Notes

Sequential Sample Injection Examination in Pipe Radial Submission Chromatography.
Compared with other TRY assays, the biosensor based on PDNPs-Pro has the advantages of simple operation, environmental friendliness, and high sensitivity. This specific controlled-synthesis PDNPs would open up a new window for the extended application of fluorescent nanomaterials in biomedicine based on fluorescence changes induced by biological interaction.A tetraphenylethene (TPE) derivative was designed and synthesized upon conjugation with bis(thiophen-2-ylmethyl) amine (BTA) containing a mercury-binding moiety and further characterized by using Nuclear magnetic resonance (NMR), LC-MS, UV-Vis, and fluorescence spectroscopic methods. The resulting TPE-BTA exhibited comprehensive aggregation-induced emission while expressing a high quantum yield and emission intensity at 70% water fraction. The probe exhibited a good photochromic effect with a Stokes shift of 178 nm, and the emission intensity at 550 nm increased considerably with the color turning from dark green to bright green under a UV lamp upon the addition of 5 μM Hg2+. The lowest-energy conformation of the probe showed that two thiophene rings were perpendicular to the phenyl ring, while two BTA molecules were situated in a staggered form to each other. The sulfur and nitrogen atoms present in TPE-BTA were coordinated to the Hg2+ ion, and these binding sites were confirmed by the NMR parameters, X-ray photoelectron spectroscopy signals, and structural calculations. The binding of Hg2+ to TPE-BTA was believed to restrict the intramolecular motion of TPE-BTA, thus inducing it to shine brighter according to the unique aggregation-induced emission effect. The concentration of Hg2+ was determined based on the enhancement of the emission intensity, and the present probe showed an extremely high sensitivity with a limit of detection of 10.5 nM. Furthermore, TPE-BTA enabled selective detection of Hg2+ even in the presence of a 1000-fold excess of other interfering metal ions. The proposed method was successfully employed to determine Hg2+ in living HeLa cells and real water samples.The incorporation of colorimetric sensors as quality indicators in food packaging is an exciting new area of research that could improve food management. The standard approach, however, demands a reliable interface between the sensor and the food and risks food contamination which is a significant consumer concern. To overcome this challenge, herein, we develop a polydiacetylene/phospholipid agarose-based sensor that encapsulates milk in the hydrogel matrix during synthesis. The chemical recognition of free fatty acids, a product of microbial spoilage of the encapsulated milk, induces a gradual blue to red color change in the sensor. We demonstrate that the new composite material exhibits the same spoilage kinetics as regular liquid milk (digital colorimetric response 28 ± 1% and 27 ± 3% respectively), indicating the agarose does not preserve the milk ingredients nor inhibit the detection mechanism of the polydiacetylene sensors. As a result, this sensor can be attached to the external surface of food packagi and outliers based on a pixel's grayscale Z-score. This new approach to sensor design increases practicality and could be extended to the contactless quality monitoring of other foods, medicines and other products whose safety or quality is jeopardized with direct sensor contact.In this work, a new fluorescence biosensor platform based on distance-dependent photoinduced-electron transfer (PET) coupled with target cross-chain displacement cyclic amplification strategy was developed to detect MicroRNA. The DNA cross structure was cleverly designed to protect restriction site, then multiple amplification reactions of target cycle and chain replacement based on DNA cross-configuration were carried out in the presence of primer, polymerase and cutting enzyme, thus a large number of single-stranded (ss) DNA products (S1 and S2) can be exported by inputting a small amount of target miRNA. OTSSP167 The fluorescent AgNCs/DNA probe was synthesized based on high affinity of Ag to cytosine (C) rich in ssDNA acting as electron donor, and guanine (G) rich ssDNA can form G-quadruplex complex acting as electron receptor to induce PET process. S1 and S2 hybridized with flexible single-stranded DNA COM 1 and Com 2, forming rigid double-stranded DNA to inhibit fluorescence quenching PET process, so the corresponding fluorescence was recovered. Thus the miRNA-induced amplified products can specifically result in fluorescence changes by PET, and the changes increase with increasing miRNA concentration. Therefore, the proposed fluorescent biosensor can be applied to quantitative determination of miRNA-182-5p, which has great potential in early clinical diagnosis of miRNAs related diseases.The popularization of paper-based analytical devices (PADs) in analytical science has fostered research on enhancing their analytical performance for accurate and sensitive assays. With their superb recognition capability and structural stability, molecularly imprinted polymers (MIPs) have been extensively employed as biomimetic receptors for capturing target analytes in various complex matrices. The integration of MIPs as recognition elements with PADs (MIP-PADs) has opened new opportunities for advanced analytical devices with elevated selectivity and sensitivity, as well as a shorter assay time and a lower cost. This review covers recent advances in MIP-PAD fabrication and engineering based on multifarious signal transduction systems such as colorimetry, fluorescence, electrochemistry, photoelectrochemistry, and chemiluminescence. The application of MIP-PADs in the fields of biomedical diagnostics, environmental analysis, and food safety monitoring is also reviewed. Further, the advantages, challenges, and perspectives of MIP-PADs are discussed.Accurate and sensitive monitoring of the abused antibiotics is vital because excessive antibiotics in human body can cause toxicity to kidney or lead to potential loss of hearing. In this work, we described a label-free and highly sensitive fluorescent aptasensing platform for detecting kanamycin in milk samples based on the synchronization signal amplification of primer exchange reaction (PER) and metal-ion dependent DNAzyme. The target kanamycin binds the aptamer sequence hybridized on a hairpin template and initiates PER for autonomous synthesis of Mg2+-dependent DNAzyme sequences with aid of Bst-DNA polymerase at isothermal conditions. Such a synthesis process can be repeated many times to produce lots of DNAzymes to cyclically cleave the rA site in the signal hairpin substrates under the assistance of Mg2+ cofactor to liberate numerous free G-quadruplex fragments. The organic dye thioflavin T (ThT) further associates with these G-quadruplex fragments to yield substantially intensified fluorescence for sensitive detection of kanamycin with a low detection limit of 0.36 nM. In addition, the developed aptamer sensing method also shows a good selectivity for kanamycin against other interfering antibiotics, and can realize the monitoring of kanamycin added in milk samples, highlighting its potential for sensitive monitoring of trace amount of kanamycin for food safety applications.In spatial comprehensive three-dimensional chromatography (3D-LC) components are separated within a three-dimensional separation space that can lead to unprecedented resolving power, in terms of peak capacity and peak-production rate. The maximum peak capacity is the product of the peak capacities achieved in the individual dimensions when orthogonal retention mechanisms are incorporated. The parallel development of the second- and third-dimension separation stages overcomes the fundamental limitation of conventional multi-dimensional approaches, in which sampled fractions are analyzed sequentially. General considerations for chip design are discussed and possibilities and prospects to establish spatial comprehensive 3D-LC analysis are presented.Interleukin 6 (IL-6) acts as both a proinflammatory and anti-inflammatory cytokine and is generally utilized as an important diagnostic biomarker for sepsis. In addition, the high levels of IL-6 measured in plasma have been associated with pathological inflammation. A novel quartz crystal microbalance (QCM) immunoassay method was presented for high sensitivity and selectivity detection of interleukin-6 (IL-6) based on gold nanoparticles functionalized sulfur-doped graphene quantum dot (AuNPs/S-GQD) and hollow ZnS-CdS nanocage (h-ZnS-CdS NC). Firstly, AuNPs/S-GQD nanocomposite was synthesized in the presence of tetrachloroauric acid and then conjugated onto anti-IL-6 antibodies by amino-gold affinity. The sandwich-type QCM immunoassay probe was prepared by immune-reaction between AuNPs/S-GQD/QCM immobilized with anti-IL-6 capture antibodies and h-ZnS-CdS NC including detection anti-IL-6 antibodies in the presence of target IL-6. The prepared QCM immunoassay probe was characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), x-ray diffraction (XRD) method, x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The QCM immunosensor showed a linearity range (0.01-2.0 pg mL-1) and a low detection limit (3.33 fg mL-1). Lastly, high stable and selective QCM immunosensor was applied to prepared plasma samples with good recovery.Stimuli-responsive hydrogel has been emerged as a popular tool for chemical sensing due to its unique mechanical properties. In this work, we fabricated an ascorbic acid (AA)-responsive alginate hydrogel for the visual detection of alkaline phosphatase (ALP). This alginate hydrogel (RhB@Alg/Fe3+) was crosslinked with Fe3+, and rhodamine B (RhB) was encapsulated into the hydrogel as an indicating reagent to assistant visual detection. Because of the weak affinity of Fe2+ to alginate, the presence of reductive AA can trigger the dissolution of RhB@Alg/Fe3+ to give an observable red color in the sol solution. On this basis, by using ascorbic acid 2-phosphate as a substrate of ALP, which can be hydrolyzed by ALP to produce AA, the gel-sol transition process of RhB@Alg/Fe3+ was further modulated by ALP. This finding leads to a simple visual method for ALP detection with a low detection limit of 0.37 mU/mL and an excellent selectivity over other proteins. Compared with conventional colorimetric assays, this visual sensor shows the distinct advantages of simple fabrication, cost-effectiveness and easy to implement. We believe that this study can provide a new insight into the fabrication of responsive alginate hydrogel for promising applications in chemical sensing and biomedical fields.Quantitative imaging of amyloid beta (Aβ) in brain is of great significance for pathological study and follow-up drug development of Alzheimer's disease (AD). In this work, a method using antibody-conjugated gold nanoparticles (AuNPs) was established for quantitative imaging of Aβ peptide in the brain of AD mouse by Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Aβ antibody (Anti-Aβ) was labeled with AuNPs to form the conjugate AuNPs-Anti-Aβ which was immunoreactive with Aβ in the brain slice of mouse. Quantitative imaging of Au was acquired with homogenized brain slice matrix-matched standards as external calibrants which were made by immersing in gold standard solution with different concentrations. Furthermore, the stoichiometric ratios between metal conjugates and Aβ were optimized, and the immunoreaction efficiency after labeling was also investigated. According to the molar relationship between AuNPs and Anti-Aβ (14.3) and the ratio of Anti-Aβ to Aβ (11), quantitative imaging of Aβ in brain was accomplished.
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