Ratiometric fluorescence determination of chlortetracycline based on the aggregation of copper nanoclusters triggered by aluminum ion.

The aggregation-induced emission (AIE) characteristic of copper nanoclusters (CuNC) was for the first time used to construct a ratiometric fluorescence probe (CuNC-Al3+) for detection of chlortetracycline (CTC). Aluminum ion (Al3+) can aggregate free CuNC and make it emit a bright and stable red fluorescence. A slight excess of Al3+ in CuNC-Al3+ solution can form a CTC-Al3+ complex to limit the conformational rotation of CTC molecule and enhance CTC fluorescence. So, the red fluorescence of CuNC-Al3+ probe and the enhanced CTC fluorescence are used as a reference signal and a response signal to detect CTC, respectively. The method developed shows a good linear relationship between the CTC concentration and the fluorescence intensity ratio (I495/I575) in the range 0.1-3.0 µM, and the detection limit is 25.3 nM (S/N = 3). In addition, the fluorescent color of CuNC-Al3+ probe changes from red to yellow-green as the concentration of CTC increases. Based on this observation, a fluorescent test paper has also been fabricated. Schematic illustration of Al3+ inducing CuNC to produce AIE performance and detecting CTC.

Cobalt(II)-ion-exchanged Zn-bio-MOF-1 derived CoS/ZnS composites modified electrochemical sensor for chloroneb detection by differential pulse voltammetry.

For the first time CoS-nanoparticles attached ZnS rods (CoS/ZnS composites) have been synthesized using cobalt(II)-ion-exchanged zinc-based biological metal-organic framework-1 (Zn-bio-MOF-1) as precursors by a solvothermal method. Among them, the cobalt(II)-ion-exchanged Zn-bio-MOF-1 was obtained by exchanging the dimethylammonium cations (Me2NH2+) of Zn-bio-MOF-1 with cobalt ions. A novel electrochemical sensor based on CoS/ZnS composites and molecularly imprinted polymers (MIPs) was proposed for rapid, sensitive, and highly selective detection of organochlorine pesticide chloroneb. The MIP film was obtained by cyclic voltammetry (CV), and differential pulse voltammetry (DPV) was used to detect chloroneb. Under the optimal conditions, the oxidation peak current density of chloroneb was linearly related to the concentration from 0.003 to 0.2 µM and 0.2 to 3.2 µM with a detection limit of 0.87 nM (S/N = 3) and a sensitivity of 52.27 µA·µM-1·cm-2. The proposed sensor exhibits a favorable selectivity, stability, and reproducibility, and was applied to detect chloroneb residues in licorice, cucumber, river water, and soil samples with satisfactory results.Graphical abstract.

Aspartic acid assisted one-step synthesis of stable CsPbX3@Asp-Cs4PbX6 by in situ growth in NH2-MIL-53 for ratiometric fluorescence detection of 4-bromophenoxybenzene.

A molecularly imprinted ratiometric fluorescent sensor was synthesized for the detection of 4-bromophenoxybenzene (BDE-3) based on perovskite quantum dots and metal organic framework. First, aspartic acid (Asp) was introduced during the synthesis of perovskite CsPbX3 for the formation of a core-shell structure of CsPbX3@Asp-Cs4PbX6. Due to the protection of the shell layer Cs4PbX6, the stability of the core CsPbX3 was improved significantly. Compared to CsPb(BrI)3, the ultraviolet and thermal stabilities of CsPb(BrI)3@Asp-Cs4Pb(BrI)6 were increased by 26 times and 32 times, respectively, and, compared to CsPbBr3, these stabilities of CsPbBr3@Asp-Cs4PbBr6 were increased by 3 times and 13 times, respectively. The water stabilities of CsPb(BrI)3@Asp-Cs4Pb(BrI)6 and CsPbBr3@Asp-Cs4PbBr6 were greatly improved too. Then, a ratiometric fluorescence sensor was constructed by in situ growth of CsPb(BrI)3@Asp-Cs4Pb(BrI)6 in metal organic framework (NH2-MIL-53) for the detection of BDE-3, in which the orange fluorescence of CsPb(BrI)3@Asp-Cs4Pb(BrI)6 (614 nm) was regarded as the reference signal and the cyan fluorescence of NH2-MIL-53 (494 nm) was used as the fluorescence response signal. To improve the selectivity of the sensor, the molecular imprinting polymer (MIP) was modified on the NH2-MIL-53 and an imprinting factor of 3.17 was obtained. Under 365 nm light excitation, the fluorescent response signal at 494 nm was quenched gradually by BDE-3 in the range 11.4 to 68.5 nmol/L, while the reference signal at 614 nm remained unchanged. The limit of detection and limit of quantification were 3.35 and 11.2 nmol/L, respectively, and the fluorescent color of the sensor changed gradually from cyan to green to orange, which illustrated that the developed sensor has an ability to recognize BDE-3 specifically, a good anti-interference ability, and a sensitively visual detection ability. Moreover, the sensor was successfully applied to the BDE-3 detection in polyethylene terephthalate plastic bottle, polyvinyl chloride plastic bag, and circuit board with satisfactory recoveries (96.3-108.1%) and low relative standard deviations (5%). The preparation processes of NH2-MIL-53, NH2-MIL-53-CsPb(BrI)3@Asp-Cs4Pb(BrI)6, and the MIP-NH2-MIL-53-CsPb(BrI)3@Asp-Cs4Pb(BrI)6 composites.

LC/MS-guided isolation and GNPS procedures to identify flavonoid of HCoV-OC43 inhibitors.

The screening of based target compounds supported by LC/MS, MS/MS and Global Natural Products Social (GNPS) used to identify the compounds 1-10 of Butea monsperma. They were evaluated in human malignant embryonic rhabdomyoma cells (RD cells) infected with Human coronavirus OC43 (HCoV-OC43) and showed significant inhibitory activity. Target inhibition tests showed that compounds 6 and 8 inhibited the proteolytic enzyme 3CLpro, which is widely present in coronavirus and plays an important role in the replication process, with an effective IC50 value. The study confirmed that dioxymethylene of compound 8 may be a key active fragment in inhibiting coronavirus (EC50 7.2 µM, SI > 139.1). The results have led to identifying natural bioactive compounds for possible inhibiting HCoV-OC43 and developing drug for Traditional Chinese Medicine (TCM).

A gel fluorescence sensor based on CDs@SiO2/FeS2@MIPs for the visual detection of p-chlorophenol.

There is a critical need for the rapid detection of p-chlorophenol produced by pesticide abuse and industrial wastewater discharge, which has been an urgent problem in the realm of environmental protection. Here, a green and environmentally friendly method was developed to prepare stable and low toxicity quantum dots. First, blue-green fluorescent FeS2 quantum dots (B-FeS2 QDs) were prepared with FeCl3·6H2O (an iron source) and L-cysteine (a capping agent) by the solvothermal method. By combining B-FeS2 QDs with orange carbon dots (O-CDs), a CDs@SiO2/FeS2@MIPs visual fluorescence sensor for the selective detection of p-chlorophenol was constructed. Under optimum conditions, this sensor exhibited a detection limit of 1.265 µM with a linear range of 5.00-50.00 µM and was successfully applied to detect p-chlorophenol in real samples. Moreover, this sensor was successfully applied to visual semi-quantitative detection of p-chlorophenol. This work demonstrated that these sensors, based on FeS2 QDs and CDs, had potentials for in situ and visual detection of environmental contaminants.

A peroxidase-like nanoenzyme based on strontium(II)-ion-exchanged Prussian blue analogue derivative SrCoO3/Co3O4 nanospheres and carbon quantum dots for the colorimetric detection of tigecycline in river water.

In this work, for the first time, we derived a composite of perovskite oxide SrCoO3 and Co3O4 by annealing the Prussian blue analogue exchanged with strontium ions and modified with carbon quantum dots (CQDs). Its peroxidase-like catalytic activity was explored. The peroxidase-like activity was mainly evaluated by the rate of the chromogenic reaction. When H2O2 was present in the reaction system, the colorless substrate 3,3',5,5'-tetramethylbenzidine (TMB) was oxidized into a blue product (oxTMB), and this was monitored by UV-vis absorption spectrum. Among them, the SrCoO3 and CQDs not only promoted the generation of superoxide anion radicals (O2-•) and electron-hole pairs (h+) in the reaction system, but also accelerated the electron transfer between the substrate TMB and H2O2. Therefore, the peroxidase-like catalytic activity of the reaction system was significantly improved. Moreover, the complexation of tigecycline (TGC) and CQDs@SrCoO3/Co3O4 composite enhanced the peroxidase-like catalytic activity of the reaction system. Based on this, using TGC and TMB as template molecules, a molecularly imprinted colorimetric sensor for detecting TGC was constructed. The absorbance difference of the reaction system was linear with the TGC concentration in the range of 0.02-6.0 µM, and the detection limit was 4.46 nM. Furthermore, the proposed sensor had high selectivity and applied to the detection of TGC in Pearl River water.

An admittance-controlled amplified force tracking scheme for collaborative lumbar puncture surgical robot system.

BACKGROUND: The accurate sensing and display of the delicate needle-tissue interaction force to the operator is desirable for needle insertion procedures. It not only plays a significant role in the surgical treatment effect, but also has a great significance in improving surgical safety and reducing the incidence of complications. However, the direct detection of the interaction force between the tissue and needle tip by placement of a force sensor is challenging owing to the constraints of miniaturisation, cost, and sterilisation. METHODS: In this study, a new position-based force-to-motion controller with magnified force feedback is presented to provide augmented force perception to the operator during needle insertion on the soft tissue. Furthermore, the demonstration to the position-based low level motion controller is more suitable for needle insertion surgical requirements in the cooperative robotic system. RESULTS: The proposed controller was experimentally validated by a collaborative lumbar puncture robotics system. Additionally, to provide hand tremor rejection for the stable manipulation of the puncture needle, it was demonstrated that the proposed amplified feedback force controller allowed a safer object interaction with the robotic needle insertion assistance. CONCLUSIONS: The results of the experiment show that a desirable interaction force profile is perceived by the operator during the overall insertion task operation. The admittance gain for the simplified admittance controller has a significant impact on the operator's ability to accurately control the applied force.

A sensitive visual detection of thiamethoxam based on fluorescence resonance energy transfer from NH2-SiO2@CsPbBr3 to merocyanine configuration of spiropyran.

The spiropyran (SP) compound is a typical photochromic compound. Its merocyanine configuration (MC) can accept energy and be excited by visible light, while the closed-loop configuration cannot. In this work, the SP was wrapped in ß-cyclodextrin (ß-CD-SP) firstly. When it was competitively replaced by thiamethoxam and dissociated out of ß-CD, it would be converted to MC, which could be excited by visible light around 550 nm to produce red fluorescence. Here, CsPbBr3 was selected as the energy donor based on the principle of fluorescence resonance energy transfer (FRET). In order to connect with ß-CD-SP and improve its stability, CsPbBr3 was wrapped in mesoporous silica, and then the second wrapping was performed to block those mesopores and the amination reaction was carried out (NH2-SiO2@CsPbBr3). Subsequently, NH2-SiO2@CsPbBr3 with green fluorescence (506 nm) was used as the internal standard and excitation light source for MC, and the red fluorescence of MC was used as the response signal to construct a ratiometric fluorescence sensor. When thiamethoxam was added and excited by 365 nm ultraviolet light, the energy would be transferred from NH2-SiO2@CsPbBr3 (506 nm) that emitted green fluorescence to MC, which emitted red fluorescence. So, the fluorescence color changed from green to yellow to red with the addition of the thiamethoxam. This sensor was employed to detect thiamethoxam in soil and yam.

Clinical study of periodontal endoscope-assisted subgingival scaling in the treatment of residual pocket.

OBJECTIVES: To compare the treatment effects of periodontal endoscope-assisted and traditional subgingival scaling on residual pockets. METHODS: A total of 13 patients with periodontitis from Dept. of Periodontics, West China Hospital of Stomatology, Sichuan University were recruited. After 4-6 weeks of initial treatment, the residual pockets with a probing depth (PD) of ≥4 mm and attachment loss (AL) of ≥4 mm and bleeding on probing were examined with traditional (control group) and periodontal endoscope-assisted subgingival scaling (endoscopy group) in a randomly controlled split-mouth design. At baseline and 6 weeks and 3 months after treatment, plaque index (PLI), PD, AL, and bleeding index (BI) were measured. Differences in these clinical parameters within and between groups and patient-reported outcomes were compared. RESULTS: A total of the 694 sites of 251 teeth were included in this trial. Both groups showed significant improvement in each periodontal parameters 6 weeks and 3 months after treatment (P<0.001). For sites in a single-rooted tooth, sites with PD≥5 mm, and sites without vertical alveolar bone resorption and furcation involvement, the PD in endoscopy group was significantly lower than that in the control group at 6 weeks and 3 months after treatment (P<0.05). CONCLUSIONS: Periodontal endoscope-assisted subgingival scaling resulted in better effects than traditional subgingival scaling when the residual pockets were in a single-rooted tooth, with a PD of ≥5 mm but without vertical alveolar bone resorption and furcation involvement.

[Advances in salivary protein glycosylation and its relationship with systemic and oral diseases].

Protein glycosylation is one of the most important protein post-translational modifications that can affect life activities by endowing the protein with various structural and functional features. Saliva is an easy-to-obtain, noninvasive body fluid that contains components originating from serum, gingival crevicular fluid, and oropharyngeal mucosae. In recent years, understanding of saliva has been constantly updated with the developments in related research. Studies have shown that salivary proteins can be used as diagnostic markers for certain diseases, and changes of protein glycosylation in saliva are generally considered to be related to many diseases. In this review, salivary protein glycosylation and its relationship with systemic and oral diseases were discussed.