Potential Biosafety of Mxenes: Stability,Biodegradability, Toxicity and Biocompatibility

MXenes are two-dimensional nanomaterials with unique properties that are widely used in various fields of research, mostly in the field of energy. Fewer publications are devoted to MXene application in biomedicine and the question is: are MXenes safe for use in biological systems? The sharp edges of MXenes provide the structure of ”nanoknives“ which cause damage in direct physical contact with cells. This is effectively used for antibacterial research. However, on the other hand, most studies in cultured cells and rodents report that they do not cause obvious signs of cytotoxicity and are fully biocompatible. The aim of our review was to consider whether MXenes can really be considered non-toxic and biocompatible. Often the last two concepts are confused. We first reviewed aspects such as the stability and biodegradation of MXenes, and then analyzed the mechanisms of toxicity and their consequences for bacteria, cultured cells, and rodents, with subsequent conclusions regarding their biocompatibility.     

QSBR Study on the Anaerobic Biodegradation of Chlorophenols

1 INTRODUCTION Chlorophenols (CPs) have been widely applied in such industries[1] as wood preservative, antitrust, bactericide and herbicide since 1930s. Due to the existence of phenol ring structure and chloro-atom, chlorophenols have strong toxicity and high anti- degradation ability. Previous reports show that[2, 3] chlorophenols are difficult to oxidize under aerobic condition, whereas anaerobic biological treatment can effectively reduce the toxicity towards microor- ganism so as to …     

Microbial Bioelectrochemical Reactor for Wastewater Treatment Applications

A microbial BioElectrochemical Reactor (BER) was employed for the degradation of an azo dye. Electrodes inside the BER were made of stainless steel mesh and were packed with activated carbon. Dye degradation and aromatic reduction products (e.g. aromatic amines) were analyzed. Dye removal was from 99 to 90% upon changing the residence time from 4 to 1 h in single pass mode; degradation of aromatic compounds was higher with increasing time. Electrical stimulation of the bioreactions decreases the reactor residence time at higher removal rates in comparison to a simple biotic system.     

Hyperbranched Polyglycerol-Induced Porous Silica Nanoparticles as Drug Carriers for Cancer Therapy In Vitro and In Vivo

Mesoporous silica-based nanoparticles are generally accepted as a potential platform for drug loading with a lot of advantages, except for their complex purification procedures and structures that are difficult to decompose. In this work, biocompatible hyperbranched polyglycerol is introduced to synthesize mesoporous silica nanoparticles (MSNs). The materials possess good biocompatibility, controlled release, and biodegradability. They also show passive targeting capability through the enhanced permeability and retention effect and can be excreted from the biological system. The method avoids the needs to employ traditional surfactants and complicated purified procedures, which make these MSNs an efficient delivery system for cancer therapy.     

聚乳酸眼科植入材料的制备及其降解性能

聚乳酸眼科植入材料的制备及其降解性能卓仁禧＊尹超吴颖楠祝磊曾水清（武汉大学化学系武汉４３００７２）（同济医科大学附属协和医院武汉）关键词聚乳酸，制备，生物可降解性，眼科植入材料１９９６－０８－１８收稿，１９９７－０１－１７修回国家自然科学基金资助项目...     

生物降解聚合物膜的制备及防肌腱粘连作用

生物降解聚合物膜的制备及防肌腱粘连作用甘志华景遐斌＊（中国科学院长春应用化学研究所高分子物理联合开放研究实验室长春１３００２２）张仲文徐莘香（白求恩医科大学第一临床医院长春）关键词肌腱粘连，生物降解，聚合物膜１９９６－０７－２１收稿，１９９６－０９－...     

Development and In Vivo Test of Sol-Gel Derived Bone Grafting Materials

A novel bioceramic derived via sol gel method was developed and very good resorption properties in long term period of implantation were established.Calcium phosphate materials are bioactive, osteoconductive materials used as guides for bone regeneration. An identical sequence of events apparently occurred at the contact of the ceramics when implanted in vivo. Two kinds of calcium phosphate ceramics have been produced in a form of threads with 1 mm in diameter: hydroxyapatite SiO₂-containing ceramic and hydroxyapatite—-tricalcium phosphate SiO₂-containing ceramic. Above mentioned calcium phosphate ceramic established an interconnecting macroporous structure, which is responsible for growth of bone and for replacement of ceramic by bone. Three ranges of pores were designed.Viscosity measurements were made to control the point of gelation and production phase of transplant material.In vivo experiments were carried out for 5 weeks and 8 months. The results after the short period of examination have shown the early stage of bone formation and material dissolution. Within 6 months nearly 100% of implanted ceramic was resorpted and new bone around place of intervention was formed.     

Characterizing biodegradation of PLA and PLA-g-AA/starch films using a phosphate-solubilizing bacillus species

The use of PLA and PLA-g-AA/starch as materials for the controlled release of encapsulated PSB was evaluated. The results showed that the bacterium degraded both the PLA and the PLA-g-AA/starch composite films, resulting in cell release. Severe disruption of the film structure occurred after incubation for 60-90 d. The PLA-g-AA/starch (20 wt.-%) films were more biodegradable than those made of PLA and also suffered a more pronounced decrease in molecular weight and intrinsic viscosity. Although blending of starch appeared to enhance the biodegradability of the PLA films, the pattern of degradation was quite similar for both types of films. The rate of cell release depends on the biodegradability of the film.     

Self-accelerated biodegradation of electrospun poly(ethylene glycol)-poly(l-lactide) membranes by loading proteinase K

Proteinase K was successfully loaded inside ultrafine fibers of poly(ethylene glycol)-poly(l-lactide) (PELA) by emulsion electrospinning. A core/shell fiber structure was formed and verified by a transmission electron microscope. In vitro biodegradation of electrospun PELA membranes containing proteinase K (PELA-P) was examined in Tris-HCl buffer solution at pH 8.6 and 37 °C in comparison with electrospun PELA membranes without proteinase K. During biodegradation, mass loss, water absorption, pH value of the incubated buffer, fibrous morphology and thermal properties were monitored. Results suggested that PELA-P membranes degraded significantly faster than PELA membranes. A significant drop in pH value of the buffer after incubation of PELA-P membranes for 1 d was observed, and after 7 d, PELA-P membranes lost their fibrous appearance and masses almost completely. In contrast, electrospun PELA membranes did not show any obvious changes. The obtained electrospun PELA-P membranes exhibited self-accelerated biodegradability and could benefit drug controlled release and tissue regeneration.     

Polyurethanes with separately tunable biodegradation behavior and mechanical properties for tissue engineering

Two series (random and block) poly(glycolide‐co‐ε‐caprolactone) macrodiols with various glycolide to ε‐caprolactone ratios (50/50 and 30/70, R‐PG50C, R‐PG30C, B‐PG50C, and B‐PG30C) were synthesized. Next, segmented polyurethanes (PUs) were synthesized based on the synthesized macrodiols, 1,6‐hexamethylene diisocyanate and 1,4‐butanediol (PU‐R30, PU‐R50, PU‐B30, and PU‐B50). Effect of glycolide (G) and ε‐caprolactone (C) monomers arrangement (random or block) on the PUs properties were investigated via FTIR, ¹H NMR, DSC, TGA, DMA, SEM, and mechanical tests. All PUs illustrated T_g (−33°C to −48°C) and T_m (102°C to 139°C) corresponding to the soft and the hard segments, respectively. Polymers based on block macrodiols also showed T_m related to the soft segments. While PUs underwent a two‐step thermal degradation, the PUs based on block macrodiols indicated higher degradation temperature. Dynamic mechanical analysis results evidenced development of a well‐defined microphase separated structure in PU‐R30. Contact angle (about 70°‐80°) and water uptake (around 20% after 24 hours) of the PU films are close to those suitable for tissue engineering materials. The PU based on R‐PG30C (PU‐R30) exhibited the highest tensile strength (2.87 MPa) followed by PU‐B50 and PU‐R50. Over a 63‐day in vitro degradation study in phosphate buffered saline, the PUs showed variable weight loss (up to 40%) depending on their soft segments composition and arrangement. Also, the PUs showed no cytotoxicity. Thus, these PUs with tunable biodegradation rate and mechanical properties are suitable candidates for tissue engineering.