The rational design of ice recrystallization inhibition (IRI) materials is challenging due to the poor understanding of the IRI mechanism at the molecular level. Here we report several new findings about IRI. (1) A dense hydroxyl monolayer of small molecules, e.g. 6-aza-2-thiothymine (ATT), adsorbed on a nanogold surface was demonstrated, for the first time, to have IRI activity. Five structural analogues adsorbed on groups nanogold with outward hydroxyl or methyl were created to evidence the origin of IRI activity. (2) Their IRI mechanism is closely related to the density of hydroxyls on a nanogold surface. However, the hydrophobic interaction in our model is not essential for macroscopic IRI activity. (3) A molecular dynamics simulation elucidates the hydroxyl density dependent IRI trajectories underlying the experimental observations, and the radial distribution function reveals that the methyl even slightly hinders the formation of hydrogen bonding due to a hydrophobic interaction. This work sheds more light on the IRI mechanism that should help in the customization of novel IRI materials.

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Surface-enhanced Raman spectroscopy (SERS) with ultrasensitive vibrational fingerprints enables quick identification and trace detection of various kinds of molecules. But proteins usually have low Raman cross sections and are difficult to generate recognizable signals in direct SERS detection. Recently, nucleic acid-peptide conjugates are emerging with great potential in structuring, assembling, catalyzing, sensing, etc., and the coupling of aptamers further enables superior biological recognition and programmability. Here, we develop the aptamer−peptide conjugates as a new kind of SERS probe for direct high-specific profiling abnormal protein levels in cancer patients. The aptamer conjugated with glutathione (GSH) functions as both the recognition element and the SERS reporters that can simultaneously generate SERS fingerprints of both peptides and nucleic acids. This kind of biocompatible probe appears to have excellent performance in high-salt environments and realizes rapid, simple, and multisignal detection of thrombin (TB). Data-driven soft independent modeling of class analogy (DD-SIMCA) is used to distinguish SERS profiles of actual blood samples and realize the identification and classification of cancer patients. Furthermore, the effect of low-temperature storage time on blood samples is analyzed by tracking the changes of SERS profiles; the results hint that plasma samples stored under 4 °C for more than 2 days could generate false negative results due to TB hydrolysis, which has important implications for clinical sample analysis. This kind of nucleic acid-peptide conjugate provides new ideas for SERS sensing strategy in the future.

High-throughput surface-enhanced Raman scattering (SERS) reader, especially for liquid sample testing, is of great significance and huge demand in biology, environment, and other analytical fields. Inspired by the principle of microplate reader, herein, we developed a microplate-SERS reader for semiautomatic and high-throughput assays by virtue of three-dimensional liquid interfacial arrays (LIAs). For the first time, the formation of LIA in oil-in-water state, water-in-oil state, and two-dimensional plane state is realized by operating the hydrophilicity (contact angle) of the container. Through the force analysis of LIA, the effect of organic (O) phase density on the relative position of LIA was quantified. In addition, the optimized reader offers fast and continuous semiautomatic detection of 12 samples below 10 min with great signal reproducibility (calibration with the characteristic peak of O phase as the internal standard). The isolated wells in the microplate prevent analyte cross talk, allowing accurate quantification of each sample. Multiplex analysis capability highlights that this reader has the ability of rapid identification and quantification of samples containing various analytes and concentrations. The results demonstrate high-resolution dual and triple analyte detection with fully preserved signal and Raman features of individual analytes in a mixture, which implies that it also has excellent anticounterfeiting applications. This microplate-SERS reader combines the superior advantages of the LIA, microplate, and SERS techniques to retrieve the molecular vibrational fingerprints of various chemicals in complex media.

In situ monitoring of chemical reactions has attracted great attention in many fields. Here we successfully in situ track the degradation reaction process of a dye pollutant, methylene blue (MB),...