Chemical Biology Approach to Reveal the Importance of Precise Subcellular Targeting for Intracellular Staphylococcus aureus Eradication.

Intracellular bacterial pathogens, such as Staphylococcus aureus, that may hide in intracellular vacuoles represent the most significant manifestation of bacterial persistence. They are critically associated with chronic infections and antibiotic resistance, as conventional antibiotics are ineffective against such intracellular persisters due to permeability issues and mechanistic reasons. Direct subcellular targeting of S. aureus vacuoles suggests an explicit opportunity for the eradication of these persisters, but a comprehensive understanding of the chemical biology nature and significance of precise S. aureus vacuole targeting remains limited. Here, we report an oligoguanidine-based peptidomimetic that effectively targets and eradicates intracellular S. aureus persisters in the phagolysosome lumen, and this oligomer was utilized to reveal the mechanistic insights linking precise targeting to intracellular antimicrobial efficacy. The oligomer has high cellular uptake via a receptor-mediated endocytosis pathway and colocalizes with S. aureus persisters in phagolysosomes as a result of endosome-lysosome interconversion and lysosome-phagosome fusion. Moreover, the observation of a bacterium's altered susceptibility to the oligomer following a modification in its intracellular localization offers direct evidence of the critical importance of precise intracellular targeting. In addition, eradication of intracellular S. aureus persisters was achieved by the oligomer's membrane/DNA dual-targeting mechanism of action; therefore, its effectiveness is not hampered by the hibernation state of the persisters. Such precise subcellular targeting of S. aureus vacuoles also increases the agent's biocompatibility by minimizing its interaction with other organelles, endowing excellent in vivo bacterial targeting and therapeutic efficacy in animal models.

Potentiation of Vancomycin: Creating Cooperative Membrane Lysis through a "Derivatization-for-Sensitization" Approach.

Gram-negative bacteria, especially the ones with multidrug resistance, post dire challenges to antibiotic treatments due to the presence of the outer membrane (OM), which blocks the entry of many antibiotics. Current solutions for such permeability issues, namely lipophilic-cationic derivatization of antibiotics and sensitization with membrane-active agents, cannot effectively potentiate the large, globular, and hydrophilic antibiotics such as vancomycin, due to ineffective disruption of the OM. Here, we present our solution for high-degree OM binding of vancomycin via a hybrid "derivatization-for-sensitization" approach, which features a combination of LPS-targeting lipo-cationic modifications on vancomycin and OM disruption activity from a sensitizing adjuvant. 106- to 107-fold potentiation of vancomycin and 20-fold increase of the sensitizer's effectiveness were achieved with a combination of a vancomycin derivative and its sensitizer. Such potentiation is the result of direct membrane lysis through cooperative membrane binding for the sensitizer-antibiotic complex, which strongly promotes the uptake of vancomycin and adds to the extensive antiresistance effectiveness. The potential of such derivatization-for-sensitization approach was also supported by the combination's potent in vivo antimicrobial efficacy in mouse model studies, and the expanded application of such strategy on other antibiotics and sensitizer structures.

A magneto-fluorescence bacteria assay strategy based on dual colour sulfide fluorescent nanoparticles with high near-IR conversion efficiency.

Anti-Stokes fluorescence induced by near-IR (NIR) radiation is particularly advantageous for the bioassay of complex samples, but most of the commonly used NIR-induced fluorescence nanomaterials such as up-conversion nanoparticles (UCNPs) do not exhibit satisfactory fluorescence intensity and work against achieving a highly sensitive bioassay. In this study, we a construct sensitive and specific bacteria biosensor based on the NIR-stimulated CaS: Eu, Sm, Mn and SrS: Ce, Sm, Mn nanoparticles. The fluorescent nanoparticles are conjugated with bacteria recognition fragments. In addition, the independent emission bands of these two types of fluorescent nanoparticles make it possible to detect and quantify Gram-positive strain and Gram-negative strain, simultaneously. Intense fluorescence and magnetic enrichment of magneto-fluorescence systems enable bacteria discrimination with the naked eye and improve sensitivity in trace bacteria detection (<20 CFU mL-1). The linear relationship between the fluorescence intensity and bacterial concentration is established with a detection range of 25-106 CFU mL-1. Furthermore, this NIR-excited assay strategy demonstrates better anti-interference capability than UV/visible-excited assay methods, showing high potential and practical value for medical diagnostics and bacteria monitoring.

Efficient photocatalytic inactivation of E. coli by Mn-CdS/ZnCuInSe/CuInS2 quantum dots-sensitized TiO2 nanowires.

A novel visible light-driven photocatalyst (represented as Mn-CdS/ZCISe/CIS/TiO2) for the passivation of E. coli was prepared with TiO2 nanowires as support and using CuInS2 (CIS) and ZnCuInSe (ZCISe) quantum dots (QDs), as well as Mn-doped CdS (Mn-CdS) nanoparticles (NPs) as sensitizers. The use of CIS and ZCISe QDs and Mn-CdS NPs extends the light harvest region to visible light. The photoelectric conversion efficiency was consequently improved, with a photocurrent density of 12.5 mA cm-2, about 60 times that of pure TiO2 nanowires. The germicidal efficiency of the photocatalyst was assessed by passivation of E. coli, 96% bacteria in 50 ml 105 colony forming units (CFU) ml-1 solution were killed within 50 min. Besides the high efficiency, the composite has good stability and satisfactory recycling performance. The antibiotic mechanism was also performed by using photoluminescence and a scavenging agent of different active matter, revealing that the photo-generated holes play a major role in the sterilization process.

Water-soluble ZnCuInSe quantum dots for bacterial classification, detection, and imaging.

Bacteria are everywhere and pose severe threats to human health and safety. The rapid classification and sensitive detection of bacteria are vital steps of bacterial community research and the treatment of infection. Herein, we developed optical property-superior and heavy metal-free ZnCuInSe quantum dots (QDs) for achieving rapid discrimination of Gram-positive/Gram-negative bacteria by the naked eye; driven by the structural differences of bacteria, ZnCuInSe QDs are effective in binding to Gram-positive bacteria, especially Staphylococcus aureus (S. aureus), in comparison with Gram-negative bacteria and give discernable color viewed by the naked eye. Meanwhile, based on its distinctive fluorescence response, the accurate quantification of S. aureus was investigated with a photoluminescence system in the concentration ranges of 1 × 103 to 1 × 1011 CFU/mL, with a limit of detection of 1 × 103 CFU/mL. Furthermore, we demonstrated the feasibility of ZnCuInSe QDs as a fluorescence probe for imaging S. aureus. This simple strategy based on ZnCuInSe QDs provides an unprecedented step for rapid and effective bacterial discrimination, detection, and imaging.

Rational design of specific ligands for human serum albumin separation and applications.

Human serum albumin is widely used in clinical practice, and the development of new ligands with high affinity is beneficial to improve its separation efficiency. The Site II of human serum albumin is an active binding site of various molecules such as l-tryptophan, which was studied with molecular simulation to obtain insights for the design of new ligands. The results showed that the carboxyl and indolyl groups of l-tryptophan were critical for the binding on Site II. Seven ligands containing carboxyl groups and indolyl groups were designed, and molecular simulation showed that indole-3-pentanoic acid was the best ligand. A new ligand combined indole-3-acetic acid and cysteine was designed for easier resin preparation, and molecular simulation also indicated that the new ligand bound strongly to Site II. Resins with the new ligand designed was prepared and static adsorption experiments indicated that the new resin had high adsorption capacity of human serum albumin and strong salt tolerance. Finally, recombinant human serum albumin was separated from yeast broth with high purity of 90.4% and recovery of 94.2%, which indicated that the new resin had good adsorption selectivity and strong potential for applications.

Bi, Fe, and Ti ternary co-doped ZrO2 nanocomposites as a mass spectrometry matrix for the determination of bisphenol A and tetrabromobisphenol A in tea.

Bi, Fe, and Ti ternary co-doped ZrO2 (BFT-ZrO2) nanocomposites have been prepared by a sol-gel process and used as both adsorbent and matrix for the enrichment and determination of small molecules by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS). The BFT-ZrO2 nanocomposites not only can selectively enrich a wide variety of low-mass toxic pollutants but can also be used as an excellent matrix to enhance the laser desorption/ionization efficiency with low background noise and uniform co-crystalline film. Low limits of detection (LODs) (0.1 pg mL-1 for bisphenol A (BPA), 2 pg mL-1 for tetrabromobisphenol A (TBBPA), 0.1 pg mL-1 for alizarin (AZ), 0.001 pg mL-1for bisphenol S (BPS), 0.01 pg mL-1 for indigo blue (ID), 0.01 pg mL-1 for pentachlorophenol (PCP), 100 pg mL-1 for estradiol (E2), 0.001 pg mL-1 for cetyltrimethylammonium bromide (CTAB), 0.1 pg mL-1 for crystal violet (CV), 1 pg mL-1 for malachite green (MG), 0.01 pg mL-1 for rhodamine B (RhB), and 0.01 pg mL-1 for perfluorooctane sulfonate (PFOS) were achieved. The relative standard deviations (RSDs) of shot-to-shot are 9.4-24% and of sample-to-sample 5.2-17%. The BFT-ZrO2 matrix was successfully applied to the determination of TBBPA and BPA in tea samples. This method shows a new strategy for determination of toxic compounds in tea. Graphical abstract.

Reduced titania nanosheets as an effective visible-light germicide.

Two-dimensional reduced titania nanosheets (RTNs), synthesized by a solvothermal method, reveal significant visible light-activated germicidal activity. XRD, XPS, EPR, TEM and Raman show successful reduction of anatase TiO2, resulting in Ti3+ formation as well as an increase in the concentration of {001} facets. The RTNs possess a bandgap energy of approximately 2.86 eV, and demonstrate strong absorption over the visible spectrum. Under simulated solar light (λ = 320-780 nm, 70 mW cm-2) the RTNs are found to completely inactivate Escherichia coli bacteria within 1 h. Our study indicates the RTNs have significant potential for ameliorating antibiotic-resistant bacteria in clinical settings under ambient lighting conditions.

Apatinib, a selective VEGFR2 inhibitor, improves the delivery of chemotherapeutic agents to tumors by normalizing tumor vessels in LoVo colon cancer xenograft mice.

Tumor vascular normalization has been proposed as a therapeutic strategy for malignant neoplasms, which can also interpret the synergistic effect of anti-angiogenesis agents combined with chemotherapy. Apatinib (Apa), a highly selective VEGFR2 inhibitor, attracts much attentions due to its encouraging anticancer activity, especially in the clinical trials of combined treatment. In this study, we investigated whether Apa could promote vascular normalization in tumor in a certain time window. Mice bearing LoVo colon cancer xenograft were orally administrated Apa (150 mg kg-1 per day) for 5, 7, 10, or 12 days. Apa significantly inhibited tumor growth and decreased the microvessel density. Using multi-photon microscopy and electron microscopy, we found that Apa improved tumor vessel morphology by pruning distorted vessel branches and decreased the gap between endothelial cells after a 7-day treatment. Furthermore, Apa decreased vessel leakage and increased pericyte coverage on vascular endothelial cells, suggesting that tumor vessels were more mature and integrated. The intratumoral distribution of adriamycin (ADR) in Apa group was improved from day 7 to 10 without change in plasma drug concentration. Tumor blood perfusion was also increased in this window, and the expression of hypoxia induced factor 1α was downregulated, suggesting the effect of Apa on alleviating tumor hypoxic micro-environment. In conclusion, Apa may improve the effective perfusion of tumor vessels and increase the intratumoral distribution of ADR in a certain time window via normalizing tumor vessels. This normalization window (7 to 10 days of treatment) may contribute to develop a regimen of combined medication in clinic use of Apa.

Cobalt-doped nanoporous carbon as SALDI-TOF-MS adsorbent and matrix for quantification of cetyltrimethylammonium bromide, Rhodamine B and Malachite Green at sub-ppt levels.

Cobalt-doped nanoporous carbon (Co-NPC) with dodecahedral shape was pyrolytically synthesized and applied as a sorbent and matrix for the enrichment and analysis of small molecules by surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS). Extremely low detection limits were accomplished for cetyltrimethylammonium bromide (1 fg·mL-1), and Rhodamine B (1 fg·mL-1) in water, and Malachite Green and its metabolite in fish blood and fish extracts (pg·mL-1 concentrations). Graphical abstract Schematic representation of cobalt-doped nanoporous carbons (Co-NPCs) applied as SALDI matrix for analysis of toxic contaminants in fish and receipt papers. The Co-NPCs have a high desorption/ionization efficiency and low limit of detection.

Eu,Sm,Mn-Doped CaS Nanoparticles with 59.3% Upconversion-Luminescence Quantum Yield: Enabling Ultrasensitive and Facile Smartphone-Based Sulfite Detection.

Eu,Sm,Mn-doped CaS (ESM-CaS) nanoparticles demonstrate a remarkable upconversion luminescence (UCL) efficiency with a quantum yield of nearly 60%, enabling many new applications and devices. We describe an ESM-CaS nanoparticle-based paper test strip for one-shot quantitative measurement of sulfite concentration using a smartphone-based reader. The integrated UCL-based sulfite detection system features high sensitivity and facile operation without the need for separation and pretreatment. Moreover, the design principles are general in nature and so can be tailored for the detection and quantification of a variety of other analytes.

Preparation of Bi0.15Fe0.15TiO2 Nanocomposites for the Highly Selective Enrichment of Phosphopeptides.

Novel Bi0.15Fe0.15TiO2 nanocomposites (B0.15F0.15TNs) were synthesized for the first time by a modified sol-gel technology and successfully applied to selective extraction and enrichment of phosphopeptides from digested protein mixture solutions and real samples (tissue protein extract from human liver). The codoping of Bi and Fe into TiO2 results in a significant enhancement in both the enrichment efficiency and selectivity. Compared with the commercial available TiO2 extractant, the proposed B0.15F0.15TNs possess a lower detection limit (2 × 10-9 M) and higher selectivity at a low weight ratio of 1:1200 (phosphopeptides/nonphosphopeptides). Additionally, a total of 223 phosphorylation sites were identified from the human liver lysate after enrichment by the B0.15F0.15TNs. In addition, the synthesis of B0.15F0.15TNs is quite easy, of high yield, and inexpensive.

A Promising Microtubule Inhibitor Deoxypodophyllotoxin Exhibits Better Efficacy to Multidrug-Resistant Breast Cancer than Paclitaxel via Avoiding Efflux Transport.

Multidrug resistance (MDR) is a common limitation for the clinical use of microtubule-targeting chemotherapeutic agents, and it is the main factor for poor prognoses in cancer therapy. Here, we report on deoxypodophyllotoxin (DPT), a promising microtubule inhibitor in phase 1, as a promising candidate to circumvent this obstacle. DPT remarkably suppressed tumor growth in xenograft mice bearing either paclitaxel (PTX)-sensitive MCF-7/S or acquired resistance MCF-7/Adr (MCF-7/A) cells. Also, DPT exhibited similar accumulation in both tumors, whereas PTX displayed much a lower accumulation in the resistant tumors. In vitro, DPT exhibited a much lower resistance index (0.552) than those of PTX (754.5) or etoposide (38.94) in both MCF-7/S and MCF-7/A cells. Flow cytometry analysis revealed that DPT (5 and 10 nM) caused arrest of the G2/M phase in the two cell lines, whereas PTX (up to 10 nM) had no effect on cell-cycle progression of the MCF-7/A cells. Microtubule dynamics assays revealed that DPT destabilized microtubule assembly in a different mode. Cellular pharmacokinetic assays indicated comparable intracellular and subcellular accumulations of DPT in the two cell lines but a much lower retention of PTX in the MCF-7/A cells. Additionally, transport assays revealed that DPT was not the substrate of P-glycoprotein, breast cancer resistance protein, or MDR-associated protein 2, indicating a lower occurrence rate of MDR. DPT might be a promising microtubule inhibitor for breast cancer therapy, especially for treatment of drug-resistant tumors.

ZnO-functionalized mesoporous inner-empty nanotheranostic platform: upconversion imaging guided chemotherapy with pH-triggered drug delivery.

Here we report a novel drug delivery system using mesoporous inner-empty upconversion microspheres carrying drugs with ZnO quantum dots (UCMPS@ZnO) acting as a 'door-keeper' for pH-triggered drug release. Compared to other upconversion drug delivery systems, it is smarter, simpler, more efficient and more biocompatible. In particular, the UCMPS@ZnO microspheres show low cytotoxicity, are simple to produce and have a high drug loading rate (15%). Promisingly, a mice treatment experiment demonstrated that the multifunctional nanoparticles have efficient inhibition of tumor growth after a 14-day treatment. This makes UCMPS@DOX-ZnO microspheres a promising theranostic candidate in cancer treatment and clinical trials.

A highly selective fluorescent probe for in vitro and in vivo detection of Hg(2+) .

In this paper, a simple fluorescent probe, rhodamine B derivatives (RS), was designed and prepared for sensitive detection of Hg(2+) in CH3CN/H2O (5/5, v/v). RS exhibits high selectivity and sensitivity toward Hg(2+) over other common metal ions, displaying a significant color change from colorless to pink in the presence of Hg(2+). The fluorescence responses remain stable over a broad pH range (5.0 to 9.0) and are suitable for detection under physiological conditions. Experimental results of HeLa cells and zebrafish show that RS is cell and organism permeable. We also demonstrate the acquisition of images of Hg(2+) in HeLa cells and zebrafish by using a simple fluorescence confocal imaging technique.

Development of enzyme-linked immunosorbent assay for determination of polybrominated diphenyl ether BDE-121.

Our interests are in the development of immunoassay-based fast scanning methods for persistent organic pollutants. To develop the immunoassay method of polybrominated diphenyl ether (PBDE), a model compound of PBDE, 2,3',4,5',6-pentabromodiphenylether (BDE-121), has been chosen to develop its antibody and the competitive indirect enzyme-linked immunosorbent assay (ELISA) is developed. The hapten of BDE-121 containing reactive carboxylic acid was synthesized and conjugated to carrier proteins (bovine serum albumin [BSA] and ovalbumin [OVA]). Anti-BDE-121 polyclonal antibody was then developed in rabbits as a result of immunization with the BDE-121-BSA conjugate. The optimal amount of coating antigen BDE-121-OVA conjugate and the dilution of antiserum needed in the ELISA were determined with the checkerboard method, and the effects of the properties of PBST (phosphate-buffered saline and Tween 20) buffer (pH and salt concentration) and chemical solvent (types and concentrations) on the ELISA were investigated to achieve a rapid robust assay with high sensitivity. Under the optimized conditions, the developed indirect ELISA shows a linear detection range from 1.74 to 84.1 ng/ml, with an IC50 value of 8.07 ng/ml and a detection limit of 0.644 ng/ml. In total, 11 kinds of compounds were tested for calculating the cross-reactivity, which was less than 8% for nearly all of them. Real samples were analyzed by the proposed immunoassay and gas chromatography/mass spectrometry (GC/MS).

Synthesis of haptens and development of an indirect enzyme-linked immunosorbent assay for tris(2,3-dibromopropyl) isocyanurate.

A competitive indirect enzyme-linked immunosorbent assay (ciELISA) was developed for detection of tris(2,3-dibromopropyl) isocyanurate (TBC). Polyclonal antibodies against TBC were raised from synthesized haptens and then screened against various coating antigens. After optimization of the immunoassay conditions, the linear range and IC50 value of the assay were 0.30-100 and 5.17 µg/L, respectively, with little cross-reactivity (≤2%). Recovery of various samples (water, serum, soil) was tested and the values ranged from 68% to 110%. This ciELISA was also applied to determine TBC in the riverside soil of the Liuyang River, and the results were compared with the data obtained by UHPLC-MS/MS. The experimental assay results confirmed that this proposed immunoassay is a specific, sensitive, and reliable method for determination and monitoring of TBC.

Natural cotton fibers as adsorbent for solid-phase extraction of polycyclic aromatic hydrocarbons in water samples.

A natural material, cotton fiber, has been applied as a solid-phase extraction (SPE) adsorbent for sample preparation for the analysis of polycyclic aromatic hydrocarbons (PAH) in water samples using high-performance liquid chromatography. The cotton fiber was used directly without any chemical modifications, which avoided a complex synthesis process and consumption of a large volume of organic solvent. The conditions affecting the extraction efficiency were optimized to achieve high detection sensitivity, and included elution solvent, ultrasonic elution time, extraction time, sample volume, salt concentration and organic modifier addition. Under the optimal conditions, the detection limits for seven PAH compounds could reach up to 0.1-2.0 ng L(-1). The method accuracy was evaluated using recovery measurements in standard spiked samples and good recoveries of 70.69-110.04% with relative standard deviations of less than 10% have been achieved. Consequently, the method developed was successfully applied for determining PAH in environmental samples: snow water, metal-fabrication factory wastewater and Xiangjiang River water, with PAH contents ranging from 13.2 to 83.1 ng L(-1). Therefore, using cotton fiber as a new SPE adsorbent, was easy to prepare, had a low cost and great reusability, and this implies it is a promising method for sample preparation.

Increased Thyroid DPP4 Expression Is Associated With Inflammatory Process in Patients With Hashimoto Thyroiditis.

CONTEXT: Dipeptidyl peptidase-4 (DPP4) is originally described as a surface protein in lymphocytes. Lymphocyte infiltration and subsequent destruction of thyroid tissue have been considered as the central pathological mechanism in Hashimoto thyroiditis (HT). OBJECTIVE: The present study aimed to investigate DPP4 expression in peripheral blood and thyroid tissue in HT patients, and explore the role of DPP4 in the pathophysiological process of HT. METHODS: This case-control study recruited 40 drug-naive HT patients and 81 control individuals. Peripheral blood and thyroid specimens were collected for assessing the expression and activity of DPP4. Moreover, single-cell RNA sequencing (scRNA-seq) analysis of 6 "para-tumor tissues" samples from scRNA-seq data set GSE184362 and in vitro cell experiments were also conducted. RESULTS: The HT patients had similar DPP4 serum concentration and activity as the controls. However, the expression and activity of DPP4 was significantly increased in the thyroid of the HT group than in the control group. The scRNA-seq analysis showed that DPP4 expression was significantly increased in the HT group, and mainly expressed in T cells. Further in vitro studies showed that inhibition of lymphocyte DPP4 activity with sitagliptin downregulated the production of inflammatory factors in co-cultured thyroid cells. CONCLUSION: DPP4 expression was significantly increased in the thyroid of the HT group compared with the control group, and was mainly localized in the lymphocytes. Inhibition of lymphocyte DPP4 activity reduced the production of inflammatory factors in co-cultured thyroid cells. Therefore, inhibition of DPP4 may have a beneficial effect by alleviating inflammatory reactions in HT patients.

A supersensitive electrochemical sensor based on RCA amplification-assisted "silver chain"-linked gold interdigital electrodes and CRISPR/Cas9 for the detection of Staphylococcus aureus in food.

With the rising emphasis on food safety, technology to rapidly identify Staphylococcus aureus (S. aureus) is of great significance. Herein, we developed a novel electrochemical biosensor based on the CRISPR/Cas9 system and rolling circle amplification (RCA)-assisted "silver chain"-linked gold interdigital electrodes (Au-IDE). This sensor utilizes RCA to create DNA long chains that span the Au-IDE, and CRISPR/Cas9 as a recognition component to recognize capture/target dsDNA. Additionally, we used silver staining technology to improve detection sensitivity. Then, we detected S. aureus through impedance changes that occurred when the silver chain between the Au-IDE was connected or broke, with a limit of detection (LOD) of 7 CFU/mL and a detection time of 1.5 h. Lastly, we successfully employed this sensor to detect S. aureus in real food samples, making it a promising tool for food monitoring.