The biological and therapeutic assessment of a P(3HB-co-4HB)-bioactive glass-graphene composite biomaterial for tissue regeneration.

An ideal wound dressing should create a healing environment that relieves pain, protects against infections, maintains moisture, removes debris, and speeds up wound closure and repair. However, conventional options like gauze often fall short in fulfilling these requirements, especially for chronic or nonhealing wounds. Hence there is a critical need for inventive formulations that offer efficient, cost-effective, and eco-friendly alternatives. This study focuses on assessing the innovative formulation based on a microbial-derived copolymer known as poly(3-hydroxybutyrate-co-4-hydroxybutyrate), P(3HB-co-4HB) bioactive glass and graphene particles, and exploring their biological response in vitro and in vivo-to find the best combination that promotes cell adhesion and enhances wound healing. The formulation optimized at concentration of bioactive glass (1 w/w%) and graphene (0.01 w/w%) showed accelerated degradation and enhanced blood vessel formation. Meanwhile biocompatibility was evaluated using murine osteoblasts, human dermal fibroblasts, and standard cell culture assays, demonstrating no adverse effects after 7 days of culture and well-regulated inflammatory kinetics. Whole thickness skin defect using mice indicated the feasibility of the biocomposites for a faster wound closure and reduced inflammation. Overall, this biocomposite appears promising as an ideal wound dressing material and positively influencing wound healing rates.

Development and physiochemical assessment of graphene-bioactive glass-P(3HB-co-4HB) composite scaffold as prospect biomaterial for wound healing.

The clinical management of wounds presents a considerable challenge because dressing selection must prioritise the provision of appropriate barrier and the healing properties, consider patient's compliance factors such as comfort, functionality and practicality. This study primarily aimed to develop a composite scaffold patch for potential application in wound healing. Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] is a biopolymer that originated from bacteria. It is well-recognised owing to its distinctive mechanical and physical characteristics suitable for biomedical applications. Graphene (G) and bioactive glass (BG) are biocompatible towards humans, and enhanced properties are achievable by adding biopolymer. In this study, composite scaffolds were developed by combining P(3HB-co-4HB) at a distinct proportion of 4HB monomer reinforced with G (3.0 wt.%) and BG (2.5 wt.%) by using solvent casting, resulting in two types of composite scaffolds: P(3HB-co-25%4HB)/G/BG and P(3HB-co-37%4HB)/G/BG. A successful composite scaffold as a unified structure was achieved based on chemical assessments of organic and inorganic elements within the composites. The pure polymer displayed a smooth surface, and the BG and G addition into the composite scaffolds increased surface roughness, forming irregular pores and protuberances. The wettability and hydrophilicity of the composites significantly improved up to 40% in terms of water uptake. An increment in crystallisation temperature diminished the flexibility of the composite's scaffolds. Evaluation of Presto Blue biocompatibility demonstrated nontoxic behaviour with a dosage of less than 25.00 mg ml-1of composite scaffold-conditioned media. The L929 fibroblast cells displayed excellent adhesion to both types of composite scaffolds, as evidenced by the increased percentage of cell viability observed throughout 14 d of exposure. These findings demonstrate the importance of optimising each component within the composite scaffolds and their interrelation, paving the way for excellent material properties and enhancing the potential for wound healing applications.

Characterization, hazard identification, and risk assessment of volatile organic compounds in Poly(butylene adipate-co-terephthalate)-based food contact articles.

The chemical safety of poly (butylene adipate-co-terephthalate) (PBAT) based food contact articles (FCAs) has aroused increasing toxicological concerns in recent years, but the chemical characterization and associated risk assessment still remain inadequate as it fails to elucidate the distribution pattern and discern the potential genotoxic and carcinogenic hazards of the identified substances. Herein, the volatile organic compounds (VOCs) in 50 batches of PBAT-based FCAs of representative categories and 10 batches of PLA and PBAT pellets were characterized, by which 237 VOCs of 10 chemical categories were identified and exhibited characteristic distribution patterns in the chemical spaces derived from their molecular descriptors. Chemical hazards associated with the identified VOCs were discerned by a hazard-driven classification scheme integrating hazard-related knowledge from multiple publicly available sources, and 34 VOCs were found to bear genotoxic or carcinogenic hazards and to feature higher average molecular weight than the other VOCs. Finally, the Risk and hazard quotient (HQ) calculated as the metrics of risk suggested that all identified VOCs posed acceptable risks (Risk<10-4 or HQ < 1), whereas oxolane, butyrolactone, N,N-dimethylacetamide, 2-butoxyethanol, benzyl alcohol, and 1,2,3-trichloropropane posed non-negligible (Risk>10-6) genotoxic or carcinogenic risk and thus should be of prioritized concern to promote the chemical safety of PBAT-based FCAs.

Use of sustainable packaging materials for fresh beef vacuum packaging application and product assessment using physicochemical means.

Packaging material should guarantee the longest possible shelf life of food and help to maintain its quality. The aim of the study was to assess the physicochemical changes taking place during 28-day ageing of beef steaks packed in two types of multilayer films containing biodegradable polymers - polylactic acid (NAT/PLA) and Mater-Bi® (NAT/MBI). The control group consisted of steaks packed in synthetic polyamide/polyethylene (PA/PE) film. The samples stored in NAT/PLA had significantly lower purge loss than the control samples and the lowest expressible water amount after 14 and 21 days. Following blooming, the most favourable colour was shown in steaks stored in NAT/MBI, with the highest values for the L*, a* and C* parameters and the R630/580 ratio, a high proportion of oxymyoglobin, and the lowest share of metmyoglobin. All steaks, regardless of the type of packaging material, had acceptable tenderness and were stable in terms of lipid oxidation.

Design, clinical applications and post-surgical assessment of bioresorbable 3D-printed craniofacial composite implants.

This study details the design, fabrication, clinical trials' evaluation, and analysis after the clinical application of 3D-printed bone reconstruction implants made of nHAp@PLDLLA [nanohydroxyapatite@poly(L-lactide-co-D,L-lactide)] biomaterial. The 3D-printed formulations have been tested as bone reconstruction Cranioimplants in 3 different medical cases, including frontal lobe, mandibular bone, and cleft palate reconstructions. Replacing one of the implants after 6 months provided a unique opportunity to evaluate the post-surgical implant obtained from a human patient. This allowed us to quantify physicochemical changes and develop a spatial map of osseointegration and material degradation kinetics as a function of specific locations. To the best of our knowledge, hydrolytic degradation and variability in the physicochemical and mechanical properties of the biomimetic, 3D-printed implants have not been quantified in the literature after permanent placement in the human body. Such analysis has revealed the constantly changing properties of the implant, which should be considered to optimize the design of patient-specific bone substitutes. Moreover, it has been proven that the obtained composition can produce biomimetic, bioresorbable and bone-forming alloplastic substitutes tailored to each patient, allowing for shorter surgery times and faster patient recovery than currently available methods.

In vitro assessment of Momordica charantia/Hypericum perforatum oils loaded PCL/Collagen fibers: Novel scaffold for tissue engineering.

The research on tissue engineering applications has been progressing to manufacture ideal tissue scaffold biomaterials. In this study, a double-layered electrospun biofiber scaffold biomaterial including Polycaprolactone (PCL)/Collagen (COL) fibrous inner layer and PCL/ Momordica charantia (MC) and Hypericum perforatum (HP) oils fibrous outer layer was developed to manufacture a functional, novel tissue scaffold with the advantageous mechanical and biological properties. The main approach was to combine the natural perspective using medicinal oils with an engineering point of view to fabricate a potential functional scaffold for tissue engineering. Medicinal plants MC and HP are rich in functional oils and incorporation of them in a tissue scaffold will unveil their potential to augment both new tissue formation and wound healing. In this study, a novel double-layered scaffold prototype was fabricated using electrospinning technique with two PCL fiber layers, first is composed of collagen, and second is composed of oils extracted from medicinal plants. Initially, the composition of plant oils was analyzed. Thereafter the biofiber scaffold layers were fabricated and were evaluated in terms of morphology, physicochemistry, thermal and mechanical features, wettability, in vitro bio-degradability. Double-layered scaffold prototype was further analyzed in terms of in vitro biocompatibility and antibacterial effect. The medicinal oils blend provided antioxidant and antibacterial properties to the novel PCL/Oils layer. The results signify that inner PCL/COL layer exhibited advanced biodegradability of 8.5% compared to PCL and enhanced wettability with 11.7° contact angle. Strength of scaffold prototype was 5.98 N/mm2 thanks to the elastic PCL fibrous matrix. The double-layered functional biofiber scaffold enabled 92% viability after 72 h contact with fibroblast cells and furthermore provided feasible attachment sites for the cells. The functional scaffold prototype's noteworthy mechanical, chemical, and biological features enable it to be suggested as a different novel biomaterial with the potential to be utilized in tissue engineering applications.

Identification of non-volatile non-intentionally added substances from polyester food contact coatings and genotoxicity assessment of polyester coating's migrates.

Can's polyester coatings are intended to replace epoxy-phenolic ones due to rising safety concern regarding the potential release of bisphenol A under increased regulations and consumer pressure. In this study, hazard linked to the migration of non-intentionally added substances from a single polyester-coated tin plate (5 batches) to canned food has been studied. Migration tests were performed using acetonitrile (ACN) and ethanol (EtOH) 95 %. Non-targeted analyses by liquid chromatography-high-resolution mass spectrometry revealed the presence of four cyclic oligoesters classified as Cramer class III substances with an estimated exposure (calculated for French population only) below the threshold of toxicological concern value of 1.5 µg/kg b.w./day, suggesting a no safety concern. Moreover, migrates were tested using in vitro genotoxicity DNA damage response (DDR) test and mini mutagenicity test (MMT) with different strains of S. Typhimurium using direct incorporation (TA100, TA98, TA102, TA1537) and pre-incubation (TA100, TA98) methods. Samples were negative in both bioassays suggesting the absence of genotoxicity/mutagenicity of the mixtures. To verify any false negative response due to matrix effect, migrates were spiked with corresponding positive controls in parallel with the MMT and the DDR test. No matrix effect was observed in these experimental conditions.

Bioactive and Hemocompatible PLA/Lignin Bio-Composites: Assessment of In Vitro Antioxidant Activity for Biomedical Applications.

In this study, acetylated soda lignin (ASL) and non-acetylated soda lignin (SL) were extruded with PLA in different concentrations to fabricate antioxidant polylactic acid (PLA)/lignin composites for potential biomedical applications. After lignin acetylation, good compatibility was observed between PLA and lignin in scanning electron microscopy images. All the PLA/ASL composites displayed higher mechanical properties than PLA/SL composites. PLA/ASL5 displayed the highest mechanical characteristics with elongation at break of 10% and tensile strength of 57 MPa, while PLA/SL15 and PLA/SL20 demonstrated superior UV-blocking potential with UV transmittance less than 10%. Addition of ASL in PLA lead to an increase in the hydrophobic character, with all the PLA/ASL displaying a higher water contact angle. The antioxidant test using 2,2-diphenyl-1-picrylhydrazyl assay showed that PLA/SL composites rendered superior radical scavenging activity (RSA), with PLA/SL20 composites displaying an RSA of 80%. Furthermore, in vitro antioxidant activity and cytocompatibility were analyzed using human colon cancer cells (HCT-15) and gastric epithelial cells (NCC-24). In vitro antioxidant activity, evaluated by H2O2 exposure was confirmed by a live/dead assay. PLA/SL composites protected both types of cells from oxidative stress. In addition, all PLA/SL and PLA/ASL composites promoted cell proliferation compared to PLA. PLA/SL5 and PLA/SL10 displayed the highest cell proliferation of all composites. Lastly, all PLA/SL and PLA/ASL composites had a hemoglobin release less than 2%. The antioxidant properties, cytocompatibility, and hemocompatibility of lignin/PLA demonstrated in our study indicate that these lignin/PLA composites possess the desirable attributes for potential biomedical applications.

Cost-effective protocol to produce 3D-printed electrochemical devices using a 3D pen and lab-made filaments to ciprofloxacin sensing.

A novel conductive filament based on graphite (Gr) dispersed in polylactic acid polymer matrix (PLA) is described to produce 3D-electrochemical devices (Gr/PLA). This conductive filament was used to additively manufacture electrochemical sensors using the 3D pen. Thermogravimetric analysis confirmed that Gr was successfully incorporated into PLA, achieving a composite material (40:60% w/w, Gr and PLA, respectively), while Raman and scanning electron microscopy revealed the presence of defects and a high porosity on the electrode surface, which contributes to improved electrochemical performance. The 3D-printed Gr/PLA electrode provided a more favorable charge transfer (335 Ω) than the conventional glassy carbon (1277 Ω) and 3D-printed Proto-pasta® (3750 Ω) electrodes. As a proof of concept, the ciprofloxacin antibiotic, a species of multiple interest, was selected as a model molecule. Thus, a square wave voltammetry (SWV) method was proposed in the potential range + 0.9 to + 1.3 V (vs Ag|AgCl|KCl(sat)), which provided a wide linear working range (2 to 32 µmol L-1), 1.79 µmol L-1 limit of detection (LOD), suitable precision (RSD < 7.9%), and recovery values from 94 to 109% when applied to pharmaceutical and milk samples. Additionally, the sensor is free from the interference of other antibiotics routinely employed in veterinary practices. This device is disposable, cost-effective, feasibly produced in financially limited laboratories, and consequently promising for evaluation of other antibiotic species in routine applications.

Effect of poly (ethylene glycol) on 3D printed PLA/PEG blend: A study of physical, mechanical characterization and printability assessment.

The growing popularity of additive manufacturing in the science, industry is associated with high-quality products for futuristic applications. This study presents an in-depth characterization and analysis of the effect of poly (ethylene glycol) (PEG) having molecular weight 6000 g/mol used with various concentrations (1%,3%,5%) to modify the 3D printed Polylactide (PLA) part. The influence of PEG on the morphology, structure, thermal, wettability and mechanical properties of the 3D-printed PLA/PEG part was investigated. Herein, the mechanical property of injection moulding, 3D printed specimens, and finite element analysis (FEA) simulation results were also compared. The structure and properties of PLA/PEG blends were different from those of virgin PLA. By DSC analysis, it was found that the glass transition temperature (Tg) and cold crystallization temperature decreased in the case of the PLA/PEG blend. From TGA it was observed that PLA/PEG blend was thermally stable. It was shown that with the addition of PEG into PLA the tensile strength and young's modulus decrease, whereas elongation percentage and impact strength increase predominantly. The contact angle results indicate that the addition of PEG lowers the contact angle value of the PLA/PEG blend (from 69.32 ± 1.4° to 45.67 ± 1.2°) and increases surface wettability. With 5% PEG loading, PLA/PEG blend showed optimum structural and mechanical properties together with simple processibility.

Appraising co-composting efficiency of biodegradable plastic bags and food wastes: Assessment microplastics morphology, greenhouse gas emissions, and changes in microbial community.

Biodegradable plastic bags (BPBs) to collect food waste and microplastics (MPs) produced from their biodegradation have received considerable scientific attention recently. Therefore, the current study was carried out to assess the co-composting efficiency of biodegradable plastic bags (polylactic acid (PLA) + polybutylene terephthalate (PBAT) + ST20 and PLA + PBAT+MD25) and food waste. The variations in greenhouse gas (GHG) emissions, microbial community and compost fertility were likewise assessed. Compared with the control, PLA + PBAT+ST20 and PLA + PBAT+MD25 both accelerated organic matter degradation and increased temperature. Moreover, PLA + PBAT+ST20 aggravated CH4 and CO2 emissions by 12.10 % and 11.01 %, respectively. PLA + PBAT+MD25 decreased CH4 and CO2 emissions by 5.50 % and 9.12 %, respectively. Meanwhile, compared with PLA + PBAT+ST20, the combined effect of plasticizer and inorganic additive in PLA + PBAT+MD25, reduced the NO3--N contents, seed germination index (GI) and compost maturity. Furthermore, adding BPBs changed the richness and diversity of the bacterial community (Firmicutes, Proteobacteria and Bacteroidetes). Likewise, redundancy analysis (RDA) showed that the co-compost system of BPBs and food waste accelerated significantly bacterial community succession from Firmicutes and Bacteroidetes at the initial stage to Proteobacteria and Actinobacteria at the mature stage, increased co-compost temperature to over 64 °C and extended thermophilic composting phase, and promoted the degradation of MPs. Additionally, according to structural equation model quantification results, the inorganic additive of PLA + PBAT+MD25 had more serious toxicity to microorganisms and had significantly adverse effects on GI through CO2-C (λ = -0.415, p < 0.05) and NO3--N (λ = -0.558, p < 0.001), thus reduced compost fertility and quality. The results also indicated that the BPBs with ST20 as an additive could be more suitable for industrial composting than the BPBs with MD25 as an additive. This study provided a vital basis for understanding the potential environmental and human health risks of the MPs' generated by the degradation of BPBs in compost.

Cost effective media optimization for PHB production by Bacillus badius MTCC 13004 using the statistical approach.

Polyhydroxybutyrate (PHB) has significant potential for replacing non-biodegradable traditional plastic, which is responsible for several global environmental issues. The main problem with switching to bio-based alternatives for petrochemical plastics is the large price gap on the market. To overcome this problem, the present research was focused on the utilization of inexpensive substrates i.e. agricultural residues for cost-effective PHB production by endospore-forming bacteria Bacillus badius MTCC 13004. For efficient PHB production, Box-Behnken Design (BBD) was selected for media optimization and to observe the interactive effects of four variables i.e. pH, Na acetate, Banana peel, and mustard cake. PHB yield of 2.11 g/L was attained under optimized conditions compared to non-optimized conditions (0.72 g/L). FTIR spectra analysis of PHB extracted from Bacillus badius was found to be similar to commercial PHB. NMR data was also matched with the chemical shift signals CH, CH2, and CH3 of PHB. The melting temperature (Tm) and glass transition temperature (Tg) of PHB from Bacillus badius was found to be 165.14 and 2.68 °C, respectively. Further, PCR protocol was also designed to amplify key enzymes of the PHB synthesis pathway i.e. PHB synthase (phb C gene).

Bioactive and Physico-Chemical Assessment of Innovative Poly(lactic acid)-Based Biocomposites Containing Sage, Coconut Oil, and Modified Nanoclay.

The bioactivity of the versatile biodegradable biopolymer poly(lactic acid) (PLA) can be obtained by combining it with natural or synthetic compounds. This paper deals with the preparation of bioactive formulations involving the melt processing of PLA loaded with a medicinal plant (sage) and an edible oil (coconut oil), together with an organomodifed montmorillonite nanoclay, and an assessment of the resulting structural, surface, morphological, mechanical, and biological properties of the biocomposites. By modulating the components, the prepared biocomposites show flexibility, both antioxidant and antimicrobial activity, as well as a high degree of cytocompatibility, being capable to induce the cell adherence and proliferation on their surface. Overall, the obtained results suggest that the developed PLA-based biocomposites could potentially be used as bioactive materials in medical applications.

Preparation, Characterization, and Wound Healing Assessment of Curcumin-Loaded M-MOF (M = Cu, Zn)@Polycaprolactone Nanocomposite Sponges.

The fabrication of multifunctional scaffolds has attracted much attention in biological fields. In this research, some novel composites of Cu(II) or Zn(II) metal-organic framework (M-MOF) and polycaprolactone (PCL), M-MOF@PCL, have been fabricated as multifunctional scaffolds for application in the tissue engineering (TE) field. The porous three-dimensional sponges were prepared by the salt leaching method. Then, the M-MOF@PCL composite sponges have been prepared by in situ synthesis of M-MOF in the presence of the as-obtained PCL sponge to gain a new compound with proper features for biological applications. Finally, curcumin was attached to the M-MOF@PCL as a bioactive compound that can act as a wound-healing agent, anti-oxidant, and anti-inflammatory. The presence of the M-MOF in final composites was investigated by different methods such as FTIR (Fourier-transform infrared), XRD (X-ray diffraction), SEM (scanning electron microscope), EDS (energy-dispersive X-ray spectroscopy), and TEM (transmission electron microscope). SEM images confirmed the porous structure of the as-obtained composites. According to the EDS and TEM images, M-MOFs were uniformly incorporated throughout the PCL sponges. The water sorption capacities of the blank PCL, Cu-MOF@PCL, and Zn-MOF@PCL were determined as 56%, 155%, and 119%, respectively. In vivo investigation on a third-degree burn model in adult male Wistar rats exhibited an accelerated wound healing for Cu-MOF@PCL compared to with Zn-MOF@PCL and the control group.

Assessment of the structures contribution (crystalline and mesophases) and mechanical properties of polycaprolactone/pluronic blends.

Films of biodegradable blends of polycaprolactone (PCL) and Pluronics F68 and F127 were manufactured by an industrial thermo-mechanical process to be applied as potential delivery systems. The effects of Pluronics on the structure (mesophase organization), and thermal and mechanical properties of polycaprolactone were investigated using differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), polarized optical microscopy (POM) and tensile mechanical tests. The addition of Pluronics affected the crystallization process by changing the relative amounts of crystalline, amorphous, and meso- (condis + plastic) phases. The melting transition and XRD profiles were deconvoluted to assess the individual contribution of the different crystal morphologies. Furthermore, it was found that the mechanical properties of the blends depended on the ratio and type of Pluronic. Thus, Pluronic F127 showed a larger mesophase content than its F68 counterpart with PCL and blends with enhanced ductility.

Dynamic Monte Carlo Simulations of Strain-Induced Crystallization in Multiblock Copolymers: Effects of Asymmetric Block Rigidity.

Thermoplastic elastomers such as polyether-b-polyamides (or -polyesters), polyurethanes (or with -urea) and olefin block copolymers are commonly processed through a stretching process for achieving high elasticity and high toughness in their products, while the size diversity of semicrystalline microdomains of hard blocks appears as the key factor. By means of dynamic Monte Carlo simulations of strain-induced crystallization of locally concentrated and diluted crystallizable blocks alternatingly connected with noncrystallizable blocks in diblock and tetrablock copolymers, we have studied the size diversity of semicrystalline microdomains presumably raised by local concentration fluctuations of crystallizable blocks and found the dilution effects to persist from diblock to tetrablock copolymers. In the present work, we continued to study the effects of asymmetric block rigidity between crystallizable and noncrystallizable blocks on strain-induced crystallization of concentrated and diluted crystallizable blocks in diblock copolymers. The results showed that when crystallizable blocks hold higher thermodynamic rigidity than noncrystallizable blocks, the large semicrystalline domains become larger and the small semicrystalline domains become more, enhancing their size diversity. However, asymmetric kinetic rigidity has little effect. Our observations imply that industrial stretching processing could enhance the toughness of semicrystalline thermoplastic elastomers when their crystallizable blocks hold a higher thermodynamic rigidity relative to noncrystallizable blocks. Our integrated approach paved the way for a better understanding of the structure-property relationship in thermoplastic elastomers.

Biocompatibility Assessment of Polylactic Acid (PLA) and Nanobioglass (n-BG) Nanocomposites for Biomedical Applications.

Scaffolds based on biopolymers and nanomaterials with appropriate mechanical properties and high biocompatibility are desirable in tissue engineering. Therefore, polylactic acid (PLA) nanocomposites were prepared with ceramic nanobioglass (PLA/n-BGs) at 5 and 10 wt.%. Bioglass nanoparticles (n-BGs) were prepared using a sol-gel methodology with a size of ca. 24.87 ± 6.26 nm. In addition, they showed the ability to inhibit bacteria such as Escherichia coli (ATCC 11775), Vibrio parahaemolyticus (ATCC 17802), Staphylococcus aureus subsp. aureus (ATCC 55804), and Bacillus cereus (ATCC 13061) at concentrations of 20 w/v%. The analysis of the nanocomposite microstructures exhibited a heterogeneous sponge-like morphology. The mechanical properties showed that the addition of 5 wt.% n-BG increased the elastic modulus of PLA by ca. 91.3% (from 1.49 ± 0.44 to 2.85 ± 0.99 MPa) and influenced the resorption capacity, as shown by histological analyses in biomodels. The incorporation of n-BGs decreased the PLA crystallinity (from 7.1% to 4.98%) and increased the glass transition temperature (Tg) from 53 °C to 63 °C. In addition, the n-BGs increased the thermal stability due to the nanoparticle's intercalation between the polymeric chains and the reduction in their movement. The histological implantation of the nanocomposites and the cell viability with HeLa cells higher than 80% demonstrated their biocompatibility character with a greater resorption capacity than PLA. These results show the potential of PLA/n-BGs nanocomposites for biomedical applications, especially for long healing processes such as bone tissue repair and avoiding microbial contamination.

Fabrication of heparinized small diameter TPU/PCL bi-layered artificial blood vessels and in vivo assessment in a rabbit carotid artery replacement model.

Increasingly growing problems in vascular access for long-term hemodialysis lead to a considerable demand for synthetic small diameter vascular prostheses, which usually suffer from some drawbacks and are associated to high failure rates. Incorporating the concept of in situ tissue engineering (TE) into synthetic small diameter blood vessels, for example, thermoplastic poly(ether urethane) (TPU) ones, could provide an alternative approach for vascular access that profits from the advantages of excellent mechanical properties of synthetic polymer materials (early cannulation) and unique biointegration regeneration of autologous neovascular tissues (long-term fistulae). In this study, a kind of heparinized small diameter (d = 2.5 mm) TPU/poly(ε-caprolactone) (TPU/PCL-Hep) bi-layered blood vessels was electrospun with an inner layer of PCL and an outer layer of TPU. Afterward, the inner surface heparinization was conducted by coupling H2N-PEG-NH2 to the corroded PCL layer and then heparin to the attached H2N-PEG-NH2 via the EDCI/NHS chemistry. Herein a heparinized PCL inner layer could not only inhibit thrombosis, but also provide sufficient space for the neotissue regeneration via biodegradation with time. Meanwhile, a TPU outer layer could confer the vascular access the good mechanical properties, such as flexibility, viability and fitness of elasticity between the grafts and host blood vessels as evidenced by the adequate mechanical properties, such as compliance (4.43 ± 0.07%/ 100 mmHg), burst pressure (1447 ± 127 mmHg) and suture retention strength (1.26 ± 0.07 N) without blood seepage after implantation. Furthermore, a rabbit carotid aortic replacement model for 5 months was demonstrated 100% animal survival and 86% graft patency. Puncture assay also revealed the puncture resistance and self-sealing (hemostatic time < 2 min). Histological analysis highlighted neotissue regeneration, host cell infiltration and graft remodeling in terms of extracellular matrix turnover. Altogether, these results showed promising aspects of small diameter TPU/PCL-Hep bi-layered grafts for hemodialytic vascular access applications.

Structural assessment of the bioplastic (poly-3-hydroxybutyrate) produced by Bacillus flexus Azu-A2 through cheese whey valorization.

The demand for the production of biodegradable plastics has significantly increased. Bioplastics have become an essential alternative to the threats of the daily consumable plastics, sourced from fossil fuels, to the environment. Polyhydroxyalkonates (PHAs) are a ubiquitous group of bioderived and biodegradable plastics, however their production is limited by the costs associated mainly with the carbon sources. Herein, this study aims to reduce the PHAs production cost by using a by-product from the dairy industry, i.e., cheese whey (CW), as a sole carbon source. The developed process recruits an aquatic isolate, Bacillus flexus Azu-A2, and is optimized via studying various parameters using the shaking flasks technique. The results showed that the maximum PHA production (0.95 g L-1) and PHA content (20.96%, w/w), were obtained after incubation period 72 h at 45 °C, 100 rpm agitation rate, 50% CWS concentration, pH 8.5, and 1.0 g L-1 ammonium chloride. Physiochemically, Fourier transform infrared spectroscopy (FTIR), gas chromatography-mass spectroscopy (GC-MS), nuclear magnetic resonance (NMR), and energy-dispersive X-ray (EDX) techniques, emphasized the type of the extracted PHA as polyhydroxybutyrate (PHB). The thermal properties of PHB were measured using differential scanning calorimetry (DSC), recording melting transition temperature (Tm) at 170.96 °C. Furthermore, a scanning electron microscope (SEM) visualized a homogenous microporous structure for the thin PHB biofilm. In essence, this study highlights the ability of Bacillus flexus Azu-A2 to produce a good yield of highly purified PHB at reduced production cost from dairy CW. Consequently, the current study paves the way for an improved whey management strategy.

Study on the influence of advanced treatment processes on the surface properties of polylactic acid for a bio-based circular economy for plastics.

New biotechnological processes using microorganisms and/or enzymes to convert carbonaceous resources, either biomass or depolymerized plastics into a broad range of different bioproducts are recognized for their high potential for reduced energy consumption and reduced GHG emissions. However, the hydrophobicity, high molecular weight, chemical and structural composition of most of them hinders their biodegradation. A solution to reduce the impact of non-biodegradable polymers spread in the environment would be to make them biodegradable. Different approaches are evaluated for enhancing their biodegradation. The aim of this work is to develop and optimize the ultrasonication (US) and UV photodegradation and their combination as well as dielectric barrier discharge (DBD) plasma as pre-treatment technologies, which change surface properties and enhance the biodegradation of plastic by surface oxidation and thus helping bacteria to dock on them. Polylactic acid (PLA) has been chosen as a model polymer to investigate its surface degradation by US, UV, and DBD plasma using surface characterization methods like X-ray Photoelectron Spectroscopy (XPS) and Confocal Laser Microscopy (CLSM), Atomic Force Microscopy (AFM) as well as FT-IR and drop contour analysis. Both US and UV affect the surface properties substantially by eliminating the oxygen content of the polymer but in a different way, while plasma oxidizes the surface.