Internal Concentration Polarization in the Polyamide Active Layer of Thin-Film Composite Membranes.

A free-standing polyamide (PA) film is fabricated via in situ release from a thin-film composite (TFC) membrane achieved through the removal of the polysulfone support. The structure parameter S of the PA film is measured to be 24.2 ± 12.6 µm, which is about 87-fold of its film thickness. A significant decline in water flux of the PA film from an ideal forward osmosis membrane is observed. We find that the decline is predominantly influenced by the internal concentration polarization (ICP) of the PA film based on our experimental measurements and theoretical calculations. We propose that the asymmetric hollow structures of the PA layer with dense crusts and cavities may be the underlying cause of the occurrence of the ICP. More importantly, the structure parameter of the PA film can be reduced and its ICP effect can be mitigated by tuning its structures with fewer and shorter cavities. Our results for the first time provide experimental evidence to prove that the PA layer of the TFC membrane has the ICP effect, which could potentially provide fundamental insights into the influence of structural properties of PA on the membrane separation performance.

A retrospective study of iRoot BP Plus pulpotomy compared with Vitapex pulpectomy for irreversible pulpitis of primary molars with the presence of coronal pulp tissue.

BACKGROUND: Pulpotomy has been successfully performed in immature and mature permanent teeth with irreversible pulpitis but rarely in primary teeth. AIM: To evaluate the outcomes of iRoot BP Plus pulpotomy and Vitapex pulpectomy in primary molars with irreversible pulpitis. DESIGN: We selected 130 primary molars of 99 patients, aged 3-7 years, diagnosed with irreversible pulpitis with coronal pulp tissue and treated with iRoot BP Plus pulpotomy or Vitapex pulpectomy (median follow-up period: 18 months). They were divided into the pulpotomy (n = 88) and pulpectomy (n = 42) groups according to treatment procedure. The pulpotomy group was further divided into asymptomatic (n = 46) and symptomatic (n = 42) subgroups according to preoperative symptoms. The chi-squared test and Cox regression were performed to analyze the outcomes. RESULTS: Clinical and radiographic success rates were significantly higher in the pulpotomy group (98.9% and 95.5%) than in the pulpectomy group (88.1% and 54.8%) and did not differ significantly between asymptomatic and symptomatic pulpotomy subgroups. CONCLUSION: Irreversible pulpitis of primary molars with coronal pulp tissue can be successfully treated with iRoot BP Plus pulpotomy. Early intraradicular resorption of materials is the main adverse outcome of Vitapex pulpectomy.

Advances in Algin and Alginate-Hybrid Materials for Drug Delivery and Tissue Engineering.

In this review, we aim to provide a summary of recent research advancements and applications of algin (i.e., alginic acid) and alginate-hybrid materials (AHMs) in medical fields. Algin/alginate are abundant natural products that are chemically inert and biocompatible, and they have superior gelation properties, good mechanical strengths, and biodegradability. The AHMs have been widely applied in wound dressing, cell culture, tissue engineering, and drug delivery. However, medical applications in different fields require different properties in the AHMs. The drug delivery application requires AHMs to provide optimal drug loading, controlled and targeted drug-releasing, and/or visually guided drug delivery. AHMs for wound dressing application need to have improved mechanical properties, hydrophilicity, cell adhesion, and antibacterial properties. AHMs for tissue engineering need improved mechanical properties that match the target organs, superior cell affinity, and cell loading capacity. Various methods to produce AHMs that meet different needs were summarized. Formulations to form AHMs with improved stability, drug/cell-loading capacity, cell adhesion, and mechanical properties are active research areas. This review serves as a road map to provide insights into the strategies to develop AHMs in medical applications.

Soft materials as biological and artificial membranes.

The past few decades have seen emerging growth in the field of soft materials for synthetic biology. This review focuses on soft materials involved in biological and artificial membranes. The biological membranes discussed here are mainly those involved in the structure and function of cells and organelles. As building blocks in medicine, non-native membranes including nanocarriers (NCs), especially liposomes and DQAsomes, and polymeric membranes for scaffolds are constructed from amphiphilic combinations of lipids, proteins, and carbohydrates. Artificial membranes can be prepared using synthetic, soft materials and molecules and then incorporated into structures through self-organization to form micelles or niosomes. The modification of artificial membranes can be realized using traditional chemical methods such as click reactions to target the delivery of NCs and control the release of therapeutics. The biomembrane, a lamellar structure inlaid with ion channels, receptors, lipid rafts, enzymes, and other functional units, separates cells and organelles from the environment. An active domain inserted into the membrane and organelles for energy conversion and cellular communication can target disease by changing the membrane's composition, structure, and fluidity and affecting the on/off status of the membrane gates. The biological membrane targets analyzing pathological mechanisms and curing complex diseases, which inspires us to create NCs with artificial membranes.

Exposure and respiratory infection risk via the short-range airborne route.

Leading health authorities have suggested short-range airborne transmission as a major route of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). However, there is no simple method to assess the short-range airborne infection risk or identify its governing parameters. We proposed a short-range airborne infection risk assessment model based on the continuum model and two-stage jet model. The effects of ventilation, physical distance and activity intensity on the short-range airborne exposure were studied systematically. The results suggested that increasing physical distance and ventilation reduced short-range airborne exposure and infection risk. However, a diminishing return phenomenon was observed when the ventilation rate or physical distance was beyond a certain threshold. When the infectious quantum concentration was less than 1 quantum/L at the mouth, our newly defined threshold distance and threshold ventilation rate were independent of quantum concentration. We estimated threshold distances of 0.59, 1.1, 1.7 and 2.6 m for sedentary/passive, light, moderate and intense activities, respectively. At these distances, the threshold ventilation was estimated to be 8, 20, 43, and 83 L/s per person, respectively. The findings show that both physical distancing and adequate ventilation are essential for minimising infection risk, especially in high-intensity activity or densely populated spaces.

Gut Organoid as a New Platform to Study Alginate and Chitosan Mediated PLGA Nanoparticles for Drug Delivery.

Intestinal organoids can be used as an ex vivo epithelial model to study different drug delivery effects on epithelial cells' luminal surface. In this study, the impact of surface charge on the delivery of 5-ASA loaded PLGA nanoparticles into the lumen of organoids was investigated. Alginate and chitosan were used to coat the nanoparticles and provide negative and positive charges on the particles, respectively. The organoid growth and viability were not affected by the presence of either alginate- or chitosan-coated nanoparticles. It was shown that nanoparticles could be transported from the serosal side of the organoids to the lumen as the dye gradually accumulated in the lumen by day 2-3 after adding the nanoparticles to the Matrigel. By day 5, the dye was eliminated from the lumen of the organoids. It was concluded that the positively charged nanoparticles were more readily transported across the epithelium into the lumen. It may be attributed to the affinity of epithelial cells to the positive charge. Thus, the organoid can be utilized as an appropriate model to mimic the functions of the intestinal epithelium and can be used as a model to evaluate the benefits of nanoparticle-based drug delivery.

INTRAOCULAR APPLICATION OF FIBRIN GLUE AS AN ADJUNCT TO PARS PLANA VITRECTOMY FOR RHEGMATOGENOUS RETINAL DETACHMENT.

PURPOSE: To evaluate the efficacy of intraocular application of fibrin glue to seal the retinal breaks during standard pars plana vitrectomy for primary rhegmatogenous retinal detachment. METHODS: Twenty-six eyes of 26 rhegmatogenous retinal detachment patients were included in the study. Fibrin glue was used to seal the retinal breaks during standard pars plana vitrectomy in all 26 eyes. Each eye was completely filled with a balanced saline solution at the end of the surgery. The success rate of the reattachment surgery, change in best-corrected visual acuity, intraocular pressure, and occurrence of intraoperative and postoperative complications were recorded and analyzed. RESULTS: All eyes, with a mean age of 45.1 ± 18.3 years, were treated with pars plana vitrectomy surgery. During pars plana vitrectomy surgery, the fibrin glue showed excellent adherence and compliance to the retina. The glue was no longer visible through ultrasound scan 14.85 ± 4.56 days after surgery. The retinal breaks were sealed completely, and retina attached in all 26 eyes with no occurrence of rhegmatogenous retinal detachment during the follow-up period. The best-corrected visual acuity at 6 months after operation was significantly improved from preoperation best-corrected visual acuity. After operation, two eyes (2/26) developed an epiretinal membrane. Although three eyes (3/26) had a transient increased intraocular pressure during the 1st week after surgery, the intraocular pressure lowered to the normal range after the application of timolol. One eye (1/26) required daily topical antiglaucoma drops to lower the intraocular pressure. No adverse effects of fibrin glue were observed. CONCLUSION: The fibrin glue provided a superior adhesive effect for sealing retinal breaks, while showing no additional adverse effects. It is a worthy alternative to gas tamponade for rhegmatogenous retinal detachment vitrectomy surgery.

Preoperative Computed Tomography-Guided Localization for Pulmonary Nodules with Glue and Dye.

BACKGROUND: This study was aimed to describe a new localization technique developed using medical glue and methylene blue dye, and characterized the localization results and postoperative outcome to evaluate its safety and usefulness. METHODS: This retrospective study was conducted at our center from January 2016 to April 2018. Totally 346 consecutive patients with 383 nodules who underwent preoperative computed tomography (CT)-guided medical glue and methylene blue dye localization, followed by lung resection, were enrolled in this study. RESULTS: Mean nodule size was 7.7 ± 3.7 mm (range: 2-30 mm), with a mean depth from pleura or fissure of 9.4 ± 9.3 mm (range: 0-60 mm). The success rate of CT-guided localization for pulmonary nodules was 99.5% (381/383) of the nodules. Localization-related complications included mild pneumothorax in 16 (4.6%) patients, mild hemothorax in 7 (2.0%) patients, and hemoptysis in 1 (0.3%) patient. Pleural reaction occurred in 7 (2.0%) and pain in 25 (7.2%) patients. All 383 nodules were resected successfully, with conversion to thoracotomy only required in two patients for adhesion and calcification of lymph nodes. All patients recovered well postoperatively, with a short postoperative hospital stay (3.7 ± 2.0 days) and a low complication rate (2.6%, 9/346). CONCLUSION: CT-guided medical glue and methylene blue dye localization prior to video-assisted thoracoscopic surgery (VATS) lung resection was a novel, safe, and technically feasible method, with a high-technical success rate and a low-complication rate. It allowed surgeons to easily locate and detect the nodules and estimate the surgical margin.

Effects of di-n-butyl phthalate and di-2-ethylhexyl phthalate on pollutant removal and microbial community during wastewater treatment.

Due to the wide use of plastic products and the releasability of plasticizer into surrounding environment, the hazards, residues and effects of phthalic acid esters (PAEs) in ecosystems have been paid more and more attention. Little information is available about the effects of PAEs on the normal wastewater treatment, although the distribution of PAEs in soil and other ecosystems is closely related to the discharge of sewage. In this study, the effects of high concentrations of di-n-butyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP) on pollutant removal and the microbial community during landfill leachate treatment was investigated. After domestication, the activated sludge was used in the co-treatment of landfill leachate and simulated domestic wastewater. We verified that this process reduced the toxicity of landfill leachate. However, high concentrations of added DBP and DEHP were removed first, while the removal of these pollutants from raw landfill leachate was limited. The results of high-throughput sequencing revealed that the bacterial diversity was diminished and the microbial community structure was significantly affected by the addition of DBP and DEHP. The DBP and DEHP samples had 79.05% and 82.25% operational taxonomic units (OTU), respectively, in common with the raw activated sludge. Many genera of PAE-degrading bacteria that had no significant evolutionary relationship were found in the raw activated sludge. And the widespread presence of PAE-degrading bacteria could effectively keep the concentrations of PAEs low during the wastewater treatment.

Facile one-step targeted immobilization of an enzyme based on silane emulsion self-assembled molecularly imprinted polymers for visual sensors.

Immobilized enzymes play significant roles in many practical applications. However, the enzymes need to be purified before immobilization by conventional immobilizing methods, and the purification process is expensive, laborious, complicated and results in a decrease of the enzymatic activity. So, we present a novel method by a facile one-step targeted immobilization of an enzyme without a purification process from complex samples. For this purpose, a novel molecularly imprinted polymer was prepared via a silane emulsion self-assembly method using boric acid-modified Fe3O4 nanoparticles as magnetic nuclei, horseradish peroxidase as a template, 3-aminopropyltriethoxysilane as a functional monomer and tetraethyl orthosilicate as a crosslinking agent. The molecularly imprinted polymers were characterized using a scanning electron microscope, X-ray photoelectron spectroscope, vibrating sample magnetometer and X-ray diffractometer. The as-prepared and characterized materials were employed to immobilize horseradish peroxidase from a crude extract of horseradish. Moreover, the immobilized horseradish peroxidase was employed to develop visual sensors for the detection of glucose and sarcosine. This study demonstrated that the molecularly imprinted polymers prepared via the silane emulsion self-assembly method can facilely immobilize horseradish peroxidase from a crude extract of horseradish without any purification process. The developed visual method based on the immobilized horseradish peroxidase shows great potential applications for the visual detection of glucose and sarcosine.

Antibiofouling polysulfone ultrafiltration membranes via surface grafting of capsaicin derivatives.

Biofouling is a critical issue in the membrane separation process as it can increase the operational cost by lower down membrane permeability. Covalent binding of an antibacterial agent on the membrane surface to kill microorganisms to hinder biofouling formation process draws great attention. In this study, we used three kinds of capsaicin derivatives, MBHBA, HMBA, and HMOBA, to fabricate antibiofouling membrane via UV-assisted photo grafting method. The influence of these capsaicin derivatives on membrane properties was investigated and compared. The results suggest that HMBA showed the best UV activity, followed by HMOBA and MBHBA successively. Due to the difference of functional groups among capsaicin derivatives, there is an increase in membrane wettability of HMBA and HMOBA-modified membranes, while there is a decrease for MBHBA-modified membrane. MBHBA-modified membrane showed enhanced irreversible fouling, which is in contrast to that of HMBA- and HMOBA-modified membranes. The modified membranes showed similar antibacterial activity against Escherichia coli. The practicability of the modified membranes was examined by dipping them into tap water and seawater for 30 days, and the results displayed the modified surfaces have the potential to relieve biofouling for separation membranes.

Association of Salivary Helicobacter pylori Infection with Oral Diseases: a Cross-sectional Study in a Chinese Population.

OBJECTIVE: The aim of this study was to detect the prevalence of oral H.pylori among adults and to investigate the correlation between H.pylori infection and common oral diseases. STUDY DESIGN: A cross-sectional study was performed among adults Chinese who took their annual oral healthy examination at The First Affiliated Hospital, Zhejiang University School of Medicine, China. RESULTS: The study included 1050 subjects in total and oral H.pylori infection occurred in 60.29% of the subjects. The prevalence rates of oral H.pylori in patients with periodontal diseases (63.42%) and caries (66.91%) were significantly increased than those without oral diseases (54.07%), respectively (P < 0.05), while the difference between subjects with recurrent aphthous stomatitis and controls was not significant. In addition, the differences of positive rates of H.pylori with or without history of gastric ulcer were statistically significant (69.47% vs 58.26%, P<0.05). Presenting with periodontal diseases (OR 1.473;95% CI 1.021 to 2.124), caries (OR 1.717; 1.127 to 2.618), and having history of gastric ulcer (OR 1.631; 1.164 to 2.285) increased the risk of H.pylori infection. CONCLUSIONS: Oral H.pylori infection is common in adult Chinese, which is significantly associated with oral diseases including periodontal diseases and caries.

p27(kip1) deficiency accelerates dentin and alveolar bone formation.

To assess the role of p27(kip1) in regulating dental formation and alveolar bone development, we compared the teeth and mandible phenotypes of homozygous p27(kip1) -deficient (p27(-/-) ) mice with their wild-type littermates at 2 weeks of age. At 2 weeks of age, dental mineral density, dental volume and dentin sialoprotein-immunopositive areas were increased significantly, whereas the predentin area : total dentin area and biglycan-immunopositive area : dentin area ratios were decreased significantly in p27(-/-) mice compared with their wild-type (WT) littermates. Mandible mineral density, cortical thickness, alveolar bone volume, type I collagen and osterix-immunopositive areas, osteoblast number and activity and mRNA expression of Runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP), osteocalcin and bone morphogenetic protein (bmp2) were all significantly increased in the mandibles, as was the number and surface of tartrate-resistant acid phosphatase-positive osteoclasts in the alveolar bone of p27(-/-) mice compared with their WT littermates. Furthermore, the percentage of proliferating cell nuclear antigen-positive cells in Hertwig's epithelial root sheath and protein expression of cyclin E and cyclin-dependent kinase 2 were increased significantly in p27(-/-) mice relative to their WT littermates. The results from this study indicate that p27 plays a negative regulatory role in dentin formation and alveolar bone development.

Effect of laser process parameters on the pores, surface roughness, and hardness of laser selective melting of dental cobalt-chrome alloys.

OBJECTIVES: To address the quality problems caused by high porosity in the preparation of dental cobalt-chrome alloy prosthetics based on selective laser melting (SLM) technology, we investigated the influence mechanism of different forming process parameters on the microstructure and properties of the materials. Moreover, the range of forming process parameters that can effectively reduce defects was precisely defined. METHODS: The effects of laser power, scanning speed, and scanning distance on the pore properties, surface roughness, and hardness of dental cobalt-chrome alloy were investigated by adjusting the printing parameters in the process of SLM. Through metallographic analysis, image analysis, and molten pool simulation, the pore formation mechanism was revealed, and the relationship between the porosity and energy density of SLM dental cobalt-chrome alloy was elucidated. RESULTS: When the linear energy density was higher than 0.18 J/mm, the porosity defect easily appeared at the bottom of the molten pool. When the laser energy density was lower than 0.13 J/mm, defects occurred in the gap of the molten pool due to insufficient melting of powder. In particular, when the linear energy density exceeded the threshold of 0.30 J/mm or was below 0.12 J/mm, the porosity increased significantly to more than 1%. In addition, we observed a negative correlation between free surface roughness and energy density and an inverse relationship between macroscopic hardness and porosity. CONCLUSIONS: On the basis of the conditions of raw materials and molding equipment used in this study, the key process parameters of SLM of molding parts with porosity lower than 1% were successfully determined. Specifically, these key parameters included the line energy density, which ranged from 0.13 J/mm to 0.30 J/mm, and the scan spacing should be strictly controlled below 90 µm.

Enhanced fermentation and deconstruction of natural wheat straw by Trichoderma asperellum T-1 and its positive transcriptional response.

Microorganisms harvest energy from agricultural waste by degrading its structure. By comparing with Trichoderma reesei QM6a in cellulase production, straw deconstruction and transcriptome response, Trichoderma asperellum T-1 was identified to be prioritized for the fermentation of natural straw. Cellulase activity of T-1 was 50%-102% higher than QM6a. And the degradation rate of hemicellulose and ligin in wheat straw by T-1 reached 40% and 42%. Time-driven changes in the gene expression of extracellular proteins involved in polysaccharide, xylan, and hemicellulose metabolism and hydrolysis indicated that T-1 positively responded in both solid state fermentation and submerged fermentation for lignocellulose degradation. A significantly enriched category encoding carbohydrate-binding modules is considered critical for the deconstruction of the natural structure by T-1. The findings highlight the superiority of T. asperellum T-1 in straw fermentation, base on which, the construction of efficient microbial agents is expected to enhance the utilization of biomass.

Vaccine-like controlled-release delivery of an immunomodulating peptide to treat experimental autoimmune encephalomyelitis.

The objective of this work is to use colloidal gel from alginate-chitosan-PLGA complex to deliver Ac-PLP-BPI-NH2-2 peptide in a controlled-release manner as a vaccine-like therapeutic to suppress experimental autoimmune encephalomyelitis (EAE) in the mouse model. Oppositely charged PLGA nanoparticles were prepared by a solvent diffusion method. The carboxyl group of the alginate and the amine group of the chitosan coated the nanoparticles with negative and positive charges, respectively. The peptide (Ac-PLP-BPI-NH2-2), designed to bind to MHC-II and ICAM-1 simultaneously, was formulated into the colloidal gel by physical mixture. Vaccine-like administration of the peptide-loaded colloidal gel (Ac-PLP-BPI-NH2-2-NP) was achieved by subcutaneous (sc) injection to EAE mice. Disease severity was measured using clinical scoring and percent change in body weight. Cytokine production was determined using the splenocytes from Ac-PLP-BPI-NH2-2-NP-treated mice and compared to that of controls. Ac-PLP-BPI-NH2-2-NP suppressed and delayed the onset of EAE as well as Ac-PLP-BPI-NH2-2 when delivered in a vaccine-like manner. IL-6 and IL-17 levels were significantly lower in the Ac-PLP-BPI-NH2-2-NP-treated mice compared to the mouse group treated with blank colloidal gel, suggesting that the mechanism of suppression of EAE is due to a shift in the immune response away from Th17 production. The results of this study suggest that a one-time sc administration of Ac-PLP-BPI-NH2-2 formulated in a colloidal gel can produce long-term suppression of EAE by reducing Th17 proliferation.

Effect of polystyrene nanoplastics on cell apoptosis, glucose metabolism, and antibacterial immunity of Eriocheir sinensis.

The adverse effects of plastic waste and nanoplastics on the water environment have become a focus of global attention in recent years. In the present study, using adult Chinese mitten crabs (Eriocheir sinensis) as an animal model, the bioaccumulation and the in vivo and in vitro toxicity of polystyrene nanoplastics (PS NPs), alone or in combination with the bacteria, were investigated. This study aimed to investigate the effects of PS NPs on apoptosis and glucose metabolism in Chinese mitten crabs, and whether PS NPs could synergistically affect the antibacterial immunity of crabs. We observed that NPs were endocytosed by hemocytes, which are immune cells in crustaceans and are involved in innate immunity. The RNA sequencing data showed that after hemocytes endocytosed NPs, apoptosis and glucose metabolism-related gene expression was significantly induced, resulting in abnormal cell apoptosis and a glucose metabolism disorder. In addition, exposure to NPs resulted in changes in the antimicrobial immunity of crabs, including changes in antimicrobial peptide expression, survival, and bacterial clearance. In summary, NPs could be endocytosed by crab hemocytes, which adversely affected the cell apoptosis, glucose metabolism, and antibacterial immunity of Eriocheir sinensis. This study revealed the effects of NPs on crab immunity and lays the foundation for further exploration of the synergistic effect of NPs and bacteria.

Adsorption of tetracycline and Cd(II) on polystyrene and polyethylene terephthalate microplastics with ultraviolet and hydrogen peroxide aging treatment.

Microplastics (MPs) could serve as vectors of antibiotics and heavy metals through sorption and desorption. However, the combined adsorption process of antibiotics and heavy metals on aged MPs has rarely been studied. In this study, combined adsorption/desorption of tetracycline (TC) and Cd(II) on/from polystyrene (PS) and polyethylene terephthalate (PET) MPs, as well as ultraviolet (UV) and H2O2 aged MPs, was investigated. The specific surface areas of the MPs increased after UV and H2O2 aging. Adsorption experiments showed that the pseudo-second-order kinetic model and Freundlich model fitted adsorption of TC and Cd(II) on all of the MPs. The adsorption capacities of TC and Cd(II) were higher on aged MPs than on the pristine MPs, especially on H2O2 treated MPs. TC adsorption on the MPs was hardly affected by Cd(II), and Cd(II) adsorption was not significantly affected by TC when the solution pH value was below 8.0. Cd(II) slightly enhanced TC adsorption on the MPs at pH 8.0, especially on the aged MPs. The TC adsorption capacities increased with increasing pH, reaching a maximum at pH 5.0 or 6.0, and they then decreased, while the largest level of Cd(II) adsorption was at approximately pH 6.0. Adsorption of TC and Cd(II) on the pristine and aged MPs was thermodynamically favorable and spontaneous. The trend of the desorption rates of TC and Cd(II) from the MPs in different background solutions was ultrapure water < surface water < simulated gastric fluid. The desorption rates of TC and Cd(II) from the aged MPs were lower than those from the pristine MPs. The results revealed the mechanism of the TC and Cd(II) combined adsorption process on aged MPs, which will provide insight for understanding the aging process and its potential effects on sorption and desorption of antibiotics and heavy metals in the real environment.

Effects of polyethylene glycol on the surface of nanoparticles for targeted drug delivery.

The rapid development of drug nanocarriers has benefited from the surface hydrophilic polymers of particles, which has improved the pharmacokinetics of the drugs. Polyethylene glycol (PEG) is a kind of polymeric material with unique hydrophilicity and electrical neutrality. PEG coating is a crucial factor to improve the biophysical and chemical properties of nanoparticles and is widely studied. Protein adherence and macrophage removal are effectively relieved due to the existence of PEG on the particles. This review discusses the PEGylation methods of nanoparticles and related techniques that have been used to detect the PEG coverage density and thickness on the surface of the nanoparticles in recent years. The molecular weight (MW) and coverage density of the PEG coating on the surface of nanoparticles are then described to explain the effects on the biophysical and chemical properties of nanoparticles.

Manipulate intestinal organoids with niobium carbide nanosheets.

Multifunctional two-dimensional nanosheet materials have attracted attention in biomedical fields due to their unique physiochemical and biological properties. Interactions between intestinal stem cells and Engineered Nanomaterials (ENMs) are an essential area in research with the growing diagnosis of gastrointestinal (GI) diseases. One unique type of two-dimensional metal carbide nanomaterial, niobium carbide (Nb2 C), has shown promising properties for potential applications in this field, such as biocompatibility, stability, and high photothermal conversion efficiency. In this study, Nb2 C nanosheets were prepared by spark plasma sintering and HF etching. Various concentrations of Nb2 C nanosheets were placed inside intestinal organoids, which mimic the real functions of an intestinal system. These organoids were formed from intestinal crypts that were isolated from mice and grew into self-maintained systems. Through growth analysis, surface area calculations, and cell viability tests, it was concluded that an optimal concentration of nanosheets exists that may offer stimulation to intestinal cells while having no toxic effects. A high concentration of nanosheets in the organoids inhibited growth, whereas the control and low concentration of nanosheets showed no reduced growth rate. When placed under infrared exposure, the organoids with nanosheets offered stimulation and showed more viability after time as compared to the control organoids with no nanosheets. These results show overall potential benefits of placing low concentration Nb2 C nanosheets in intestinal systems to protect and stimulate cell survivability when undergoing various treatments.