Stepwise degradable PGA-SF core-shell electrospinning scaffold with superior tenacity in wetting regime for promoting bone regeneration.

Regenerating bone in the oral and maxillofacial region is clinically challenging due to the complicated osteogenic environment and the limitation of existing bone graft materials. Constructing bone graft materials with controlled degradation and stable mechanical properties in a physiological environment is of utmost importance. In this study, we used silk fibroin (SF) and polyglycolic acid (PGA) to fabricate a coaxial PGA-SF fibrous scaffold (PGA-SF-FS) to meet demands for bone grafts. The SF shell exerted excellent osteogenic activity while protecting PGA from rapid degradation and the PGA core equipped scaffold with excellent tenacity. The experiments related to biocompatibility and osteogenesis (e.g., cell attachment, proliferation, differentiation, and mineralization) demonstrated the superior ability of PGA-SF-FS to improve cell growth and osteogenic differentiation. Furthermore, in vivo testing using Sprague-Dawley rat cranial defect model showed that PGA-SF-FS accelerates bone regeneration as the implantation time increases, and its stepwise degradation helps to match the remodeling kinetics of the host bone tissue. Besides, immunohistochemical staining of CD31 and Col-1 confirmed the ability of PGA-SF-FS to enhance revascularization and osteogenesis response. Our results suggest that PGA-SF-FS fully utilizing the advantages of both components, exhibites stepwise degradation and superior tenacity in wetting regime, making it a promising candidate in the treatment of bone defects.

Colorimetric-SERS dual-mode sensing of Pb(II) ions in traditional Chinese medicine samples based on carbon dots-capped gold nanoparticles as nanozyme.

Peroxidase (POD)-mimicking nanozymes have got great progress in the sensing field, but most nanozyme assaying systems are built with a single-signal output mode, which is vulnerable to the effect of different factors. Thus, establishment of a dual-signal output mode is necessary for acquiring dependable and durable performance. This work described an Fe doped noradrenaline-based carbon dots and Prussian blue (Fe,NA-CDs/PB) nanocomposite as a POD-like nanozyme and modified gold nanoparticles (AuNPs) for the colorimetric and surface-enhanced Raman scattering (SERS) dual-mode sensor of Pb(II) in traditional Chinese medicine samples. With 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 3,3',5,5'-tetramethylbenzidine (TMB) as the substrates, it was found that the addition of Pb(II) inhibited the POD-like activity of Fe,NA-CDs/PB and AuNPs, so it was used for colorimetric and SERS dual-mode assays. The POD-like activity was shown to be a "ping-pong" catalytic mechanism, whereas the addition of Pb(II) produced noncompetitive inhibition with modulatory effects on Fe,NA-CDs/PB. The linear response range for colorimetric and SERS sensor detection of Pb(II) was 0.01-1.00 mg/L with the detection limit of 5 µg/L and 8 µg/L, respectively. This dual-mode detection system shows excellent selectivity. More importantly, the Pb(II) in traditional Chinese medicine samples have successfully assayed with good recovery from 90.4 to 108.9 %.

Effect of low-temperature degradation on the fatigue performance of dental strength-gradient multilayered zirconia restorations.

OBJECTIVES: Fatigue and low-temperature degradation (LTD) are the main factors contributing to zirconia restoration failure. This study evaluated the effect of LTD on the fatigue performance of the novel "strength & shade-gradient" multilayered zirconia restorations. METHODS: Discs (15 mm × 1.2 mm) of each yttria content layer from a newly developed strength-gradient multilayered zirconia were fabricated and under accelerated aging in an autoclave at 134℃ for 0 h, 32 h, and 64 h. Then, the phase transformation, microstructure, and mechanical properties after LTD were assessed. In addition, the crown samples, including the multi-Zir, 3Y-Zir, and 5Y-Zir were fabricated, and their monotonic and fatigue load before and after LTD, percentage of fatigue degradation (Sd) and the fracture morphology were investigated. Statistical analyses were performed using paired samples t-test (α' = α/3 = 0.017), one-way ANOVA and Weibull analysis. RESULTS: After LTD, the phase transformation, surface roughness, depth of transformed zone, and residual stress were increased and inversely associated with the yttria content. The indentation elastic modulus and hardness after LTD decreased; however, there was no significant difference between the different yttria content layers. The monotonic and fatigue load of multi-Zir restorations decreased, but their Weibull modulus increased, and Sd decreased, similar to 3Y-Zir. The crack origin was associated with the cervical region. CONCLUSION: These results show that although LTD reduces the absolute fatigue strength of strength-gradient multilayered zirconia restorations, it also reduces the effect of cyclic fatigue itself on the strength of zirconia (relative to monotonic strength), which might be due to the increase of residual stress. CLINICAL SIGNIFICANCE: The novel "strength & shade-gradient" multilayered zirconia restorations show a promising performance during in vitro LTD and fatigue test and their reliability to some extent is comparable to 3Y-Zir. Yet, further in vivo longitudinal studies are warranted to confirm their precise performance.

Enhancing diabetic wound healing with a pH-responsive nanozyme hydrogel featuring multi-enzyme-like activities and oxygen self-supply.

Diabetic wound treating remains a challenging due to bacterial infections, oxidative stress, tissue hypoxia, and high glucose levels. Herein, a multi-enzyme-like activities nanocomposite (Mo,Fe/Cu,I-Ag@GOx) was designed and anchored to a multifunctional fluorescence hydrogel. The nanozyme gel, loaded with glucose-oxidase (GOx), exhibits intrinsic GOx, peroxidase (POD)-, oxidase (OXD)-, catalase (CAT)- and superoxide dismutase (SOD)-like activities with pH-switchable glucose-initiated cascade reaction for diabetic wound healing. In the first cascade-reaction, initiated by GOx, the nanozyme gel catalyzes glucose and O2 into gluconic acid and H2O2 to further generate superoxide anion radical (O2·-) and hydroxyl radicals (·OH) to eradicate bacteria. In the second cascade-reaction, as the wound pH changes alkalescent microenvironment, the nanozyme gel simulates SOD to transform O2·- into O2 and H2O2, and then decomposes endogenous and exogenous H2O2 into O2 via CAT-like activity to reduce oxidative stress and alleviate hypoxia. The gel by calcium ion (Ca2+) cross-linked sodium alginate (SA) and chitosan (CS) containing nanozyme was constructed with injectability, adhesion and fluorescence properties, as well as beneficial biocompatible. Importantly, the water/alcohol solubility of the nanozyme gel allows it to be used as a dressing without causing secondary injury to the wound. The multifunctional fluorescence hydrogel exhibits efficiently promote pro-angiogenesis and bacteria-infected wound healing.

Ultrasound and defect engineering-enhanced nanozyme with high laccase-like activity for oxidation and detection of phenolic compounds and adrenaline.

Perusing metal-based redox nanozyme offers new opportunity for pollutant removal and biosensor, but ultrasound (US)-driven laccase-like nanozyme remains a significant challenge, especially in combination with defect engineering strategy. Herein, the Cu2Ov@Ce-TCPP was synthesized by doping Ce3+ on the surface of Cu2O nanocube and then coating with the porphyrin sonosensitizer. The Ce-doped porphyrin metal-structure in nanozyme was demonstrated to generate oxygen vacancy defects, which could obviously promote the laccase-like activity of Cu2Ov@Ce-TCPP nanozyme under US. XPS characterization and density functional theory (DFT) theoretical calculation revealed that the ultrasonic stimulation is beneficial to accelerate the electron transfer rate and O2 adsorption to improve catalytic activity, and Cu2Ov@Ce-TCPP nanozyme exhibits low adsorption energy and activation energy due to the presence of oxygen defect site, resulting in high laccase-like activity. The interaction between Ce atom and porphyrin structure also improved the sonocatalytic ability of the nanozyme. Meanwhile, Cu2Ov@Ce-TCPP nanozyme has been used for detecting and degrading a series of phenolic compounds. The detection adrenaline method has a linear range of 3.3-1000 µM and a detection limit as low as 0.96 µM with good reproducibility. The developed US-enhancing and recyclable laccase-like nanozyme system provides a promising strategy for the oxidation and detection of phenolic compounds.

Colorimetric detection for raloxifene based on Cu-PTs nanozyme with peroxidase-like activity.

The amorphous Cu-containing phosphomolybdate (Cu-PTs) composite with high peroxidase (POD)-like activity at neutral conditions was explored as biosensors for raloxifene (RAF) detection. The strong attraction between negatively charged Cu-PTs and positively charged substrates 3,3',5,5'-tetramethylbenzidine (TMB), as well as the acceleration of the conversion of active Cu+/Cu2+ by the Cu/W bimetallic redox couples were demonstrated to play significant roles in POD-like activity in physiological environment. When RAF is presence, it can bind to the surface of Cu-PTs and changes the chemical signal on the material surface, leading to the decreased POD-like activity. Based on this, a colorimetric method was established for the sensitive assay of RAF with a lower limit of detection (LOD) of 0.025 mg/L and good recovery from 90.13% to 108.9%. This work paves a new way to design a POD-like colorimetric protocol for tracing RAF in pharmaceutical products and environmental samples.

Fluorescence detection of dopamine based on the peroxidase-like activity of Fe3O4-MWCNTs@Hemin.

A novel Fe3O4-MWCNTs@Hemin nanocomposite was synthesized using hemin and Fe3O4 with multi-walled carbon nanotubes (MWCNTs) by one-step hydrothermal methods. The as-prepared Fe3O4-MWCNTs@Hemin nanocomposites exhibited excellent peroxidase-like activities in the activation of H2O2. The mechanisms, kinetics, and catalytic performances of Fe3O4-MWCNTs@Hemin were systematically studied. Fe3O4-MWCNTs@Hemin can oxidize dopamine (DA) to dopaquinone in the presence of H2O2, and the intermediate products dopaquinone can further react with ß-naphthol to generate a highly fluorescent derivative at 415 nm excitation wavelength. Therefore, an innovative fluorescence platform for the detection of DA was developed. The fluorescence intensity increased linearly with DA concentration in the range 0.33 to 107 µM, with a low detection limit of 0.14 µM. Due to the excellent activity, substrate universality, fast response, high selectivity, and sensitivity of Fe3O4-MWCNTs@Hemin, the proposed fluorescence method was used to analyze complex biological blood samples with a satisfactory result. It demonstrated the significant potential for developing effective and dependable fluorescent analytical platforms for preserving human health.

SERS detection of Hg2+ and aflatoxin B1 through on-off strategy of oxidase-like Au@HgNPs/carbon dots.

In this work, cerium-doped carbon dots (Ce-CDs) both as a reducing agent and template hybrid gold nanoparticles (AuNPs) with weak oxidase-like (OXD) activity was synthesized for the detection of Hg2+ and aflatoxin B1 (AFB1). The AuNPs can catalyze efficiently mercury ion (Hg2+) reduction to the metallic (Hg0) to form Au-Hg amalgam (Au@HgNPs). The obtained Au@HgNPs with strong OXD-like activity oxidize without Raman-active leucomalachite green (LMG) into the Raman-active malachite green (MG) and simultaneously as the SERS substrates by the formed Raman "hot spot" through MG-induced Au@HgNPs aggregation. While AFB1 was introduced resulting in the SERS intensity decreasing due to Hg2+ with AFB1 via carbonyl group to inhibit the aggregation of Au@HgNPs. The work paves a new path for the design of a nanozyme-based SERS protocol for tracing Hg2+ and AFB1 residues in foodstuff analysis.

A multi-enzyme-like activity exhibiting mussel-inspired nanozyme hydrogel for bacteria-infected wound healing.

Bacterial infection, tissue hypoxia, and inflammatory and oxidative stress are several key problems in wound healing of chronic infections. Herein, a multi-enzyme-like activity exhibiting multifunctional hydrogel made up of mussel-inspired carbon dot reduced-Ag (CDs/AgNPs) and Cu/Fe-nitrogen-doped carbon (Cu,Fe-NC) was designed. Due to the loss of glutathione (GSH) and oxidase (OXD)-like activity of the nanozyme (decomposes O2 to generate a superoxide anion radical (O2˙-) and hydroxyl radical production (˙OH)), the multifunctional hydrogel exhibited excellent antibacterial performance. More importantly, during the bacterial elimination within the inflammatory phase of wound healing, the hydrogel could act as a catalase (CAT)-like agent to supply adequate O2 by catalyzing intracellular H2O2 for hypoxia abatement. The catechol groups on the CDs/AgNPs endowed them with the dynamic redox equilibrium properties of phenol-quinones, thus providing the hydrogel with mussel-like adhesion properties. The multifunctional hydrogel was shown to excellently promote bacterial infection wound healing and maximize the efficiency of nanozymes.

Specific colorimetric detection of methylmercury based on peroxidase-like activity regulation of carbon dots/Au NPs nanozyme.

Methylmercury (MeHg+) is one of the common organic species of mercury, and has much higher toxicity than inorganic mercury. Based on the selective enhancement of the activity of nanozyme (NA-CDs/AuNPs) by MeHg+, a novel colorimetric nanoprobe for MeHg+ assay is proposed. The noradrenaline-based carbon dots (NA-CDs) as the reducing agent was applied to prepare the NA-CDs/AuNPs. The formation of gold amalgamation (Au@HgNPs) between nanozyme and MeHg+ allows to simultaneously accelerate the electron transfer from Au and Hg to NA-CDs and the generation of radicals (i.e. ∙OH, ∙O2- and ∙CH3). The NA-CDs/AuNPs has an outstanding anti-interference performance even in the presence of different mercury. Further density functionality theory (DFT) calculations revealed that the formation of Au@HgNPs via MeHg+ contributes to the significantly lowered activation energy, resulting in the peroxidase-like activity generation and acceleration. This leads to rapid (10 min) and specific colorimetric detection of MeHg+ with the detection limit of 0.06 µg L-1. This introduces a novel method for simple and sensitive detection of MeHg+, giving a new horizon for the assay of organometallic compounds.

A portable smartphone-based detection of glyphosate based on inhibiting peroxidase-like activity of heptanoic acid/Prussian blue decorated Fe3O4 nanoparticles.

The rapid and onsite detection of glyphosate in tobacco products is still a great challenge. In this study, a novel smartphone-assisted sensing platform for the detection of glyphosate has been successfully proposed through the peroxidase-like activity of Fe3O4-based nanozyme. Heptanoic acid/Prussian blue (PB) decorated Fe3O4 nanoparticles (Fe3O4@C7/PB) could catalyze and oxidize 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS, colorless) into a steel blue colored product in the presence of hydrogen peroxide. Glyphosate could specifically inhibit the peroxidase-like activity of Fe3O4@C7/PB by occupying the active site, thereby the glyphosate detection could be accomplished within 10 min by monitoring the color change of ABTS. This study has developed a smartphone-based portable detection platform for online analysis of glyphosate with a detection limit of 0.1 µg mL-1. The absorbance response curve of glyphosate showed good linearity in the concentration range of 0.125-15 µg mL-1 at 415, 647, and 730 nm. Moreover, by employing a co-precipitation technology and inhibiting the peroxidase-like activity, the glyphosate analysis would be less affected by the tobacco sample matrix. The nanosensor possesses excellent selectivity and anti-interference ability, which has application value in actual samples for onsite screening.

Methodology improvement of bulk compressive creep test: Deformation measurement and loading rate.

OBJECTIVES: (1) To identify improvements when bulk compressive creep testing of dental resin composite materials to reduce the sensitivity to the surface morphology and parallelism of specimens, to generate more accurate strain (displacement) measurement values. (2) To investigate the effect of loading rate on the creep and recovery behavior under bulk compressive creep test. METHODS: Cylindrical composite resin specimens were subjected to bulk compressive creep test with conventional and modified methodology (with/without introduction of stainless steel hemisphere and preload process). Furthermore, specimens undertook different loading rates ranging from 1 N/s to 50 N/s. Maximum deformation, creep deformation, permanent set as well as percentage of recovery during the creep and recovery procedure were compared, and surface topography changes before and after preload process was evaluated by laser scanning confocal. Burgers model was used to investigate the effect of improvements to each part of viscoelastic deformation of resin specimens. RESULTS: (1) The influence of surface evenness of resin specimens could be reduced by addition of preload process before the bulk compressive creep test resulting in significantly decreased permanent set (p = 0.002), and increased recovery to 91.7 % (p < 0.001). While the standard deviation of maximum deformation, permanent set and percentage of recovery had the smallest values when hemisphere was introduced to loading chain. (2) With increasing loading rate of bulk compressive creep tests, creep deformation increased and this trend became statistically significant when the loading rate reached 50 N/s. SIGNIFICANCE: The accuracy of deformation measurement during bulk compressive creep test could be improved by means of introducing stainless steel hemisphere to the loading chain, and adding preload process to loading protocol.

Simulated Enzyme Activity and Efficient Antibacterial Activity of Copper-Doped Single-Atom Nanozymes.

Nanozymes with good biocompatibility are novel antibacterial agents because they mimic the structure and properties of enzymes and destroy bacterial structures by generating reactive oxygen species in large quantities. Herein, we synthesized a Cu single-atom nanozyme (Cu-N-C) with intrinsic peroxidase- and oxidase-like activities. Cu-N-C can generate ·OH and O2·- during oxidase-catalyzed reactions, which have good antibacterial effects. Meanwhile, the antimicrobial performance can be further enhanced by light emitting diode light incubation due to photocatalysis. Lethal disruption of the membrane structure was confirmed by biofilm staining and scanning electron microscopy analysis. Notably, the antibacterial effect of Cu-N-C (MIC = 16 µg/mL) was significantly better than that of vancomycin (MIC = 1500 µg/mL), a commonly used drug for methicillin-resistant Staphylococcus aureus, and Cu-N-C outperformed the positive control cephalexin and gentamicin in terms of resistance development (27.3% less production of drug-resistant bacteria). Good biocompatibility was also verified using the MTT method, hemolysis analysis, and routine blood measurements in mice. The results of this work suggest that Cu-N-C has great potential for clinical applications as an efficient metal antimicrobial agent.

Hemin loaded Zn-N-C single-atom nanozymes for assay of propyl gallate and formaldehyde in food samples.

Single-atom nanozymes (SAzymes) show distinct advantages in catalytic activity and selectivity owing to their stability and special characteristic of maximum atomic utilization. Inspired by the structure of natural horseradish peroxidase (HRP), we developed a simple method for specific determination of both propyl gallate (PG) and formaldehyde (HCHO) by utilizing the intrinsic peroxidase mimics activity of hemin (hem) loaded Zn-nitrogen-carbon single-atom nanozymes (Zn-N-C@hem SAzymes). Zn-N-C@hem was prepared via a salt-template strategy and self-assembly, where hemin exhibits enhancing peroxidase-like activity can catalyze oxidation of colorless PG to yellow product. Upon introduction of HCHO into Zn-N-C@hem/PG system, complete suppression of PG oxidation was showed, resulting in distinguished decrease in absorbance. The colorimetric sensors of PG and HCHO based on Zn-N-C@hem/PG were developed at their respective linear range of concentration 1.25-200 mg/kg and 5-250 mg/kg. The practicability of the rapid analysis of PG and HCHO in food samples has been verified with reliable results.

A super-hydrophobic perfluoropolyether coated polytetrafluoroethylene sheets substrate for detection of acetamiprid surface-enhanced Raman spectroscopy.

In this paper, a hydrophobic substrate as concentrators including an inner layer of polytetrafluoroethylene (PTFE) and an outer layer covered a thin layer of perfluoropolyether (PFPE) was constructed to achieve a higher sensitivity for acetamiprid (AC) SERS detection. The condensation effect of the PTFE-PFPE hydrophobic substrate-induced aggregation of gold nanoparticles (Au NPs) result ''hot spots'' for SERS. The hydrophobic substrate is better reproducibility (RSD < 5%) compared with that on a conventional silicon wafer. A further application of the hydrophobic substrate was demonstrated by the detection of AC in tea samples within a detection range of 0.03 mg/L to 3 mg/L. The hydrophobic substrate eliminates the problem of solution diffusion to avoid the "coffee ring" effect (When a droplet adheres to a solid surface, the suspended molecular particles usually deposit on the edge of the droplet to form a ring).

Construction of AuNPs/Cu,I-CD-based colorimetric sensor: Catalytic oxidation of TBHQ and the catalytic inhibition of HCHO.

Various research groups have been paying huge attention to tune the metal states in metal-carbon hybrid materials. Herein, a mixed-valence copper-iodine co-doped carbon dots (Cu,I-CDs, Cu2+/Cu+/Cu0) were prepared through a one-step hydrothermal method, which displayed an intrinsic reduction performance under given conditions. Moreover, AuNPs/Cu,I-CDs composite was fabricated using Cu,I-CDs as reductant and stabilizer. Among them, the AuNPs/Cu,I-CDs composite exhibited the highest oxidase- and peroxidase-like activities, which was used for the colorimetric detection of tert-butyl hydroquinone (TBHQ), with the detection limits of 23.45 µg/kg. Interestingly, the catalytic oxidation of TBHQ to oxidized TBHQ (TQ) could be inhibited by formaldehyde (HCHO). Therefore, a colorimetric sensor for HCHO was developed with the detection limit 0.335 mg/L. The catalytic mechanism for TBHQ was investigated by employing scavengers of different reactive species, indicating the significant roles of •O2- in the catalytic process. Therefore, it is believed that the as-prepared AuNPs/Cu,I-CDs nanozyme has promising potential applications in the fields of biomedicine and food safety.

Survival Rates of Splinted and Nonsplinted Prostheses Supported by Short Dental Implants (≤8.5 mm): A Systematic Review and Meta-Analysis.

PURPOSE: To evaluate and compare the implant survival rates, marginal bone loss, and mechanical complications of prostheses supported by splinted and nonsplinted short implants (≤8.5 mm). MATERIAL AND METHODS: Electronic database (MEDLINE, CENTRAL, Web of Science, and EMBASE) and manual searches up to May 2021 were conducted to identify studies comparing splinted and nonsplinted short implants (≤8.5 mm). The primary outcome was implant survival rate. Secondary outcomes were marginal bone loss and mechanical complications. The quality of included studies and risk-of-bias were assessed according to the Newcastle-Ottawa Scale. A random-effects model was used to analyze the data. RESULTS: Twelve studies fulfilled the inclusion criteria and featured 1506 short implants (596 nonsplinted and 910 splinted) with a follow-up time ranging from 1 to 16 years. Quantitative analysis found no statistically significant differences between splinted and nonsplinted short implants (≤8.5 mm) for survival rate (RR = 0.98; 95% CI 0.96, 1.01; p = 0.26)) and marginal bone loss (SMD = -0.08; 95% CI - 0.23, 0.07; p = 0.28). Veneer chipping, abutment screw breakage, screw loosening, and loss of retention were reported in the selected studies as common complications. However, no statistically significant difference was found between splinted and nonsplinted short implants (RR = 0.56; 95% CI 0.20, 1.54; p = 0.26). CONCLUSIONS: Within the limitations of the present meta-analysis, it might be concluded that splinted short implants (≤8.5 mm) do not present superior performance in survival rate, marginal bone maintenance and prevention of mechanical complications compared with single-unit prostheses.

A multifunctional nanozyme-based enhanced system for tert-butyl hydroquinone assay by surface-enhanced Raman scattering.

An Au-based nanozyme composite (AuNPs/Cu,I) was constructed by using Cu,I-doped carbon dots (Cu,I-CDs) as the reducing agent as well as the nanozyme. Notably, AuNPs/Cu,I nanozyme not only possessed the intrinsic activity of mimicking enzymes of superoxide dismutase, peroxidase, and catalase at different conditions but was also employed as surface-enhanced Raman spectroscopy (SERS) enhancer. The combination of Cu,I-CDs and AuNPs promoted the electron transferability, leading to increased peroxidase-like activity and superoxide-like activity. Compared to the individual Cu,I-CDs and AuNPs nanozyme, the AuNPs/Cu,I composite demonstrated promising peroxidase-like activity by transferring electrons instead of generating OH. Interestingly, the multienzyme-like activity of AuNPs/Cu,I nanozyme could be finely tuned by changing the composition of Cu0/Cu+ and Au. The tert-butyl hydroquinone (TBHQ) as the substrate could be catalyzed with AuNPs/Cu,I nanozyme to produce red substances, resulting in a significant Raman enhancement effect at the same time, showing good linear range from 0.11 to 10 mg L-1. Overall, the current investigation provides a flexible and controllable way to design multifunctional nanozymes along with the Raman enhancement strategy based on the catalysis of nanozyme.

Lower Somatic Mutation Levels in the λ Light-Chain Repertoires with Chronic HBV Infection.

To investigate the characteristics of the immunoglobulin light-chain repertoires with chronic HBV infection, the high-throughput sequencing and IMGT/HighV-QUEST were adapted to analyze the κ (IgK) and λ (IgL) light-chain repertoires from the inactive HBV carriers (IHB) and the healthy adults (HH). The comparative analysis revealed high similarity between the κ light-chain repertoires of the HBV carriers and the healthy adults. Nevertheless, the proportion of IGLV genes with ≥90% identity as the germline genes was higher in the IgL light-chain repertoire of the IHB library compared with that of HH library (74.6% vs. 69.1%). Besides, the frequency of amino acid mutations in the CDR1 regions was significantly lower in the IgL light-chain repertoire of the IHB library than that of the HH library (65.52% vs. 56.0%). These results suggested the lower somatic mutation level in the IgL repertoire of IHB library, which might indicate the biased selection of IGLV genes in the IgL repertoire with chronic HBV infection. These findings might lead to a better understanding of the characteristics of the light-chain repertoires of HBV chronically infected individuals.

Spectrofluorimetric determination of Cr(VI) and Cr(III) by quenching effect of Cr(III) based on the Cu-CDs with peroxidase-mimicking activity.

The study presents a spectrofluorimetric method for the determination of Cr(III) based on 2,3-diaminophenazine (DAP) as fluorescent nano sensor. With the peroxidase-mimicking activity of copper-doped carbon dots (Cu-CDs), colorless o-phenylenediamine (OPD) was oxidized to fluorescent DAP in the presence of H2O2 via generation of hydroxyl radicals. The Cr(III) was found to decrease the fluorescent intensity of the Cu-CDs-mediated OPD oxidation system. Cr(VI) species were reduced to Cr(III) by employing 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) as the reductant, and a novel spectrofluorimetric method for the highly sensitive detection of speciation Cr(VI) and Cr(III) was developed. The Cu-CDs nanozyme was prepared from ethylenediaminetetraacetic acid copper disodium salt (Na2[Cu (EDTA)]) by one-step pyrolysis method. Under optimal conditions, the fluorescence intensity of DAP is linearly proportional to the Cr(III) ion concentration in the range of 5 × 10-6 to 1.5 × 10-4 mol L-1 and the detection limit is 1.2 × 10-7 mol L-1. The method has a good anti-interference performance against some metal ions, such as, Hg2+, Co2+, Cu2+, Mg2+, Ba2+, K+, Mn2+, Ni2+, Al3+, and Fe3+. The proposed method was successfully applied in the determination of Cr(VI) and Cr(III) in water samples.