Liquid Interfacial Coassembly of Plasmonic Arrays and Trace Hydrophobic Nanoplastics in Edible Oils for Robust Identification and Classification by Surface-Enhanced Raman Spectroscopy.

The ubiquity of micro-/nanoplastics poses a visible threat to the environment, aquatic organisms, and human beings and has become a global concern. Here, we proposed a liquid interface-based strategy using surface-enhanced Raman spectroscopy to coassemble nanoplastics and gold nanoparticles into a dense and homogeneous plasmonic array, thereby enabling the rapid and sensitive detection of trace nanoplastics. In addition, due to the uniqueness of the oil-water immiscible two-phase interface, we achieved ideal results for the detection of nanoplastics in a complex matrix (e.g., aqueous environment and edible oil) with a detection limit of µg/mL. With the aid of the principal component analysis algorithm, the differentiation and identification of multiple nanoplastic components (e.g., polystyrene, polyethylene, and polyethylene terephthalate) in aqueous environments and common hazards (e.g., Bap and Phe) in edible oil were achieved. Therefore, our self-assembled plasmonic arrays are expected to be used for monitoring environmental pollution and food safety.

Identification of cuproptosis-related long noncoding RNA signature for predicting prognosis and immunotherapy response in bladder cancer.

Bladder cancer (BC) is the most common malignant tumour of the urinary system and one of the leading causes of cancer-related death. Cuproptosis is a novel form of programmed cell death, and its mechanism in tumours remains unclear. This study aimed to establish the prognostic signatures of cuproptosis-related lncRNAs and determine their clinical prognostic value. RNA sequencing data from The Cancer Genome Atlas were used to detect the expression levels of cuproptosis-related genes in BC. Cuproptosis-related lncRNAs linked to survival were identified using co-expression and univariate Cox regression. Furthermore, consensus cluster analysis divided the lncRNAs into two subtypes. Subsequently, we established a signature model consisting of seven cuproptosis-related lncRNAs (AC073534.2, AC021321.1, HYI-AS1, PPP1R26-AS1, AC010328.1, AC012568.1 and MIR4435-2Hg) using least absolute shrinkage and selection operator regression. Survival analysis based on risk score showed that the overall survival and progression-free survival of patients in the high-risk group were worse than those in the low-risk group. Multivariate Cox analysis demonstrated the independent prognostic potential of this signature model for patients with BC. Moreover, age and clinical stage were also significantly correlated with prognosis. The constructed nomogram plots revealed good predictive power for the prognosis of patients with BC and were validated using calibration plots. Additionally, enrichment analysis, Single sample gene set enrichment analysis and immune infiltration abundance analysis revealed significant differences in immune infiltration between the two risk groups, with high levels of immune cell subset infiltrations observed in the high-risk group accompanied by various immune pathway activation. Moreover, almost all the immune checkpoint genes showed high expression levels in the high-risk group. Moreover, TIDE analysis suggested that the high-risk group was more responsive to immunotherapy. Finally, eight drugs with low IC50 values were screened, which may prove to be beneficial for patients in the high-risk group.

Gold nanocluster-based ratiometric fluorescent probe for biosensing of Hg2+ ions in living organisms.

Gold nanoclusters (Au NCs) have become a new alternative to conventional fluorescent probes in biosensing and imaging. Herein, a gold nanocluster-based nanocomplex displaying single-excitation and dual-emission fluorescence property was fabricated by the conjugation of red-emitting glutathione-protected gold nanoclusters (Au-GSH NCs) and green-emitting fluorescein isothiocyanate (FITC) molecules. The inorganic-organic nanocomplex possesses good ratiometric fluorescence sensing ability with one emission peak showing a sensitive fluorescence response towards Hg2+ ions and the other acting as the internal reference. The nanocomplex was demonstrated to have high stability, excellent biocompatibility, high intracellular penetrability and good biological imaging ability. It was employed as a sensitive nanosensor for rapid sensing and imaging of Hg2+ ions in living cells and zebrafish with high contrast.

Tracking structural changes of protein residues by two-dimensional correlation surface-enhanced Raman spectroscopy.

In-situ tracking structural changes of protein residues was developed by two-dimensional correlation surface-enhanced Raman spectroscopy (2DC-SERS). The change order of SERS fingerprints during artificial nitrification of edible bird's nest (EBN) was interpreted as the structural changes of amino acid residues. It inherently realizes reliable recognition of natural EBN and artificially dyed fakes. Both this direct structural tracking of protein residues and the indirect azo dye testing of nitrites/nitrosamines could be used as indicators for discriminating different EBN before and after the artificial dyeing. Limit of detection (LOD) for nitrite and NDMA is about 40.6 ppb and 88.1 ppb, respectively. A conceptual logical circuit of the OR gate was constructed by considering the protein structural indicator (INPUT1) and the nitrite indicator (INPUT2) as two independent inputs for automatic recognition of different EBN samples. A data-driven analog soft independent modeling (DD-SIMCA) model could quickly distinguish normal EBN from A-EBN with 98% specificity.

Highly luminescent gold nanocluster assemblies for bioimaging in living organisms.

Fluorescent gold nanoclusters are promising nanomaterials for biomedical applications but confronted with low emission efficiency and poor surface functionality. Herein, three kinds of highly luminescent and functionalized gold nanocluster nano-assembled structures were fabricated by poly-l-arginine surface engineering for luminescence improvement. The assembly is employed for imaging the glutathione molecule in cells and living organisms with low background and high sensitivity.

Surface motif sensitivity of dual emissive gold nanoclusters for robust ratiometric intracellular imaging.

Here, we report novel dual-emissive gold nanoclusters (d-Au NCs) that have two distinctive emissions (420 and 630 nm) under a single wavelength excitation. The two-stage formation mechanism evidences their sensitive response to valine and trivalent chromium ions (Cr3+) in completely different spectral ratiometric modes in living cells with high contrast to successfully avoid signal fluctuations.

Direct Discrimination of Edible Oil Type, Oxidation, and Adulteration by Liquid Interfacial Surface-Enhanced Raman Spectroscopy.

The quality and safety of edible oils is a momentous but formidable challenge, especially regarding identification of oil type, oxidation, and adulteration. Most conventional analytical methods have bottlenecks in sensitivity, specificity, accessibility, or reliability. Surface-enhanced Raman spectroscopy (SERS) is promising as an unlabeled and ultrasensitive technique but limited by modification of inducers or surfactants on metal surfaces for oil analysis. Here, we develop a quantitative SERS analyzer on two-liquid interfacial plasmonic arrays for direct quality classification of edible oils by a portable Raman device. The interfacial plasmonic array is self-assembled through mixing the gold nanoparticle (GNP) sols and oil sample dissolved in chloroform without any surfactants or pretreatments. Different kinds of edible oils dissolved in chloroform directly participate in self-assembly of plasmonic arrays that finally localizes onto a three-dimensional (3D) oil/water interface. The 3D plasmonic array is self-healing, shape adaptive, and can be transferred to any glass containers as a substrate-free SERS analyzer for direct Raman measurements. It produces sensitive responses of SERS on different kinds of edible oils. By virtue of principal component analysis (PCA), this analyzer is able to quickly distinguish six edible oils, oxidized oils, and adulterated oils. Moreover, the solvent chloroform generates unique and stable SERS bands that can utilized as an inherent internal standard (IIS) to calibrate SERS fluctuation and greatly improve quantitation accuracy. Compared to conventional lab methods, this analyzer avoids complex and time-consuming preprocessing and provides significant advantages in cost, speed, and utility. Our study illuminates a facile way to determine edible oil quality and promises great potential in food quality and safety analysis.

Cross-linking structure-induced strong blue emissive gold nanoclusters for intracellular sensing.

Fluorescent gold nanoclusters (Au NCs) are new emerging fluorescent nanomaterials with broad application prospects but limited by the complicated preparation, low quantum yield (QY) and poor biological applications. Here we develop a one pot etching approach for synthesizing fluorescent Au NCs by using the common citrate-capped gold nanoparticles (Au NPs) as the precursor and the poly(amidoamine) (PAMAM) dendrimer as the etching and templating agent. The synthesis conditions are optimized and products are characterized in detail. The results confirm that we have successfully synthesized PAMAM-templated Au NCs (Au-PAMAM NCs) with strong blue emission at 453 nm and a high fluorescence QY of 18%. The optical properties are remarkably superior to that of most other reported fluorescent Au NCs since the formed specific cross-linking structures of Au-PAMAM NCs rigidify the surface Au(i)-ligands and enhance the inner aurophilic interactions. Interestingly, Au-PAMAM NCs display a sensitive and selective fluorescence response toward temperature and Cr2O72- ions, respectively. Quantitative analysis reveals the excellent capacity to distinguish temperature in the range of 15 °C-80 °C and to sense Cr2O72- in a linear range of 0-55 µM with a detection limit of 1.9 µM. Experiments evidence that there is no interference when sensing each of these targets, making Au-PAMAM NCs potential fluorescent probes for these two targets. By means of the small size, excellent water solubility, negligible cytotoxicity, and great cell penetration ability, Au-PAMAM NCs are successfully applied to monitor the dynamic change of temperature and Cr2O72- ions in living cells. This study paves the way for synthesizing high emission and highly biocompatible Au NCs with promising potential in biosensing and imaging in the future.

Halide-assisted activation of atomic hydrogen for photoreduction on two-liquid interfacial plasmonic arrays.

Here, we show a two-liquid interfacial 3D plasmonic array for SERS examination on direct photoreduction of p-nitrothiophenol (4-NTP) to p-aminothiophenol (4-ATP) without the need for traditional catalysts and reductants, revealing the mechanism of halide-assisted activation of atomic hydrogen and the balance between the enhancing effect from etching of the Ag surface and the weakening effect from the reduction of the 4-NTP molecules, which provides insights into the light-to-energy conversion schemes on noble metal surfaces.

Self-Healing Plasmonic Metal Liquid as a Quantitative Surface-Enhanced Raman Scattering Analyzer in Two-Liquid-Phase Systems.

Liquid-state interfacial plasmonic systems are emerging as an alternative for the quantitation and practicability of the surface-enhanced Raman scattering (SERS) technique in analytical science, especially for complex liquid-phase systems. Here we show a general strategy for the three-dimensional (3D) self-assembly of gold nanoparticle (GNP) arrays on a spherical oil-water (O-W) interface, denoted as a plasmonic metal liquid (PML). The PML has excellent self-healing and shape-adaptive features; it can be transferred into containers of any shape; and it presents fast, quantitative, and multiplex SERS capability. Accurate control of nanoparticle density (PD) on the 3D interface enables tunable SERS strength. In situ synchrotron radiation small angle X-ray scattering (SR-SAXS) provides evidence that the interfacial PD is quantifiable and can be precisely regulated in the range of 24-216 particles/µm2, which produces optimizable Raman enhancement. The strongest SERS signal is achieved at 167 particles/µm2 with GNP diameters of approximately 64 nm. In particular, the O phase acts not only as the assembly media for spherical PML arrays but also as the extracting agent for targets with different natures in complex media. Moreover, the O phase with continuous-phase features generates inherent and sharp SERS fingerprints and provides an effective internal standard (IS) for calibrating the fluctuation of samples and measuring conditions. By virtue of the triple roles of the O phase, the PML platform exhibits excellent mechanical stability, detection sensitivity, and signal reproducibility. This study demonstrates the concept of a fast and quantitative liquid-state SERS platform in common cuvettes on a portable Raman device that is as simple as a spectrophotometer.

Mirrorlike Plasmonic Capsules for Online Microfluidic Raman Analysis of Drug in Human Saliva and Urine.

Plasmonic capsules are emerging for novel applications in biochemical sensing, tunable optics, targeted delivery, etc. Here, we develop an online mirrorlike plasmonic capsule microfluidic (PCM) system through citrate-capped Au nanoparticle (GNP) arrays on three-dimensional (3D) oil/water (O/W) two-liquid interface without any inducers or promoters. The PCM-based surface-enhanced Raman scattering (PCM-SERS) system realizes multisample, multiplex, and high-throughput analysis of targeted molecules in complex media by a portable Raman device. Excellent O-in-W features of the GNP capsules ensure less surface contamination of the inner channel and avoid cross-contamination between different capsules. Sequential detection of five analytes in different capsules is easily achieved in about 1 min, and both dual-analyte and triple-analyte detection in a single capsule demonstrate the excellent sensitivity even with analyte concentrations differing by 2 orders of magnitude. The uniform distribution of GNPs at the two-liquid interface leads to excellent reproducibility of SERS signals. In addition, the O phase of the capsule filling produces fingerprint vibrations in SERS signals and is used as the inherent internal standard (IIS) to improve the quantitation of SERS detection. The O phase also as a good extraction agent realizes efficient separation and enrichment of an illicit drug, methamphetamine (MA), in human saliva and urine. By virtue of principal component analysis (PCA), the PCM-SERS platform easily realizes autoclassification of trace MA, with concentrations down to ppm levels. This study promises great potentials of plasmonic capsules for in situ monitoring molecular events in confined spaces, especially in multiliquid systems.

Liquid-state quantitative SERS analyzer on self-ordered metal liquid-like plasmonic arrays.

Liquid interfacial plasmonic platform is emerging for new sensors, catalysis, and tunable optical devices, but also promises an alternative for practical applications of surface-enhanced Raman spectroscopy (SERS). Here we show that vigorous mixing of chloroform with citrate-capped gold nanorod sols triggers the rapid self-assembly of three-dimensional plasmonic arrays at the chloroform/water (O/W) interface and produces a self-healing metal liquid-like brilliant golden droplet. The O phase itself generates stable SERS fingerprints and is a good homogeneous internal standard for quantitative analysis. This platform presents reversible O/W encasing in a common cuvette determined just by surface wettability of the container. Both O-in-W and W-in-O platforms exhibit excellent SERS sensitivity and reproducibility for different analytes by the use of a portable Raman device. It paves the way toward a practical and quantitative liquid-state SERS analyzer, likened to a simple UV-Vis spectrometer, that is far superior to typical solid substrate-based or nanoparticle sol-based analysis.

Conformational sensitivity of surface selection rules for quantitative Raman identification of small molecules in biofluids.

Biofluid analysis by surface-enhanced Raman scattering (SERS) is usually hindered by nonspecific interferences. It is challenging to drive targeted molecules towards sensitive areas with specific capture and quantitative recognition in complex biofluids. Herein, a highly specific and quantitative SERS analyzer for small molecule dopamine (DA) in serum is demonstrated on a portable Raman device by virtue of a transducer of mercaptophenylboronic acid (MPBA) and a site-directed decoration of plasmonic Ag dendrites on a superhydrophobic surface. Theoretical simulations of molecular vibrations and charge distributions demonstrate the predomination of Raman surface selection rules in molecular reorientation upon the binding of DA. This recognition event is translated into ratiometric changes in the spectral profile which evidences excellent capability on SERS quantitation. The rules can well distinguish DA from its common interferents including fructose, glucose, sucrose and ascorbic acid which all generate weak but completely opposite spectral changes. Moreover, benefitting from the wettability difference, the target DA in diluted serum can be specifically enriched on a transducer-capped Ag surface, and the adsorption of other interferences is resisted by superhydrophobic features. It paves a new way for labelling a single SERS tag to simultaneously realize the identification and quantification of small molecules in complex biological media.

Organic Solvent as Internal Standards for Quantitative and High-Throughput Liquid Interfacial SERS Analysis in Complex Media.

Liquid-state interfacial nanoparticle arrays for surface-enhanced Raman scattering (SERS) promises a practical, substrate-free, and rapid analysis but faces a great challenge to develop a batch and uniform fabrication strategy with stable internal standards (IS) because of the difficulties in precisely locating both the IS tags and analytes in the same local structure under the harsh conditions of biphasic liquid interface. Here, we develop a fast batch preparation of self-ordered dense Au nanoparticle (GNP) arrays on cyclohexane/water biphasic interface in 96-well plates with the assist of acetone as the phase-crossing inducer. The acetone can extract the pesticide molecules via a simple dipping sample peels and can rapidly capture and locate the pesticide molecule into the plasmonic hotspots. Meanwhile, this phase-crossing solvent, acetone itself, generates stable SERS signal and is used as the IS tags to calibrate the signal fluctuation. This platform presents an excellent uniformity with a relative standard deviation (RSD) of 5.9% compared to the RSD of 14.5% without the IS's correction and a good sensitivity with a limit of detection (LOD) of 1 nM thiram. This high-throughput strategy for analyzing pesticide residues at fruit peels reached detection levels of nanograms per square centimeter (ng/cm2). Combined with the 96-well plates, this platform greatly facilitates the self-assembly and multiplex sampling. The self-ordered arrays at two immiscible phases interface evidenced the detection of both the oil-soluble thiabendazole and the water-soluble thiram molecules and also realized the multiplex and two-phase detection of these two pesticides. This platform offers vast possibilities for on-site sensing of various analytes and paves a new way for the quantitative and high-throughput SERS analyzer just as convenient as the microplate reader.