Highly secretory expression of recombinant cowpea chlorotic mottle virus capsid proteins in Pichia pastoris and in-vitro encapsulation of ruthenium nanoparticles for catalysis

The applications of viral protein cages have expanded rapidly into the fields of bionanotechnology and materials science. However, the low-cost production of viral capsid proteins (CPs) on a large scale is always a challenge. Herein, we develop a highly efficient expression system by constructing recombinant Pichia pastoris cells as a “factory” for the secretion of soluble cowpea chlorotic mottle virus (CCMV) CPs. Under optimal induction conditions (0.9 mg/mL of methanol concentration at 30 °C for 96 h), a high yield of approximately 95 mg/L of CCMV CPs was harvested from the fermentation supernatant with CPs purity >90%, which has significantly simplified the rest of the purification process. The resultant CPs are employed to encapsulate Ruthenium (Ru) nanoparticles (NPs) via in-vitro self-assembly to prepare hybrid nanocatalyst, i.e. Ru@virus-like particles (VLPs). The catalytic activity over Ru@VLPs was evaluated by reducing 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The results indicate that, with the protection of protein cages, Ru NPs were highly stabilized during the catalytic reaction. This results in enhanced catalytic activity (reaction rate constant k = 0.14 min−1) in comparison with unsupported citrate-stabilized Ru NPs (Ru-CA) (k = 0.08 min−1). Additionally, comparatively lower activation energy over Ru@VLPs (approximately 32 kJ/mol) than that over Ru-CA (approximately 39 kJ/mol) could be attributed to the synergistic effect between Ru NPs and some functional groups such as amino groups (–NH2) on CPs that weakened the activation barrier of 4-NP reduction. Therefore, enhanced activity and decreased activation energy over Ru@VLPs demonstrated the superiority of Ru@VLPs to unsupported Ru-CA

Compartmentalized Thin Films with Customized Functionality via Interfacial Cross-linking of Protein Cages

Hybrid thin films with a high loading and homogeneous dispersion of functional nanoparticles (and/or molecules) find applications in (bio)-sensors and electronic devices. The fabrication of such hybrid thin films, however, suffers from the complex and diverse surface and physicochemical properties of individual nanoparticles. To address this challenge, a facile and general strategy toward compartmentalized thin films through the interfacial cross-linking of viral protein cages is reported. Employing these protein cages, gold nanoparticles, as well as enzyme horseradish peroxidase, are encapsulated into virus-like particles and then cross-linked into thin films with a thickness varying from monolayer to submicron dimensions. These compartmentalized thin films not only ensure that the cargo is homogeneously dispersed, but also display good catalytic activity. This strategy is, in principle, applicable for a wide range of (bio)-organic nanocontainers, enabling the versatile fabrication of 2D thin films with extensive application prospects.</p

Electron Fluxes in Biocathode Bioelectrochemical Systems Performing Dechlorination of Chlorinated Aliphatic Hydrocarbons

Bioelectrochemical systems (BESs) are regarded as a promising approach for the enhanced dechlorination of chlorinated aliphatic hydrocarbons (CAHs). However, the electron distribution and transfer considering dechlorination, methanogenesis, and other bioprocesses in these systems are little understood. This study investigated the electron fluxes in biocathode BES performing dechlorination of three typical CAHs, 1,1,2,2-tetrachloroethene (PCE), 1,1,2-trichloroethene (TCE) and 1,2-dichloroethane (1,2-DCA). Anaerobic sludge was inoculated to cathode and biocathode was acclimated by the direct acclimation and selection. The constructed biocathode at −0.26 V had significantly higher dechlorination efficiency (E24h &gt; 99.0%) than the opened circuit (E24h of 17.2–27.5%) and abiotic cathode (E24h of 5.5–10.8%), respectively. Cyclic voltammetry analysis demonstrated the enhanced cathodic current and the positive shift of onset potential in the cathodic biofilm. Under autotrophic conditions with electrons from the cathode as sole energy source (columbic efficiencies of 80.4–90.0%) and bicarbonate as sole carbon source, CAHs dechlorination efficiencies were still maintained at 85.0 ± 2.0%, 91.4 ± 1.8%, and 84.9 ± 3.1% for PCE, TCE, and 1,2-DCA, respectively. Cis-1,2-dichloroethene was the final product for PCE and TCE, while 1,2-DCA went through a different dechlorination pathway with the non-toxic ethene as the final metabolite. Methane was the main by-product of the heterotrophic biocathode, and methane production could be enhanced to some extent by electrochemical stimulation. The various electron fluxes originating from the cathode and oxidation of organic substrates might be responsible for the enhanced CAHs dechlorination, while methane generation and bacterial growth would probably reduce the fraction of electrons provided for CAH dechlorination. The study deals with the dechlorination and competitive bioprocesses in CAH-dechlorinating biocathodes with a focus on electron fluxes

Compartmentalized supramolecular hydrogels based on viral nanocages towards sophisticated cargo administration

Introduction of compartments with defined spaces inside a hydrogel network brings unique features, such as cargo quantification, stabilization and diminishment of burst release, which are all desired for biomedical applications. As a proof of concept, guest-modified cowpea chlorotic mottle virus (CCMV) particles and complementary guest-modified hydroxylpropyl cellulose (HPC) were non-covalently cross-linked through the formation of ternary host-guest complexes with cucurbit[8]uril (CB[8]). Furthermore, CCMV based virus-like particles (VLPs) loaded with tetrasulfonated zinc phthalocyanine (ZnPc) were prepared, with a loading efficiency up to 99%, which are subsequently successfully integrated inside the supramolecular hydrogel network. It was shown that compartments provided by protein cages not only help to quantify the loaded ZnPc cargo, but also improve the water solubility of ZnPc to avoid undesired aggregation. Moreover, the VLPs together with ZnPc cargo can be released in a controlled way without an initial burst release. The photodynamic effect of ZnPc molecules was retained after encapsulation of capsid protein and release from the hydrogel. This line of research suggests a new approach for sophisticated drug administration in supramolecular hydrogels.</p

Glycosylation on Spermatozoa, a Promise for the Journey to the Oocyte

Spermatozoa experience a long and tough transit in male and female genital tracts before successful fertilization. Glycosylation helps spermatogenesis, epididymal maturation, passing through cervical mucus, avoiding killing of the female immunologic system, and shaking hands between sperm and egg. Changes in glycosylations along the transit ensure that the right things happen at the right time and place on spermatozoa. Aberrant glycosylations on spermatozoa will negatively affect their fertility. Thus, we developed a lectin array method to examine the glycocalyx of spermatozoa, which will help observe glycosylations occurring on spermatozoa in a normal or abnormal conditions, such as spermatozoa with DEF126 mutation and poor freezability. Intriguingly, binding levels of ABA (Agaricus bisporus agglutinin), a lectin marking the inner layer of the glycocalyx, were changed in these subfertile spermatozoa, which indicates that the integrity of glycocalyx is critical for sperm fertility. In this chapter, we reviewed the impacts of glycosylations on sperm fertility, the lectin array method, and its potential application for sperm function assessment

Case Report: Proximal bronchial injury in small-cell lung cancer patient after moderately hypofractionated radiotherapy

BackgroundProximal bronchial injury is a frequently observed complication in patients with central lung cancer following high-dose stereotactic body radiotherapy, whereas it is rarely reported after moderately hypofractionated radiotherapy. In this article, we present a case of proximal bronchial injury in a patient with small-cell lung cancer after moderately hypofractionated radiotherapy.Case presentationA 45-year-old male patient with no history of smoking was diagnosed with limited stage small-cell lung cancer. According to guidelines of the National Comprehensive Cancer Network, the patient was treated with chemoradiotherapy, which included etoposide and cisplatin as well as radiotherapy at a dose of 65 Gy/26 fractions. Three months after radiotherapy, the tumor disappeared; however, stenosis of the right main bronchus, right upper lobe bronchus, and intermediate bronchus, as well as atelectasis of the right upper and middle lobes, occurred and gradually worsened. Anti-infection and hormonal therapy were ineffective. One year after radiotherapy, grade 3 damage was formed in the proximal bronchus according to the Common Terminology Criteria for Adverse Events (version 5.0). Following endoscopic balloon dilatation of the right main bronchus, asthma symptoms of the patient were reduced.ConclusionThis case reminds us that it is necessary to implement a proximal bronchial dose constraint and prevent the occurrence of dose hot spot in the proximal bronchus when administering moderately hypofractionated radiotherapy with a physical dose exceeding 65 Gy

In situ Carbon Modification of g-C3N4 from Urea Co-crystal with Enhanced Photocatalytic Activity Towards Degradation of Organic Dyes Under Visible Light

An in situ strategy was introduced for synthesizing carbon modified graphitic carbon nitride(g-C3N4) by using urea/4-aminobenzoic acid(PABA) co-crystal(PABA@Urea) as precursor materials. Via co-calcination of the PABA co-former and the urea in PABA@Urea co-crystals, C guest species were generated and compounded into g-C3N4 matrix in situ by replacing the lattice N of the carbon nitride and forming carbon dots onto its layer surface. The carbon modification dramatically enhanced visible-light harvesting and charge carrier separation. Therefore, visible light photo-catalytic oxidation of methylene blue(MB) pollution in water over the carbon modified g-C3N4 (C/g-C3N4) was notably improved. Up to 99% of methylene blue(MB) was eliminated within 60 min by the optimal sample prepared from the PABA@Urea co-crystal with a PABA content of 0.1%(mass ratio), faster than the degradation rate over bare g-C3N4. The present study demonstrates a new way to boost up the photocatalysis performance of g-C3N4, which holds great potential concerning the degradation of organic dyes from water

Global diversity and distribution of antibiotic resistance genes in human wastewater treatment systems

Antibiotic resistance poses a significant threat to human health, and wastewater treatment plants (WWTPs) are important reservoirs of antibiotic resistance genes (ARGs). Here, we analyze the antibiotic resistomes of 226 activated sludge samples from 142 WWTPs across six continents, using a consistent pipeline for sample collection, DNA sequencing and analysis. We find that ARGs are diverse and similarly abundant, with a core set of 20 ARGs present in all WWTPs. ARG composition differs across continents and is distinct from that of the human gut and the oceans. ARG composition strongly correlates with bacterial taxonomic composition, with Chloroflexi, Acidobacteria and Deltaproteobacteria being the major carriers. ARG abundance positively correlates with the&nbsp;presence of mobile genetic elements, and 57% of the 1112 recovered high-quality genomes possess putatively mobile ARGs. Resistome variations appear to be driven by a complex combination of stochastic processes and deterministic abiotic factors

Global diversity and biogeography of bacterial communities in wastewater treatment plants

Microorganisms in wastewater treatment plants (WWTPs) are essential for water purification to protect public and environmental health. However, the diversity of microorganisms and the factors that control it are poorly understood. Using a systematic global-sampling effort, we analysed the 16S ribosomal RNA gene sequences from ~1,200 activated sludge samples taken from 269 WWTPs in 23 countries on 6 continents. Our analyses revealed that the global activated sludge bacterial communities contain ~1 billion bacterial phylotypes with a Poisson lognormal diversity distribution. Despite this high diversity, activated sludge has a small, global core bacterial community (n = 28 operational taxonomic units) that is strongly linked to activated sludge performance. Meta-analyses with global datasets associate the activated sludge microbiomes most closely to freshwater populations. In contrast to macroorganism diversity, activated sludge bacterial communities show no latitudinal gradient. Furthermore, their spatial turnover is scale-dependent and appears to be largely driven by stochastic processes (dispersal and drift), although deterministic factors (temperature and organic input) are also important. Our findings enhance our mechanistic understanding of the global diversity and biogeography of activated sludge bacterial communities within a theoretical ecology framework and have important implications for microbial ecology and wastewater treatment processes