Occurrence of Chlorinated Derivatives of Bisphenol S in Paper Products and Their Potential Health Risks through Dermal Exposure.

The occurrence of chlorinated derivatives of bisphenol S (Clx-BPS) and BPS was investigated in nine types of paper products (n = 125), including thermal paper, corrugated boxes, mail envelopes, newspapers, flyers, magazines, food contact paper, household paper, and business cards. BPS was found in all paper product samples, while Clx-BPS were mainly found in thermal paper (from below the limit of detection (

Sulfur vacancy-enhanced In2S3-x hollow microtubes for photocatalytic Cr (VI) and tetracycline removal.

Morphological regulation and defect engineering are efficient methods for photocatalytic technology by improving photon absorption and electron dissociation. Herein, In2S3-x hollow microtubes with S-vacancies (MIS) were fabricated via a simple solvothermal reaction using In-based metal-organic frameworks (In-MOFs) as a precursor. Experimental results demonstrate that the hollow structure and optimal S-vacancies can jointly accelerate the photocatalytic reaction, attributed to a larger specific surface area, more active sites, and faster electron transfer efficiency. The champion MIS(2) displayed significantly better photocatalytic activity for Cr(VI) reduction and tetracycline (TC) degradation. The Cr(VI) reduction rate by MIS(2) is 3.67 and 2.82 times higher than those of optimal In2S3 template-free (HIS(2)) and MIS(1) with poor S-vacancies, respectively. The removal efficiency of TC by MIS(2) is 1.37 and 1.15 times higher than those of HIS(2) and MIS(1). Further integration of MIS(2) with aerogel simplifies the recovery process significantly.

Associations of long-term mortality with serum uric acid at admission in acute decompensated heart failure with different phenotypes.

BACKGROUND AND AIMS: It remains unclear whether the long-term prognostic value of serum uric acid (SUA) at admission differs in acute decompensated heart failure (HF) patients across the spectrum of left ventricular ejection fraction (EF). METHODS AND RESULTS: In 2375 patients (38.9% women; mean age, 68.8 years), we assessed the risk of long-term (>1 year) all-cause mortality associated with per 1-SD increase in SUA at admission, using multivariable Cox regression in HF with preserved (HFpEF), mildly reduced (HFmrEF) and reduced (HFrEF) EF. During a median follow-up of 4.1 years, the long-term mortality rate was 39.9%. In all patients, the multivariable-adjusted hazard ratio (HR) expressing the risk of long-term mortality associated with SUA was 1.18 (95% CI, 1.11-1.26; P < 0.001). Compared with the low tertile of the SUA distribution, the sex- and age-adjusted cumulative incidence of long-term mortality was higher in the top tertile. In patients with HFpEF and HFrEF, SUA predicted the risk of long-term mortality with HRs amounting to 1.12 (95% CI, 1.02-1.21; P = 0.012) and 1.28 (95% CI, 1.12-1.47; P < 0.001), respectively. However, there were no associations between the risk of mortality and SUA in HFmrEF. Furthermore, age, sex, NYHA class, and the prevalence of coronary heart disease interacted significantly with SUA for predicting long-term mortality. CONCLUSION: Higher levels of SUA at admission were associated with higher risk of long-term mortality in patients with different HF subtypes. The risk conferred by SUA was age and sex dependent. Our observations highlight that measuring SUA at admission may help to improve risk stratification.

Simple high-performance liquid chromatography-ultraviolet method for simultaneous separation and detection of 14 bisphenol pollutants in building materials.

A high-performance liquid chromatography-ultraviolet method was developed for rapidly and simultaneously analyzing novel and typical bisphenols in building materials, including bisphenol S, diphenolic acid, bisphenol F, bisphenol E, bisphenol A, bisphenol B, bisphenol AF, bisphenol AP, bisphenol C, bisphenol FL, bisphenol Z, bisphenol BP, bisphenol M, and bisphenol P. By using a Kromasil 100-5 C18 column, these bisphenols were completely separated in 40 min via gradually increasing the concentration of methanol in the mobile phase from 45 to 80% during the elution process. In particular, this method achieved the synchronous analysis of bisphenol S, diphenolic acid, bisphenol FL, bisphenol BP, and bisphenol M through HPLC, which were difficult to separate and had to be identified and detected through mass spectrometry. The limits of detection of the method ranged from 0.002 to 0.040 mg/L for these 14 bisphenols, with a precision of less than 4.9% (n = 7, c = 0.05 mg/L). The analytical results for five types of building materials (phenolic, epoxy, polycarbonate, polyester, and polysulfone resins) indicated that the proposed method is appropriated for the rapid measurement of bisphenols in real samples.

Design of Smartphone-Assisted Point-of-Care Platform for Colorimetric Sensing of Uric Acid via Visible Light-Induced Oxidase-Like Activity of Covalent Organic Framework.

Monitoring of uric acid (UA) levels in biological samples is of great significance for human health, while the development of a simple and effective method for the precise determination of UA content is still challenging. In the present study, a two-dimensional (2D) imine-linked crystalline pyridine-based covalent organic framework (TpBpy COF) was synthesized using 2,4,6-triformylphloroglucinol (Tp) and [2,2'-bipyridine]-5,5'-diamine (Bpy) as precursors via Schiff-base condensation reactions and was characterized with scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), Powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR) spectroscopy, and Brunauer-Emmett-Teller (BET) assays. The as-synthesized TpBpy COF exhibited excellent visible light-induced oxidase-like activity, ascribed to the generation of superoxide radicals (O2•-) by photo-generated electron transfer. TpBpy COF could efficiently oxidase the colorless substrate 3,3',5,5'-tetramethylbenzydine (TMB) into blue oxidized TMB (oxTMB) under visible light irradiation. Based on the color fade of the TpBpy COF + TMB system by UA, a colorimetric procedure was developed for UA determination with a detection limit of 1.7 µmol L-1. Moreover, a smartphone-based sensing platform was also constructed for instrument-free and on-site detection of UA with a sensitive detection limit of 3.1 µmol L-1. The developed sensing system was adopted for UA determination in human urine and serum samples with satisfactory recoveries (96.6-107.8%), suggesting the potential practical application of the TpBpy COF-based sensor for UA detection in biological samples.

Efficient Adsorption and Extraction of Glutathione S-Transferases with Glutathione-Functionalized Graphene Oxide-Polyhedral Oligomeric Silsesquioxane Composite.

Glutathione S-transferases (GSTs) are important type-II detoxification enzymes that protect DNA and proteins from damage and are often used as protein tags for the expression of fusion proteins. In the present work, octa-aminopropyl caged polyhedral oligomeric silsesquioxane (OA-POSS) was prepared via acid-catalyzed hydrolysis of 3-aminopropyltriethoxysilane and polymerized on the surface of graphene oxide (GO) through an amidation reaction. Glutathione (GSH) was then modified to GO-POSS through a Michael addition reaction to obtain a GSH-functionalized GO-POSS composite (GPG). The structure and characteristics of the as-prepared GPG composite were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravity analysis, and surface charge analysis. The specific binding interactions between glutathione and GST gave GPG favorable adsorption selectivity towards GST, and other proteins did not affect GST adsorption. The adsorption behavior of GST on the GPG composite conformed to the Langmuir isotherm model, and the adsorption capacity of GST was high up to 364.94 mg g-1 under optimal conditions. The GPG-based solid-phase adsorption process was applied to the extraction of GST from a crude enzyme solution of pig liver, and high-purity GST was obtained via SDS-PAGE identification.

Preparation of Polyoxometalate-Based Composite by Solidification of Highly Active Cobalt-Containing Polytungstate on Polymeric Ionic Liquid for the Efficient Isolation of Proteinase K.

A novel porous polyoxometalate (POM)-based composite (Co4PW-PDDVAC) was prepared via the solidification of water-soluble polytungstate (Co4PW) on the polymeric ionic liquid dimethyldodecyl-4-polyethylene benzyl ammonium chloride (PDDVAC) via a cation-exchange reaction. The solidification was confirmed by EDS, SEM, FT-IR, TGA, and so on. The strong covalent coordination and hydrogen-bonding interaction between the highly active Co2+ of the Co4PW and the aspartic acid residues of proteinase K endowed the obtained Co4PW-PDDVAC composite with excellent proteinase K adsorption properties. Thermodynamic investigations indicate that the adsorption behavior of proteinase K was consistent with the linear Langmuir isothermal model, giving an adsorption capacity as high as 1428 mg g-1. The Co4PW-PDDVAC composite was applied in the selective isolation of highly active proteinase K from Tritirachium album Limber crude enzyme fluid.

Investigation of H2O2 Electrochemical Behavior on Ferricyanide-Confined Electrode Based on Ionic Liquid-Functionalized Silica-Mesostructured Cellular Foam.

In this work, ionic liquid (IL) of 1-propyl-3-methyl imidazolium chloride-functionalized silica-mesostructured cellular foam (MCF) was prepared. The obtained MCF-IL was used to construct the Fe(CN)63--confined electrode (MCF-IL-Fe(CN)63-/PVA) and H2O2 electrochemical behavior on the electrode was investigated. It was found that H2O2 was oxidized on the freshly prepared electrode while catalytically electro-reduced on the acid pretreated one. Cyclic voltametric results revealed that the real catalyst for catalytic reduction of H2O2 was Prussian blue (PB) rather than Fe(CN)63-. The electrocatalytic ability of the acid-pretreated MCF-IL-Fe(CN)63-/PVA electrode offered a wide linear range for H2O2 detection. The present study on H2O2 electrochemical behavior on an MCF-IL-Fe(CN)63-/PVA electrode might provide useful information for further developing integrated Fe(CN)63--mediated biosensors as H2O2 is extensively involved in the classic reaction containing oxidase enzymes.

Determination of nitric oxide using light-emitting diode-based colorimeter with tubular porous polypropylene membrane cuvette.

On the basis of the Griess-Saltzman (GS) reaction, an optical device for nitric oxide (NO) detection in exhaled breath and atmosphere was developed by employing the light-emitting diode (LED, 560 nm) as the light source, light-to-voltage converter (LVC) as the detector, and porous polypropylene membrane tube (PPMT) as the cuvette. The PPMT was filled with GS reagents and covered with a coaxial jacket tube for gas collection and color reaction; two ends of the PPMT were connected with the LED and LVC to detect the change of light transmissivity in the wavelength range of 530 to 590 nm mainly. A gas absorber filled with GS reagents was installed prior to another absorber filled with KMnO4 solution to eliminate the interference of coexisting NO2. Under the optimized experimental conditions, the device achieved a limit of detection (3σ/k) of 4.4 ppbv for NO detection. The linearity range of this device was divided into two segments, i.e., 25 to 100 ppbv and 50 to 1000 ppbv, with both coefficients of determination > 0.99. The relative standard deviation was 2.7% (n = 9, c = 100 ppbv), and the analytical time was 5.5 min per detection. The minimum detectable quantity was decreased to 1.18 ng, which was ~ 100 times lower than the original GS method (115 ng). The present device was applied for determination of NO in exhaled breath, vehicle exhaust, and air. In addition to satisfactory spiking recoveries (i.e., 103% and 107%), the analytical results of the present device were in agreement with the results obtained by the standard method. These results assured the practicality of the developed device for NO detection in real environmental samples.

Genome-Wide Identification and Expression Profiling of the BZR Transcription Factor Gene Family in Nicotiana benthamiana.

Brassinazole-resistant (BZR) family genes encode plant-specific transcription factors (TFs), play essential roles in the regulation of plant growth and development, and have multiple stress-resistance functions. Nicotiana benthamiana is a model plant widely used in basic research. However, members of the BZR family in N. benthamiana have not been identified, and little is known about their function in abiotic stress. In this study, a total of 14 BZR members were identified in the N. benthamiana genome, which could be divided into four groups according to a phylogenetic tree. NbBZRs have similar exon-intron structures and conserved motifs, and may be regulated by cis-acting elements such as STRE, TCA, and ARE, etc. Organ-specific expression analysis showed that NbBZR members have different and diverse expression patterns in different tissues, and most of the members are expressed in roots, stems, and leaves. The analysis of the expression patterns in response to different abiotic stresses showed that all the tested NbBZR members showed a significant down-regulation after drought treatment. Many NbBZR genes also responded in various ways to cold, heat and salt stress treatments. The results imply that NbBZRs have multiple functions related to stress resistance.

Protein Corona-Triggered Catalytic Inhibition of Insufficient POSS Polymer-Caged Gold Nanoparticles for Sensitive Colorimetric Detection of Metallothioneins.

Metallothioneins (MTs) are important biomarkers for the early diagnosis of heavy metal poisoning and malignancies. Convenient and cost-effective approaches for the rapid detection of MTs are therefore highly desirable for clinical monitoring. Herein, by taking advantage of the enzyme-mimetic activity of nanoparticles and protein corona-based recognition, insufficient polyhedral oligomeric silsesquioxane (POSS) polymer-caged gold nanoparticles (denoted as PP-AuNPs) are developed for the sensitive colorimetric analysis of MTs. In the presence of MTs, the catalytic reduction of yellow 4-nitrophenol to colorless 4-aminophenol is inhibited due to masking of the exposed PP-AuNPs catalytic surface with MTs corona. MTs are quantified by the presented color contrast with a superior sensitivity up to a 1.5 nM detection limit. Most importantly, the heavy metal ion- and aptamer-free PP-AuNPs platform exhibits excellent selectivity toward MTs over various ions, neutral biomolecules, and protein species, and successful applications are demonstrated by the detection of MTs in complex biological samples.

Three-Dimensional DNA Nanomachine Biosensor by Integrating DNA Walker and Rolling Machine Cascade Amplification for Ultrasensitive Detection of Cancer-Related Gene.

Stochastic DNA walkers capable of traversing on three-dimensional (3D) tracks have received great deal of attention. However, DNA walker-based biosensors exhibit limited amplification efficiency because of their slow walking kinetics and low processivity. Herein, by taking advantage of the high processivity of a DNA rolling machine, a sensitive ratiometric DNA nanomachine biosensor is designed. The biosensor is constructed with hairpin-loaded Au nanoparticles (NPs) (hpDNA@AuNPs) as a DNA walker and AgNCs-decorated magnetic NPs (AgNCs@MNPs) as a DNA rolling machine. In the presence of target DNA, exonuclease III (Exo III)-powered DNA walker is activated to accomplish first-stage amplification via a burnt-bridge mechanism, generating a great deal of toehold-loaded AuNPs (Toehold@AuNPs) to hybridize with magnetic nanoparticles loaded with silver-nanoclusters-labeled DNA (AgNCs@MNPs) with the assistance of Exo III. These trigger rapid rolling of AuNPs on the AgNCs@MNPs surface and release free AgNCs, converting the biological signal into a mass spectrometric signal ratio (107Ag/197Au) with detection by ICP-MS. A linear range of 0.5-500 fmol L-1 is achieved with a detection limit of 119 amol L-1 for the p53 gene. The practical applicability of the biosensor has been demonstrated in the accurate assay of the p53 gene in the human blood.

Gallic acid disruption of Aß1-42 aggregation rescues cognitive decline of APP/PS1 double transgenic mouse.

Alzheimer's disease (AD) treatment represents one of the largest unmet medical needs. Developing small molecules targeting Aß aggregation is an effective approach to prevent and treat AD. Here, we show that gallic acid (GA), a naturally occurring polyphenolic small molecule rich in grape seeds and fruits, has the capacity to alleviate cognitive decline of APP/PS1 transgenic mouse through reduction of Aß1-42 aggregation and neurotoxicity. Oral administration of GA not only improved the spatial reference memory and spatial working memory of 4-month-old APP/PS1 mice, but also significantly reduced the more severe deficits developed in the 9-month-old APP/PS1 mice in terms of spatial learning, reference memory, short-term recognition and spatial working memory. The hippocampal long-term-potentiation (LTP) was also significantly elevated in the GA-treated 9-month-old APP/PS1 mice with increased expression of synaptic marker proteins. Evidence from atomic force microscopy (AFM), dynamic light scattering (DLS) and thioflavin T (ThT) fluorescence densitometry analyses showed that GA significantly reduces Aß1-42 aggregation both in vitro and in vivo. Further, pre-incubating GA with oligomeric Aß1-42 reduced Aß1-42-mediated intracellular calcium influx and neurotoxicity. Molecular docking studies identified that the 3,4,5-hydroxyle groups of GA were essential in noncovalently stabilizing GA binding to the Lys28-Ala42 salt bridge and the -COOH group is critical for disrupting the salt bridge of Aß1-42. The predicated covalent interaction through Schiff-base formation between the carbonyl group of the oxidized product and ε-amino group of Lys16 is also critical for the disruption of Aß1-42 S-shaped triple-ß-motif and toxicity. Together, these studies demonstrated that GA can be further developed as a drug to treat AD through disrupting the formation of Aß1-42 aggregation.

Gold nanoparticles stabilized with four kinds of amino acid-derived carbon dots for colorimetric and visual discrimination of proteins and microorganisms.

A colorimetric array is described for the sensitive discrimination of proteins and microorganisms. Carbon dots (CDs) were prepared from citric acid and one of the amino acids glycine, lysine, serine or aspartic acid. They act as stabilizers for gold nanoparticles (AuNPs). The interactions between target protein and the CD/AuNPs induce a different aggregation behavior. This provides the basis for colorimetric discrimination of protein species and results in color changes from red/purple to purple/blue. Specific response patterns are analyzed by linear discriminant analysis. Twelve kinds of proteins with different pI and molecular weight were visually discriminated at nanomolar concentration levels. Alternatively, discrimination can be performed by measurement of the ration of absorbance at 525 nm and 620 nm. The discrimination sensitivity is as low as 2 nM. The method can differentiate between BSA and HSA. Twelve proteins were successfully distinguished in (spiked) urine samples. The discrimination accuracy is 100% at the 500 nM protein concentration level. In addition, different strains of microorganisms (E. coli O157:H7, E.coli ER2738, P. aeruginosa CICC10204; P. aeruginosa CICC21954; B.subtilis CICC10071; B.subtilis CICC10275) can be discriminated successfully via this array. Graphical abstract A CD/AuNPs-based colorimetric array sensor is proposed for the discrimination of protein, offering a discrimination sensitivity low down to 2 nM. The accurate differentiations of microorganisms originated from same species are achieved.

Specific Isolation of Glycoproteins with Mesoporous Zirconia-Polyoxometalate Hybrid.

A novel mesoporous zirconia-polyoxometalate ZrO2 -P8 W48 hybrid was prepared using a surfactant-assisted solvent evaporation technique. The acid-base reaction between the Zr-OH groups of zirconium oxides and P8 W48 was followed by self-assembly with an amphiphilic triblock copolymer as template to obtain a polyoxometalate-based hybrid. The ZrO2 -P8 W48 hybrid was characterized by Fourier-transform infrared spectroscopy (FT-IR), thermal gravimetric assay (TGA), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDXS), X-ray diffraction (XRD), and nitrogen sorption/desorption. Owing to the multiple hydrogen-bonding interactions between the P8 W48 moiety and the hydroxyl groups of glycoproteins, the ZrO2 -P8 W48 hybrid exhibited highly selective isolation of glycoproteins from complex matrices that included various non-glycoproteins. The retained glycoproteins could be readily recovered using a 0.01 mol L-1 cetane trimethyl ammonium bromide (CTAB) solution as stripping reagent, with recovery rates of 92, 100, 100, 100, and 74% for the five target glycoproteins, Ovalbumin (Ova), conalbumin (ConA), immunoglobulin G from human serum (IgG), γ-globulin from bovine milk (γ-Glo), and horseradish peroxidase (HRP), respectively. The ZrO2 -P8 W48 hybrid was successfully applied to the isolation of glycoproteins from egg white and human serum samples, as confirmed by SDS-PAGE and LC-MS/MS assays.

Online High Temporal Resolution Measurement of Atmospheric Sulfate and Sulfur Trioxide with a Light Emitting Diode and Liquid Core Waveguide-Based Sensor.

High temporal resolution components analysis is still a great challenge for the frontier of atmospheric aerosol research. Here, an online high time resolution method for monitoring soluble sulfate and sulfur trioxide in atmospheric aerosols was developed by integrating a membrane-based parallel plate denuder, a particle collector, and a liquid waveguide capillary cell into a flow injection analysis system. The BaCl2 solution (containing HCl, glycerin, and ethanol) was enabled to quantitatively transform sulfate into a well-distributed BaSO4 solution for turbidimetric detection. The time resolution for monitoring the soluble sulfate and sulfur trioxide was 15 h-1. The limits of detection were 86 and 7.3 µg L-1 ( S/ N = 3) with a 20 and 200 µL SO42- solution injection, respectively. Both the interday and intraday precision values (relative standard deviation) were less than 6.0%. The analytical results of the certificated reference materials (GBW(E)08026 and GNM-M07117-2013) were identical to the certified values (no significant difference at a 95% confidence level). The validity and practicability of the developed device were also evaluated during a firecracker day and a routine day, obviously revealing the continuous variance in atmospheric sulfate and sulfur trioxide in both interday and intraday studies.

Core-Corona Magnetic Nanospheres Functionalized with Zwitterionic Polymer Ionic Liquid for Highly Selective Isolation of Glycoprotein.

A novel zwitterionic polymer ionic liquid functionalized magnetic nanospheres, shortly as Fe3O4@PCL-PILs, is synthesized by grafting ionic liquid VimCOOHBr onto polymer ε-caprolactone (PCL) modified magnetic nanospheres via esterification and surface-initiated free radical polymerization. This established synthesis strategy offers the obtained magnetic nanospheres with well-defined core-corona structure, compact grafting layer, favorable zwitterionic and negative-charged surface, and high magnetic susceptibility. The as-prepared Fe3O4@PCL-PILs nanospheres exhibit typical "zwitterionic hydrophilic interaction liquid chromatography (ZIC-HILIC)" behaviors toward protein binding, and selectively adsorption of glycoprotein is achieved. The adsorption capacity of the magnetic nanospheres toward Immunoglobulin G is high up to 1136.4 mg g-1, and the captured Immunoglobulin G could be efficiently recovered by using 0.5% NH3 H2O (v/v) as stripping reagent, providing a recovery of 80.5%. Fe3O4@PCL-PILs nanospheres are then employed as sorbent for the selective isolation of Immunoglobulin G from human whole blood, obtaining high-purity Immunoglobulin G as demonstrated by polyacrylamide gel electrophoresis assays.

Triptolide derivatives as potential multifunctional anti-Alzheimer agents: Synthesis and structure-activity relationship studies.

Owning to the promising neuroprotective profile and the ability to cross the blood-brain barrier, triptolide has attracted extensive attention. Although its limited solubility and toxicity have greatly hindered clinical translation, triptolide has nonetheless emerged as a promising candidate for structure-activity relationship studies for Alzheimer's disease. In the present study, a series of triptolide analogs were designed and synthesized, and their neuroprotective and anti-neuroinflammatory effects were then tested using a cell culture model. Among the triptolide derivatives tested, a memantine conjugate, compound 8, showed a remarkable neuroprotective effect against Aß1-42 toxicity in primary cortical neuron cultures as well as an inhibitory effect against LPS-induced TNF-α production in BV2 cells at a subnanomolar concentration. Our findings provide insight into the different pharmacophores that are responsible for the multifunctional effects of triptolide in the central nervous system. Our study should help in the development of triptolide-based multifunctional anti-Alzheimer drugs.

Folic acid modified copper nanoclusters for fluorescent imaging of cancer cells with over-expressed folate receptor.

Water-soluble and functional copper nanoclusters (CuNCs) were prepared by using folic acid (FA) that serves both as a reducing reagent and a stabilizer. FA also acts as a functional ligand on the surface of the CuNCs, and this can be exploited to target the folate receptor which is over-expressed on the surface of HeLa cells. The FA-modified CuNCs nanoclusters have an average size of ca. 0.9 nm and are stable in aqueous medium for 30 days. Under photoexcitation at λex 270 and 350 nm, the FA-CuNCs display strong blue fluorescence with an emission peak at 440 nm. The FA-CuNCs exhibit low cytotoxicity and favorable biocompatibility as demonstrated by an MTT assay. A cell viability of >80% is found when incubating HeLa cells for 20 h with FA-CuNCs at levels of up to 200 µg mL-1. The targeting capability of the FA-CuNCs is demonstrated by live cell imaging. It is shown that HeLa cells with over-expressed folate receptor are much brighter than A549 cells where the receptor is not over-expressed. This is further corroborated by the fact that the copper content in HeLa cells (1.5 pg/cell) is 6.5-fold higher than that of A549 cells (0.23 pg/cell), both measured after the same incubation time of 3 h. If free FA is introduced into the cell culture medium, the folate receptors will be preoccupied with FA, and this results in a significant decrease in the cellular uptake of the FA-CuNCs by HeLa cells. Graphical Abstract Biocompatible copper nanoclusters (CuNCs) coated with folic acid (FA) were prepared and are shown to be viable probes for the differentiation between FR-positive HeLa cells and FR-negative A549 cells.

Polyhedral Oligomeric Silsesquioxane Polymer-Caged Silver Nanoparticle as a Smart Colorimetric Probe for the Detection of Hydrogen Sulfide.

The rapid and accurate detection of hydrogen sulfide is of great concern due to its unique role on environmental pollution and signal transmission in physiological systems. Herein, we report a smart colorimetric probe for the selective detection of H2S. The probe is prepared via a surfactant-free route with cross-linked polyhedral oligomeric silsesquioxane (POSS) polymer cage as capping ligand and reducing agent under microwave irradiation, called poly-POSS-formaldehyde polymer (PPF) cage-AgNPs or PPF-AgNPs for short. The caged silver nanoparticles are well-dispersed with narrow size distribution within 6.0-8.4 nm. Chloride ions and aldehyde groups in PPF make the nucleation and growth of Ag nanoparticles accomplished within a very short time of 1 min. The positively charged PPF-AgNPs exhibit excellent selectivity to H2S against other anionic species and thiols due to the specific Ag-H2S interaction, where the favorable protection effect of PPF polymer cage from the nanoparticle aggregation is demonstrated. The colorimetric probe presents a quick response to H2S (<3 min) and favorable sensitivity within a linear range of 0.7-10 µM along with a detection limit of 0.2 µM. The probe is well demonstrated by analysis of H2S in various water and biological samples.