Competing esterification and oligomerization reactions of typical long-chain alcohols to secondary organic aerosol formation.

Organosulfate (OSA) nanoparticles, as secondary organic aerosol (SOA) compositions, are ubiquitous in urban and rural environments. Hence, we systemically investigated the mechanisms and kinetics of aqueous-phase reactions of 1-butanol/1-decanol (BOL/DOL) and their roles in the formation of OSA nanoparticles by using quantum chemical and kinetic calculations. The mechanism results show that the aqueous-phase reactions of BOL/DOL start from initial protonation at alcoholic OH-groups to form carbenium ions (CBs), which engage in the subsequent esterification or oligomerization reactions to form OSAs/organosulfites (OSIs) or dimers. The kinetic results reveal that dehydration to form CBs for BOL and DOL reaction systems is the rate-limiting step. Subsequently, about 18% of CBs occur via oligomerization to dimers, which are difficult to further oligomerize because all reactive sites are occupied. The rate constant of BOL reaction system is one order of magnitude larger than that of DOL reaction system, implying that relative short-chain alcohols are more prone to contribute OSAs/OSIs than long-chain alcohols. Our results reveal that typical long-chain alcohols contribute SOA formation via esterification rather than oligomerization because OSA/OSI produced by esterification engages in nanoparticle growth through enhancing hygroscopicity.

Rapid detection of antibiotic resistance genes in lactic acid bacteria using PMMA-based microreactor arrays.

The emergence of lactic acid bacteria (LABs) resistant to existing antimicrobial drugs is a growing health crisis. To decrease the overuse of antibiotics, molecular diagnostic systems that can rapidly determine the presence of antibiotic resistance (AR) genes in LABs from yogurt samples are needed. This paper describes a fully integrated, miniaturized plastic chip and closed-tube detection chemistry that performs multiplex nucleic acid amplification. High-throughput identification of AR genes was achieved through this approach, and six AR genes were analyzed simultaneously in < 2 h. This time-to-result included the time required for the extraction of DNA. The detection limit of the chip was 103 CFU mL-1, which was consistent with that of tube LAMP. We detected and identified multiple DNAs, including streptomycin, tetracycline, and vancomycin resistance-associated genes, with complete concordance to the Kirby-Bauer disk diffusion method.Key Points• A miniaturized chip was presented, and multiplex nucleic acid amplification was performed.• The device can be integrated with LAMP for rapid detection of antibiotic resistance genes.• The approach had a high throughput of AR gene analysis in lactic acid bacteria.

[Enrichment Characteristics and Ecological Risk Prediction of Pathogens on Typical Microplastic Biofilms].

As an emerging niche colonized by microorganisms, microplastics may selectively enrich pathogens, resulting in crucial ecological risks and potential threats to public health in aquatic environments. However, the enrichment characteristics and ecological risks of pathogens on different microplastic biofilms remain unclear. In this study, 16S rRNA high-throughput sequencing technology was used to investigate the differences in the bacterial community structure, occurrence characteristics of pathogens, and prediction of ecological risks on five typical microplastic biofilms of polyethylene （PE）, polypropylene （PP）, polystyrene （PS）, polyethylene terephthalate （PET）, and polyvinyl chloride （PVC） through a field in-situ incubation experiment. The results showed that after 28 d of in situ incubation, the macroscopic biofilms were formed on the surface of all microplastics, and the diversity and richness of the bacterial community on all microplastic biofilms were higher than in the surrounding water, indicating that the microorganisms in the surrounding water were selectively enriched on microplastics. Each type of microplastic biofilm had formed a unique bacterial community structure； in particular, PVC microplastics were more inclined to selectively enrich the members of Proteobacteria. A total of 47 human pathogens were identified using the HPB database, including six antibiotic resistance pathogens belonging to the lists of critical priority control. The number and total abundance of human pathogens detected on microplastic biofilm were higher than those in the surrounding water, and the dominant pathogens such as Bartonella, Burkholderia, and Brucella were selectively enriched on microplastic biofilms. Microbial phenotype prediction results based on BugBase showed that three functional phenotypes including biofilm formation, mobile element contained, and potentially pathogenic on microplastic biofilms had significantly increased by 2.38%-5.57%, 0.82%-7.13%, and 3.04%-8.30%, respectively, which were mainly contributed by α-Proteobacteria and γ-Proteobacteria. These results not only indicate that the selective enrichment of opportunistic pathogens on microplastic biofilms may lead to the increased risk of pathogenicity and antibiotic resistance co-spread but also provide reference for the accurate assessment of ecological risks caused by microplastic pollution in aquatic environments.

Bioinspired artificial spider silk photocatalyst for the high-efficiency capture and inactivation of bacteria aerosols.

Bioaerosol can cause the spread of disease, and therefore, capture and inactivation of bioaerosols is desirable. However, filtration systems can easily become blocked, and are often unable to inactivate the bioaerosol once it is captured. Herein, we reported a bioinspired artificial spider silk (ASS) photocatalyst, consisting of a periodic spindle structure of TiO2 on nylon fiber that can efficiently capture and concentrate airborne bacteria, followed by photocatalytic inactivation in situ, without a power-supply exhaust system. The ASS photocatalyst exhibits a higher capture capacity than the nylon fiber substrate and a photocatalytic inactivation efficiency of 99.99% obtained under 4 h irradiation. We found that the capture capacity of the ASS photocatalyst can be mainly attributed to the synergistic effects of hydrophilicity, Laplace pressure differences caused by the size of the spindle knots and surface energy gradients induced by surface roughness. The bacteria captured by the ASS photocatalyst are inactivated by photocatalysis within droplets or at the air/photocatalyst interfaces. This strategy paves the way for constructing materials for bioaerosol purification.

An improved solvent evaporation method to produce poly (lactic acid) microspheres via foam-transfer.

The aim of this work was to study an improved solvent evaporation method to prepare poly (lactic acid) (PLA) microspheres via foam-transfer. Since the foaming process and its transfer were critical to the improved method, they have been studied. Additionally, the delivery capability of foams was studied as a function of the oil/water ratio, the stirring rate, the concentration of polyvinyl alcohol (PVA) and ethanol (EtOH) in the aqueous phase (ωPVA, ωEtOH). It was found that foaming varied during the preparation process and it influenced the properties of PLA microspheres. When the oil/water ratio (w/w) ≥ 3:10, stirring rate ≥ 600 r/min, ωPVA ≥ 1 wt%, and ωEtOH = 0 wt%, solvent evaporation was able to produce enough foams for foam-transfer, which helped to deliver more than 89 wt% PLA microspheres to the receiving vessel. However, ωPVA ≤ 0.3 wt% and ωEtOH = 20 wt% were unfavorable for maintaining the spherical shape of PLA microspheres and caused the aggregation. The methodology was further used to prepare azoxystrobin-loaded PLA microspheres successfully with a high encapsulation efficiency of 86.54%. This work is meaningful since it enables an efficient and continuous route to prepare functional biodegradable polymer microspheres.

Temperature and H2O2-operated nano-valves on mesoporous silica nanoparticles for controlled drug release and kinetics.

Temperature and H2O2 dual-responsive nanoparticles were fabricated from ferrocene modified mesoporous silica (MSN-Fc) and ß-cyclodextrin-poly(N-isopropylacrylamide) (ß-CD-PNIPAM) star-shaped polymer due to the host-guest interactions for controlled drug release. The formation and structure of ß-CD-PNIPAM@MSN-Fc composite nanoparticles was confirmed by FTIR, TGA, TEM and N2 adsorption-desorption isotherms. The size of nanoparticles was about 100-150 nm with well-ordered mesoporous structure and PNIPAM chains coating on the surface as outer shell. The channels of MSNs and hydrophobic cavities of ß-CD were all contributed to the high drug loading capacity for nanoparticles. The release of DOX from nanoparticles was enhanced with the increase of temperature above LCST or adding H2O2 in ambient O2. The release kinetics were studied using different models to explain drug release mechanism. Furthermore, the drug loaded composite nanoparticles exhibited excellent anti-cancer activity.

Antiviral activity of sophoridine against enterovirus 71 in vitro.

ETHNOPHARMACOLOGICAL RELEVANCE: Enterovirus 71 (EV71) has a propensity to cause hand-foot-and-mouth disease (HFMD) epidemics associated with neurological sequelae. Unfortunately, no drugs are currently available for the clinical treatment of EV71 infections. Sophoridine (SRI) is one of the most abundant alkaloids in Sophora flavescens Aiton (Leguminosae), which has been used to treat fever, throat inflammation, cancer, and other diseases. MATERIALS AND METHODS: In this study, we found that SRI inhibits EV71 infection in Vero cells. To study the antiviral activity of SRI, Vero cells were divided into 3 treatment groups based on the timing of SRI dosing: prior to viral adsorption (Group A), during viral adsorption (Group B), and after viral adsorption (Group C). We further revealed the antiviral activity of SRI with the attachment assay and the penetration assay. For Group A, 50% viability of Vero cells was observed at a SRI concentration of 61.39 µg/mL, whereas for Groups B, 50% viability was observed at SRI concentrations of 196.86 µg/mL. Furthermore, 29.7% cell viability was observed even at a SRI concentration of 1000 µg/mL in Groups C. The results show that SRI was highly effective against EV71 when Vero cells were pretreated with SRI for 2 h (Group A). Further researches indicate SRI was highly effective at inhibiting EV71 attachment when the SRI concentrations over 250 µg/mL (P < 0.001). CONCLUSIONS: We have shown that Vero cell viability increases when SRI is administered prior to viral adsorption. This suggests that SRI has the considerable potential as an antiviral for EV71 disease prevention.

Synthesis of temperature/pH dual-sensitive supramolecular micelles from ß-cyclodextrin-poly(N-isopropylacrylamide) star polymer for drug delivery.

In this paper, temperature and pH dual-sensitive supramolecular micelles were constructed from star polymer ß-cyclodextrin-poly(N-isopropylacrylamide) (ß-CD-PNIPAM) and benzimidazole terminated poly(ε-caprolactone) (BM-PCL). The supramolecular micelles were formed based on the reversible host-guest recognition between ß-CD and BM. The size of supramolecular micelles was about 50-100 nm and the LCST was about 30.5 ℃. The drug loading efficiency of supramolecular micelles for DOX was high due to the hydrophobic micelles core of PCL and hydrophobic cavity of ß-CD. The release of drugs from supramolecular micelles was suppressed at neutral solution and room temperature but accelerated at acidic solution and 37 ℃. The drug loaded supramolecular micelles exhibited higher anti-cancer activity than free drugs. These temperature and pH dual-sensitive supramolecular micelles might possess potential applications for anticancer drug delivery.

Dual pH-sensitive supramolecular micelles from star-shaped PDMAEMA based on ß-cyclodextrin for drug release.

Star-shaped poly(2-(dimethylamino)ethyl methacrylate) based on ß-cyclodextrin (ß-CD-(PDMAEMA)7) was synthesized by means of atomic transfer radical polymerization (ATRP). Dual pH-sensitive supramolecular micelles were formed from ß-CD-(PDMAEMA)7 and benzimidazole modified poly(ε-caprolactone) (BM-PCL) through the host-guest interactions between ß-CD and benzimidazole. The supramolecular micelles have regular spherical structure with hydrophobic ß-CD/BM-PCL as the core and pH-sensitive PDMAEMA as the shell. The hydrophobic PCL as well as the hydrophobic cavity of ß-CD can efficiently encapsulate doxorubicin (DOX) with the drug-loading content and entrapment efficiency up to 40% and 86%. The drug release from micelles accelerated when the pH decreased from 7.0 to 2.0 and the temperature increased from 25 °C to 45 °C. MTT assay showed that drug loaded supramolecular micelles exhibited excellent anti-cancer activity than free DOX. These supramolecular micelles have promising potential applications as intelligent nanocarriers in drug delivery system.

Supramolecular assembly of poly(ß-cyclodextrin) block copolymer and benzimidazole-poly(ε-caprolactone) based on host-guest recognition for drug delivery.

A well-defined double hydrophilic poly(ß-cyclodextrin)-containing diblock copolymer PEG-b-PCD was synthesized by atom transfer radical polymerization (ATRP). Complex micelles with defined core-shell structure were formed based on the host-guest interactions between poly(ß-cyclodextrin) block copolymer and benzimidazole modified poly(ε-caprolactone) (BM-PCL). The hydrophobic PCD/BM-PCL resided in the core of micelles, while the hydrophilic poly(ethylene glycol) (PEG) chains acted as the micelles shell. The micelles exhibited regular spheres with diameter of about 255nm. The drug loading efficiency of micelles for doxorubicin (DOX) was high due to the hydrophobic core containing poly(ß-CD) and PCL. The in vitro release demonstrated that DOX-loaded polymer micelles exhibited an enhanced sustained manner after an initial burst release. The release of drugs was accelerated as the pH reduced from 7.0 to 2.0 and the temperature increased from 25 to 37°C. These results indicate that the complex micelles have potential applications in controlled drug delivery.

Polymeric hollow spheres assembled from ALG-g-PNIPAM and ß-cyclodextrin for controlled drug release.

In this paper, thermo-sensitive polymeric hollow spheres assembled from sodium alginate-graft-poly(N-isopropylacrylamide) (ALG-g-PNIPAM) and ß-cyclodextrin (ß-CD) were prepared for controlled release of 5-fluorouracil (5-FU). In aqueous solutions, ß-CD and PNIPAM formed rod-like segments through inclusion complexation interactions and sodium alginate acted as coil segments, which resulted in the formation of hollow structures. The size and wall thickness of assemblies increased with the increase of ß-CD in mixtures. The lower critical solution temperature (LCST) of hollow spheres varied in the range of 35-37°C. The hollow spheres exhibited high drug loading efficiency for 5-FU due to the hydrophilic cavities. The initial composition of mixtures, temperature and pH had a significant effect on the inclusion ability and drug release. Increasing temperatures above the LCST or decreasing pH to acidic conditions, a more rapid release rate was observed.

Thermo-sensitive complex micelles from sodium alginate-graft-poly(N-isopropylacrylamide) for drug release.

Polymer micelles with environmentally sensitive properties have potential applications in biomedicine. In this paper, thermo-sensitive complex micelles assembled from biocompatible graft copolymers sodium alginate-graft-poly(N-isopropylacrylamide) (SA-g-PNIPAM) and divalent metal ions were prepared for controlled drug release. The polymer micelles had core-corona structure, which was constituted by metal ions (Ba(2+), Zn(2+), Co(2+)) cross-linked sodium alginate as the core and thermo-sensitive PNIPAM chains as the corona. Formation of polymer micelles was determined by Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The polymer micelles were observed as regular spheres with good polydispersity and excellent performance on drug encapsulation and release ability. The cumulative release of 5-fluorouracil (5-FU) from micelles was controlled by pH, ionic strength or temperature of surroundings. The superior properties of sensitive polymer micelles induced by metal ions are expected to be utilized in controlled drug delivery systems.

Pollution characteristics and health risk assessment of volatile organic compounds emitted from different plastic solid waste recycling workshops.

The pollution profiles of volatile organic compounds (VOCs) emitted from different recycling workshops processing different types of plastic solid waste (PSW) and their health risks were investigated. A total of 64 VOCs including alkanes, alkenes, monoaromatics, oxygenated VOCs (OVOCs), chlorinated VOCs (ClVOCs) and acrylonitrile during the melting extrusion procedure were identified and quantified. The highest concentration of total VOCs (TVOC) occurred in the poly(acrylonitrile-butadiene styrene) (ABS) recycling workshop, followed by the polystyrene (PS), polypropylene (PP), polyamide (PA), polyvinyl chloride (PVC), polyethylene (PE) and polycarbonate (PC) workshops. Monoaromatics were found as the major component emitted from the ABS and PS recycling workshops, while alkanes were mainly emitted from the PE and PP recycling processes, and OVOCs from the PVC and PA recycling workshops. According to the occupational exposure limits' (OEL) assessment, the workers suffered acute and chronic health risks in the ABS and PS recycling workshops. Meanwhile, it was found that most VOCs in the indoor microenvironments were originated from the melting extrusion process, while the highest TVOC concentration was observed in the PS rather than in the ABS recycling workshop. Non-cancer hazard indices (HIs) of all individual VOCs were <1.0, whereas the total HI in the PS recycling workshop was 1.9, posing an adverse chronic health threat. Lifetime cancer risk assessment suggested that the residents also suffered from definite cancer risk in the PS, PA, ABS and PVC recycling workshops.

Formation of thermo-sensitive polyelectrolyte complex micelles from two biocompatible graft copolymers for drug delivery.

Thermo-sensitive polyelectrolyte complex (PEC) micelles assembled from two biocompatible graft copolymers chitosan-g-poly(N-isopropylacrylamide) (CS-g-PNIPAM) and carboxymethyl cellulose-g-poly(N-isopropylacrylamide) (CMC-g-PNIPAM) were prepared for delivery of 5-fluorouracil (5-FU). The PEC micelles showed a narrow size distribution with core-shell structure, in which the core formed from positively charged CS and negatively charged CMC by electrostatic interactions and the shell formed from thermo-sensitive PNIPAM. The synthesized PEC micelles have lower critical solution temperatures (LCST) in the region of 37°C, which is favorable for smart drug delivery applications. The hydrogen bondings between PEC micelles and 5-FU increased the drug loading. Changing temperature, pH or ionic strength, a sustained and controlled release was observed due to the deformation of PEC micelles. Adding glutaraldehyde, a chemical crosslinking reagent, was an efficient way to reinforce the micelles structure and decrease the initial burst release. Cytotoxicity assays showed that drug-loaded PEC micelles retained higher cell inhibition efficiency in HeLa cells.

16p13.3 duplication associated with non-syndromic pierre robin sequence with incomplete penetrance.

BACKGROUND: Pierre Robin sequence (PRS) is a condition present at birth. It is characterized by micrognathia, cleft palate, upper airway obstruction, and feeding problems. Multiple etiologies including genetic defects have been documented in patients with syndromic, non-syndromic, and isolated PRS. CASE PRESENTATION: We report a 4-year-old boy with a complex small supernumerary marker chromosome (sSMC) who had non-syndromic Pierre Robin sequence (PRS). The complex marker chromosome, der(14)t(14;16)(q11.2;p13.13), was initially identified by routine chromosomal analysis and subsequently characterized by array-comparative genomic hybridization (array CGH) and confirmed by fluorescence in situ hybridization (FISH). Clinical manifestations included micrognathia, U-type cleft palate, bilateral congenital ptosis, upslanted and small eyes, bilateral inguinal hernias, umbilical hernia, bilateral clubfoot, and short fingers and toes. To our best knowledge, this was the first case diagnosed with non-syndromic PRS associated with a complex sSMC, which involved a 3.8 Mb gain in the 14q11.2 region and an 11.8 Mb gain in the 16p13.13-pter region. CONCLUSIONS: We suggest that the duplicated chromosome segment 16p13.3 possibly may be responsible for the phenotypes of our case and also may be a candidate locus of non-syndromic PRS. The duplicated CREBBP gene within chromosome 16p13.3 is associated with incomplete penetrance regarding the mandible development anomalies. Further studies of similar cases are needed to support our findings.

pH-sensitive polyelectrolyte complex micelles assembled from CS-g-PNIPAM and ALG-g-P(NIPAM-co-NVP) for drug delivery.

In this paper, pH-sensitive polyelectrolyte complex micelles assembled from two oppositely charged graft copolymers chitosan-g-poly(N-isopropylacrylamide) (CS-g-PNIPAM) and sodium alginate-g-poly(N-isopropylacrylamide-co-N-vinyl-pyrrolidone) [ALG-g-P(NIPAM-co-NVP)] were prepared for controlled release of 5-fluorouracil (5-FU). The polyelectrolyte complex micelles showed a narrow size distribution with core-shell structure, where the core formed from positively charged CS and negatively charged ALG by electrostatic interactions. The hydrogen bonding interactions between micelles and 5-FU improved the drug loading. Changing temperature or pH, a controlled drug release was observed. Glutaraldehyde, as a chemical cross-linking agent, was used to improve the micelles stability and decrease the initial burst release. Cytotoxicity assays showed that drug-loaded micelles retained high cell inhibition efficiency in Hela cells. These novel complex micelles with environmentally sensitive properties are expected to be useful in the field of intelligent drug delivery system.

Thermo- and pH-sensitive ionic-crosslinked hollow spheres from chitosan-based graft copolymer for 5-fluorouracil release.

Thermo- and pH-sensitive ionic-crosslinked hollow spheres from self-assembly of chitosan-graft-poly(N-isopropylacrylamide) (CS-g-PNIPAM) for controlled release of 5-fluorouracil were studied. CS-g-PNIPAM aggregated into core-shell micelles with collapsed PNIPAM as the core and CS as the shell at the temperature above LCST. Ionic crosslinking reagent sodium tripolyphosphate (TPP) was used to crosslink the shell to form hollow spheres after cooling to room temperature. The size of hollow spheres was manipulated by changing pH or temperature of the environment. The CS-g-PNIPAM hollow spheres with plenty of inner cavities showed high loading capacity for 5-fluorouracil due to the polymer-drug interactions. Release of 5-fluorouracil from nanoparticles was accelerated at the temperature above LCST ascribed to the destruction of polymer-drug interactions and the decrease of particles size. Changing pH or ionic strength deformed the structure hollow spheres, which led to the increase of drug release. These hollow nanoparticles with environmentally sensitive properties are expected to be utilized in the field of intelligent drug delivery.

Thermo-sensitive chitosan based semi-IPN hydrogels for high loading and sustained release of anionic drugs.

Thermo-sensitive poly(N-isopropyl acrylamide-co-vinyl pyrrolidone)/chitosan [P(NIPAM-co-NVP)/CS] semi-IPN hydrogels with improved loading capacity and sustained release for anionic drugs NAP were prepared by free-radical polymerization. The LCST of hydrogels was adjusted to the vicinity of body temperature by introducing hydrophilic NVP. The presence of CS in semi-IPN networks improves the swelling behavior and provides a high affinity for anionic drug NAP due to the strong interactions between NAP molecules and CS chains. Release of NAP was suppressed at pH 2.2 and 5.0 and accelerated at pH 7.4 due to the deprotonation of amino groups in CS. Increasing temperature above LCST, hydrogels showed a continuous release of NAP without burst diffusion due to the shrinkage of PNIPAM restraining the drug release.

Synthesis of thermo-sensitive CS-g-PNIPAM/CMC complex nanoparticles for controlled release of 5-FU.

In this paper, self-assembled thermo-sensitive polyelectrolyte complex nanoparticles formed from chitosan-graft-poly(N-isopropylacrylamide)/carboxymethyl cellulose (CS-g-PNIPAM/CMC) were prepared for entrapment and release of 5-fluorouracil (5-FU). The morphology and size of the nanoparticles were observed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The polyelectrolyte complex nanoparticles showed a narrow distribution with an average diameter of about 200 nm. The hydrogen bonding interaction between nanoparticles and 5-FU was determined by Fourier-transformed infrared spectroscopy (FTIR). Increasing temperature or pH of the solutions, a sustained and controlled drug release was observed. The chemical cross-linking was an efficient way to decrease the drug release rate at the initial stage. The novel complex nanoparticles with environmentally sensitive properties are expected to be used in the field of intelligent drug delivery system.