Refining shape and size of silver nanoparticles using ion irradiation for enhanced and homogeneous SERS activity.

We present green synthesis of silver nanoparticles in water using unirradiated and Ag 15 + ion irradiated phytoextracts of Bergenia Ciliata leaf, Eupatorium adenophorum leaf, Rhododendron arboreum leaf and flower. The use of different plant extracts and their subsequent ion irradiation allow for successful refinement of nanoparticle size and morphology. Due to changes in reducing and capping agents the nanoparticle surface functionalization also varies which not only controls the morphology but also allows for surface oxidation and aggregation processes. In this work, we have synthesized silver nanoparticles which exhibit sizes in the range from 13 to 24 nm and having shapes like spherical, quasispherical, trigonal, hexagonal, cylindrical, dendritic assemblies, and porous nanoparticles. Owing to changes in the size and shape of the nanoparticles, their direct bandgap (2.05 eV - 2.48 eV) and local surface plasmon resonance (420 nm - 490 nm) could also be tuned. These nanoparticles are examined as SERS substrates, where their enhancement factors, limit of detection for methylene blue, and SERS substrate homogeneity have been tested. It has been observed the nanoparticles synthesized using unirradiated plant extracts present an enhancement factor of 10 6 with a limit of detection 10 - 8 M. Whereas nanoparticles with refined morphology and shapes upon irradiation present high enhancement factors of >10 7 and detection limit down to 10 - 9 M. In addition, uniformity in Raman spectra over the SERS substrates has been obtained for selected Ag NPs substrates synthesized using irradiated extracts with minimum relative standard deviation in enhancement factor < 12%.

Colorimetric-SERS dual-mode sensing of Pb(II) ions in traditional Chinese medicine samples based on carbon dots-capped gold nanoparticles as nanozyme.

Peroxidase (POD)-mimicking nanozymes have got great progress in the sensing field, but most nanozyme assaying systems are built with a single-signal output mode, which is vulnerable to the effect of different factors. Thus, establishment of a dual-signal output mode is necessary for acquiring dependable and durable performance. This work described an Fe doped noradrenaline-based carbon dots and Prussian blue (Fe,NA-CDs/PB) nanocomposite as a POD-like nanozyme and modified gold nanoparticles (AuNPs) for the colorimetric and surface-enhanced Raman scattering (SERS) dual-mode sensor of Pb(II) in traditional Chinese medicine samples. With 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 3,3',5,5'-tetramethylbenzidine (TMB) as the substrates, it was found that the addition of Pb(II) inhibited the POD-like activity of Fe,NA-CDs/PB and AuNPs, so it was used for colorimetric and SERS dual-mode assays. The POD-like activity was shown to be a "ping-pong" catalytic mechanism, whereas the addition of Pb(II) produced noncompetitive inhibition with modulatory effects on Fe,NA-CDs/PB. The linear response range for colorimetric and SERS sensor detection of Pb(II) was 0.01-1.00 mg/L with the detection limit of 5 µg/L and 8 µg/L, respectively. This dual-mode detection system shows excellent selectivity. More importantly, the Pb(II) in traditional Chinese medicine samples have successfully assayed with good recovery from 90.4 to 108.9 %.

Sea hedgehog-inspired surface-enhanced Raman scattering biosensor probe for ultrasensitive determination of Staphylococcus aureus in food supplements.

Staphylococcus aureus contamination in food supplements poses substantial challenges to public health and large-scale production but the sensitive detection in a timely manner remains a bottleneck. Drawing inspiration from the sea hedgehog, gold nanostars (AuNSs) were leveraged to design an ultrasensitive surface-enhanced Raman scattering (SERS) biosensor for the determination of Staphylococcus aureus in food supplements. Besides the surface enhancement furnished by the AuNSs, Raman reporter molecules and specific aptamers sequentially self-assembled onto these AuNSs to construct the "three-in-one" SERS biosensor probe for label-based quantitation of Staphylococcus aureus. Following incubation with contaminated health product samples, the gold nanostars@Raman reporter-aptamer specifically recognize and assemble around Staphylococcus aureus cells, forming a distinctive sea hedgehog structure. This unique configuration results in an amplified Raman signal at 1338 cm-1 and an enhancement factor of up to 6.71 × 107. The entire quantitative detection process can be completed within 30 min, boasting an exceptional limit of detection as low as 1.0 CFU mL-1. The method exhibits a broad working range for the determination of Staphylococcus aureus, with concentrations spanning 2.15 CFU mL-1 to 2.15 × 105 CFU mL-1. Furthermore, it demonstrates outstanding precision, with relative standard deviation values consistently below 5.0%. As a showcase to validate the practicality of the SERS method, we conducted tests on determining Staphylococcus aureus in a herbal food supplement, i.e., Ginkgo Biloba extract (GBE); the results align closely with those obtained through the conventional lysogeny broth agar plate method, pointing to the potential applicability in real-world scenarios.

Ratiometric SERS quantification of SO2 vapor based on Au@Ag-Au with Raman reporter as internal standard.

Practical gas sensing application requires sensors to quantify target analytes with high sensitivity and reproducibility. However, conventional surface enhanced Raman scattering (SERS) sensor lacks reproducibility and quantification arising from variations of "hot spot" distribution and measurement conditions. Here, a ratio-dependent SERS sensor was developed for quantitative label-free gas sensing. Au@Ag-Au nanoparticles (NPs) were filtered onto anodic aluminum oxide (AAO) forming Au@Ag-Au@AAO SERS substrate. 4-MBA was encapsulated in the gap of Au@Ag-Au and served as the internal standard (IS) to calibrate SERS signal fluctuation for improved quantification ability. Combined with headspace sampling method, SO2 residue in traditional Chinese medicine (TCM) can be extracted and captured on the immediate vicinity of Au@Ag-Au surface. The intensity ratio I613 cm-1/I1078 cm-1 showed excellent linearity within the range of 0.5 mg/kg-500 mg/kg, demonstrating superior quantification performance for SO2 detection. Signals for concentration as low as 0.05 mg/kg of SO2 could be effectively collected, much lower than the strictest limit 10 mg/kg in Chinese Pharmacopoeia. Combined with a handheld Raman spectrometer, handy and quantitative TCM quality evaluation in aspect of SO2 residue was realized. This ratiometric SERS sensor functioned well in rapid on-site SO2 quantification, exhibiting excellent sensitivity and simple operability.

Mesoporous Silica-Layered Gold Nanorod Core@Silver Shell Nanostructures for Intracellular SERS Imaging and Phototherapy.

Precision diagnosis-guided efficient treatment is crucial to extending the lives of cancer patients. The integration of surface-enhanced Raman scattering (SERS) imaging and phototherapy into a single nanoplatform has been considered a more accurate diagnosis and treatment strategy for cancer nanotheranostics. Herein, we constructed a new type of mesoporous silica-layered gold nanorod core@silver shell nanostructures loaded with methylene blue (GNR@Ag@mSiO2-MB) as a multifunctional nanotheranostic agent for intracellular SERS imaging and phototherapy. The synthesized GNR@Ag@mSiO2-MB nanostructures possessed a uniform core-shell structure, strong near-infrared (NIR) absorbance, photothermal conversion efficiency (65%), dye loading ability, SERS signal, and Raman stability under phototherapy conditions. Under single 785 nm NIR laser irradiation, the intracellular GNR@Ag@mSiO2-MB nanostructures were dramatically decreased to <9%, which showed excellent photothermal and photodynamic effects toward cancer cell killing, indicating that the combination of photothermal therapy (PTT) and photodynamic therapy (PDT) of the GNR@Ag@mSiO2-MB nanostructures could greatly enhance the therapeutic efficacy of cancer cell death. GNR@Ag@mSiO2-MB nanostructures demonstrated a strong Raman signal at 450 and 502 cm-1, corresponding to the δ(C-N-C) mode, suggesting that the Raman bands of GNR@Ag@mSiO2-MB nanostructures were more efficient to detect CT-26 cell SERS imaging with high specificity. Our results indicate that GNR@Ag@mSiO2-MB nanostructures offer an excellent multifunctional nanotheranostic platform for SERS imaging and synergistic anticancer phototherapy in the future.

A highly effective SERS platform formed by the fabrication of Ag@ZIF-8@Au nanoparticles for rapid detection of acetamiprid in environment.

The unreasonable spraying and random migration of acetamiprid may cause pollution of crops, soil and water resources in the environment, resulting in threatening ecosystem and human health. However, the monitoring of acetamiprid using mass spectrum in the environment encounters challenges due to high-cost instruments and complex processing time. Herein, we fabricated a rapid and reliable SERS method based on Ag@ZIF-8@Au platforms for tracing acetamiprid residues in the environment. In this method, a MOF material named ZIF-8 is coated with silver nanoparticles and distributed internally between AgNPs and AuNPs to enhance Raman signal, which can enrich pesticide molecules into the hotspots area provided by noble material and helps avoid the oxidation of silver nanoparticles. High sensitivity (LOD of 9.027 × 10-10 M for acetamiprid, and SERS enhancement factor of 4.3 × 107), excellent reproducibility (6.496% or 7.198% RSD for 30 random points) and superior stability (3.127% RSD for 6 weeks) were achieved using the proposed method. Acetamiprid with concentrations from 10-4 to 10-9 M were successfully detected by SERS method. Furthermore, the linear detection models of acetamiprid in different environment matrices (lake water, tea leaves, tea garden soil, oranges and oranges orchard soil) were established and all the correlation coefficient (R2) were higher than or equal to 95%, indicating the excellent adaptability of Ag@ZIF-8@Au platform in environment. The randomly spiked concentrations of acetamiprid were also tested with good recovery values and low relative error values, further confirming the reliability of the detection method.

Cyclometalated Ir(III) theranostic molecular probe enabled mitochondria targeted fluorescence-SERS-guided phototherapy in breast cancer cells.

The increased energy demands inherent in cancer cells necessitate a dependence on mitochondrial assistance for their proliferation and metastatic activity. Herein, an innovative photo-medical approach has been attempted, specifically targeting mitochondria, the cellular powerhouses, to attain therapeutic benefit. This strategy facilitates the rapid and precise initiation of apoptosis, the programmed cell death process. In this goal, we have synthesized cyclometalated Iridium (III) molecular probes, denoted as Ir-CN and Ir-H, with a nitrile (CN) and a hydrogen-functionalized bipyridine as ancillary ligands, respectively. Ir-CN has shown superior photosensitizing properties and lower dark cytotoxicity compared to Ir-H in the breast cancer cell line MCF-7, positioning it as the preferred probe for photodynamic therapy (PDT). The synthesized Ir-CN induces alterations in mitochondrial membrane potential, disrupting the respiratory chain function, and generating reactive oxygen species that activate signaling pathways leading to cell death. The CN-conjugated bipyridine ligand in Ir-CN contributes to the intense red fluorescence and the positive charge on the central metal atom facilitates specific mitochondrial colocalization (colocalization coefficient of 0.90). Together with this, the Iridium metal, with strong spin-orbit coupling, efficiently generates singlet oxygen with a quantum yield of 0.79. Consequently, the cytotoxic singlet oxygen produced by Ir-CN upon laser exposure disrupts mitochondrial processes, arresting the electron transport chain and energy production, ultimately leading to programmed cell death. This mitochondrial imbalance and apoptotic induction were dually confirmed through various apoptotic assays including Annexin V staining and by mapping the molecular level changes through surface-enhanced Raman spectroscopy (SERS). Therefore, cyclometalated Ir-CN emerges as a promising molecular probe for cancer theranostics, inducing laser-assisted mitochondrial damage, as tracked through bimodal fluorescence and SERS.

Au-Ag OHCs-based SERS sensor coupled with deep learning CNN algorithm to quantify thiram and pymetrozine in tea.

Pesticide residue detection in food has become increasingly important. Herein, surface-enhanced Raman scattering (SERS) coupled with an intelligent algorithm was developed for the rapid and sensitive detection of pesticide residues in tea. By employing octahedral Cu2O templates, Au-Ag octahedral hollow cages (Au-Ag OHCs) were developed, which improved the surface plasma effect via rough edges and hollow inner structure, amplifying the Raman signals of pesticide molecules. Afterward, convolutional neural network (CNN), partial least squares (PLS), and extreme learning machine (ELM) algorithms were applied for the quantitative prediction of thiram and pymetrozine. CNN algorithms performed optimally for thiram and pymetrozine, with correlation values of 0.995 and 0.977 and detection limits (LOD) of 0.286 and 29 ppb, respectively. Accordingly, no significant difference (P greater than 0.05) was observed between the developed approach and HPLC in detecting tea samples. Hence, the proposed Au-Ag OHCs-based SERS technique could be utilized for quantifying thiram and pymetrozine in tea.

Determination of Dicofol in Tea Using Surface-Enhanced Raman Spectroscopy Coupled Chemometrics.

Dicofol is a highly toxic residual pesticide in tea, which seriously endangers human health. A method for detecting dicofol in tea by combining stoichiometry with surface-enhanced Raman spectroscopy (SERS) technology was proposed in this study. AuNPs were prepared, and silver shells were grown on the surface of AuNPs to obtain core-shell Au@AgNPs. Then, the core-shell Au@AgNPs were attached to the surface of a PDMS membrane by physical deposition to obtain a Au@AgNPs/PDMS substrate. The limit of detection (LOD) of this substrate for 4-ATP is as low as 0.28 × 10-11 mol/L, and the LOD of dicofol in tea is 0.32 ng/kg, showing high sensitivity. By comparing the modeling effects of preprocessing and variable selection algorithms, it is concluded that the modeling effect of Savitzky-Golay combined with competitive adaptive reweighted sampling-partial least squares regression is the best (Rp = 0.9964, RPD = 10.6145). SERS technology combined with stoichiometry is expected to rapidly detect dicofol in tea without labels.

Single versus Double Coffee-Ring Effect Patterns in Thin-Layer Chromatography Coupled with Surface-Enhanced Raman Spectroscopic Analysis of Anti-Diabetic Drugs Adulterated in Herbal Products.

In thin-layer chromatography coupled with surface-enhanced Raman spectroscopy (TLC-SERS), the coffee ring effect (CRE) describes the formation of a ring-shape spot (blank in the middle and darker on the edge) caused by the aggregation of silver nanoparticles (Ag NPs), alone (single CRE) or with the analytes (double CRE). In this work, the SCRE and DCRE were investigated in two anti-diabetic drugs, hydrophobic glibenclamide (GLB) and more hydrophilic metformin (MET). The SCRE occurred in GLB analysis, as opposed to the DCRE that occurred in MET. It was proven that for optimization of the TLC-SERS analytical procedure, it is necessary to distinguish the CRE patterns of analytes. Additionally, MET and GLB were analyzed with the developed TLC-SERS method and confirmed by another validated method using high-performance liquid chromatography. Four herbal products collected on the market were found to be adulterated with GLB or/and MET; among those, one product was adulterated with both MET and GLB, and two products were adulterated with GLB at a higher concentration than the usual GLB prescription dose. The TLC-SERS method provided a useful tool for the simultaneous detection of adulterated anti-diabetic herbal products, and the comparison of the SCRE and DCRE provided more evidence to predict CRE patterns in TLC-SERS.

Ratiometric SERS aptasensing for simultaneous quantitative detection of histamine and tyramine in fishes.

Herein, a SiO2@Ag NPs core/shell nanoparticles were synthesized to fabricate a surface-enhanced Raman spectroscopy (SERS) sensor for the simultaneous determination of histamine (HIS) and tyramine (TYR) based on specific aptamer recognition and ratiometric strategy. SiO2@Ag NPs with 4-thiosaminophenol (4-ATP) and Nile blue A (NBA) molecules were used as an internal standard (IS) and labeled with aptamers corresponding to HIS and TYR, respectively. Raman reporter molecules ROX and Cy5 labeled complementary DNA (cDNA) were then hybridized with aptamers to form rigid double-stranded DNA. After the HIS and TYR were captured by their aptamers, resulting in the dissociation of cDNA and separated from the SERS substrate. Therefore, the SERS signal intensity at 1503 cm-1 of ROX and 1358 cm-1 of Cy5 tagged on the terminal of cDNA decreased with the concentration of HIS and TYR increasing, while the SERS signal intensity at 1079 cm-1 of 4-APT and 592 cm-1 of NBA on the substrate remain stable. Thus, the concentrations of HIS and TYR can be determined by the I1503/I1079 and I1358/I592 values, respectively. This sensing strategy achieves a lower detection limit of 0.2 ng/mL for HIS and 0.05 ng/mL for TYR, respectively, demonstrating promising applications in sensitive detection of BAs in animal-derived foodstuff.

Rapid detection of nicotine and benzoic acid in e-liquids with surface-enhanced Raman scattering and artificial intelligence-assisted spectrum interpretation.

Electronic cigarettes have rapidly gained acceptance recently. Nicotine-containing electronic cigarette liquids (e-liquids) are prohibited in some countries, but are permitted and simply available online in others. A rapid detection method is therefore required for on-site inspection or screening of a large amount of samples. Our previous study demonstrated a surface-enhanced Raman scattering (SERS)-based approach to identify nicotine-containing e-liquids; without any pre-treatment, e-liquid can be directly tested on our solid-phase SERS substrates, made of silver nanoparticle arrays embedded in anodic aluminium oxide nanochannels (Ag/AAO). However, this approach required manual determination of spectral signatures and negative samples should be validated in the second round detection. Here, after examining 406 commercial e-liquids, we refined this approach by developing artificial intelligence (AI)-assisted spectrum interpretations. We also found that nicotine and benzoic acid can be simultaneously detected in our platform. This increased test sensitivity because benzoic acid is usually used in nicotine salts. Around 64% of nicotine-positive samples in this study showed both signatures. Using either cutoffs of nicotine and benzoic acid peak intensities or a machine learning model based on the CatBoost algorithm, over 90% of tested samples can be correctly discriminated with only one round of SERS measurement. False negative and false positive rates were 2.5-4.4% and 4.4-8.9%, respectively, depending on the interpretation method and thresholds applied. The new approach takes only 1 microliter of sample and can be performed in 1-2 min, suitable for on-site inspection with portable Raman detectors. It could also be a complementary platform to reduce samples that need to be analyzed in the central labs and has the potential to identify other prohibited additives.

A facile heat-treatment solid phase microextraction method for SERS detection of isocarbophos in tea using a hand-held Raman spectrometer.

A facile sensor system based on heat-treatment solid phase microextraction and Surface-Enhanced Raman Scattering (HT-SPME-SERS) was established for in-situ detection of isocarbophos in complex tea matrix. Starting from the action optimization of temperature control unit and air flow control unit, pesticide molecules volatilizing from solution are efficiently captured by substrate and generate real-time SERS signals by a hand-held Raman spectrometer, and the sensor system based on HT-SPME-SERS was finally established. A novel SERS substrate of Cu@rGO@Ag was developed as HT-SPME-SERS material, where reduced graphene oxide (rGO) enriched pesticide molecules by π-π stacking. A superior detection sensitivity brought by the ultra-high enhancement effect of Cu@rGO@Ag substrate was obtained. A good linear relationship between Raman intensity and isocarbophos concentration was obtained and the limit of detection (LOD) was as low as 0.00451 ppm. The detection results obtained from the sensor system have been verified by gas chromatography-mass spectrometer (GC-MS), showing its great application potential for the safety of agricultural products.

Highly sensitive technique for detection of adulterants in centella herbal samples using surface enhanced Raman spectroscopy (SERS).

The trace level detection of adulterants in food, nutritional supplements and medicinal herbs is highly challenging in the field of food processing and herbal industries. In addition, laborious sample processing procedures and well trained personnel are required to analyse the samples using conventional analytical equipments. In this study, a highly sensitive technique with minimal sampling processes and human intervention is proposed for the trace amount detection of pesticidal residues in centella powder. Herein, graphene oxide gold (GO-Au) nanocomposite coated parafilm is developed as substrate by simple dropcasting technique to facilitate dual surface enhanced Raman signal. The dual SERS enhancement involving chemical enhancement from graphene and electromagnetic signal enhancement from gold nanoparticles is utilized for detection of chlorpyrifos in the ppm level concentration. The flexible polymeric surfaces could be the better choice for SERS substrates due to their inherent properties such as flexibility, transparency, roughness and hydrophobicity. Among the various types of flexible substrates explored, GO-Au nanocomposites coated parafilm substrates showed better Raman signal enhancement. Parafilm coated with GO-Au nanocomposites is successful in achieving detection limits down to 0.1 ppm of chlorpyrifos in centella herbal powder sample. Thus, the fabricated parafilm based GO-Au SERS substrates could be used as a screening tool at quality control of herbal product manufacturing sectors for trace level detection of adulterants in herbal samples from their unique chemical and structural information.

Effects of Au@Ag core-shell nanostructure with alginate coating on male reproductive system in mice.

Despite the widespread use of silver nanoparticles (NPs), these NPs can accumulate and have toxic effects on various organs. However, the effects of silver nanostructures (Ag-NS) with alginate coating on the male reproductive system have not been studied. Therefore, this study aimed to investigate the impacts of this NS on sperm function and testicular structure. After the synthesis and characterization of Ag-NS, the animals were divided into five groups (n = 8), including one control group, two sham groups (received 1.5 mg/kg/day alginate solution for 14 and 35 days), and two treatment groups (received Ag-NS at the same dose and time). Following injections, sperm parameters, apoptosis, and autophagy were analyzed by the TUNEL assay and measurement of the mRNA expression of Bax, Bcl-2, caspase-3, LC3, and Beclin-1. Fertilization rate was assessed by in vitro fertilization (IVF), and testicular structure was analyzed using the TUNEL assay and hematoxylin and eosin (H&E) staining. The results showed that the NS was rod-shaped, had a size of about 60 nm, and could reduce sperm function and fertility. Gene expression results demonstrated an increase in the apoptotic markers and a decrease in autophagy markers, indicating apoptotic cell death. Moreover, Ag-NS invaded testicular tissues, especially in the chronic phase (35 days), resulting in tissue alteration and epithelium disintegration. The results suggest that sperm parameters and fertility were affected. In addition, NS has negative influences on testicular tissues, causing infertility in men exposed to these NS.

[Governor vessel moxibustion combined with western medication for mild to moderate depression with kidney-yang deficiency: a randomized controlled trial].

OBJECTIVE: To compare the therapeutic efficacy of governor vessel moxibustion combined with fluoxetine hydrochloride capsule, simple fluoxetine hydrochloride capsule and placebo moxibustion combined with fluoxetine hydrochloride capsule for mild to moderate depression with kidney-yang deficiency. METHODS: A total of 126 patients with mild to moderate depression with kidney-yang deficiency were randomized into a governor vessel moxibustion group (42 cases, 2 cases dropped off), a western medication group (42 cases, 1 case dropped off) and a placebo moxibustion group (42 cases, 1 case dropped off). The western medication group was given fluoxetine hydrochloride capsule orally, 20 mg a time, once a day. On the basis of the treatment in the western medication group, governor vessel moxibustion was applied from Dazhui (GV 14) to Yaoshu (GV 2) in the governor vessel moxibustion group, once a week; placebo moxibustion was applied in the placebo moxibustion group, once a week. Treatment of 8 weeks was required in the 3 groups. Before and after treatment, the scores of Hamilton depression scale-17 (HAMD-17), Asberg's rating scale for side effects (SERS) and TCM clinical symptom were compared, and the clinical efficacy was evaluated. RESULTS: After treatment, the scores of HAMD-17, SERS and TCM clinical symptom were decreased compared before treatment in the 3 groups (P<0.05), the decrease ranges of above scores in the governor vessel moxibustion group were larger than those in the western medication group and the placebo moxibustion group (P<0.05). The total effective rate was 92.5% (37/40) in the governor vessel moxibustion group, which was higher than 75.6% (31/41) in the western medication group and 80.5% (33/41) in the placebo moxibustion group (P<0.05). CONCLUSION: Governor vessel moxibustion combined with fluoxetine hydrochloride capsule can improve the degree of depression and relieve the clinical symptoms in mild to moderate depression patients with kidney-yang deficiency, the efficacy is superior to simple fluoxetine hydrochloride capsule, and can reduce the fluoxetine hydrochloride capsule-induced adverse effect to a certain extent.

Surface-enhanced Raman scattering integrating with machine learning for green tea storage time identification.

The rapid and accurate identification of complex samples still remains a great challenge, especially for those with similar compositions. In this work, we report an integration strategy consisting of surface-enhanced Raman scattering (SERS) and machine learning to discriminate complex and similar analytes, in this case green tea products with different storage times. Surface-functionalized Ag nanoparticles (NPs) were used as a SERS substrate to reveal the changes in the sensory components of green tea with variable storage time. Principal components analysis (PCA)-based support vector machine (SVM) classification was used to extract the key spectral features and identify green tea with different storage times. The results showed that such an integration strategy achieved high predictive accuracy on time tag discrimination for green tea. The multiclass SVM classifier successfully recognized green tea with different storage times at a prediction accuracy of 95.9%, sensitivity of 96.6%, and specificity of 98.8%. Therefore, this work illustrates that the SERS-based PCA-SVM platform might be a facile and reliable tool for the identification of complex matrices with subtle differentiations.

Al2O3@Ag composite structure as SERS substrate for sensitive detection of sodium thiocyanate.

Sodium thiocyanate (NaSCN) can be added to fresh milk to enhance the sterilization ability of the lactoperoxidase system (LP system) in milk, extending shelf life. However, excessive intake of NaSCN can be harmful to human health because it can prevent absorption of iodine leading to disease. Also NaSCN can be used as a marker to distinguish smokers from non-smokers. In this work, we successfully synthesized meatball-like Al2O3@Ag composite structures as surface-enhanced Raman scattering (SERS) substrates using a simple wet chemical method adapted to conventional laboratory conditions. The substrate exhibited strong SERS enhancement for NaSCN. Under the optimal experiment conditions, we obtained a detection limit of 0.28 µg L-1 and a quantification limit of 1 µg L-1, R2 = 0.992. Based on the analysis of the intensity of SERS characteristic peak, the substrate had good reproducibility and uniformity. In summary, the Al2O3@Ag composite structure achieved sensitive SERS detection of NaSCN. Combining the facile and low-cost methods, we believe that the SERS detection method developed in this work can be used as a potential candidate for biosensing applications in the future.

Governor vessel moxibustion combined with western medication for mild to moderate depression with kidney-yang deficiency: a randomized controlled trial / 中国针灸

OBJECTIVE@#To compare the therapeutic efficacy of governor vessel moxibustion combined with fluoxetine hydrochloride capsule, simple fluoxetine hydrochloride capsule and placebo moxibustion combined with fluoxetine hydrochloride capsule for mild to moderate depression with kidney-yang deficiency.@*METHODS@#A total of 126 patients with mild to moderate depression with kidney-yang deficiency were randomized into a governor vessel moxibustion group (42 cases, 2 cases dropped off), a western medication group (42 cases, 1 case dropped off) and a placebo moxibustion group (42 cases, 1 case dropped off). The western medication group was given fluoxetine hydrochloride capsule orally, 20 mg a time, once a day. On the basis of the treatment in the western medication group, governor vessel moxibustion was applied from Dazhui (GV 14) to Yaoshu (GV 2) in the governor vessel moxibustion group, once a week; placebo moxibustion was applied in the placebo moxibustion group, once a week. Treatment of 8 weeks was required in the 3 groups. Before and after treatment, the scores of Hamilton depression scale-17 (HAMD-17), Asberg's rating scale for side effects (SERS) and TCM clinical symptom were compared, and the clinical efficacy was evaluated.@*RESULTS@#After treatment, the scores of HAMD-17, SERS and TCM clinical symptom were decreased compared before treatment in the 3 groups (P<0.05), the decrease ranges of above scores in the governor vessel moxibustion group were larger than those in the western medication group and the placebo moxibustion group (P<0.05). The total effective rate was 92.5% (37/40) in the governor vessel moxibustion group, which was higher than 75.6% (31/41) in the western medication group and 80.5% (33/41) in the placebo moxibustion group (P<0.05).@*CONCLUSION@#Governor vessel moxibustion combined with fluoxetine hydrochloride capsule can improve the degree of depression and relieve the clinical symptoms in mild to moderate depression patients with kidney-yang deficiency, the efficacy is superior to simple fluoxetine hydrochloride capsule, and can reduce the fluoxetine hydrochloride capsule-induced adverse effect to a certain extent.

Rapid detection of multiple colorant adulteration in Keemun black tea based on hemp spherical AgNPs-SERS.

This study synthesized stable and sensitive hemp spherical AgNPs as the SERS substrate for the simultaneous and rapid detection of sunset yellow, lemon yellow, carmine and erythrosine adulteration in black tea. With R6G as the probe molecule, the AgNPs were determined to have satisfactory stability over 60 days with an enhancement factor of 108. The effects of three variable screening methods on model performance were compared. Among them, CARS-PLS exhibited superior performance for the quantification of all the four colorants, with prediction set correlation coefficients of 0.95, 0.97, 0.99 and 0.88, respectively. The differentiation of the mixed colorants was also achieved, with recoveries ranging from 91.87 % to 106.5 % with RSD value <1.97 %, demonstrating the high accuracy and precision of the proposed method. The results indicate that AgNPs-based SERS is an effective method and has substantial potential for application in the identification and quantification of colorant in tea.