Progressing Ultragreen, Energy-Efficient Biobased Depolymerization of Poly(ethylene terephthalate) via Microwave-Assisted Green Deep Eutectic Solvent and Enzymatic Treatment

Effective interfacing of energy-efficient and biobased technologies presents an all-green route to achieving continuous circular production, utilization, and reproduction of plastics. Here, we show combined ultragreen chemical and biocatalytic depolymerization of polyethylene terephthalate (PET) using deep eutectic solvent (DES)-based low-energy microwave (MW) treatment followed by enzymatic hydrolysis. DESs are emerging as attractive sustainable catalysts due to their low toxicity, biodegradability, and unique biological compatibility. A green DES with triplet composition of choline chloride, glycerol, and urea was selected for PET depolymerization under MW irradiation without the use of additional depolymerization agents. Treatment conditions were studied using Box-Behnken design (BBD) with respect to MW irradiation time, MW power, and volume of DES. Under the optimized conditions of 20 mL DES volume, 260 W MW power, and 3 min MW time, a significant increase in the carbonyl index and PET percentage weight loss was observed. The combined MW-assisted DES depolymerization and enzymatic hydrolysis of the treated PET residue using LCC variant ICCG resulted in a total monomer conversion of ≈16% (w/w) in the form of terephthalic acid, mono-(2-hydroxyethyl) terephthalate, and bis-(2-hydroxyethyl) terephthalate. Such high monomer conversion in comparison to enzymatically hydrolyzed virgin PET (1.56% (w/w)) could be attributed to the recognized depolymerization effect of the selected DES MW treatment process. Hence, MW-assisted DES technology proved itself as an efficient process for boosting the biodepolymerization of PET in an ultrafast and eco-friendly manner.

Inhibition of Neovascularization and Inflammation in a Mouse Model of Corneal Alkali Burns Using Cationic Liposomal Tacrolimus

Eye drops account for more than 90% of commercialized ophthalmic drugs. However, eye drops have certain shortcomings, such as short precorneal retention time and weak corneal penetration. The requirement of frequent instillation of eye drops also causes poor patient compliance, which may lead to further aggravation of the disease. We aimed to develop a cationic liposome formulation to increase the bioavailability of the therapeutic agent and solve the aforementioned problems. In the present study, we prepared cationic liposomal tacrolimus (FK506) with a surface potential of approximately +30 mV, which could bind to the negatively charged mucin layer of the ocular surface. Our results showed that the content of FK506 in the cornea was increased by 93.77, 120.30, 14.24, and 20.36 times at 5, 30, 60, and 90 min, respectively, in the FK506 liposome group (0.2 mg/ml) compared with the free drug group (0.2 mg/ml). Moreover, FITC-labeled FK506 liposomes significantly prolonged the ocular surface retention time to 50 min after a single dose. In addition, the results of the Cell Counting Kit-8 assay, live and dead cell assay, sodium fluorescein staining, and hematoxylin and eosin staining all indicated that FK506 liposomes had good biological compatibility in both human corneal epithelial cells and mouse eyeballs. Compared with the free drug at the same concentration, FK506 liposomes effectively inhibited vascular endothelial growth factor-induced green fluorescent protein-transduced human umbilical vein endothelial cell migration and tube formation in vitro. In a mouse corneal neovascularization model induced by alkali burns, FK506 liposomes (0.2 mg/ml) enhanced corneal epithelial recovery, inhibited corneal neovascularization, and reduced corneal inflammation, and its therapeutic effect was better than those of the commercial FK506 eye drops (1 mg/ml) and the free drug (0.2 mg/ml). Collectively, these results indicate that cationic FK506 liposomes could increase the efficacy of FK506 in the corneal neovascularization model. Therefore, cationic FK506 liposomes can be considered as a promising ocular drug delivery system.

Production, characterization and biological evaluation of nanocapsules containing tricresol formalin and their comparison with the free form

Ethnopharmacological relevance: Tricresol formalin is composed of 90% formaldehyde and 10% cresols, highly volatile, has action at a distance, has been used in endodontics since the 20th century, and it remains widely used in Brazil in dental treatments, in necrotic teeth and with periapical lesions. However, there is still controversy regarding the biological compatibility under the conditions of clinical use of this drug, as the studies carried out on this substance and its components are not consistent with its clinical use. Formaldehyde is reported as a potential cytotoxic substance, because when in direct contact with cells it is responsible for a cytogenotoxic response, so an alternative to increase stability and ensure the safe administration of this compound in direct contact with cells would be nanoencapsulation. The use of nanomaterials provides numerous advantages, as the main interests are increased solubility and drug release control. Study objective: This study aimed to produce and characterize nanocapsules containing tricresol formalin as active, evaluating and comparing the in vitro cytotoxic effect of free and nanostructured forms.Materials and methods: a nanoparticle was produced, optimization of the preparation method and characterization of nanocapsules containing tricresol formalin. Were performed antimicrobiological tests, tests for cell viability through the tetrazolium method assay (MTT), free radical production, double strand DNA damage, and nitric oxide production. Results: The formulation used did not show toxic behavior against human peripheral blood mononuclear cells and showed a significant reduction in the toxicity of tricresol formalin in human fibroblast cells. The nanostructures showed values ​​similar to the free form for antimicrobial activity. The nanoparticles showed mean particle size of 192.3 ± 2.5 nm, PDI of 0.101 ± 0.013, zeta potencial of -17.7 ± 2.8 mV, and pH of 5.48 ± 0.3. Conclusion: Thus, it is evident that nanocapsules containing tricresol formalin can become a safer alternative for use within endodontics.

Chemical and biological compatibility of different injection waters with Zubair Formation Water of Upper Sand Member in Zubair Oil Field, South of Iraq

Water injection by water flooding was used to enhance and increase oil production in Zubair oil field, southern Iraq. Physical-chemical and biological analysis of five water samples from different sources were collected to evaluate its compatibility with formation water using biological experiments and chemical compatibility simulation. The results show that injection water is classified weakly acidic-weakly alkaline and saline water, whereas surface water samples are considered weakly acid-weakly alkaline. The total dissolved solids results show brackish types accept for Formation water which classified weakly acid and Brine water. All the studied water samples contain bacteria colonies of Escherichia coli and Coliform expect for one sample, while Sulfate Reducing Bacteria was founded in all studied samples. Mathematical model of chemical compatibility between studied water samples and Zubair Formation water of the scale prediction model show that there are no needs for any inhibition treatments of all scales except for Geothite and Dolomite that should be treated before water injection. The biological compatibility experiments results show Formation damage about (61%) and (69%) in the studied core samples, while Bactria in water injection caused formation damage about (20%) and (51%).

Quantitative Assessment of the Development of Micromycete Colony on the Surfaces of Polymers and Polymer Composites

The need to ensure the possibility of widespread use of electronic and mobile health-saving technologies requires not only the formation of an appropriate information technology infrastructure and the development of effective algorithms for processing a large amount of personal information. Development of medical devices for recording physiological processes also involves the creation of innovative biologically compatible materials that allow sensors and medical sensors to work continuously in 24/7 mode. Taking into account the long-term positive experience of using large-capacity thermoplastics and elastomers in medical equipment, it seems promising to use the corresponding polymers as the main materials of wearable electronics for medical purposes. At the same time, to ensure the biological compatibility of the materials under discussion, it is necessary to minimize the possibility of the development of pathogenic microorganisms on surfaces in contact with living tissues. This type of pathogenic organisms (pathogens of a number of dangerous diseases – mycoses) includes some types of microscopic fungi - micromycetes (in particular, Aspergillus niger van Tiegem; Aspergillus terreus Thom; Penicillium cycopium Westling). The article examines the effect of surface modification by gas-phase fluorination on the nature and degree of development of a mixed colony of micromycetes on the surfaces of experimental samples made of several types of thermoplastics (polyvinyl chloride, polypropylene, low-density polyethylene, polyethylene terephthalate) and elastomers (butyl- and butadiene-nitrile rubbers, as well as ethylene, propylene and dicyclopentadiene copolymers). The nature and degree of development of colonies are quantitatively described using the original methodology developed earlier. The effect of fluorination on the nanotexture and chemical composition of the surface and near-surface layers of experimental samples was demonstrated using scanning electron microscopy (SEM) and IR Fourier spectroscopy (IRFS). The dynamics and efficiency of fluorination are described using a linearized hyperbolic model, the parameters of which are set by the least squares method.

Dual-Crosslinked Oxidized Pectin/N-Succinyl Chitosan Hydrogel Containing Graphene Oxide Nanosheets for Tissue Engineering Application

Biopolymer-based hydrogels are commonly used in clinical applications. In the present study, N- succinyl chitosan (NSC), oxidized pectin (OP), and graphene oxide (GO) were used to develop a new dual-crosslinked hydrogel system. The dynamic OP/NSC/GO hydrogel showed quick gelation and great injectability due to the cooperation of hydrogen interaction between the GO nanosheets and the NSC and OP macromolecules and Schiff-based crosslinking by amino and aldehyde functional groups of polysaccharide derivatives. The performance of the above-mentioned hydrogel was improved when the GOs were embedded. When the GO content was 6 (mg/ml), the hydrogel showed the best overall performance, with a 10-minute healing time, a quick gelation time (~ 13s), acceptable swelling ability, suitable conductivity, great hemocompatibility, and strong biological compatibility. These results showed that the composite hydrogel could be used as a promising conductive injectable self-healing hydrogel for tissue engineering applications.

Dynamic Mechanical Properties of Selective-laser-melting-processed Ti6Al4V

The relative density grading of metal lattice structures becomes a favourable design for bone plants since these structures are suitable for human implantation and have good biological compatibility. The unit cell structure designed using this method is better than that designed by traditional 3D modelling software, especially when using a bionic unit cell design created by a triple periodic minimum surface (TPMS). In this study, the manufacturability of Gyroids was tested by studying three different designs: the relative density of 30%, 20%, and 10% sheet structure. The main purpose is to understand the influence of relative density on the static compression performance of the sheet-like Gyroids structure. This study qualitatively analyses the influence of the relative density of the Gyroids lattice structure prepared by the selective laser melting technology on the compressive strength, elastic modulus, energy absorption and failure mechanism. As the relative density of the sheet structure decreases, the compressive strength decreases. The elastic modulus of the sheet structure of 10% is slightly higher than that of 20%, showing a different trend from the compressive strength. At the same time, the energy absorption per unit volume increases when the relative density decreases and becomes smaller, and the failure modes of the three relative densities all show a 45° fracture failure.

Physico-Chemical Characterization and In Vitro Biological Evaluation of a Bionic Hydrogel Based on Hyaluronic Acid and l-Lysine for Medical Applications

Hyaluronic acid (HA) is an endogenous polysaccharide, whose hydrogels have been used in medical applications for decades. Here, we present a technology platform for stabilizing HA with a biocrosslinker, the amino acid L-lysine, to manufacture bionic hydrogels for regenerative medicine. We synthetized bionic hydrogels with tailored composition with respect to HA concentration and degree of stabilization depending on the envisaged medical use. The structure of the hydrogels was assessed by microscopy and rheology, and the resorption behavior through enzymatic degradation with hyaluronidase. The biological compatibility was evaluated in vitro with human dermal fibroblast cell lines. HA bionic hydrogels stabilized with lysine show a 3D network structure, with a rheological profile that mimics biological matrixes, as a harmless biodegradable substrate for cell proliferation and regeneration and a promising candidate for wound healing and other medical applications.