Desirable Biodegradability Research Articles

Ultrathin Molybdenum Carbide MXene with Fast Biodegradability for Highly Efficient Theory‐Oriented Photonic Tumor Hyperthermia

AbstractThe explosion of emerging high‐performance 2D MXenes in theranostic nanomedicine is still at the preliminary stage. Despite tremendous efforts devoted to photonic tumor hyperthermia, current photothermal‐conversion nanoagents still suffer from critical issues preventing further clinical translation such as low biodegradability. Here, for the first time, the construction of novel 2D molybdenum carbide (Mo2C) MXenes for photonic tumor hyperthermia is reported. The structure of both bulk Mo2Ga2C ceramic and Mo2C MXene is fully revealed. Especially, computational simulation, as a novel strategy and a powerful tool for photonic‐performance prediction, is employed to reveal that Mo2C MXene is featured with intense near‐infrared (NIR) absorption, covering the first and the second biological transparency window (NIR I and II). After further surface engineering with polyvinyl alcohol (PVA), Mo2C‐PVA nanoflakes exhibit high biocompatibility and fast degradability. Importantly, it is experimentally corroborated that Mo2C‐PVA nanoflakes possess intriguing broad absorption band spanning NIR in both the I and II regions, and desirable photothermal‐conversion efficiency (24.5% for NIR I and 43.3% for NIR II). This study not only broadens the nanomedical applications of MXene by fabricating novel material members (Mo2C), but also provides the paradigm of inorganic multifunctional biomedical nanoplatform with desirable biodegradability and high therapeutic performance.

Osteoclast-Responsive, Injectable Bone of Bisphosphonated-Nanocellulose that Regulates Osteoclast/Osteoblast Activity for Bone Regeneration.

An injectable bone may serve as a minimally invasive therapy for large orthopedic defects and osteoporosis and an alternative to allografting and surgical treatment. However, conventional bone substitutes lack the desirable biodegradability, bioresponsibility, and functionality to regulate the bone regeneration process. Here, we report an injectable, bioresponsive bone composed of bisphosphonate-modified nanocellulose (pNC) as a bone substitute for bone regeneration. Composites composed of nanofibrillated cellulose and β-tricalcium phosphate (β-TCP) mimic bone structures in which apatite reinforces collagen fibrils. Bisphosphonate groups on nanocellulose provide reversible, physical cross-linking with β-TCP, apatite formation, binding property to bone, and pH responsiveness. When the pH drops to ∼4.5, which corresponds to an osteoclast-induced pH decrease, pNC-β-TCP composite degrades and releases pNC. pNC suppresses osteoclast formation and pit formation. This osteoclast-responsive property allows for controlling the degradation rate of the composite. Moreover, the composite of pNC, α-tricalcium phosphate (α-TCP), and β-TCP enhances osteoblast differentiation. This injectable bone substitute of pNC that regulates osteoclast/osteoblast activity has enormous potential for the treatment of bone diseases and prevention of locomotive syndrome.

Biodegradable 2D Fe-Al Hydroxide for Nanocatalytic Tumor-Dynamic Therapy with Tumor Specificity.

Therapeutic nanocatalysis has emerged as an intriguing strategy for efficient cancer‐specific therapy, but the traditional inorganic nanocatalysts suffer from low catalytic efficiency and difficulty in biodegradation, hindering their further clinical translation. Herein, a tumor microenvironment‐triggered, biodegradable and biocompatible nanocatalyst employing 2D hydroxide nanosheet is presented, and is shown to have high catalytic capacity to efficiently produce abundant hydroxyl radicals under the tumor microenvironment and consequently kill tumor cells selectively. A polyethylene glycol (PEG)‐conjugated Fe2+‐containing hydroxide nanosheet is successfully constructed via a facile but efficient bottom‐up approach that concurrently realizes nanosheet synthesis and PEGylation. Importantly, the nanosheets are featured with high catalytic activity to disproportionate H2O2 in tumors, and consequently generate abundant hydroxyl radicals at a high reaction rate under tumorous acidic condition; the highly toxic hydroxyl radicals, as a result, cause the death of tumor cells in vitro and suppress the tumor growth in vivo without the use of any supplementary toxic agent, only with the biocompatible nanocatalysts. Meanwhile, the desirable biodegradation and biocompatibility of the hydroxide nanosheet render a high degree of safety to the organism. Therefore, this work provides the first paradigm of biodegradable 2D nanocatalytic platform with concurrently high catalytic‐therapeutic performance and biosafety for efficient tumor‐specific treatment.

Effect of thermal hydrolysis sludge supernatant as carbon source for biological denitrification with pilot-scale two-stage anoxic/oxic process and nitrogen balance model establishment

To recover carbon source (C-source) from waste activated sludge (WAS) and enhance the nitrogen removal performance, a pilot-scale system consisting of two-stage anoxic/oxic (A/O) process and low-temperature thermal hydrolysis process (THP) was proposed. The C-source recovery parameters for pilot THP were determined by systematically considering the results of orthogonal jar experiment, hydrolyzed sludge biodegradability and actual pilot situation. The results showed that supernatant from WAS treated by pilot-scale THP showed desirable biodegradability (BOD5/SCOD 0.62) and C/N (16) at the condition of heating temperature of 80 °C, heating time of 90 min and sludge water content of 98%. The performances of two-stage A/O process for 35 days indicated that the effluent quality could comply with the preset discharge standard, and hydrolysed sludge supernatant could be utilised as C-source for biological denitrification. A nitrogen balance model was established for two-stage A/O process, which showed high simulation accuracy and could be applied to optimize the operation parameters to meet TN discharge standard.

Preparation, characterization, and antioxidative activity of Bletilla striata polysaccharide/chitosan microspheres for oligomeric proanthocyanidins

ABSTRACTNovel oligomeric proanthocyanidins/Bletilla striata polysaccharide/chitosan (OPC/BSP/CTS) microspheres were obtained by spray-drying method. The morphology, size, physicochemical characterization, and in vitro release behavior of the formulation were evaluated. The results of scanning electron microscopy showed OPC-loaded microspheres with considerably wrinkled surfaces and drug-free microspheres with smooth surfaces. Particle-size analysis showed that the diameters of the OPC/BSP/CTS microspheres were 1–5 µm, with uniform distribution (polydispersity below 0.465). Fourier transform infrared indicated the occurrence of a chemical reaction between BSP and CTS. The OPC formed intermolecular hydrogen bonds with BSP/CTS carriers or transmuted amorphous structure. Differential scanning calorimetry displayed the absence of interaction; OPC was only physically encapsulated in the polymer matrix and OPC changed the crystallinity. All the microspheres showed desirable biodegradation rates; the high CTS content retarded their degradation and extended administration times. OPC/BSP/CTS microspheres showed pronounced antioxidant activity than pure OPC. These microspheres can be used as a potential platform to efficiently deliver unstable drugs as a sustained-release oral drug delivery system.

Controlled Release Pulmonary Administration of Curcumin Using Swellable Biocompatible Microparticles

This study involves a promising approach to achieve sustained pulmonary drug delivery. Dry powder particulate carriers were engineered to allow simultaneous aerosol lung delivery, evasion of macrophage uptake, and sustained drug release through a controlled polymeric architecture. Chitosan grafted with PEG was synthesized and characterized (FTIR, EA, DSC and 2D-XRD). Then, a series of respirable amphiphilic hydrogel microparticles were developed via spray drying of curcumin-loaded PLGA nanoparticles with chitosan-grafted-PEG or chitosan. The nanoparticles and microparticles were fully characterized using an array of physicochemical analytical methods including particle size, surface morphology, dynamic swelling, density, moisture content and biodegradation rates. The PLGA nanoparticles and the hydrogel microspheres encapsulating the curcumin-loaded PLGA nanoparticles showed average size of 221-243 nm and 3.1-3.9 μm, respectively. The developed carriers attained high swelling within a few minutes and showed low moisture content as dry powders (0.9-1.8%), desirable biodegradation rates, high drug loading (up to 97%), and good sustained release. An aerosolization study was conducted using a next generation impactor, and promising aerosolization characteristics were shown. In vitro macrophage uptake studies, cytotoxicity and in vitro TNF-α assays were performed for the investigated particles. These assays revealed promising biointeractions for the respirable/swellable nano-micro particles developed in this study as potential carriers for sustained pulmonary drug delivery.

Reactive Processing of Cellulose Acetate/Corn Starch Biodegradable Composite Materials and their Characterization

Simultaneous grafting of poly(e-caprolactone) (PCL) onto cornstarch as well as cellulose diacetate (CDA) and their composite machining were tried and succeeded by reactive processing using a twin screw extruder to result in plasticization of CDA, and at the same time, to obtain water-resistant and highly biomass-containing biodegradable composite materials. The properties of the composites obtained were examined through solvent fractionation, FT-IR, 1H NMR, tensile test, thermal flow test, SEM observation, water absorption test and biodegradability test. It was demonstrated that the composite materials containing maximum 60% cornstarch and maximum 70% biomass could be produced by the reactive processing method and they have good tensile property, processability, water resistance, and biodegradability. Especially the materials of which matrix polymer, PCL grafted CDA (PCL-g-CDA) in the degree of molar substitution range, 1.72–1.84 showed desirable biodegradability, having a certain induction period before rapid degradation, being attributable to the strong interaction between cornstarch and PCL-g-CDA, which is caused by somewhat long PCL chains grafted on both starch granules and CDA molecules. Furthermore, it was found that starch could accelerate the biodegradation rate of the matrix polymer, associating with starch degradation because of increase in surface area for microbial attack and its naturalization.

Characterization of porous poly(D,L‐lactic‐co‐glycolic acid) sponges fabricated by supercritical CO2 gas‐foaming method as a scaffold for three‐dimensional growth of Hep3B cells

This study presents the application of the porous poly(D,L-lactic-co-glycolic acid) (PLGA) sponges fabricated from an organic solvent free supercritical gas foaming technique. Two formulations of PLGA sponges with different co-polymer compositions (85:15 and 50:50) were fabricated as novel scaffolds to guide human hepatoma cell line, Hep3B cell growth in vitro. The PLGA sponges showed desirable biodegradability and exhibited uniform pore size distribution with moderate interconnectivity. It was observed in this study that cells cultured on PLGA sponges showed lower proliferation rate as compared to the control during 14 days of culture as measured by using total DNA and methylthiazol tetrazolium (MTT) assays. However, the cells cultured on the sponges tended to aggregate to form cell islets which were able to express better hepatic functions. The enzyme-linked immunosorbent assay (ELISA) results showed that the cell-sponge constructs secreted 1.5-3.0 times more albumin than the control when normalized to cellular content. In a similar fashion, its detoxification ability was also predominantly higher than that of the control as indicated by the ethoxyresorufin-O-deethylase (EROD) results. By comparing the cells growing on the two formulations of PLGA sponges, it was found that the PLGA 85:15 sponge exhibited better conductive and desirable environment for hep3B cells as justified by better cell infiltration, higher proliferation and hepatic function than the PLGA 50:50 sponge.

Novel approaches for remediation of pesticide pollutants

The use of synthetic pesticides has become an indispensable tool in agriculture for the control of pests. Therefore, the search for remedies and techniques for decontamination and detoxification of a pesticide-contaminated environment has become an important part of the research. Currently, bioremediation seems to be one of the most environmentally safe and cost-effective methods. In nature, the existence of abundant material resources can be used to degrade the environmental pesticide pollutants. At present, a number of microorganisms, capable of degrading pesticides, have been isolated and characterised. For insects, insecticide resistance-associated esterases have been purified and characterised from several insect species, and a new family of cytochrome P450 apparently associated with insecticide resistance in the tobacco budworm, was discovered. Generally, two bioremediation approaches have been used one directly based on microorganisms, and the other involved in isolated enzymes. For the former, in addition to using natural microorganism strains, with genetic techniques certain desirable biodegradation pathways from different organisms are brought together in a single host. However, because of their own limits, especially problems associated with releasing genetically altered microorganisms into the environment, the strategy based on enzymes seems more feasible. In the long term, collaborations between microbiologists, biochemists, and engineers will become increasingly important to efficiently dispose of the pesticide pollutants.

Characterization and Regulation of Catabolic Genes

Although a wide range of microorganisms have been discovered that are able to degrade highly stable, toxic xenobiotics, still many pollutants persist in the environment. Recent advances in the field of r-DNA technology has provided solutions to these problems. One important factor limiting the bioremediation of sites contaminated with certain hazardous wastes is the slow rate of degradation. This slow rate limits the practicality of using bacteria in remediating contaminated sites. It is possible to extend the range of substrates that an organism can utilize. It is even possible to endow an organism with the ability to degrade a predetermined range of xenobiotics. Because biotechnological processes are based on natural activities of microorganisms and costitute variations in classic domestic waste treatment processes, they are publicly more accepted. This is an area where genetic engineering can make a marked improvement by manipulating catabolic genes of microorgnisms. Advances in r-DNA technology have opend up new avenues to move toward the goal of genetically engineered microorganisms to function as “designer biocatalysts” in which certain desirable biodegradation pathways or enzymes from different organisms are brought together in a single host with the aim of performing specific detoxification. In the last 2 decades much progress has been made in this direction, and as a result catabolic genes have been cloned and characterized for organochlo-rines, polychlorinatedbiphenyls, chlrobenzoates, naphthalene etc. The aim of this review is to provide an insight in the recent advances made on characterization and expression of catabolic genes that encode the degradation/detoxification of these pesistent and toxic xenobiotic compounds.