Competitive Adsorption of a Monoclonal Antibody and Nonionic Surfactant at the PDMS/Water Interface.

Interfacial adsorption of monoclonal antibodies (mAbs) can cause structural deformation and induce undesired aggregation and precipitation. Nonionic surfactants are often added to reduce interfacial adsorption of mAbs which may occur during manufacturing, storage, and/or administration. As mAbs are commonly manufactured into ready-to-use syringes coated with silicone oil to improve lubrication, it is important to understand how an mAb, nonionic surfactant, and silicone oil interact at the oil/water interface. In this work, we have coated a polydimethylsiloxane (PDMS) nanofilm onto an optically flat silicon substrate to facilitate the measurements of adsorption of a model mAb, COE-3, and a commercial nonionic surfactant, polysorbate 80 (PS-80), at the siliconized PDMS/water interface using spectroscopic ellipsometry and neutron reflection. Compared to the uncoated SiO2 surface (mimicking glass), COE-3 adsorption to the PDMS surface was substantially reduced, and the adsorbed layer was characterized by the dense but thin inner layer of 16 Å and an outer diffuse layer of 20 Å, indicating structural deformation. When PS-80 was exposed to the pre-adsorbed COE-3 surface, it removed 60 wt % of COE-3 and formed a co-adsorbed layer with a similar total thickness of 36 Å. When PS-80 was injected first or as a mixture with COE-3, it completely prevented COE-3 adsorption. These findings reveal the hydrophobic nature of the PDMS surface and confirm the inhibitory role of the nonionic surfactant in preventing COE-3 adsorption at the PDMS/water interface.

Reactive Oxygen Species Triggered Oxidative Degradation of Polystyrene in the Gut of Superworms (Zophobas atratus Larvae).

Oxidative decomposition of polystyrene (PS) by insects has been previously demonstrated, yet little is known about the oxidation mechanism and its effect on the metabolism of plastics within the insect gut. Here, we demonstrate the generation of reactive oxygen species (ROS) in the gut of superworms (Zophobas atratus larvae) under different feeding trails, which in turn induced the oxidative decomposition of ingested PS. The ROS were commonly generated in the larva gut, and PS consumption resulted in a significant increase of ROS with a maximum ·OH of 51.2 µmol/kg, which was five times higher than in the bran feeding group. Importantly, scavenging of ROS significantly decreased the oxidative depolymerization of PS, indicating a vital role of ROS in effective PS degradation in the gut of superworms. Further investigation suggested that the oxidative depolymerization of PS was caused by the combinatorial effect of ROS and extracellular oxidases of gut microbes. These results demonstrate that ROS were extensively produced within the intestinal microenvironment of insect larvae, which greatly favored the digestion of ingested bio-refractory polymers. This work provides new insights into the underlying biochemical mechanisms of plastic degradation in the gut.

Adsorption and Desorption of Steroid Hormones by Microplastics in Seawater.

This study evaluated the adsorption and desorption of 17ß-estradiol (E2) and 17α-ethynylestradiol (EE2) on microplastics in seawater. The effects of microplastic materials and particle sizes on adsorption of E2 and EE2 were explored. Moreover, effects of salinity, pH, humic acid (HA) concentrations, and initial E2/EE2 concentrations on adsorption were also discussed. Increase in salinity, HA concentration, and initial E2/EE2 concentration would enhance adsorption of E2/EE2 on microplastics. Adsorption capacity of E2/EE2 firstly increased to reach the highest at pH of 8.0 and then decreased when pH further increased. Pseudo-second-order kinetics better fitted adsorption data of E2 while pseudo-first-order model yielded better fitting results for EE2. Freundlich isotherm was better to fit the adsorption data of E2 while Langmuir isotherm yielded better fitting results for EE2. Desorption capacity of E2/EE2 on microplastics was over 40% of its adsorption capacity. This study provides new insights on microplastics and endocrine disrupting chemicals.

Unique Bacterial Community of the Biofilm on Microplastics in Coastal Water.

Being immersed in seawater for a few days, microorganisms will adhere to the surface of different materials and form biofilms. After being immersed in seawater for 1 week, high-throughput sequencing method was used to analyze the bacterial community structure of the biofilms on the surface of microbeads with different materials including steel, SiO2, and polyvinyl chloride (PVC). Operational taxonomic unit clustering results showed that some differences existed in the bacterial communities attached to the surface of different microbeads. Each microbead made by different material had its unique bacterial community. The heatmap indicated that the dominant genera on the surface of different microbeads were different from each other. Quantitative analysis showed that the relative abundance of dominant genera were different among different types of microbeads. Beta diversity analysis and principal component analysis showed that difference in the bacterial community on surface of steel-bead and PVC-bead was the most significant.

Effects of Conventional Surfactants on the Activity of Designed Antimicrobial Peptide.

In this article, the interaction between a designed antimicrobial peptide (AMP) G(IIKK)3I-NH2 (G3) and four typical conventional surfactants (sodium dodecyl sulfonate (SDS), hexadecyl trimethyl ammonium bromide (C16TAB), polyoxyethylene (23) lauryl ether (C12EO23), and tetradecyldimethylamine oxide (C14DMAO)) has been studied through surface tension measurement and circular dichroism (CD) spectroscopy. The antimicrobial activities of AMP/surfactant mixtures have also been studied with Gram-negative Escherichia coli, Gram-positive Staphylococcus aureus, and the fungus Candida albicans. The cytotoxicity of the AMP/surfactant mixtures has also been assessed with NIH 3T3 and human skin fibroblast (HSF) cells. The surface tension data showed that the AMP/SDS mixture was much more surface-active than SDS alone. CD results showed that G3 conformation changed from random coil, to ß-sheet, and then to α-helix with increasing SDS concentration, showing a range of structural transformation driven by the different interactions with SDS. The antimicrobial activity of G3 to Gram-negative and Gram-positive bacteria decreased in the presence of SDS due to the strong interaction of electrostatic attraction between the peptide and the surfactant. The interactions between G3 and C16TAB, C12EO23, and C14DMAO were much weaker than SDS. As a result, the surface tension of surfactants with G3 did not change much, neither did the secondary structures of G3. The antimicrobial activities of G3 were little affected in the presence of C12EO23, slightly improved by C14DMAO, and clearly enhanced by cationic surfactant C16TAB due to its strong cationic and antimicrobial nature, consistent with their surface physical activities as binary mixtures. Although AMP G3 did not show activity to fungus, the mixtures of AMP/C16TAB and AMP/C14DMAO could kill C. albicans at high surfactant concentrations. The mixtures had rather high cytotoxicity to NIH 3T3 and HSF cells although G3 is nontoxic to cells. Cationic AMPs can be formulated with nonionic, cationic, and zwitterionic surfactants during product development, but care must be taken when AMPs are formulated with anionic surfactants, as the strong electrostatic interaction may undermine their antimicrobial activity.

Modulation of Antimicrobial Peptide Conformation and Aggregation by Terminal Lipidation and Surfactants.

The function and properties of peptide-based materials depend not only on the amino acid sequence but also on the molecular conformations. In this paper, we chose a series of peptides Gm(XXKK)nX-NH2 (m = 0, 3; n = 2, 3; X = I, L, and V) as the model molecules and studied the conformation regulation through N-terminus lipidation and their formulation with surfactants. The structural and morphological transition of peptide self-assemblies have also been investigated via transmission electron microscopy, atomic force microscopy, circular dichroism spectroscopy, and small-angle neutron scattering. With the terminal alkylation, the molecular conformation changed from random coil to ß-sheet or α-helix. The antimicrobial activities of alkylated peptide were different. C16-G3(IIKK)3I-NH2 showed antimicrobial activity against Streptococcus mutans, while C16-(IIKK)2I-NH2 and C16-G3(IIKK)2I-NH2 did not kill the bacteria. The surfactant sodium dodecyl sulfonate could rapidly induce the self-assemblies of alkylated peptides (C16-(IIKK)2I-NH2, C16-G3(IIKK)2I-NH2, C16-G3(VVKK)2V-NH2) from nanofibers to micelles, along with the conformation changing from ß-sheet to α-helix. The cationic surfactant hexadecyl trimethyl ammonium bromide made the lipopeptide nanofibers thinner, and nonionic surfactant polyoxyethylene (23) lauryl ether (C12EO23) induced the nanofibers much more intensively. Both the activity and the conformation of the α-helical peptide could be modulated by lipidation. Then, the self-assembled morphologies of alkylated peptides could also be further regulated with surfactants through hydrophobic, electrostatic, and hydrogen-bonding interactions. These results provided useful strategies to regulate the molecular conformations in peptide-based material functionalization.

Potential risks of microplastics combined with superbugs: Enrichment of antibiotic resistant bacteria on the surface of microplastics in mariculture system.

Microplastics have become emerging pollutants and served as potential vectors for harmful bacteria, while rare information on the emergency and propagation of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) on the surface of microplastics is available. This study investigated the enrichment of ARB, especially multi-antibiotic resistant bacteria (MARB), on the surface of microplastics in mariculture system. Polyethylene terephthalate accounted for the highest proportion (75%) in the collected microplastics. The counts of cultivable ARB in microplastic samples were 6.40 × 106-2.48 × 108 cfu/g, which were 100-5000 times higher than those in water samples. The ratios of cultivable ARB to total cultivable bacteria from microplastic samples were higher than those from water samples. High-throughput sequencing showed that the diversity and abundance of cultivable ARB in the microplastic samples was high with the predominant bacterial genera of Vibrio, Muricauda and Ruegeria. Total 160 MARB isolates were obtained and most of isolates were obtained from the microplastic samples. MARB isolates resisting or intermediating to four and three antibiotics accounted for much higher proportions in the microplastic samples, and the higher percentage of antibiotic resistance was to penicillin, sulfafurazole, erythromycin and tetracycline. The dominant multiple antibiotic resistance profile was TET-SFX-ERY-PEN, which accounted for 25.4% in microplastic samples and 23.9% in water samples. In typical MARB isolates, the positive detection rate of ARGs was up to 80.0% in microplastic samples while that was 65.3% in water samples. Five types of class 1 integrons (intI1) associated gene cassette arrays and seven types of gene cassettes were detected in microplastic samples, which were more than those in water samples. These results revealed that microplastics were hazardous pollutants for the enrichment of ARB, especially superbugs, and the spread of antibiotic resistance.

Recent Advances in Studying Interfacial Adsorption of Bioengineered Monoclonal Antibodies.

Monoclonal antibodies (mAbs) are an important class of biotherapeutics; as of 2020, dozens are commercialized medicines, over a hundred are in clinical trials, and many more are in preclinical developmental stages. Therapeutic mAbs are sequence modified from the wild type IgG isoforms to varying extents and can have different intrinsic structural stability. For chronic treatments in particular, high concentration (≥ 100 mg/mL) aqueous formulations are often preferred for at-home administration with a syringe-based device. MAbs, like any globular protein, are amphiphilic and readily adsorb to interfaces, potentially causing structural deformation and even unfolding. Desorption of structurally perturbed mAbs is often hypothesized to promote aggregation, potentially leading to the formation of subvisible particles and visible precipitates. Since mAbs are exposed to numerous interfaces during biomanufacturing, storage and administration, many studies have examined mAb adsorption to different interfaces under various mitigation strategies. This review examines recent published literature focusing on adsorption of bioengineered mAbs under well-defined solution and surface conditions. The focus of this review is on understanding adsorption features driven by distinct antibody domains and on recent advances in establishing model interfaces suitable for high resolution surface measurements. Our summary highlights the need to further understand the relationship between mAb interfacial adsorption and desorption, solution aggregation, and product instability during fill-finish, transport, storage and administration.

Histological response to combination therapy with nucleos(t)ide analogs and peginterferon alpha in treatment-naïve chronic hepatitis B patients.

Although nucleos(t)ide analog (NA) monotherapy is effective in hepatitis B virus suppression and fibrosis regression, serological response rates are not satisfactory. Studies assessing the benefits of combination therapy with NAs and peginterferon alpha (PegIFNα) in patients with chronic hepatitis B (CHB) have produced conflicting results and mainly focused on serological outcomes. Histological changes in response to combination therapy have not been evaluated in real-world practice. This study aimed to evaluate the histological changes in response to NA-PegIFNα combination therapy in CHB patients and to comprehensively compare the efficacy of NA-PegIFNα combination therapy and NA monotherapy. We conducted a retrospective analysis of data from 40 CHB patients who underwent either NA-PegIFNα combination therapy or NA monotherapy. Changes in histology at 48 weeks after treatment initiation were evaluated. Serological characteristics were also analysed and compared between the NA-PegIFNα combination therapy and NA monotherapy groups and between histological responders and nonresponders. Compared to baseline biopsies, both fibrosis staging and necroinflammatory grading scores were significantly lower in the second biopsies examined post-treatment in both groups. Nearly all patients experienced a reduction in inflammation (87.5% in both groups), but there was a subgroup of patients who exhibited either no significant improvement or fibrosis progression (33.3% and 31.2% in the NA monotherapy and NA-PegIFNα combination therapy groups, respectively). Nearly, all patients achieved ALT normalization and sustained virological response (SVR) after 48 weeks of antiviral treatment. Approximately one-third of individuals (36.8% and 30% in the two groups, respectively) achieved HBeAg loss at 48 weeks after treatment initiation. Although there were no significant differences in overall rates of histological, biochemical, virological and serological responses between the two groups, an earlier virological response and a higher cumulative SVR rate over time were observed during long-term follow-up in patients treated with NA-PegIFNα combination therapy (P = 0.0129). Trends of more rapid HBeAg loss and a higher cumulative HBeAg loss rate throughout long-term follow-up were also observed but were not statistically significant. The ALT normalization rates at 24 and 48 weeks after treatment initiation were associated with the histological response. Significant regression of fibrosis and resolution of necroinflammation were induced with either NA-PegIFNα combination therapy or NA monotherapy. Significant biochemical, virological and serological responses were observed in both groups, and the response rates at 48 weeks were similar in the two groups. Over time during long-term follow-up, the virological and serological responses were faster and superior following the combination regimen.

Histological responses of peginterferon alpha add-on therapy in patients with chronic hepatitis B with advanced liver fibrosis after long-term nucleos(t)ide analog treatment.

Although long-term antiviral treatment with nucleos(t)ide analogs (NAs) can lead to histological improvement in patients with chronic hepatitis B (CHB), a substantial proportion of patients still fail to achieve regression of fibrosis. Here, we investigated whether peginterferon alpha (Peg-IFNα） add-on therapy had benefits on fibrosis regression in patients with sustained severe fibrosis even after long-term NA treatment. We conducted a retrospective analysis of data from 50 patients with CHB receiving 48 weeks of Peg-IFNα add-on therapy. All enrolled patients had advanced fibrosis or cirrhosis (S score ≥ 3) at baseline and underwent NA treatment for at least 1 year before Peg-IFNα addition. Paired liver biopsies before and after Peg-IFNα add-on treatment and laboratory tests at baseline, 24 weeks of treatment, 48 weeks of treatment and long-term follow-up were analysed. Of the 50 patients enrolled in this study, 34 patients (68.0%) had significant regression of fibrosis, and 42 (84.0%) showed significant remission of inflammation after Peg-IFNα add-on treatment. Compared with nonresponders, patients with significant histological improvement showed faster hepatitis B surface antigen (HBsAg) decline and tended to have higher cumulative hepatitis B e antigen (HBeAg) and HBsAg loss rates during long-term follow-up. Peg-IFNα add-on therapy led to significant regression of fibrosis and resolution of inflammation in patients with advanced fibrosis after long-term NA treatment.

One-Step Fabrication of Bio-Compatible Coordination Complex Film on Diverse Substrates for Ternary Flexible Memory.

Recently, resistance random access memories (RRAMs) have been studied extensively, because the demand for information storage is increasing. However, it remains challenging to obtain a flexible device because the active materials involved need to be nontoxic, nonpolluting, distortion-tolerable, and biodegradable as well adhesive to diverse flexible substrates. In this paper, tannic acid (TA) and an iron ion (FeIII ) coordination complex were employed as the active layer in a sandwich-like (Al/active layer/substrate) device to achieve memory performance. A nontoxic, biocompatible TA-FeIII coordination complex was synthesized by a one-step self-assembly solution method. The retention time of the TA-FeIII memory performance was up to 15 000 s, the yield up to 53 %. Furthermore, the TA-FeIII coordination complex can form a high-quality film and shows stable ternary memory behavior on various flexible substrates, such as polyethylene terephthalate (PET), polyimide (PI), printer paper, and leaf. The device can be degraded by immersing it in vinegar solution. Our work will broaden the application of organic coordination complexes in flexible memory devices with diverse substrates.

Reversible Thermoresponsive Peptide-PNIPAM Hydrogels for Controlled Drug Delivery.

Mixed thermoreversible gels were successfully fabricated by the addition of a thermosensitive polymer, poly(N-isopropylacrylamide) (PNIPAM), to fibrillar nanostructures self-assembled from a short peptide I3K. When the temperature was increased above the lower critical solution temperature of the PNIPAM, the molecules collapsed to form condensed globular particles, which acted as cross-links to connect different peptide nanofibrils and freeze their movements, resulting in the formation of a hydrogel. Since these processes were physically driven, such hydrogels could be reversibly switched between the sol and gel states as a function of temperature. As a model peptide, I3K was formulated with PNIPAM to produce a thermoreversible sol-gel system with a transition temperature of ∼33 °C, which is just below the body temperature. The antibacterial peptide of G(IIKK)3I-NH2 could be conveniently encapsulated in the hydrogel by the addition of the solution at lower temperatures in the sol phase and then increasing the temperature to be above 33 °C for gelation. The hydrogel gave a sustained and controlled linear release of G(IIKK)3I-NH2 over time. Using the peptide nanofibrils as three-dimensional scaffolds, such thermoresponsive hydrogels mimic the extracellular matrix and could potentially be used as injectable hydrogels for minimally invasive drug delivery or tissue engineering.

Sustained serological and complete responses in HBeAg-positive patients treated with Peginterferon alfa-2b: a 6-year long-term follow-up of a multicenter, randomized, controlled trial in China.

BACKGROUND: Pegylated interferon (PEG-IFN) alfa-2b is recommended for chronic hepatitis B (CHB). We aimed to investigate the sustainability of off-treatment responses among Chinese HBeAg-positive CHB patients treated with PEG-IFN alfa-2b from a randomized trial. METHODS: Eligible Chinese patients (n = 322) were followed up by one visit after a median of 6 years (LTFU) following their participation in a randomized trial evaluating the efficacy of three PEG-IFN alfa-2b dosing regimens (1.0 or 1.5 µg/kg/wk. 24 weeks or 1.5 µg/kg/wk. 48 weeks). Primary endpoints at the LTFU were sustained SR and CR (SR/CR at the end of original study [EOS] and at the LTFU). SR was defined as HBeAg loss and seroconversion to anti-HBe and CR as HBeAg loss and seroconversion to anti-HBe and HBV-DNA < 2000 IU/mL. RESULTS: The proportions of patients achieving sustained SR among patients who had SR at EOS were high in three treatment groups (61.9, 65.5, 76.5%, respectively, p = 0.46); treatment with PEG-IFN alfa-2b 1.5 µg/kg/wk. 48 weeks had the highest proportion of a sustained CR among patients who had CR at EOS (75.0%, p = 0.05). A considerable number of patients achieved sustained SR (18.2-29.9%) and sustained CR (14.8-18.3%) after EOS despite no further NA treatment. At the LTFU, rates of SR and CR were less than 70.0 and 50.0%, respectively, among all enrolled patients regardless of additional nucleos(t)ide analogs before the LTFU. CONCLUSIONS: PEG IFN alfa-2b therapy had considerable off-treatment sustainability in Chinese HBeAg positive chronic hepatitis B patients with serological and complete responses.

Effects of microplastics on distribution of antibiotic resistance genes in recirculating aquaculture system.

Microplastics and antibiotic resistance genes (ARGs) are two kinds of emerging contaminants with frequent detection in coastal regions. However, rare information on co-occurrence of microplastics and ARGs in coastal recirculating aquaculture system (RAS) is available. This study performed field sampling and laboratory analysis to investigate the distribution of microplastics and ARGs in a typical RAS farm. The results showed that microplastics were detected in all water samples with the abundances ranging from 58 to 72 items/m3. Absolute abundances of total 10 ARGs in water samples ranged from 3.24 × 105 to 7.83 × 105 copies/mL while those on microplastic samples were in the range of 1.59 × 109-1.83 × 109 copies/g. Microbial communities of microplastics and water showed significant difference at both phylum and genus levels. Microbial community diversity of microplastics was higher than that of water. ARGs including tetG, qnrS, sul1, sul2, and ermF possessed relatively more active relationships with bacterial community in water and on microplastics of the RAS farm. The results suggested that microplastics might be an important reservoir of ARGs in RAS farms. The findings of this study will provide useful information on pollution control and environmental management for both microplastics and ARGs in coastal aquaculture systems.

Adsorptive removal of bisphenol A, chloroxylenol, and carbamazepine from water using a novel ß-cyclodextrin polymer.

The emerging organic micro-pollutants, such as bisphenol A (BPA), chloroxylenol (PCMX) and carbamazepine (CBZ), have raised concerns owing to their adverse impact on human health and ecological security. In this study, a novel cyclodextrin polymer (ß-CDP) has been successfully prepared by nucleophilic substitution of ß-cyclodextrin with tetrafluoroterephthalonitrile (TFP). The removal of three emerging organic micro-pollutants (BPA, CBZ and PCMX) by ß-CDP under a single or mixture adsorption system was examined, and the adsorption behavior was investigated by adsorption kinetics and isotherm study. The maximum adsorption capacity of ß-CDP for BPA, PCMX and CBZ according to Langmuir isotherm in single system was 164.4, 144.1 and 136.4 mg/g, respectively. Compared with single system, the competitive adsorption of each pollutant on ß-CDP in mixture system was only slightly inhibited. Changing the pH, raising the presence of fulvic acid (FA) or ionic strength had no significant influence on the adsorption of BPA, PCMX and CBZ onto ß-CDP. The removal of these three organic micro-pollutants was related to the value of logKow of the contaminants. These results demonstrated remarkable advantages of ß-CDP material relevant to organic micro-pollutants removal in wastewater treatment.

Efficient production and characterization of homopolymeric poly(3-hydroxyvalerate) produced by Bacillus strain PJC48.

Aliphatic polyester, poly(3-hydroxyvalerate) (PHV), is commonly produced as a granular component in bacterial cells of various species. Based on 16S rDNA gene sequence analysis, strain PJC48 was identified as a Bacillus species. The current study is aimed to screen for a high-yield strain that can produce PHV efficiently and to increase PHV product yield by optimizing the fermentative process. We identified a high-producer strain based on Nile red staining. Characterization of the PHV produced by PJC48 by nuclear magnetic resonance spectroscopy revealed that it consisted of (R)-3-hydroxyvalerate monomers. The suggested model was validated by response surface methodology. Optimization of the PHV yield resulted in an increase of 32.75% compared to control, with a maximum production of 1.64 g/L after 48 H.

Promotion of neuronal regeneration by using self-polymerized dendritic polypeptide scaffold for spinal cord tissue engineering.

Tissue engineering technology is applicable for study of nerve regeneration after spinal cord injury. Many natural and artificial scaffold are not applicable because of poor mechanical properties and cell compatibility. Polypeptides with fine three-dimensional structure and cell compatibility and are widely used in tissue engineering research. The purpose of this study was to verify the neuronal differentiation of neural stem cells by using self-polymerize dendritic polypeptide for spinal cord tissue engineering. Neural stem cells were isolated from cerebral cortex of neonatal SD rats.Conventional media was triggered the 1wt% nano peptide solution self polymerizated to formed a nano gel. The gel was tested by scanning electron microscope and transmission electron microscope. Neural stem cells were inoculated onto gel or on Polylysine-coated slides with fetal bovine serum or not. SD rats were randomized divided into four groups. neural stem cells and self-polymerized peptide were transplanted into spinal cord injury models. Then we test the Density of NF-positive axons in the spinal cord injury area at 8 weeks after surgery and MS score of the locomotive function of hind limbs among mice of four groups. Neural stem cells were showed anti Nestin (+), anti NSE (+), anti GFAP (+). The gel tested by scanning electron microscope was showed thick wall structure, another one tested by transmission electron microscope was showed self-polymerized dendritic nanofibers, which contains several spacings. The cells in serum group were differentiate into neurons, but non serum group were not. These results suggest that the self-assembling peptide nanofiber scaffold(SAPNS) were cytocompatible to neural stem cells which were differentiated into neurons. A large number of axonal regeneration and recovery of joint function of hind limb were appeared. The self-polymerized Peptide maybe used as practical tissue engineering materials as future.

Patterned Thermoresponsive Microgel Surfaces to Control Cell Detachment.

The aim of this work is to examine how adhered individual cells could detach from the patterned, discontinuous thermoresponsive coating substrate and how different patterns in the form of thermoresponsive squares and gaps would affect cell detachment. Microgels prepared from copolymerization of N-isopropylacrylamide and styrene (pNIPAAmSt) were spin-coated on polyethylenimine (PEI) precoated glass coverslips to form a uniform microgel monolayer; then a surface-moisturized PMDS stamp was used to contact the microgel monolayer at room temperature. The thin layer of water on the PDMS stamp surface worked as an ink to penetrate the microgels so that any microgels in direct contact with the wet stamp surface became swollen and could be peeled away, while uncontacted microgels formed patterns. Using this method, various patterns with different thermo-island diameters and gaps could be fabricated. NIH3T3 fibroblast cells were then cultured on these patterns to study their detachment behavior. It was found that cells could detach not only from these discontinuous thermoresponsive coatings, but also from the patterned surfaces with the thermoresponsive area being as low as 20% of the cell spread area.

Mass Continuous Suture versus Layered Interrupted Suture in Transverse Abdominal Incision Closure after Liver Resection.

BACKGROUND: Abdominal incision closure technique seriously influences patient prognosis. Most studies have focused on the different suture techniques and materials on midline incision, while little data are available in wide transverse or oblique incisions after liver resection (LR). The aim of the present study is to compare the two major incision suture methods after LR in our institute: Mass continuous suture (group P) and layered interrupted suture (group S). STUDY DESIGN: 258 patients undergoing LR with abdominal transverse or oblique incisions were prospectively enrolled. They were divided into two groups according to different abdominal incision suture methods and compared with the preoperative, intraoperative parameters, and postoperative wound complications. RESULTS: There were 118 patients in group P and 140 patients in group S, which was similar in general condition, primary disease, liver, and renal function. Incision length, total operation time, intraoperative blood loss, or perioperative antibiotics use were not different between the two groups. However, abdominal incision closure time and interval time for stitches removing after operation was significantly shorter in group P than group S (both p < 0.001). After a median follow-up of 16 months, the incidence of wound infection and fat liquefaction was more than two times higher in group S than group P, which, however, was not statistically different. Moreover, there was no difference in wound disruption or incisional hernia between the two groups. CONCLUSIONS: Although similar in occurrence of postoperative wound complications, mass continuous suture with polydioxanone seemed to be more timesaving in incision closure and motivated in wound healing.

Novel synthesis strategy for composite hydrogel of collagen/hydroxyapatite-microsphere originating from conversion of CaCO3 templates.

Inspired by coralline-derived hydroxyapatite, we designed a methodological route to synthesize carbonated-hydroxyapatite microspheres from the conversion of CaCO3 spherulite templates within a collagen matrix under mild conditions and thus constructed the composite hydrogel of collagen/hydroxyapatite-microspheres. Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) were employed to confirm the successful generation of the carbonated hydroxyapatite phase originating from CaCO3, and the ratios of calcium to phosphate were tracked over time. Variations in the weight portion of the components in the hybrid gels before and after the phase transformation of the CaCO3 templates were identified via thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) shows these composite hydrogels have a unique multiscale microstructure consisting of a collagen nanofibril network and hydroxyapatite microspheres. The relationship between the hydroxyapatite nanocrystals and the collagen fibrils was revealed by transmission electron microscopy (TEM) in detail, and the selected area electron diffraction (SAED) pattern further confirmed the results of the XRD analyses which show the typical low crystallinity of the generated hydroxyapatite. This smart synthesis strategy achieved the simultaneous construction of microscale hydroxyapatite particles and collagen fibrillar hydrogel, and appears to provide a novel route to explore an advanced functional hydrogel materials with promising potentials for applications in bone tissue engineering and reconstruction medicine.