Formation of Nano- and Microplastics and Dissolved Chemicals During Photodegradation of Polyester Base Fabrics with Polyurethane Coating.

Polyurethane (PU) synthetic leathers possess an intricate plastic composition, including polyester (PET) base fabrics and upper PU resin, but the release of fragments from the complexes is unclear. Therefore, we investigated the photodegradation trends of PET base fabrics with PU coating (PET-U) as a representative of composite plastics. Attention was paid to the comparison of the photoaging process of PET-U with that of pure PET base fabric (PET-P). To reveal the potential for chain scission, physical and chemical changes (e.g., surface morphology, molecular weight, and crystallinity) of the two fabrics were explored. The generation of microplastic fibers (MPFs) and microplastic particles (MPPs) was distinguished. Compared with PET-P, PET-U showed a similar but delayed trend in various characteristics and debris release rate as the photoaging time prolonged. Even so, after 360 h of illumination, the generated number of MPs (including MPFs and MPPs) rose considerably to 9.32 × 107 MPs/g, and the amount of released nanoplastics (NPs) increased to 2.70 × 1011 NPs/g from PET-U. The suppression of MP formation from PET-U was potentially directed by the physical shielding of the upper PU layer and the dropped MPs, which resisted the photochemical radical effect. The components of dissolved organic matter derived from plastics (P-DOM) were separated by molecular weight using a size-exclusion chromatography-diode array detector-organic carbon detector/organic nitrogen detector (SEC-DAD-OCD/OND), and the results showed that a larger amount of carbon- and nitrogen-containing chemical substances were generated in PET-U, accompanied by more aromatic and fluorescent compounds. The results provided theoretical bases and insights for future research on the risks of plastic debris from PU synthetic leathers on aquatic organisms and indicated feasible directions for exploring combined pollution studies of plastics.

Improvement of short-term hypothermic preservation of microencapsulated hepatocytes.

OBJECTIVES: To determine the optimal storage solution containing suitable protective agents for the preservation of microencapsulated hepatocytes at 4 °C as well as the optimum incubation time after hypothermic preservation. RESULTS: L15 was the optimum solution for both maintaining microcapsule integrity and cell viability. Furthermore, 5 %(v/v) PEG (20 or 35 kDa) added to Leibovitz-15 medium was optimal for microencapsulated C3A cells, enhancing cell viability and liver-specific functions, including albumin and urea synthesis as well as CYP1A2 and CYP3A4 activities. The transcription levels of several CYP450-related genes were also dramatically increased in cells incubated in the optimal solution. Pre-incubation for 2 h was the optimal time for restoring favorable levels of CYP1A2 and CYP3A4 activities in microencapsulated C3A cells for short term, 2 day storage. CONCLUSIONS: Leibovitz-15 medium supplemented with 5 % (v/v) PEG is a promising cold solution for microencapsulated hepatocytes at 4 °C, with an incubation of 2 h at 37 °C after hypothermic preservation being the best incubation duration for further cell application.

Elucidating the production and inhibition of melanoidins products on anaerobic digestion after thermal-alkaline pretreatment.

The refractory organics released from waste activated sludge (WAS) are unwanted produced in thermal-alkaline pretreatment, which are not well documented. In this study, we refer to them as melanoidins products (MPs) with characteristics of high molecular weight and inhibition to microbes. The results showed that these MPs from thermal-alkaline (80 °C and pH 10) pretreatment of WAS were identified with a broad molecular weight (>1000 Da). Dark-colored MPs were further verified from glucose and tryptophan as the model components, with values of UV280 and UV420 increasing. The produced MPs with a molecular weight of 1220, 6835, and even 21,200,000 Da were confirmed by SEC-HPLC. Unexpectedly, MPs were found to be electroactive with higher redox peak values than that of humic acids, which were almost not degraded by anaerobes as revealed by SEC-HPLC and 3D-EEM spectra. For the first time, the results demonstrated that MPs delayed volatile fatty acids production and reduced the methane yield (22-26% lower), which was likely attributed to the toxicity and/or electrons competition with anaerobes such as Methanosaeta. Thus, it is clear that MPs negatively impact anaerobic digestion after thermal-alkaline pretreatment, which shall be re-evaluated to minimize MPs when producing biochemicals from WAS.

Using FTIR Imaging to Investigate Silk Fibroin-Based Materials.

The secondary structures of silk fibroin (SF) are critical in the determination of the mechanical properties of the animal silks. Different characterization techniques, such as X-ray diffraction, nuclear magnetic resonance, Raman spectroscopy, and Fourier transform infrared (FTIR) technique, have been applied to study the secondary structure of animal silks. Among these techniques, FTIR is most widely used as it is sensitive to all secondary structures of proteins. Especially with the development of FTIR imaging, it is now possible to image the secondary structures of proteins at the micrometer scale, so as to understand the spatial distribution of proteins and the interaction of proteins with other materials at specific locations of interest. In this chapter, we present the methods and protocols of FTIR imaging to silk protein-based materials. We primarily introduce how to set up the instruments and accessories, as well as how to choose the appropriate imaging methods and sample preparation methods according to sample morphologies. The critical protocols for data analysis are also introduced in the last section.

Light-powered Escherichia coli cell division for chemical production.

Cell division can perturb the metabolic performance of industrial microbes. The C period of cell division starts from the initiation to the termination of DNA replication, whereas the D period is the bacterial division process. Here, we first shorten the C and D periods of E. coli by controlling the expression of the ribonucleotide reductase NrdAB and division proteins FtsZA through blue light and near-infrared light activation, respectively. It increases the specific surface area to 3.7 µm-1 and acetoin titer to 67.2 g·L-1. Next, we prolong the C and D periods of E. coli by regulating the expression of the ribonucleotide reductase NrdA and division protein inhibitor SulA through blue light activation-repression and near-infrared (NIR) light activation, respectively. It improves the cell volume to 52.6 µm3 and poly(lactate-co-3-hydroxybutyrate) titer to 14.31 g·L-1. Thus, the optogenetic-based cell division regulation strategy can improve the efficiency of microbial cell factories.

Employing ATP as a New Adjuvant Promotes the Induction of Robust Antitumor Cellular Immunity by a PLGA Nanoparticle Vaccine.

Tumor vaccines based on synthetic human papillomavirus (HPV) oncoprotein E7 and/or E6 peptides have shown encouraging results in preclinical model studies and human clinical trials. However, the clinical efficacy may be limited by the disadvantages of vulnerability to enzymatic degradation and low immunogenicity of peptides. To further improve the potency of vaccine, we developed a poly(lactide-co-glycolide)-acid (PLGA) nanoparticle, which encapsulated the antigenic peptide HPV16 E744-62, and used adenosine triphosphate (ATP), one of the most important intracellular metabolites and an endogenous extracellular danger signal for the immune system, as a new adjuvant component. The results showed that PLGA nanoparticles increased the in vivo stability, lymph node accumulation, and dendritic cell (DC) uptake of the E7 peptide; in addition, ATP further increased the migration, nanoparticle uptake, and maturation of DCs. Preventive immunization with ATP-adjuvanted nanoparticles completely abolished the growth of TC-1 tumors in mice and produced long-lasting immunity against tumor rechallenge. When tumors were fully established, therapeutic immunization with ATP-adjuvanted nanoparticles still significantly inhibited tumor progression. Mechanistically, ATP-adjuvanted nanoparticles significantly improved the systemic generation of antitumor effector cells, boosted the local functional status of these cells in tumors, and suppressed the generation and tumor infiltration of immunosuppressive Treg cells and myeloid-derived suppressor cells. These findings indicate that ATP is an effective vaccine adjuvant and that nanoparticles adjuvanted with ATP were able to elicit robust antitumor cellular immunity, which may provide a promising therapeutic vaccine candidate for the treatment of clinical malignancies, such as cervical cancer.

Glutathione responsive cubic gel particles cyclodextrin metal-organic frameworks for intracellular drug delivery.

Novel cubic gel particles (ssCGP) with Glutathione (GSH) triggered drug release features were prepared by crosslinking the cyclodextrin based metal-organic frameworks (CD-MOFs) templets with a newly synthesized biodegradable disulfide bond-bearing linker and removing of the potassium ion in sequence. The morphology and size of ssCGP were investigated by field emission scanning electron microscope (FESEM) and dynamic light scattering. Energy dispersive x-ray spectroscopy (EDX), fourier transform infrared spectroscopy (FT-IR), powder x-ray diffraction (PXRD) and Brunauer-Emmett-Teller (BET) were employed to characterize the structure of ssCGP. ssCGP have regular hexahedron shape with edge length about 200-400 nm. Excellent ability of drug adsorption was achieved by using doxorubicin (DOX) as a model drug. The GSH triggered drug release of ssCGP was observed both in GSH contained solutions and intracellular environments. ssCGP have been demonstrated as a biocompatible porous nanocarrier, particular for intracellular drug delivery.

Nanobiopolymers Fabrication and Their Life Cycle Assessments.

Living organisms produced nanopolymers (nanobiopolymers for short), such as nanocellulose, nanochitin, nanosilk, nanostarch, and microbial nanobiopolymers, having received widely scientific and engineering interests in recent years. Compare with petroleum-based polymers, biopolymers are sustainable and biodegradable. The unique structural features that stem from nanosized effects, such as ultrahigh aspect ratio and length-diameter ratio, further endow nanobiopolymers with high transparence and versatile processability. To fabricate these nanobiopolymers, a variety of mechanical, chemical, and synthetic biology techniques have been developed. The applications of the isolated nanobiopolymers have been extended from polymer fillers into wide emerging high-tech fields, such as biomedical devices, bioplastics, display panels, ultrafiltration membranes, energy storage devices, and catalytic supports. Accordingly, in the review, the authors first introduce isolation techniques to fabricate nanocellulose, nanochitin, nanosilk, and nanostarch. Then, the authors summarized the nanobiopolymers produced from biosynthetic pathway, including microbial polyamides, polysaccharides, and polyesters. On the other hand, most of these techniques require high energy consumption and usage of chemical reagents. In this regard, life cycle assessment offered a quantitative route to precisely evaluate and compare environmental benefits of different artificial isolation approaches, which are also summarized in the second section of the review.

Reconstruction of a Genome-scale Metabolic Network of Komagataeibacter nataicola RZS01 for Cellulose Production.

Bacterial cellulose (BC) is widely used in industries owing to its high purity and strength. Although Komagataeibacter nataicola is a representative species for BC production, its intracellular metabolism leading to BC secretion is unclear. In the present study, a genome-scale metabolic network of cellulose-producing K. nataicola strain RZS01 was reconstructed to understand its metabolic behavior. This model iHZ771 comprised 771 genes, 2035 metabolites, and 2014 reactions. Constraint-based analysis was used to characterize and evaluate the critical intracellular pathways. The analysis revealed that a total of 71 and 30 genes are necessary for cellular growth in a minimal medium and complex medium, respectively. Glycerol was identified as the optimal carbon source for the highest BC production. The minimization of metabolic adjustment algorithm identified 8 genes as potential targets for over-production of BC. Overall, model iHZ771 proved to be a useful platform for understanding the physiology and BC production of K. nataicola.