Laponite nanoparticle-crosslinked carboxymethyl cellulose-based injectable hydrogels with efficient underwater-specific adhesion for rapid hemostasis.

Tissue adhesives have attracted intense and increasing interest due to their multiple biomedical applications. Despite the rapid development of adhesive hydrogels, huge challenges remain for materials that can ensure strong adhesion and seal hemostasis in aqueous and blood environments. To address this issue, we have developed an innovative design of PAA-based coacervate hydrogel with strong wet adhesion capability through a simple mixture of PAA copolymers with oxidized-carboxymethylcellulose (OCMC), and tannic acid (TA) as the main components, and structurally enhanced with natural clays (Laponite XLG). The absorbed TA provides solid adhesion to dry and wet substrates via multiple interactions, which endows the XLG-enhanced coacervate with the desired underwater adhesive strength. More importantly, the dielectric constant is introduced to evaluate the polarity of the tested samples, which may be used as guidance for the design of mussel-inspired adhesives with even better underwater adhesive properties. In vivo hemorrhage experiments further confirmed that the hydrogel adhesive dramatically shortened the hemostatic time to tens of seconds. Overall, the persistent adhesion and acceptable cytocompatibility of the hydrogel nanocomposite make it a promising alternative suture-free approach for rapid hemostasis at different length scales and is expected to be extended to clinical application for other organ injuries.

Polypropylene mesh coated with hyaluronic acid/polyvinyl alcohol composite hydrogel for preventing bowel adhesion.

Polypropylene (PP) mesh is the most widely used prosthetic material in hernia repair. However, the efficacy of implanted PP mesh is often compromised by adhesion between viscera and PP mesh. Thus, there is a recognized need for developing an anti-adhesive PP mesh. Here, a composite hydrogel coated PP mesh with the prevention of adhesion after hernia repair was designed. The composite hydrogel coating was prepared from polyvinyl alcohol (PVA) and hyaluronic acid (HA) by using the freezing-thawing (FT) method. To overcome the shortcoming of the long time of the traditional freezing-thawing method, a small molecule 3,4-dihydroxyphenylacetic acid (DHPA) was introduced to promote the formation of composite hydrogel. The as-prepared composite hydrogel coating displayed modulus more closely resembling that of native abdominal wall tissue. In vitro studies illustrated that the resulting meshes showed excellent coating stability, hemocompatibility, and non-cytotoxicity. In vivo experiments using a rat abdominal wall defect model demonstrated that the composite hydrogel coated PP mesh could prevent the formation of adhesion, alleviate the inflammatory response, and reduce the deposition of collagen around the damaged tissue. These disclosed results manifested that the PP mesh coated with HA/PVA composite hydrogel might be a promising application in preventing adhesion for hernia repair.

Polypropylene composite hernia mesh with anti-adhesion layer composed of PVA hydrogel and liposomes drug delivery system.

Polypropylene (PP) mesh has been widely used in hernia repair as prosthesis material owing to its excellent balanced biocompatibility and mechanical properties. However, abdominal adhesion between the visceral and PP mesh is still a major problem. Therefore, anti-adhesive PP mesh was designed with poly(vinyl alcohol) (PVA) hydrogel and liposomes drug delivery system. First, PVA hydrogel coating was formed on the surface of PP mesh with freezing-thawing processing cycles (FTP). Subsequently, the lyophilized PVA10-c-PP was immersed in rapamycin (RPM)-loaded liposome solution until swelling equilibrated to obtain the anti-adhesion mesh RPM@LPS/PVA10-c-PP. It was demonstrated that the hydrogel coating can stably fix on the surface of PP mesh even after immersed in PBS solution at 37 °C or 40 °C for up to 30 days. In vitro cell tests revealed the excellent cytocompatibility and the potential to inhibit cell adhesion of the modified PP mesh. Moreover, the anti-adhesive effects of the RPM@LPS/PVA10-c-PP mesh was evaluated through in vivo experiments. The RPM@LPS/PVA10-c-PP mesh exhibited less adhesion than original PP mesh throughout the duration of implantation. At 30 days, the adhesion score of RPM@LPS/PVA10-c-PP mesh was 1.37 ± 0.75, however the original PP was 3 ± 0.71. Furthermore, the results of H&E and Masson trichrome staining proved that the RPM@LPS/PVA10-c-PP mesh showed slighter inflammation response and significant looser fibrous tissue surrounded the PP filaments as compared to the native PP. The current findings manifested that this type of RPM@LPS/PVA10-c-PP might be a potential candidate for anti-adhesion treatment. DATA AVAILABILITY: Data will be made available on request.

Development of amphiphile 4-armed PEO-based Ti4+ complex for highly selective enrichment of phosphopeptides.

Protein phosphorylation is a reversible and important post-translational modification. Identification of phosphopeptides without enrichment is difficult for the low-abundance of phosphopeptides in real complex biological samples. Therefore, the effective and selective concentration of phosphopeptides prior to proteomic identification by mass spectrometer is necessary. In this study, we synthesized a novel titanium-based immobilized metal ion affinity chromatography material for highly selective enrichment of phosphopeptides. To improve material hydrophilia to the maximum extent, titanium ions were immobilized on the 4-armed Poly(ethylene oxide)(4µ-PEO-Ti4+), a totally soluble polymer with large molecular weight (20000 g/mol). The 4µ-PEO-Ti4+ was used to enrich phosphopeptides from tryptic digests of standard proteins and real complex biological samples, followed by MALDI-TOF MS analysis. In enrichment of phosphopeptides from 4 pmol ß-casein, the 4µ-PEO-Ti4+ performed the best property with starting material of 99-132 µg, loading buffer of 50% ACN/5% TFA (v/v), elution buffer of 10% NH3·H2O (v/v) and elution time of 30 min. The 4µ-PEO-Ti4+ has a superior detection sensitivity as low as 2 fmol for phosphopeptides. The high selectivity of 4µ-PEO-Ti4+ allows a deep enrichment of phosphopeptides of ß-casein from a mixture with BSA of 1000-fold abundant. The 4µ-PEO-Ti4+ shows great stability and endurability and can be recycled up to at least 5 times. In addition, 4µ-PEO-Ti4+ could detect 10 and 15 phosphopeptides from non-fat milk and nonenzymatic human saliva, respectively. In total, 4µ-PEO-Ti4+ is a novel excellent material which shows great sensitive and selective enrichment of low-abundance phosphopeptides in real complex biological samples.

Effects of heavy metal wastewater on the anoxic/aerobic-membrane bioreactor bioprocess and membrane fouling.

Heavy metals have significant negative effects on anoxic/aerobic-membrane bioreactors (A/O-MBR). The changes in the performance of A/O-MBR fed with municipal wastewater containing 0.25-2.56 mg/L (low concentrations) and 3.7-32.3mg/L (high concentrations) of zinc, copper, lead, and cadmium were studied in this paper. The nitrification rate decreased to 27% and 46%, whereas the denitrification rate decreased to 20% and 34% under treatment with low/high concentrations of heavy metals, which indicate that heavy metals more significantly affect nitrification than denitrification. Heavy metals also resulted in the increase of carbohydrate of extracellular polymer substances and a smaller particle size distribution. Scanning electron microscope images, energy-dispersive X-ray spectroscopy and atomic absorption spectrometry analysis of fouled membranes showed solid inorganic scale deposits on the membrane. All these results suggest that heavy metals affect membrane fouling in two ways: (a) modification of sludge characteristics; and (b) contribution to inorganic fouling.

Poly(lactic acid)-coated mesoporous silica nanosphere for controlled release of venlafaxine.

Two types of mesoporous silica nanospheres (MSNs) were synthesized for use as controlled-release agents. One was prepared by grafting with 5,6-dihydroxyhexylsilane (DH-MSN) and the other one by further coating with cholic acid-crosslinked poly(lactic acid) (CA-PLA-MSN). We studied the release of the antidepressant venlafaxine from each of the materials in simulated gastric fluid (SGF), in simulated gastric acid solution (SGA), and in simulated intestinal fluid without pancreatin (SIF). The CA-PLA-MSN material was able to significantly delay the release of the drug in intestinal condition compared with gastric acid surrounding due to the fast decomposition rate of PLA in gastric acid. Moreover, it successfully avoided the initial burst to a certain extent in SGF. The enzyme pepsin played a favorable obstruct role in both DH-MSN and CA-PLA-MSN systems to reduce release rate. A model based on Weibull model was built to fit the release results, and based on it, the mechanisms about release processes were brought out tentatively.