These observations suggest that the origin of SERS from single/few molecules or from the ensemble-averaged system cannot be inferred from the statistical distributions of the Raman intensity fluctuations. The present experimental observations also revealed the relation between the near-field plasmonic behaviors of the substrate with the corresponding far-field SERS spectra of the 4-MPy molecule.The development of crystal-facet metal oxide heterostructures has been of great interest owing to their rational design and multifunctional properties at the nanoscale level. Herein, we report a facile solution-based method for the synthesis of single-crystal Cu2O nanostructures (i.e. Cu2O-CuO) as a core. Graphene quantum dots (GQDs) with varying concentrations are fabricated on the surface of Cu2O extended hexapods (EHPs) in ethanol solution at room temperature via self-assembly, where copper acts as a sacrificial model and a stabilizer as well. The Cu2O crystals displayed a good sensing activity toward BPA oxidation owing to their high energy facets, dangling bonds and great proportion of surface copper atoms. Structural, morphological, chemical and vibrational investigations were performed in detail, presenting high crystallinity of hybrid nanocomposites and Cu2O-CuO heterojunction positions along with the growth of GQDs on the core of Cu2O-CuO crystals. The electrochemical sensing performance of the as-fabricated Cu2O-CuO@GQD EHPs was monitored for the determination of bisphenol A (BPA) as an early diagnostic marker and environmental contaminant. The synergistic effects of the boosted surface area, exposed Cu 111 crystallographic planes and mixed copper valences enhance redox reaction kinetics by increasing the electron shuttling rate at the electrode-analyte junction. Benefitting from the improved electrocatalytic activity for BPA oxidation, the electrochemical sensor displayed the lowest limit of detection (≤1 nM), good chemical stability, a broad linear range (2 nM-11 mM), and high sensitivity (636 μA mM-1 cm-2). The Cu2O-CuO@GQD EHP-based sensing platform was used for BPA detection in water and human serum samples. We have also constructed a pioneering electrochemical sensing platform for BPA detection in live cells, which might be used as a marker for early disease diagnosis.Herein, we established a universal and sensitive plasmonic sensing strategy for biomolecule assays by coupling the hybridization chain reaction (HCR) strategy and a triple-helix molecular switch. Upon the recognition of the target, a single-stranded DNA as a universal trigger (UT) was released from the triple-helix molecular switch (THMS). Thus, the HCR process can be triggered between two hairpins M1 and M2, resulting in the aggregation of gold nanoparticles (AuNPs) via the hybridization between the tail sequence on M1 (or M2) and a DNA-AuNP probe with a dramatic change in the absorbance at 521 nm. More specifically, the strategy, which was conducted by the introduction of target-specific recognition of THMS and universalized by virtue of altering the aptamer or DNA sequence without changing the triple-helix structure, enables simple design for multiple target detection. By taking advantage of THMS, this strategy could enable stable and sensitive detection of a variety of targets including nucleic acids, small molecules and proteins, which may possess great potential for practical applications.Drops deposited on an evaporating liquid bath can be maintained in an inverse Leidenfrost state by the vapor emanating from the bath, making them levitate and hover without effective friction. These perfectly non-wetting droplets create a depression in the liquid interface that sustains their weight, which generates repellent forces when they approach a meniscus rising against a wall. Here, we study this reflection in detail, and show that frictionless Leidenfrost drops are a simple and efficient tool to probe the shape of an unknown interface. We then use the menisci to control the motion of the otherwise elusive drops. https://www.selleckchem.com/products/kt-413.html We create waveguides to direct and accelerate them and use parabolic walls to reflect and focus them. This could be particularly beneficial in the scale up of droplet cryopreservation processes capillary interactions can be used to transport, gather and collect vitrified biological samples in absence of contact and contamination.Triplet-triplet annihilation upconversion (TTA-UC) has great potential in many fields. However, a stable TTA-UC system with adjustable UC efficiency in non-deoxygenated water is still in urgent demand. Here, the first example of short peptide-tuned UC luminescence in water is reported. With only a small amount of peptides, UC chromophores can assemble into tetrahedral microrods with adjustable size and UC efficiency. Successful TTA-UC luminescence of these microrods in water is achieved due to the regular and dense organization of molecular upconversion chromophores tuned by peptides, which allows rapid triplet exciton migration, avoids aggregation-induced quenching and screens molecular oxygen to upconversion chromophores.The ability to selectively propagate specific cells is fundamentally important to the development of clonal cell populations. Current methods rely on techniques such as limiting dilution, colony picking, and flow cytometry to transfer single cells into single wells, resulting in workflows that are low-throughput, slowed by propagation kinetics, and susceptible to contamination. Here, we developed a method, called selective laser gelation (SLG), to micropattern hydrogels in cell culture media in order to encapsulate specific cells to selectively arrest their growth. This process relies on the inverse gelation of methylcellulose, which forms a hydrogel when heated rather than cooled. Local heating using an infrared laser enables hydrogel micropatterning, while phase transition hysteresis retains the hydrogel after laser excitation. As a demonstration, we used this approach to selectively propagate transgenic CHO cells with increased antibody productivity. More generally, hydrogel micropatterning provides a simple and non-contact method for selective propagation of cells based on features identified by imaging.