Fabrication of polydimethylsiloxane (PDMS)-Based Flexible Surface-Enhanced Raman Scattering (SERS) Substrate for Ultrasensitive Detection.

This article presents a fabrication method for a flexible substrate designed for Surface-Enhanced Raman Scattering (SERS). Silver nanoparticles (AgNPs) were synthesized through a complexation reaction involving silver nitrate (AgNO3) and ammonia, followed by reduction using glucose. The resulting AgNPs exhibited a uniform size distribution ranging from 20 nm to 50 nm. Subsequently, 3-aminopropyl triethoxysilane (APTES) was employed to modify a PDMS substrate that had been surface-treated with oxygen plasma. This process facilitated the self-assembly of AgNPs onto the substrate. A systematic evaluation of the impact of various experimental conditions on substrate performance led to the development of a SERS substrate with excellent performance and an Enhanced Factor (EF). Utilizing this substrate, impressive detection limits of 10-10 M for R6G (Rhodamine 6G) and 10-8 M for Thiram were achieved. The substrate was successfully employed for detecting pesticide residues on apples, yielding highly satisfactory results. The flexible SERS substrate demonstrates great potential for real-world applications, including detection in complex scenarios.

The Unique Genetic Mutation Characteristics Based on Large Panel Next-Generation Sequencing (NGS) Detection in Multiple Primary Lung Cancers (MPLC) Patients.

BACKGROUND: With the wide application of multislice spiral computed tomography (CT), the frequency of detection of multiple lung cancer is increasing. This study aimed to analyze gene mutations characteristics in multiple primary lung cancers (MPLC) using large panel next-generation sequencing (NGS) assays. METHODS: Patients with MPLC surgically removed from the Affiliated Hospital of Guangdong Medical University from Jan 2020 to Dec 2021 enrolled the study. NGS sequencing of large panels of 425 tumor-associated genes was performed. RESULTS: The 425 panel sequencing of 114 nodules in 36 patients showed that epidermal growth factor receptor (EGFR) accounted for the largest proportion (55.3%), followed by Erb-B2 Receptor Tyrosine Kinase 2 (ERBB2) (9.6%), v-Raf murine sarcoma viral oncogene homolog B1 (BRAF), and Kirsten rat sarcoma viral oncogene (KRAS) (8.8%). Fusion target variation was rare (only 2, 1.8%). ERBB2 Y772_A775dup accounted for 73%, KRAS G12C for about 18%, and BRAF V600E for only 10%. AT-rich interaction domain 1A (ARID1A) mutations were significantly higher in invasive adenocarcinoma (IA) which contained solid/micro-papillary malignant components (p = 0.008). The tumor mutation burden (TMB) distribution was low, with a median TMB of 1.1 MUTS/Mb. There were no differences in the TMB distribution of different driver genes. In addition, 97.2% of MPLC patients (35/36) had driver gene mutations, and 47% had co-mutations, mainly in IA (45%) and invasive adenocarcinoma (MIA) (37%) nodule, with EGFR (39.4%), KRAS (9.1%), ERBB2 (6.1%), tumor protein 53 (TP53) (6.1%) predominately. CONCLUSIONS: MPLC has a unique genetic mutation characteristic that differs from advanced patients and usually presents with low TMB. Comprehensive NGS helps to diagnose MPLC and guides the MPLC clinical treatment. ARID1A is significantly enriched in IA nodules containing micro-papillary/solid components, suggesting that these MPLC patients may have a poor prognosis.

Optical metasurfaces for multiplex high-performance grating-type structural colors.

Optical metasurfaces provide a significant approach for the production of structural colors due to their excellent optical control abilities. Herein, we propose trapezoidal structural metasurfaces for achieving multiplex grating-type structural colors with high comprehensive performance originating from the anomalous reflection dispersion in the visible band. Single trapezoidal metasurfaces with different x-direction periods can tune the angular dispersion regularly from 0.036 rad/nm to 0.224 rad/nm to generate various structural colors, and composite trapezoidal metasurfaces with three kinds of combinations can achieve multiplex sets of structural colors. The brightness can be controlled by adjusting the distance between the trapezoids in a pair accurately. The designed structural colors have higher saturation than traditional pigmentary colors, whose excitation purity can reach 1.00. The gamut is about 158.1% of the Adobe RGB standard. This research has application potential in ultrafine displays, information encryption, optical storage, and anti-counterfeit tagging.

Application of Soil and Water Assessment Tool (SWAT) to evaluate the fates of nitrogenous fertilizer in subtropical mountainous watershed tea farms.

Extensive nutrient loss is one of the most challenging issues faced by agricultural production regions worldwide. However, diffuse pollution in the subtropical mountainous watersheds is rarely simulated. A watershed model with regional parameter values is essential for watershed management. In this study, SWAT, one of the most popular models was applied to simulate daily discharge (years of 2008-2014), NO3-N flux (2012-2014), and tea yield (2012-2014) in the Ping-Lin watershed (PLW) of Taiwan, as well as to test the effectiveness of a modified fertilization strategy. The results demonstrated that SWAT was capable of simulating daily discharge variation, daily riverine NO3-N flux, and tea yield in the PLW. NO3-N yield of the tea farm (47 kg/ha/yr) was 9 times higher than that of the forest (5.1 kg/ha/yr). A significant proportion (~ 50%) of the input nitrogen (including dry/wet deposition and fertilizer) infiltrated into the soil, resulting in a poor fertilizer uptake efficiency of the tea tree. It was demonstrated that the modified fertilization strategy (apply fertilizer in small rainfall event, i.e., daily rainfall < 20 mm/day, and not in a single day) could increase the nitrogen uptake and harvest yield of the tea tree by 14% and 4%, respectively, with a 10% reduction in nitrogen input. Furthermore, this strategy significantly reduced the nitrogen yields from surface flow (75%), lateral flow (36%), percolation (50%), and groundwater (48%). A popular model with verified parameter values could help in developing a win-win strategy for both farmers and regulators, thus realizing the goals of sustainable agricultural practices.

Enhanced Conversion Efficiency Enabled by Species Migration in Direct Solar Energy Storage.

Solar energy can be stored via either an indirect route in which electricity is involved as an intermediate step, or a direct route that utilizes photogenerated charge carriers for direct solar energy conversion. In this study, we investigate the fundamental difference between the direct and indirect routes in solar energy conversion using a new photoelectrochemical energy storage cell (PESC) as a model device. This PESC centers on a liquid junction that utilizes CH3 NH3 PbI3 perovskite to drive photoelectrochemical reactions of Benzoquinone (BQ) and Ferrocene (Fc) redox species. The experimental studies show that the equilibrium redox potentials are 0.1 V and -0.78 V (vs Ag/AgNO3 ) for Fc+ /Fc and BQ/BQ.- , respectively, which would produce a theoretical open-circuit voltage of 0.88 V for the storage device. The physics-based computational analysis shows a relatively flat reaction rate distribution in the electrode for the indirect route; however, in the direct route the photoelectrochemical reaction rate is critically affected by electron concentration due to strong light absorption of the perovskite material, which has been shown to vary by at least 10-fold in the transverse direction across the photoelectrode. The drastic variation of reaction rate in the photoelectrode creates an electric field that is 7.5 times stronger than the bulk electrolyte, which causes the photo-converted reaction product (i. e., BQ.- ) to drift away from the photoelectrode thereby creating a constant reaction driving force. As a result, it has been shown that the intrinsic solar to chemical conversion (ISTC) efficiency improves by ∼40 % for the direct route compared to the indirect route at 0.05 mA/cm2 .

Three-dimensional cavity-coupled metamaterials for plasmonic color and real-time colorimetric biosensors.

Plasmonic structure color has significant potential for visual biochemical sensing by simple instrumentation or even naked eye detection. Herein, we present a visual and real-time sensing strategy for refraction index sensing and detection of the biotin-avidin system based on three-dimensional cavity-coupled metamaterials. These metamaterials composed of a top array of gold disks, aluminium pillars and a bottom reflection film of aluminium have structures similar to the metal-insulator-metal structure. The insulating layer comprises air-gap cavities that are easily filled with gaseous or liquid dielectrics. Therefore, analytes can permeate into the nano-scale cavities and produce strong light-matter interactions. The sensor shows that any tiny change in the refraction index will induce a significant color variation and the sensitivity reaches 683.5 nm per refraction index unit with a figure of merit of 3.5. The color of the metamaterials changes from rose-red to violet and then loden after a monomolecular layer of thiolated biotin and streptavidin bind to the surface of the nanostructure successively. This sensing strategy offers new opportunities for the convenient detection of proteins, nucleic acids, and lipids.

Large-Scale Fabrication of Ultrasensitive and Uniform Surface-Enhanced Raman Scattering Substrates for the Trace Detection of Pesticides.

Technology transfer from laboratory into practical application needs to meet the demands of economic viability and operational simplicity. This paper reports a simple and convenient strategy to fabricate large-scale and ultrasensitive surface-enhanced Raman scattering (SERS) substrates. In this strategy, no toxic chemicals or sophisticated instruments are required to fabricate the SERS substrates. On one hand, Ag nanoparticles (NPs) with relatively uniform size were synthesized using the modified Tollens method, which employs an ultra-low concentration of Ag⁺ and excessive amounts of glucose as a reducing agent. On the other hand, when a drop of the colloidal Ag NPs dries on a horizontal solid surface, the droplet becomes ropy, turns into a layered structure under gravity, and hardens. During evaporation, capillary flow was burdened by viscidity resistance from the ropy glucose solution. Thus, the coffee-ring effect is eliminated, leading to a uniform deposition of Ag NPs. With this method, flat Ag NPs-based SERS active films were formed in array-well plates defined by hole-shaped polydimethylsiloxane (PDMS) structures bonded on glass substrates, which were made for convenient detection. The strong SERS activity of these substrates allowed us to reach detection limits down to 10-14 M of Rhodamine 6 G and 10-10 M of thiram (pesticide).