Search Results (254)

Although the effectiveness of plant-derived essential oils (EOs) against several insect pests is well-documented, their high volatility presents a challenge. In this study, the potential to enhance the insecticidal activity of Satureja hortensis L. EO, an accessible natural agent, through nanoemulsification was assessed against the cosmopolitan pest Spodoptera frugiperda (J. E. Smith, 1797). The nanoemulsion of the EO (NEEO) was prepared using Tween 80 as the emulsifying agent and high-intensity ultrasonication. Oral bioassays indicated that the NEEO was more toxic (LC₅₀ = 0.922%) than the pure EO (LC₅₀ = 1.186%). Sublethal exposure to LC₃₀ of the NEEO caused evident reductions in preadult survival, developmental time, fecundity, and oviposition period, as well as the population growth parameter net reproductive rate (R₀). The exposure to the NEEO increased catalase (CAT), glutathione S-transferase (GST), and superoxide dismutase (SOD) actions and inhibited α-esterase (α-NE), β-esterase (β-NE), and cytochrome P450 (CYP450) actions. Both the NEEO and EO inhibited acetylcholinesterase (AChE) and Na⁺/K⁺-ATPase, with higher inhibition in the NEEO group. Generally, S. hortensis NEEO enhanced toxicity, intensified physiological perturbations, and caused greater negative impacts on population growth parameters. Consequently, nanoemulsification of S. hortensis EO can be considered an effective method to strengthen the insecticidal potential of this natural agent. Full article

This study examines how olive oil acidity affects the stability of oil-in-water (O/W) nanoemulsions. Nanoemulsions were prepared using oils of 0.33, 4.67, and 12.66% w/w acidity, at 5, 10 and 15% v/v oil and 1.0, 1.5 and 2.0% v/v Tween-80, and stored for 120 h at 25 °C. High-acidity oil (12.66% w/w) produced the most stable systems, with conductivity reduced by ~40–60% compared to low-acidity oils (e.g., 31–52 μS/cm vs. 80–145 μS/cm at 10–15% oil). Viscosity ranged from 1.55 mPa·s at 0.33% w/w to 1.87 mPa·s at 12.66% w/w. The optimal formulation—12.66% w/w acidity, 5% v/v oil, and 1.0% v/v Tween-80—yielded the smallest and most stable droplets, with low PDI (~0.26) and high negative ζ-potential (−36 to −44 mV). These results indicate that elevated free fatty acids and endogenous amphiphilic compounds can act as co-surfactants, enhancing interfacial stabilization and improving nanoemulsion performance. Full article

Background/Objectives: The increasing resistance of Candida species to conventional antifungals, particularly azoles, poses a critical public health challenge due to high mortality rates associated with candidemia. This study aimed to describe the chemical composition of the essential oil from Haplopappus foliosus (EO-BAI) and evaluate its antifungal properties, along with its nanoemulsion (NE-BAI) and major constituents, against a panel of clinical Candida isolates. Methods: EO-BAI was extracted via steam distillation and analyzed using GC-MS. A nanoemulsion was synthesized through ultrasonic emulsification and characterized by DLS and microscopy (SEM/STEM). Antifungal activity (MIC/MFC) was determined following CLSI M27-A3 guidelines. Time–kill kinetic studies were conducted on C. albicans, and an in silico approach was used to describe interactions with Als9-2 and CYP51 targets. Results: The EO-BAI profile was dominated by terpinen-4-ol (27.27%) and α-bisabolol (10.40%). The NE-BAI exhibited a droplet size of approximately 22 nm with an encapsulation efficiency of 88.72%. Among the tested samples, α-bisabolol emerged as the core bioactive driver (MIC = 16 µg/mL against C. albicans). While NE-BAI showed reduced initial activity at 24 h, it demonstrated enhanced efficacy by 48 h, matching fluconazole’s potency and maintaining a definitive fungicidal effect. Docking analysis confirmed that α-bisabolol establishes stabilizing interactions with key virulence and membrane homeostasis targets. Conclusions: The NE-BAI provides a sustained delivery of its bioactive terpenes, preserving their fungicidal nature and positioning them as robust therapeutic alternatives to conventional treatments. Full article

The increasing demand for sustainable pest management has positioned essential oils (EOs) as viable bio-based alternatives to synthetic pesticides. This study investigates the insecticidal potential of Haplopappus foliosus EO, a Chilean endemic medicinal plant, against Drosophila melanogaster as a key toxicological model for fruit fly control. Chemical characterization identified 56 compounds, with 4-terpineol (27.27%) and α-bisabolol (10.40%) as the primary constituents, marking the first report of α-bisabolol in this species. To enhance bioavailability and overcome EO volatility, a nanoemulsion was developed, achieving an exceptionally small and stable particle size of 2.10 nm that remained consistent for over 90 days. Nanoencapsulation significantly optimized the EO’s efficacy, reducing the median lethal concentration (LC₅₀) from 120.26 µg/mL to a potent 54.57 µg/mL. While in vitro assays showed the free oil as a more potent acetylcholinesterase (AChE) inhibitor, molecular docking confirmed the high affinity of 4-terpineol and α-bisabolol for the enzyme’s active site, elucidating the neurotoxic mechanism at a molecular level. In silico analysis predicted a favorable human safety profile within GHS classes 4 and 5. Overall, this stable nanoformulation represents a sustainable biotechnological strategy for agricultural pest management, leveraging the synergistic effects and enhanced delivery of natural products. Full article

Stable nanoemulsions with fine droplets reduce organic solvent use and improve the dispersion of hydrophobic pesticide. However, current studies on deltamethrin nanoemulsion lack systematic formula optimization, performance evaluation and biosafety assessment. This study developed a stable deltamethrin nanoemulsion (Del@Ne) and tested its physicochemical properties, insecticidal activity and non-target safety. In 2025, the effects of surfactant ratio, dosage, preparation temperature and emulsification method on emulsion stability was systematically investigated. The optimal formula contained an active ingredient (2.5% deltamethrin), a surfactant ratio of 8:1 (#601:#500), a 6% surfactant dosage, a 17.25% oil phase (S-100:DMF = 20:3), and deionised water filled to 100%, prepared by adding deionised water to an oil phase containing deltamethrin and surfactants at 40 °C. Del@Ne exhibited small droplet size and good storage stability (TSI ≈ 1), which had better wettability on peach leaves with contact angle falling from 40.4° to 21.6° in 120 s. Del@Ne also gave higher toxicity against Myzus persicae (LC₅₀ = 66.85 mg L⁻¹) than Del@EC (80.69 mg L⁻¹), while showing lower toxicity to zebrafish, earthworms and Harmonia axyridis, as well as better biocompatibility with human L02 hepatocytes. These results provide references for rapid screening of nanoemulsion formulation parameters and also offer insights for the efficient utilization of hydrophobic pesticides. Full article

The growing demand for sustainable food preservation drives interest in edible nanoemulsions encapsulating bioactive compounds. This study developed casein–lecithin-based nanoemulsions combining carvacrol (CV)—a compound with potent antimicrobial and moderate antioxidant activity—with vitamin E (VitE)—a powerful antioxidant—as multifunctional food coatings. Three formulations were prepared via homogenization: NE-CV (2% CV), NE-VitE (2% VitE), and NE-CV/VitE (1% each). Physicochemical characterization revealed monomodal size distributions (22.7–57.7 nm), with successful encapsulation confirmed by FTIR. NE-CV/VitE exhibited intermediate particle size (34.4 nm) and zeta potential (−19.8 mV). Antioxidant activity followed NE-VitE > NE-CV/VitE > NE-CV, with the co-encapsulated system preserving VitE’s radical scavenging (EC₅₀ 10.76 µL/mL, DPPH). Remarkably, NE-CV/VitE demonstrated enhanced antibacterial activity against E. coli, requiring half the CV concentration (0.07 mg/mL) versus NE-CV alone (0.15 mg/mL), while maintaining CV dose-dependent activity against S. aureus (0.30 mg/mL). Nanoencapsulation significantly reduced CV cytotoxicity in human lymphocytes at concentrations up to 50 μg/mL (48.8% cytostasis vs. 58.9% for free CV), with no genotoxic effects observed within this range, while preserving full bioactivity. In fresh minced pork over 6-day refrigerated storage, NE-CV/VitE coating maintained pH stability (5.65–5.75), preserved red color (a* values 6.24 vs. 4.99 uncoated), reduced lipid oxidation (TBARS 0.74 vs. 0.82 mg MDA/kg), and achieved a 99% reduction (2-log) in total viable counts versus uncoated controls. The CV/VitE co-encapsulated nanoemulsion represents an integrated, safe, and effective multifunctional preservation technology with synergistic antimicrobial enhancement and uncompromised antioxidant protection, offering a natural alternative for comprehensive food quality preservation. Full article

The bioactive compounds in thyme essential oil (TEO) have been investigated as natural preservatives. However, their direct application in foods is limited by their poor water solubility and high volatility. In this context, nanoemulsions represent promising delivery systems for bioactive compounds due to their improved physicochemical stability and functional performance. This study aimed to develop and characterize TEO nanoemulsions prepared by ultrasound-assisted encapsulation using an ultrasonic probe and whey protein concentrate as a surfactant, with potential application in chicken burgers. Different sonication times (1, 3, 5, 7, and 10 min) were evaluated, and ultrasonication time was evaluated as the experimental variable. The formulation processed for 3 min presented the smallest hydrodynamic diameter (289 nm) and a homogeneous spherical morphology. The nanoemulsions showed low cytotoxicity, maintaining cell viability above 90% at all evaluated concentrations. In vitro antibacterial assays demonstrated activity against Staphylococcus aureus and antifungal effects against Aspergillus and Penicillium species. When applied to chicken burgers, the treatment containing 100 ppm of nanoencapsulated TEO contributed to reductions in S. aureus and mesophilic aerobic microorganism counts during 7 days of refrigerated storage. These findings indicate that TEO nanoemulsions present potential as natural antimicrobial systems for food preservation applications. Full article

Background/Objectives: Curcumin (CUR) has shown promising potential as a wound-healing agent for diabetic wounds; however, its efficacy is hindered by poor aqueous solubility and limited skin permeability. To overcome these limitations, CUR was loaded into myrrh oil-based nanoemulsions (NEs). Methods: The NEs were optimized using a three-factor two-level D-optimal mixture design, and characterized for droplet size, polydispersity index, and zeta potential. The optimized NE was subjected to various stability testing and incorporated into a gel base containing insulin (INS) to form CUR-INS nanoemulgel (CUR-INS-NEG). The antibacterial efficacy of CUR-INS-NEG was tested against various bacterial strains, while its wound-healing effects were evaluated in a diabetic rat wound model. Results: The surfactant/co-surfactant concentration had a greater influence on the NE properties than the oil and aqueous phase concentrations. The optimal NE had a droplet size of 155.2 ± 0.8 nm, a polydispersity index of 0.28, and a zeta potential of −31.4 ± 0.8 mV. It demonstrated sustained drug release, with further release control upon incorporation into the gel base. CUR-INS-NEG demonstrated higher in vitro antibacterial efficacy compared with blank NEG, CUR gel, and INS gel. It also showed 2- and 4-fold reduction in the MIC against S. aureus and E. coli, respectively, compared with CUR gel. In a diabetic wound model, CUR-INS-NEG outperformed both CUR gel and INS gel by enhancing anti-inflammatory and antioxidant effects, as well as collagen deposition and endothelial cell proliferation. Conclusions: The CUR-INS-NEG emerges as an effective system for diabetic wound management, delivering complementary anti-inflammatory, antioxidant, and tissue-regenerative effects of myrrh oil, CUR, and INS. Full article

Palm oil is a major agricultural commodity and an important economic driver in Asia. However, the sustainability and productivity of this crop are constantly threatened by a range of pathogenic fungi, especially Ganoderma boninense. Therefore, this study aimed to develop an eco-friendly hexaconazole-loaded nanoemulsion (Hexa-NE) for effective and targeted fungicide delivery while reducing environmental and health impacts. The optimized Hexa-NE formulation was evaluated for particle size, polydispersity index (PDI), zeta potential, pH, viscosity, and morphology using Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). Fungicide release, stability, and antifungal activity were conducted to assess the overall efficacy and performance of the formulation. The Hexa-NE exhibited particle size of 105.8 nm, a PDI of 0.358, a zeta potential of −53.53 mV. The formulation remained stable over three months of storage. It also demonstrated favourable physicochemical properties including low viscosity (30.24 mPa·s), low surface tension (23.87 mN/m), and suitable pH (6.14) for foliar application. TEM and SEM analyses confirmed spherical droplets and revealed significant hyphal damage to G. boninense. The antifungal test showed a higher inhibition of 97.1% at 0.1 µM of Hexa-NE as compared to hexaconazole solution which only 40% at the same concentration. Release studies exhibited a sustained release of hexaconazole, which may prolonged fungicidal activity. In conclusion, Hexa-NE showed promising laboratory-scale antifungal performance against G. boninense. These findings support its potential for further investigation as a nanoformulated fungicide for future greenhouse and field evaluations. Full article

Background/Objectives: This study aimed to evaluate the chemical composition and antimicrobial activity of Cordia verbenacea essential oil (EOCV) and to develop and characterize a gel-based nanoemulsion of C. verbenacea essential oil (NECV). Methods: The EOCV was chemically characterized by gas chromatography (GC-FID and GC-MS). The nanoemulsion was prepared using EOCV, the surfactants Cremophor and Plurol Oleique, and phosphate buffer at pH 5.5, and was subjected to experiments to determine its stability, irritant potential and in vitro skin permeation. Results: The main chemical compounds identified in EOCV were α-pinene (33.05%) and β-caryophyllene (25.11%). The EOCV exhibited antimicrobial activity with MIC and MBC values ranging from 6.3 to 25.0 µL/mL for the yeasts Candida albicans and C. krusei, 11.3 to 25.0 µL/mL for the Gram-positive bacteria Bacillus cereus, Staphylococcus aureus, and Enterococcus faecalis, and 12.5 to 75.0 µL/mL for the Gram-negative bacteria Acinetobacter baumannii, Klebsiella pneumoniae, and Escherichia coli. The NECV showed a droplet size of 126.80 nm, a polydispersity index (PDI) of 0.49, a zeta potential of −18.50 mV and a pH of 5.3 and remained stable for 60 days of storage at 25 °C and 4 °C. The HET-CAM irritation test showed that the formulation is non-irritating. The in vitro skin permeation assay showed that the NECV penetrated the deeper layers of the skin, demonstrating its ability to overcome the Stratum corneum barrier. Conclusions: These results are highly promising regarding the potential use of NECV for topical application for the treatment of infected skin wounds. Full article

Background/Objectives: Nanoemulsions (NEs) are a promising platform for transdermal drug delivery (TDD); however, how the polarity of the active pharmaceutical ingredient (API) influences NE structure–performance relationships remains insufficiently understood. This study aimed to systematically compare the transdermal delivery behavior of a hydrophilic API, salbutamol hemisulphate (log P ≈ 0.1), and a lipophilic API, ibuprofen (log P ≈ 3.3), incorporated into compositionally matched nanoemulsion systems. Methods: Kolliphor EL–based NEs were prepared using identical excipients, with systematic variation of oil, surfactant, and water ratios. Thirty-six formulations were produced for each API. Physical stability, droplet size, and viscosity were characterized, and in vitro skin permeation studies were conducted using excised mouse skin. Flux and cumulative permeation were quantified, and statistical analyses were performed to identify key compositional drivers of permeation. Results: Ibuprofen-containing NEs exhibited superior physical stability compared to salbutamol formulations, likely due to interfacial interactions that imparted surfactant-like behavior. Both APIs formed nanoscale droplets, with salbutamol formulations ranging from 16 to 507 nm and ibuprofen formulations spanning 12–563 nm, more frequently yielding sub-100 nm droplets. Viscosity values covered broad ranges (3–9532 mPa·s for salbutamol; 13.4–9759 mPa·s for ibuprofen), with salbutamol generating an extended high-viscosity domain at 50% (w/w) surfactant and ibuprofen showing a narrower viscosity maximum at 30–40% surfactant. Salbutamol NEs achieved high fluxes (up to 374 µg/cm²·h) and cumulative permeation of approximately 80% of the applied dose, whereas ibuprofen formulations showed markedly lower fluxes (maximum 32 µg/cm²·h) and cumulative permeation below 6%. High surfactant levels suppressed permeation for both APIs, but the dominant positive drivers differed: balanced oil–water ratios for salbutamol and hydration-dependent diffusional resistance for ibuprofen. Conclusions: These findings demonstrate that API polarity and interfacial portioning behavior decisively govern NE performance, providing a framework for rational tailoring of oil–surfactant–water ratios to maximize transdermal delivery efficiency. Full article

Oral administration of tocotrienol has poor systemic distribution due to poor selectivity by the α-tocopherol transfer protein at the liver. Local injection of tocotrienols with appropriate drug delivery systems is significant to ensure that the drug is delivered directly to the site of injury or fracture. This paper presents a tocotrienol-loaded gelatin hydrogel crosslinked with genipin for bone regeneration. This innovative method improves the incorporation and sustained delivery of tocotrienol while overcoming its incompatibility with hydrophilic biomaterials. It establishes a novel platform for targeted therapeutic applications in bone treatment. The cytotoxicity and physicochemical properties of tocotrienol were examined using the genipin-crosslinked gelatin hydrogel. A 10% tocotrienol nanoemulsion (TTE) was prepared using a sonicator and characterized with a zeta sizer and FTIR. A dose–response analysis was conducted to determine the appropriate tocotrienol concentration for hydrogel integration with gelatin (7% or 10% w/v) and crosslinked with genipin (0.1% or 0.3% w/v). The dose–response study’s tocotrienol nanoemulsion was added to gelatin before polymerization. With 141.9 nm particles and 0.150 PDI, the nanoemulsion was homogeneous and stable. The 1% tocotrienol nanoemulsion was chosen due to its viability. Formulations 1% TTE_0.1% GNP_7% GEL and 1%TTE_0.3% GNP_7% GEL had superior physicochemical properties compared to other groups. The 1% TTE_0.3% GNP_7% GEL had outstanding hydrophilicity, low weight loss, and a suitable swelling ratio for bone application. SEM scans of the surface and cross-section showed that 1% TTE_0. 3% GNP_7% GEL had interconnected pores with an optimal average pore size of 292 ± 37 μm. Adding tocotrienol to the gelatin hydrogel matrix did not affect FTIR, XRD, or EDX. In vitro cytotoxicity studies indicated >90% cell viability of hFOB 1.19 cells cultured on 1% TTE_0.1% GNP_7% GEL and 1% TTE_0.3% GNP_7% GEL (105 ± 4.36% and 95.36 ± 9.78%). Combining tocotrienol with a genipin-crosslinked gelatin hydrogel demonstrated superior physicochemical properties and no in vitro toxicity. Full article

Background/Objectives: Taiwan cinnamon leaves have been reported to be effective in improving chronic diseases. Herein, cinnamon leaf extract (CLE) and nanoemulsion (CLEN) were prepared to explore their effects in improving sexual dysfunction in rats. Methods: Following extraction with 80% ethanol and analysis by UPLC-MS/MS, CLEN was prepared using an optimal ratio of soybean oil, lecithin, Tween 80, deionized water, and CLE. A total of 48 male rats and 48 female rats were used, with the former being induced with erectile dysfunction, followed by treatment with CLEN or CLE at two doses (100 mg/kg and 50 mg/kg) for 4 weeks. After conducting the penile reflex test, male rats were paired with female rats for measurement of sexual behavior and ICP/MAP. Following sacrifice, α-SMA, nNOS, and β-III tubulin expression areas were measured by histochemical analyses; SMC/collagen ratio by Masson’s trichrome staining; and NO, cGMP, and PDE5 levels by ELISA kits. Results: CLEN was more effective than CLE in increasing intromission frequency, decreasing intromission and ejaculation latency, and recovering erectile response for improving copulatory and ejaculatory performances. A higher maximum ICP/MAP ratio was shown for CLEN through elevation of neurovascular function and erectile capacity. Additionally, CLEN efficiently reduced fibrosis, enhanced neuronal marker expression, and increased the SMC/collagen ratio, leading to penile tissue protection and neural regeneration. Both treatments showed elevated levels of NO and cGMP with a reduction in PDE5, probably through modulation of the NO-cGMP signaling pathway. Conclusions: CLEN was more effective than CLE in restoring erectile function in rats. Some more clinical trials are needed to verify this finding. Full article

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is an agricultural pest of global economic importance. Its ability to reproduce, adapt, and develop resistance necessitates the creation of effective and environmentally friendly alternative control strategies. This study aimed to evaluate the larvicidal activity of three nanoformulations (NFs) based on the essential oil (70% safrole) of Piper auritum Kunth (Piperales: Piperaceae), nanoemulsion (NE), microemulsion (ME), and silver nanoparticles (AgNPs), against second-instar larvae of S. frugiperda. The NFs were prepared using a combination of low- and high-energy methods, using Tween 80 and Span 80 as stabilizing agents. The droplet sizes of the NFs ranged from 19 to 48 nm. Stability analysis of the formulations maintained for 60 days in open systems at room temperature allowed the identification of remaining oxidized sesquiterpenes and phenylpropanoids. In in vitro bioassays, the NE demonstrated the highest larvicidal activity, with an LD₅₀ of 0.97 µg cm⁻², outperforming the other formulations by a factor of ten. Observations of morphological damage to larval and pupal tissues, along with deformation of adult specimens, confirming the toxicity of the NFs. These findings highlight the potential of essential oil-based NFs derived from P. auritum as sustainable biopesticides for integrated pest management. Full article

Background: Solid organ transplantation (SOT) is a life-saving treatment for patients with end-stage diseases and/or organ failure. However, access to healthy organs is often limited by challenges in organ preservation. Furthermore, upon transplantation, ischemia–reperfusion injury (IRI) can lead to increased organ rejection or graft failures. The work presented aims to address both challenges using an innovative nanomedicine platform for simultaneous drug and oxygen delivery. In recent studies, resveratrol (RSV), a natural antioxidant, anti-inflammatory, and reactive oxygen species (ROS) scavenging agent, has been reported to protect against IRI by inhibiting ferroptosis. Here, we report the design, development, and scalable manufacturing of the first-in-class dual-function perfluorocarbon-nanoemulsion (PFC-NE) perfusate for simultaneous oxygen and antioxidant delivery, equipped with a near-infrared fluorescence (NIRF) reporter, longitudinal, non-invasive NIRF imaging of perfusate flow through organs/tissues during machine perfusion. Methods: A Quality-by-Design (QbD)-guided optimization was used to formulate a triphasic PFC-NE with 30% w/v perfluorooctyl bromide (PFOB). Drug-free perfluorocarbon nanoemulsions (DF-NEs) and RSV-loaded nanoemulsions (RSV-NEs) were produced at 250–1000 mL scales using M110S, LM20, and M110P microfluidizers. Colloidal attributes, fluorescence stability, drug loading, and RSV release were evaluated using DLS, NIRF imaging, and HPLC, respectively. PFC-NE oxygen loading and release kinetics were evaluated during perfusion through the BMI OrganBank^® machine with the MEDOS HILITE^® oxygenator and by controlled flow of oxygen. The in vitro antioxidant activity of RSV-NE was measured using the oxygen radical scavenging antioxidant capacity (ORAC) assay. The cytotoxicity and ferroptosis inhibition of RSV-NE were evaluated in RAW 264.7 macrophages. Results: PFC-NE batches maintained a consistent droplet size (90–110 nm) and low polydispersity index (<0.3) across all scales, with high reproducibility and >80% PFOB loading. Both DF-NE and RSV-NE maintained colloidal and fluorescence stability under centrifugation, serum exposure at body temperature, filtration, 3-month storage, and oxygenation. Furthermore, RSV-NE showed high drug loading and sustained release (63.37 ± 2.48% at day 5) compared with the rapid release observed in free RSV solution. In perfusion studies, the oxygenation capacity of PFC-NE consistently exceeded that of University of Wisconsin (UW) solution and demonstrated stable, linear gas responsiveness across flow rates and FiO₂ (fraction of inspired oxygen) inputs. RSV-NE displayed strong antioxidant activity and concentration-dependent inhibition of free radicals. RSV-NE maintained higher cell viability and prevented RAS-selective lethal compound 3 (RSL3)-induced ferroptosis in murine macrophages (macrophage cell line RAW 264.7), compared to the free RSV solution. Morphological and functional protection against RSL3-induced ferroptosis was confirmed microscopically. Conclusions: This study establishes a robust and scalable PFC-NE platform integrating antioxidant and oxygen delivery, along with NIRF-based non-invasive live monitoring of organ perfusion during machine-supported preservation. These combined features position PFC-NE as a promising next-generation acellular perfusate for preventing IRI and improving graft viability during ex vivo machine perfusion. Full article