a new biofunctionalized hydrogel based on in situ crosslinking between maleimide-terminated four-arm-poly(ethylene glycol) (4–arm–PEG–Mal) and poly(ε-lysine) (ε–PL). The PEG/ε–PL hydrogels, named LG–n, were rapidly formed via amine/maleimide reaction by mixing 4–arm–PEG–Mal and ε–PL under physiological conditions. The corresponding dry gels (DLG–n) were obtained through a freeze-drying technique. ¹H NMR, FT–IR, and SEM were utilized to confirm the structures of 4–arm–PEG–Mal and LG–n (or DLG–n), and the effects of solid content on the physicochemical properties of the hydrogels were investigated. Although high solid content could increase the swelling ratio, all LG–n samples exhibited a low equilibrium swelling ratio of less than 30%. LG–7, which contained moderate solid content, exhibited optimal compression properties characterized by a compressive fracture strength of 45.2 kPa and a deformation of 69.5%. Compression cycle tests revealed that LG–n demonstrated good anti-fatigue performance. In vitro degradation studies confirmed the biodegradability of LG–n, with the degradation rate primarily governing the drug (ceftibuten) release efficiency, leading to a sustained release duration of four weeks. Cytotoxicity tests, cell survival morphology observation, live/dead assays, and hemolysis tests indicated that LG–n exhibited excellent cytocompatibility and low hemolysis rates (<5%). Furthermore, the broad-spectrum antibacterial activity of LG–n was verified by an inhibition zone method. In conclusion, the developed LG–n hydrogels hold promising applications in the medical field, particularly as drug sustained-release carriers and wound dressings. Full article