Antibacterial Iodine-Releasing Coatings of Cross-Linked Poly(N-vinylpyrrolidone) Synthesized by Solvent-Free Initiated Chemical Vapor Deposition.

Biomaterial-associated infections caused by bacteria pose a great threat to human health, and therefore, various antibacterial coatings have been developed to control bacterial infections. Povidone iodine (PVP-I) is a broad-spectrum antimicrobial agent without drug resistance to most pathogenic microorganisms and has been widely used in the clinic. However, its applications in the field of coatings are limited due to its strong water solubility. Here, we used initiated Chemical Vapor Deposition (iCVD) technique to synthesize cross-linked poly(N-vinylpyrrolidone-co-ethylene glycol dimethacrylate) (PVE) coatings to firmly immobilize poly(N-vinylpyrrolidone) (PVP) on surfaces. After complexation with iodine, PVE-I coatings exhibited potent bacteria-killing and antifouling activities against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus in vitro owing to the antibacterial effect of iodine and the hydrophilicity of VP, respectively. The killing and antifouling effects were positively correlated with the VP content. The PVE-I-2 coating displayed excellent anti-infection performance in a rat subcutaneous implantation model in vivo. This study provided a simple method for preparing stable povidone iodine coatings on surfaces via solvent-free iCVD, and combined bacteria-killing and antifouling strategies to fabricate multifunctional antibacterial coatings against bacterial infections on biomaterial surfaces.

Degradation mechanism of lignocellulose in dairy cattle manure with the addition of calcium oxide and superphosphate.

Cellulose and lignin belongs to refractory organic matters in the traditional composting. In this research, the degradation of lignocellulose in dairy cattle manure was investigated through adding calcium oxide (CaO) and superphosphate (SSP). In the presence of CaO and SSP, the degradation rate of cellulose and lignin were improved by 25.0% and 8.33%, respectively. The results indicated that the pH value in system would be slightly higher with the addition of CaO and SSP. Besides, the pH value of all cow manure piles were about 8.4 after composting rotten, which could be well neutralized by the gradually acidified soil in the southwest of China with the full effect of fertilizer released. In addition, the abundance of Bacillales, Actinomycetes, and Thermoactinomycetaceae in the experimental groups (AR) was slightly better than that in the control groups (CK) during composting, which led to a conclusion that an elaborate physical-chemical-multivariate aerobic microorganism evolution model of cellulose degradation products (PCMC) was deduced and the physical-chemical-multivariate aerobic microorganism model of lignin cycle degradation (PCML) was developed.

Investigation on extracellular polymeric substances, sludge flocs morphology, bound water release and dewatering performance of sewage sludge under pretreatment with modified phosphogypsum.

Modified phosphogypsum (MPG) was developed to improve dewaterability of sewage sludge, and dewatering performance, properties of treated sludge, composition and morphology distribution of EPS, dynamic analysis and multiple regression model on bound water release were investigated. The results showed that addition of MPG caused extracellular polymeric substances (EPS) disintegration through charge neutralization. Destruction of EPS promoted the formation of larger sludge flocs and the release of bound water into supernatant. Simultaneously, content of organics with molecular weight between 1000 and 7000 Da in soluble EPS (SB-EPS) increased with increasing of EPS dissolved into the liquid phase. Besides, about 8.8 kg•kg-1DS of bound water was released after pretreatment with 40%DS MPG dosage. Additionally, a multiple linear regression model for bound water release was established, showing that lower loosely bond EPS (LB-EPS) content and specific resistance of filtration (SRF) may improve dehydration performance, and larger sludge flocs may be beneficial for sludge dewatering.

Pre-clinical evaluation of a nanoparticle-based blood-pool contrast agent for MR imaging of the placenta.

INTRODUCTION: Non-invasive 3D imaging that enables clear visualization of placental margins is of interest in the accurate diagnosis of placental pathologies. This study investigated if contrast-enhanced MRI performed using a liposomal gadolinium blood-pool contrast agent (liposomal-Gd) enables clear visualization of the placental margins and the placental-myometrial interface (retroplacental space). Non-contrast MRI and contrast-enhanced MRI using a clinically approved conventional contrast agent were used as comparators. MATERIALS AND METHODS: Studies were performed in pregnant rats under an approved protocol. MRI was performed at 1T using a permanent magnet small animal scanner. Pre-contrast and post-liposomal-Gd contrast images were acquired using T1-weighted and T2-weighted sequences. Dynamic Contrast enhanced MRI (DCE-MRI) was performed using gadoterate meglumine (Gd-DOTA, Dotarem®). Visualization of the retroplacental clear space, a marker of normal placentation, was judged by a trained radiologist. Signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were calculated for both single and averaged acquisitions. Images were reviewed by a radiologist and scored for the visualization of placental features. Contrast-enhanced CT (CE-CT) imaging using a liposomal CT agent was performed for confirmation of the MR findings. Transplacental transport of liposomal-Gd was evaluated by post-mortem elemental analysis of tissues. Ex-vivo studies in perfused human placentae from normal, GDM, and IUGR pregnancies evaluated the transport of liposomal agent across the human placental barrier. RESULTS: Post-contrast T1w images acquired with liposomal-Gd demonstrated significantly higher SNR (p = 0.0002) in the placenta compared to pre-contrast images (28.0 ± 4.7 vs. 6.9 ± 1.8). No significant differences (p = 0.39) were noted between SNR in pre-contrast and post-contrast liposomal-Gd images of the amniotic fluid, indicating absence of transplacental passage of the agent. The placental margins were significantly (p < 0.001) better visualized on post-contrast liposomal-Gd images. DCE-MRI with the conventional Gd agent demonstrated retrograde opacification of the placenta from fetal edge to the myometrium, consistent with the anatomy of the rat placenta. However, no consistent and reproducible visualization of the retroplacental space was demonstrated on the conventional Gd-enhanced images. The retroplacental space was only visualized on post-contrast T1w images acquired using the liposomal agent (SNR = 15.5 ± 3.4) as a sharply defined, hypo-enhanced interface. The retroplacental space was also visible as a similar hypo-enhancing interface on CE-CT images acquired using a liposomal CT contrast agent. Tissue analysis demonstrated undetectably low transplacental permeation of liposomal-Gd, and was confirmed by lack of permeation through a perfused human placental model. CONCLUSIONS: Contrast-enhanced T1w-MRI performed using liposomal-Gd enabled clear visualization of placental margins and delineation of the retroplacental space from the rest of the placenta; the space is undetectable on non-contrast imaging and on post-contrast T1w images acquired using a conventional, clinically approved Gd chelate contrast agent.

A thermoresponsive supramolecular copolymer hydrogel for the embolization of kidney arteries.

Our team has previously reported a high strength thermoplastic supramolecular polymer hydrogel. However, the hydrogel required injection temperatures outside the physiological range therefore preventing its use in a living environment. In this article, we reported a thermoresponsive supramolecular copolymer hydrogel p(N-acryloyl glycinamide-co-acrylamide) (PNAGA-PAAm), which can be injected at temperatures within the physiological range. We used rheological measurements to demonstrate that the transition temperature (upper critical solution temperature) of both the moduli and gel-sol could be finely adjusted by controlling both the ratio and concentration of the monomer. Adding iohexol (contrast agent) in PNAGA-PAAm hydrogels contributed to the decreased moduli and gel-sol transition temperature due to weakening of the hydrogen bonding interactions. The cytocompatible and hemocompatible PNAGA-PAAm sol mixed with iohexol was injected into the renal arteries of rabbits through a microcatheter at a temperature within the high biological range. The transition from the injection temperature (high biological range) to body temperature (basal for the animals) quickly solidified the embolic agent without the occurrence of dehydration, therefore overcoming the main limitation of LCST-typed poly(N-isopropylacrylamide) previously reported. Angiography and histological examination demonstrated the successful embolization of both renal arteries and no recanalization was observed after 8 weeks. The PNAGA-based supramolecular copolymer hydrogel is a novel embolic agent that allows for the occlusion of larger sized arteries in a biocompatible environment.