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Endemic fluorosis has gained increasing attention as a public health concern, and the escalating risk of colitis resulting from excessive fluoride intake calls for effective mitigation strategies. This study aimed to investigate the potential mechanisms underlying the alleviation of fluoride-induced colitis by Tea polysaccharides (TPS). Under conditions of excessive fluoride intake, significant changes were observed in the gut microbiota of rats, leading to aggravated colitis. However, the intervention of TPS exerted a notable alleviating effect on colitis symptoms. Antibiotic intervention and fecal microbiota transplantation (FMT) experiments provided evidence that TPS-mediated relief of fluoride-induced colitis is mediated through its effects on the gut microbiota. Furthermore, TPS supplementation was found to modulate the structure of gut microbiota, enhance the relative abundance of Limosilactobacillus vaginalis in the gut microbiota, and promote the expression of short-chain fatty acid (SCFAs) receptors in colonic tissue. Notably, L. vaginalis played a significant role in alleviating fluoride-induced colitis and facilitating the absorption of butyric acid in the rat colon. Subsequent butyric acid intervention experiments confirmed its remarkable alleviating effect on fluoride-induced colitis. Overall, these findings provide a potential preventive strategy for fluoride-induced colitis by TPS intervention, which is mediated by L. vaginalis and butyric acid., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. All data needed to evaluate the conclusions in the paper are present in the paper and the Supplementary Materials. Additional data related to this paper may be requested from the corresponding authors., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Three functional magnetic nanocatalytic probe, which integrates recognition, catalytic amplification, and separation enrichment, is a new approach to construct a simple, fast, highly selective, and sensitive analytical method. In this article, a new magnetic nanosurface molecularly imprinted polymer nanoprobe (Fe 3 O 4 @MIP) with trifunctionality was rapidly prepared using a microwave-assisted method with magnetic Fe 3 O 4 nanoparticles as a substrate, chloramphenicol (CAP) as a template molecule, and methacrylic acid as a functional monomer. The characterized nanoprobe was found that could specifically recognize CAP, strongly catalyze the new indicator nanoreaction of fructose (DF)-HAuCl 4 . The gold nanoparticles (AuNPs) exhibit strong resonance Rayleigh scattering (RRS) and surface enhanced Raman scattering (SERS) effects. Upon addition of CAP, the SERS/RRS signals were linearly weakened. Accordingly, a new SERS/RRS analysis platform for highly sensitive and selective determination of CAP was constructed. The SERS linear range was 0.0125-0.1 nmol/L, with detection limit (DL) of 0.004 nmol/L CAP. Furthermore, it could be combined with magnet-enriched separation to further improve the sensitivity, with a DL of 0.04 pmol/L CAP. The SERS method has been used for the determination of CAP in real samples, with relative standard deviations of 2.37-9.89 % and the recovery of 95.24-107.1 %., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

This article was used potassium dichromate as the template molecule, silver nanoclusters as the nano matrix, acrylamide as the monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinking agent, and azodiisobutyronitrile (AIBN) as the initiator to prepare a new silver nanocluster surface MIP (AgNCs@MIP) nanoprobe for chromate. Upon addition of Cr(VI), it selectively adsorbs on the surface of AgNCs@MIP nanoprobes. The dichromate ion absorption peak at 350 nm overlaps with the AgNCs@MIP RRS peak at 370 nm, resulting in strong RRS energy transfer (RRS-ET) and a decrease in the RRS intensity. The decreased RRS intensity is directly proportional to the concentration of dichromate ions in the range of 0.0025-0.015 µmol/L, with a detection limit of 0.8 nmol/L. Therefore, a simple, fast, sensitive and selective RRS method for the determination of trace Cr(VI) in mineral water has been established, with a relative standard deviation of 9.2-9.8 % and recovery of 95.20 %-103.60 %., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The N and Fe doped carbon dot (CD NFe ) was prepared by microwave procedure. Using CD NFe as the nano-substrate, fipronil (FL) as the template molecule and α-methacrylic acid as the functional monomer, the molecular imprinted polymethacrylic acid nanoprobe (CD NFe @MIP) with difunction was synthesized by microwave procedure. The CD NFe @MIP was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier infrared spectroscopy, and other techniques. The results show that the nanoprobe not only distinguish FL but also has a strong catalytic effect on the HAuCl 4 -Na 2 C 2 O 4 nanogold indicator reaction. When the nanoprobes specifically recognize FL, their catalytic effect is significantly reduced. Since the AuNPs generated by HAuCl 4 reduction have strong surface-enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) effects, a SERS/RRS dual-mode sensing platform for detecting 5-500 ng/L FL was constructed. The new analytical method was applied to detect FL in food samples with a relative standard deviation (RSD) of 3.3-8.1 % and a recovery rate of 94.6-104.5 %., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

A novel highly active silver single-atom catalyst (AgSAC) was prepared by a microwave-assisted solvothermal method using silver covalent organic frameworks (AgMOF) as precursors. It was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared (IR), and surface-enhanced Raman scattering (SERS). The experiment found that AgSAC has excellent catalytic performance and can heavily catalyze the nano-reaction of chloroauric acid-malic acid (HAuCl 4 -H 2 Mi) to generate gold nanoparticles (AuNPs). The produced AuNPs have strong SERS, resonance Rayleigh scattering (RRS) and surface plasmon resonance absorption (Abs) signals. Aflatoxin B1 aptamer (Apt AFB1 ) can be adsorbed to the surface of AgSAC through electrostatic interaction, to reduce the catalytic activity of AgSAC and the SERS/RRS/Abs signal of the system. When the target molecule (AFB1) was added, it will specifically bind to Apt AFB1 and release AgSAC, restoring the catalytic activity of AgSAC, thereby restoring the SERS/RRS/Abs signal of the system. Based on this, a simple and sensitive aptamer sensing analysis platform for trace AFB1 was established, and a reasonable catalytic amplification mechanism of AgSAC was proposed. The SERS method exhibited the highest sensitivity, with a linear range of 0.005-0.225 μg/L and a detection limit of 0.002 μg/L., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

New multifunctional nanomaterial preparation and its application to trace pollutant analysis are interesting to peoples. Using terbium metal-organic framework loaded gold nanoparticles (MOF Tb @Au) as the nanosubstrate and 3-aminopropyltriethoxysilane (APTES) as the functional monomer, a new bifunctional nanosurface molecularly imprinted polymer nanoprobe of MOF Tb @Au@MIP with strongly recognition and catalytic amplification functions was prepared by the microwave sol-gel procedure. It was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier infrared spectroscopy (FTIR) and other techniques. The nanoprobe was found to specifically recognize malathion (MAL) and catalyze the L-cysteine (Cys)-HAuCl 4 nanogold indicator reaction to amplify the molecular spectral signal. The gold nanoparticles (AuNPs) generated in the system show a strong surface-enhanced Raman scattering (SERS) effect, resonant Rayleigh scattering (RRS) peak and UV absorption (Abs) peak at 1615 cm -1 , 370 nm and 520 nm, respectively. Based on this, a new SERS/RRS/Abs trimode method for the detection of MAL can be established. It has been applied to the analysis of cereal samples with satisfactory recoveries of 95.2-107.4% and precision of 3.76-9.06%., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Nitrogen-doped carbon dots (CD N ) were prepared by microwave hydrothermal method using ammonium citrate (AC) and ethylenediaminetetraacetic acid (EDTA) as precursor. It was characterized by transmission electron microscopy (TEM) and infrared spectroscopy (IR). The CD N was found to catalyze the reduction of HAuCl 4 to produce gold nanoparticles (AuNP), among which fructose was an effective reducing agent. Using malachite green (MG) as a molecular probe, the surface enhanced Raman scattering (SERS) intensity at 1617 cm -1 and the resonance Rayleigh scattering (RRS) intensity at 375 nm increased linearly with increasing CD N concentration, respectively. The catalytic activity of CD N is inhibited because the aptamer (Apt) can be adsorbed on the surface of the catalyst CD N . The aptamer (Apt)-Pb 2+ reaction and CD N -Apt adsorbing reaction were competitive reaction. When there is Pb 2+ that binds more tightly to Apt, Apt is desorbed, and the catalytic ability of CD N is restored. Accordingly, an Apt-mediated nanocatalytic amplification SERS/RRS platform for quantitative detection of lead ions was constructed. For the SERS method, the linear range was 0.5-120 nmol/L with DL of 0.11 nmol/L. For the RRS method, the Pb 2+ concentration was linear in the range of 50-400 nmol/L with the RRS intensity, and the DL was 15.32 nmol/L. The analysis platform uses CD N catalyzed nanoreactions to generate AuNP products with SERS activity as a substrate, thus overcoming the shortcomings of Pb 2+ without scattering activity, and realizing the possibility of SERS and RRS detection of metal ions. It was used for the determination of Pb 2+ in real samples with relative standard deviations were 0.94-2.71 % and recovery was 99.00-103.70 %, respectively. In addition, the mechanism of CD N nanoenzyme heterogeneous catalysis of nano-gold reactions was discussed., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

A new acetamiprid (AP) molecularly imprinted polymer (MIP) nanosol was synthesized with α-methacrylic acid as functional monomer, ethylene glycol dimethacrylate as crosslinker and 2,2'-azobisisobutyronitrile as initiator, under the microwave irradiation. It was characterized by transmission electron microscopy, specific surface area and pore size analysis, and molecular spectroscopy. The bifunctional MIP nanomaterial not only had the recognition of AP but also had a strong catalysis of the nanogold dimode indicator reaction of chloroauric acid-dopamine. The generated gold nanoparticles (AuNPs) had strong surface-enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) effects, and the two kinds of signals enhanced linearly with imprinted molecule AP increasing. Accordingly, a novel SERS/RRS nanosensor platform was constructed to detect 0.25-20 pmol/L and 0.5-50 pmol/L AP by SERS and RRS monitoring respectively. Moreover, a reliable nanocatalytic mechanism was proposed., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Terbium metal-organic framework (TbMOF) was prepared by microwave method with 1,3,5-benzenetricarboxylic acid as ligand. With HAuCl 4 as precursor and NaBH 4 as reducing agent, TbMOF-loaded gold nanoparticles (AuNPs) catalyst (TbMOF@Au 1 ) was prepared rapidly and characterized by transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. It was found that TbMOF@Au 1 has a strong catalytic effect on the HAuCl 4 -Cys nanoreaction, and the produced AuNPs have a strong resonant Rayleigh scattering (RRS) peak and surface plasmon resonance absorption (Abs) peak at 370 nm and 550 nm, respectively. With the addition of the molecular probe Victoria blue 4R (VB4r), AuNPs have a strong surface-enhanced Raman scattering (SERS) effect, the target analyte molecules are trapped in between the nanoparticles and a hot spot effect created in the process resulting in an extremely high SERS signal. A new SERS/RRS/Abs triple-mode analysis method for Malathion (MAL) was established by coupling this new TbMOF@Au 1 catalytic indicator reaction with MAL aptamer (Apt) reaction, and its SERS detection limit was 0.21 ng/mL. The SERS quantitative analysis method has been applied to the analysis of fruit samples with the recovery of 92.6-106.6 % and the precision of 2.72-8.16 %., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The traditional preparation of MXeneTi 3 C 2 is complicated. Two-dimensional MXeneTi 3 C 2 nanosheets were prepared via in-situ generation of HF etching Ti 3 AlC 2 under the microwave irradiation. Gold nanocluster doped nanosheets sol (MXene@Au) with excellent stability and strong catalysis was synthesized with no product residue reducer CO. MXene@Au nanosol can catalyze mandelic acid-HAuCl 4 to produce gold nanoparticles, which can be traced via resonance Rayleigh scattering (RRS) and surface-enhanced Raman scattering (SERS). Coupled the dual-mode nanocatalytic indicator reaction with aptamer reaction, a high sensitivity, selectivity, facile SERS/RRS dual-mode biosensnoring assay platform has been constructed for isocarbophos (ICP). The linear range of SERS was 1.0 × 10 -3 -2.5 × 10 -2  nmol/L, with a detection of limit 4.5 × 10 -5  nmol/L (S/N = 3). It has been used to detect ICP in water samples, with a good recovery (95.5-104%) and a good relative standard deviation (5.2-9.6%). This new nanocatalytic amplification biosensoring strategy can also assay other organic pesticides including malathion, glyphosate, profenofos and carbendazim. In addition, the nanocatalytic mechanism was investigated., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

A new covalent organic framework loaded-molybdate (COF Mo ) nanomaterial was prepared simply by solvothermal procedure and characterized by electron microscopy and molecular spectral techniques. The COF Mo had a strong resonance Rayleigh scattering (RRS) signal at 465 nm and a fluorescence peak at 345 nm. When the PO 4 3- was added in the system, it reacted with the molybdate, which loaded on the surface of COF particles, to form stable phosphomolybdic acid occurring RRS/fluorescence-energy transfer, the RRS and fluorescence signals were decreased. The decreased RRS/fluorescence intensities were linear to the PO 4 3- concentration in the range of 0.053-3.2 nmol/L and 0.10-3.2 nmol/L, with a detection limit of 0.050 nmol/L and 0.090 nmol/L respectively. Accordingly, a new and facile RRS/fluorescence dimode method for detection of trace PO 4 3- was established, only one fluorometer was used., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Hexavalent chromium (Cr 6+ ) has strong oxidizing property and toxicity. It has been identified as a carcinogen with obvious carcinogenic effect by the International Anti-cancer Research Center. Therefore, it has a great significance to establish a simple and sensitive method for Cr 6+ . In the solution, liquid crystal (LC) trans, trans-4-(3,4-difluorophenyl)-4'-n-pentylbicyclohexyl (DP) exhibits strong resonance Rayleigh scattering (RRS) effect due to formation DP nanoparticles. It was used firstly as nanoprobe, to establish a simple and sensitive RRS energy transfer (RRS-ET) method for the determination of trace Cr 6+ in water samples. The Cr 6+ reacts with diphenylcarbazide (DCB) to produce purple complex. It is adsorbed on the nanoprobe surface, the purple complex as energy receptor and DP as energy donor to produce RRS-ET phenomenon, to make the RRS signal of 370 nm decreasing. In the range of 3-30 nmol/L Cr 6+ , with the increase of concentration, the RRS signal decreased linearly at 370 nm, with a detection limit of 0.49 nmol/L. This new RRS-ET method was applied to the determination of Cr 6+ in water samples, with recovery of 96.0-104.7% and the relative standard deviation (RSD) of 4.44-9.98%., (Copyright © 2022 Elsevier B.V. All rights reserved.)

A cerium metal organic framework-loaded silver nanocluster (MOF CeAgNC ) is synthesized by a facile stirring procedure with trimesic acid, cerium nitrate, silver nitrate and NaBH 4 , which exhibites strong catalytic activity in the indicated reaction of HAuCl 4 -sodium lactate (SL). MOF CeAgNC can sensitively detect dopamine (DA) by surface-enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) techniques with a detection concentration range of 0.01-0.25 nmol/L and a detection limit of 0.008 nmol/L. Based on the specific binding of aptamer (Apt)-DA and the catalytic amplification strategy of MOF CeAgNC on HAuCl 4 -SL, a sensitive and convenient DA platform for dual-mode detection of SERS and RRS is constructed. In addition, the platform is successfully applied to detect DA in human serum with satisfactory recoveries (95.7-102%)., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The measurement of NH 4 + has attracted considerable attention with the increase of NH 4 + emissions in sewage caused by human activities. So far, a variety of photometric and fluorescence methods for the detection of NH 4 + have been researched and summarized, but there is no report about the use of liquid crystals (LCs) cholesteryl benzoate (CB) as a resonance Rayleigh scattering (RRS) probe to determine ammonium ions. In the NaAc-HAc buffer solution with pH = 4.80, the yellow compounds 3,5 diacetyl-1,4 dihydrolutidine (DDL) generated by the reaction of NH 4 + with acetylacetone (AT) and formaldehyde (HCHO) act as the energy receiver and CB as the donor. Because the RRS spectrum of CB overlaps with the DDL absorption spectrum, resonance Rayleigh scattering energy transfer (RRS-ET) occurs. When the NH 4 + concentration increased, the generated DDL increased, and the RRS-ET also increased, so the RRS intensity of the system at 395 nm decreased. For this reason, a fast and sensitive CB RRS-ET method was established to apply to the detection of NH 4 + in water. The detection range was 1.00 × 10 -3 - 4.66 μg/mL, and the detection limit was 6.62 × 10 -3 μg/mL. Using this method to analyze and detect NH 4 + in environmental water samples, the precision and recovery rate were between 1.30-9.30% and 95.5-109.9%, respectively. Therefore, this method has the advantages of sensitivity and simplicity., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Nanocatalytic amplification of carbon dots is a new way to improve sensitivity. The preparation of the high catalytic activity and stable iron/nitrogen-doped carbon dot (CD BFe ) sol and its application in aptamer (Apt) assay have not been reported yet. In this paper, a simple hydrothermal procedure for the preparation of CD BFe derived from Fe 2+ -2,2'-bipyridine complex has been developed. It is found that CD BFe has a strong catalytic effect on the indicator reaction of glyoxal (C 2 H 2 O 2 ) reduction of HAuCl 4 to produce gold nanoparticle (AuNP) probe with strong surface enhanced Raman scattering (SERS) at 1617 cm -1 , resonance Rayleigh scattering (RRS) effect at 370 nm and absorption (Abs) at 550 nm. A rapid and sensitive CD BFe catalytic amplification Apt method for SERS/RRS/Abs trimode detecting ultratrace lead ions was established, based on the Apt reaction mediated the nanocatalytic indicator reaction. The results show that the SERS intensity and Pb(II) concentration have a good linear relationship in the range of 1.3-16 pM, and the detection limit is the lowest. In addition, Hg(II) and As(III) can also be measured by this naocatalytic amplification- Apt assay platform., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Two COFs of BzBD and BzBD loaded Pd nanoclusters (BzBD Pd ) were prepared using 1,3,5-benzenetricarboxaldehyde (Bz), benzidine (BD) and CO reducing agent, and were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), infrared spectroscopy (IR) and other techniques. BzBD Pd can strongly catalyze the new and stable Au@NiP nanoreaction that exhibit a strong resonance Rayleigh scattering (RRS) peak at 538 nm and a surface plasmon resonance (SPR) absorption peak at 395 nm, and the sensitive and facile RRS technique was used to study the indicator reaction. Combining the nanocatalytic amplification reaction with specific aptamer (Apt) of some target molecules such as melamine (ML), urea (UR) and bisphenol A (BPA), a simple, sensitive and selective Apt RRS assay platform was established. The linear range of the RRS detection platform for melamine is 0.0025-0.04 nmol/L, and the detection limit (DL) is 1.96 × 10 -4 nmol/L. In addition, ML in real sample was analyzed, the stability of BzBD, BzBD Pd , PdNPs and the catalytic mechanism of COF Pd were also considered., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The catalytic amplification signal of polystyrene nanosphere (PN) is used to conveniently fabricate the resonance Rayleigh scattering (RRS)/surface-enhanced Raman scattering (SERS) dual-mode method to sensitively and selectively detect urea in food. PN has strong catalysis of the slow nanoreaction of citrate-Ag(I) to produce yellow silver nanoparticles (AgNP), which exhibit strong RRS effect and SERS effect with molecular probes. When aptamer (Apt) is present, the Apt is adsorbed on the PN surface, the catalysis is weakened, the AgNP is reduced, and the SERS/RRS signal is weakened. After adding urea to exhibit specific Aptamer reaction, the Apt is desorbed from the PN surface and the catalysis is restored. As urea increase, the desorbed PNs increase to produce more AgNPs indicator to increase SERS/RRS signal. The increase value △I of SERS/RRS is linearly to urea concentration. Therefore, a sensitive and selective SERS/RRS dual-mode method for urea is established based on aptamers-regulated the catalysis of PNs. This method is applied to the detection of urea in milk with satisfactory results. The relative standard deviation is 3.9-6.8% and the recovery rate is 94.5-102%., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Metal-organic framework (MOF) MOF-Fe nanosols were prepared, which exhibits strongly catalysis of the new fluorescence indicator reaction of 3, 3', 5, 5'-tetramethylbenzidine (TMB)-H 2 O 2 to produce the oxidation product TMB OX . The TMB OX fluorescent probe has a strong fluorescence peak at 405 nm. After optimizing the various conditions for the determination of H 2 O 2 system and glucose system, the linear range of fluorescence determination of H 2 O 2 was 0.75-7.5 μM, and the detection limit was 0.3 μM. Since H 2 O 2 is the product of glucose oxidase (GOD) catalyzed oxidation of glucose, and a simple and convenient fluorescence method was also established for glucose. The results show that the glucose concentration in the range of 0.2-20 μM has a good correlation with the fluorescence intensity, and the detection limit of glucose was 0.1 μM. This method has been used to detect the content of glucose in drinks with satisfactory results., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Liquid crystals (LCs) have been applied for a long time in the field of analytical chemistry. To date, there are no reports about utilization of LCs as the catalyst to amplification analytical signal. In this article, three small molecules LCs in water aqueous solutions were characterized using molecular spectra and particle size analysis. The characterization indicated that there are nanoparticles in the system. Among the them, 4-heptylbenzoic acid (HPB) exhibits the most sensitive performance in the analytical system based on the reduction of HAuCl 4 to gold nanoparticles (AuNPs) by NaH 2 PO 2 by the spectrophotometric slope evaluation procedure. As the concentration of LCs catalyst increases, the AuNPs surface plasmon resonance (SPR) absorption peak at 550 nm increases linearly, that can be utilized to amply the absorption signal. Based on the LCs catalytic amplification reaction and immunoreaction, a new SPR spectrophotometric analysis method was developed for the label-free detection of oxytetracycline, with a detection limit of 0.50 ng/mL. The method was also successfully applied for the detection of oxytetracycline-spiked environmental water samples to demonstrate its practical usefulness., (Copyright © 2021 Elsevier B.V. All rights reserved.)

As one of the essential trace elements in metabolism, iodine is crucial to maintain the normal physiological functions. Therefore, based on health and environmental protection, it is very important to realize sensitive detection of iodide ion. Herein, we developed a simple, rapid and sensitive method for the determination of iodide ion. Trypsin was used as an ideal template for the synthesis of gold nanoflower sol (AuNFs) with anisotropic surface structure and good stability. It exhibits highly active surface enhanced Raman scattering (SERS) effect and can be used as facile SERS sol substrate. The TMBox generated by the catalytic oxidation reaction of TMB-chloramine T-iodide ion is used as the SERS probe. The enhanced SERS signal intensity is linearly related to the iodide ion with high sensitivity. In addition, TMB has fluorescence effect, and the colored TMBox can produce RRS signal due to polymerization. Based on this, a quad-mode detection method of SERS, RRS, fluorescence and colorimetry for quantitative detection of trace iodide ions was established, and this method can be applied to the detection of iodide ions in natural water and drinking water., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Under microwave conditions, Au-doped carbon dots (CD Au ) were prepared using fullerene as a precursor, and characterized in details. It is found that CD Au can strongly catalyze the reaction of HAuCl 4 -fructose to generate gold nanoparticles (AuNPs). The new nanocatalytic reaction was studied by surface-enhanced Raman scattering (SERS), resonance Rayleigh scattering (RRS) and absorption (Abs) spectrometry. Based on the specific aptamer (Apt As )-As +3 reaction mediated the CD Au -HAuCl 4 -fructose nanoreaction, and the products of AuNPs as SERS/RRS/Abs trifunctional indicator nanoprobes, a new trimode Apt assay strategy was developed for detection of ultratrace As +3 . A 0.07-0.70, 0.10-0.60 and 0.20-0.70 μg L -1 were determined by SERS, RRS and Abs, with detection limits (DL) of 0.04, 0.06, 0.10 μg L -1 respectively. The aptamer-regulation CD Au catalytic amplification platform can be also used to assay 1.7-13.3 nmol L -1 Pb 2+ and 2.0-12 μmol L -1 Hg 2+ , with DL of 0.80 nmol L -1 and 0.90 μmol L -1 respectively., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Preparation of multifunctional codoped carbon dots, and their new analytical applications in surface-enhanced Raman scattering (SERS) quantitative analytical method are still challenge. To overcome these problems, the nitrogen/silver-codoped carbon dots (CD N/Ag ) with highly catalytic amplification are prepared by microwave method, and characterized by spectrophotometry and electron microscopy. The results show that CD N/Ag can strongly catalyze trisodium citrate-HAuCl 4 reaction to generate red nanogold with resonance Rayleigh scattering (RRS) effect and SERS effect using Victoria blue B (VBB) as molecular probes. The CD N/Ag catalytic amplification and specific immunoreaction of clenbuterol (Clen) are coupled with highly sensitive SERS and accurate RRS to fabricate a new dual-spectroscopic strategy with a detection limit of 0.68 pg mL -1 Clen., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Highly stable, SERS active and catalytic nanosilver sol (AgNP) was synthesized under the exposure of light wave, using AgNO 3 as precursor and sodium citrate as reducer. Under the conditions of pH 7.0 NaH 2 PO 4 -Na 2 HPO 4 buffer solution (PBS), the glucose can be catalyzed by glucose oxidase to produce H 2 O 2 specifically. Based on the nanocatalyst and SERS substrate of AgNP, H 2 O 2 can oxidize the 3,3',5,5'-tetramethylbenzidine (TMB) quickly to form a blue oxidation product (TMB ox ) that induced the AgNPs aggregation, which exhibited a strong SERS signal at 1606 cm -1 . As the concentration of glucose increases, the TMB ox molecular probes and AgNPs aggregation increase, and the intensity of SERS peak at 1606 cm -1 increase linearly. Thus, a new SERS strategy for quantitative analysis of 0.33-6.67 μmol/L glucose was developed, with a detection limit of 0.035 μmol/L, coupled the catalysis of nanosilver with glucose oxidase, and label-free molecular probe of TMB ox ., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The highly catalytic Ca-doped carbon dots (CD Ca ) were prepared by microwave procedure, that exhibit strong catalytic effect on HAuCl 4 -glucose (GLC) reaction to form gold nanoparticles (AuNPs) with high SERS activity, using Victoria blue B (VBB) as a molecular probe. The SERS intensity at 1615 cm -1 increased linearly with CD Ca increasing, due to formation of more AuNPs nanosol substrate as indicator. When thrombin aptamer (Apt) was added in this system, Apt adsorbed on the CD Ca surface to inhibit theirs catalytic activity, and the SERS intensity decreased. However, when thrombin (TB) was present, it can bind to Apt to form stable G-duplex of Apt-TB and free CD Ca catalyst in the system, and the SERS signal increased linearly. Thus a free-label Apt-SERS quantitative analysis method was developed for ultratrace TB, with a linear range of 0.0058-0.115 nmol/L and a detection limit of 0.0018 nmol/L TB., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The stable Cu 2 O nanocubic (Cu 2 ONC) sol was prepared, based on graphene oxide (GO) catalysis of glucose-Fehling's reagent reaction, and its absorption and resonance Rayleigh scattering (RRS) spectra, transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) were examined. Using the as-prepared Cu 2 ONC as RRS probe, and coupling with the neomycin sulfate (NEO) complex reaction, a new, simple, sensitive and selective RRS-energy transfer (RRS-ET) method was established for detection of neomycin sulfate, with a linear range of 1.4-112μM and a detection limit of 0.4μM. The method has been applied to the detection of neomycin sulfate in samples with satisfactory results., (Copyright © 2017 Elsevier B.V. All rights reserved.)

In acidic solutions, Bi(III) was reduced by NaBH4 to form BiH3 gas. Using I3(-)graphene oxide (GO) as absorption solution, the BiH3 gas reacted with I3(-) to form I(-) that resulted in the I3(-) concentration decreasing. In the absence of BiH3, the I3(-) concentration was high, and as receptors it was closed to the surfaces of GO which was as donors. Then the surface plasmon resonance Rayleigh scattering (RRS) energy of GO transfers to I3(-) heavily, and results in the RRS quenching severely. With the increase of the Bi(III) concentration, the receptors and the RRS energy transfer (RRS-ET) decreased, so the RRS intensity enhanced linearly at 370nm. The RRS intensity was linear to the Bi(III) concentration in 0.05-5.5μmol/L, with a detection limit of 4ng/mL Bi. A new RRS-ET spectral method was developed for the determination of trace Bi(III). Using I3(-) as the absorption solution, silver nanorod (AgNR) as sol substrate and Vitoria blue B (VBB) as molecular probe, a SERS method was developed for detection of Bi., (Copyright © 2016. Published by Elsevier B.V.)

AuRu nanoalloy (GR) with Au/Ru molar ratio of 32/1 was prepared by the sodium borohydride reduction method. It was used to label the CA125 antibody (Ab) to obtain an immunonanoprobe (GRAb) for cancer antigen 125 (CA125). In pH 7.0 citric acid-Na2HPO4 buffer solution and irradiation of ultrasound, the probes were aggregated nonspecifically to big clusters that showed a strong resonance Rayleigh scattering (RRS) peak at 278 nm. Upon addition of CA125, GRAb reacted specifically with CA125 to form dispersive immunocomplexes of CA125-GRAb in the solution and this process enhanced by the ultrasonic cavitation effect, which led to the RRS intensity decreased greatly. The decreased RRS intensity was linear to the concentration of CA125 in the range of 1.3-80 U/mL, with a detection limit of 0.6 U/mL. The proposed method was applied to detect CA125 in real sample, with satisfactory results., (Copyright © 2014 Elsevier B.V. All rights reserved.)

In pH 7.2 Tris-HCl buffer solution containing 0.09 mol/L NaCl at 80°C, the single-stranded substrate DNA hybrids with the enzyme DNA to form double-stranded DNA (dsDNA). The substrate chain of dsDNA could be cracked catalytically by Pb(2+) to produce a short single-stranded DNA (ssDNA) that adsorbed on the Au(core)Ag(shell) nanoparticle (Au/AgNP) surface to form stable Au/AgNP-ssDNA conjugate to prevent aggregation by NaCl, and it combined with rhodamine 6G (RhG) to form RhG-Au/AgNP-ssDNA probe that exhibited a strong surface-enhanced resonance Raman scattering (SERRS) peak at 1510 cm(-1). With the increase of Pb(2+) concentration, the SERRS peak increased linearly due to the more RhG-Au/AgNP-ssDNA probe forming. Under the selected conditions, the increased SERRS intensity ΔI was linear to Pb(2+) concentration in the range of 5.0×10(-8)-7.0×10(-7) mol/L, with a detection limit of 7×10(-9) mol/L Pb(2+)., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Ozone (O3) could be absorbed by boric acid-potassium iodide (BKI) absorbent solution to produce tri-iodine ion (I3(-)) that react with victoria blue B (VBB) to form the associated particle (VBB-I3)n and exhibited a strong resonance Rayleigh scattering (RRS) peak at 722 nm. Under the chosen conditions, the RRS peak intensity was linear with O3 concentration in the range of 0.2-50 μmol/L, with a linear regression equation of ΔI722=17.9c-45.4 and detection limit of 0.057 μmol/L. Accordingly, a simple, rapid and sensitive RRS spectral method was set up for determination of trace O3 in air, with satisfactory results., (Copyright © 2013 Elsevier B.V. All rights reserved.)

A stable nanosilver solution was prepared, using PEG10000 as stabilizer and NaBH(4) as reducer. In pH 6.6 Na(2)HPO(4)-NaH(2)PO(4) buffer solution containing PEG10000 and NaCl, the nanosilvers (AgNPs) were aggregated to form the stable nanosilver-aggregation (AgNPA) that could conjugate with 4-mercaptopyridine (MPy) to obtain an AgNPA-MPy surface-enhanced Raman scattering (SERS) probe with a strong SERS peak at 1097 cm(-1). When Hg(2+) concentration increased, the SERS intensity at 1097 cm(-1) decreased linearly as the stable complex of [Hg(MPy)(2)](2+) was formed and the AgNPA particles precipitate to the bottom. The decreased SERS intensity was linear to Hg(2+) concentration in the range of 50-3000 nmol/L. Based on this, a new sensitive SERS method has been proposed for the determination of trace Hg(2+) in the water sample, with satisfactory results., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The 5nm nanosilver was prepared by the sodium borohydride procedure, using sodium citrate as a stabilizing reagent. The nanosilver particle was combined with the aptamer for K(+) to form aptamer-nanosilver complex that was stabile in pH 7.0 Na(2)HPO(4)-NaH(2)PO(4) buffer solutions and in the presence of high concentration of NaCl. In 85 degrees C water bath, K(+) interacted with the aptamer to form very stable G-quadruplex that cannot stabilize the nanosilver particle. The uncombined nanosilver particles are aggregated to big particles in high concentration of NaCl, that led to the resonance scattering (RS) intensity at 470nm increased greatly. Under the selected conditions, the increased RS intensity (DeltaI) is linear to K(+) concentration in the range of 0.060-3350micromol/L, with a regression equation of DeltaI=0.177C+0.55, a correlation coefficient of 0.9964, and a detection limit of 0.006micromol/L K(+). The aptamer-nanosilver RS assay has been applied to determination of K(+) in serum and rain water, with satisfactory results.

Single strand DNA (ssDNA) was used to modify nanogold to obtain a nanogold-aptamer resonance scattering (RS) probe (NGssDNA) for Hg(2+), based on the formation of stable thymine-Hg(2+)-thymine (T-Hg(2+)-T) mismatches and aggregation of the released nanogold particles. After removing the aggregated particles by filtrate membrane, the excess NGssDNA in the filtration solution exhibit catalytic effect on the gold particle reaction between HAuCl(4) and ascorbic acid (AA) that appear as RS peak at 596nm. When Hg(2+) concentration increased, the RS intensity at 596nm decreased. The decreased intensity is linear to Hg(2+) concentration in the range of 0.00008-0.888ng/mL Hg(2+), with detection limit of 0.000034ng/mL. The nanogold-aptamer catalytic RS assay was applied to determination of Hg(2+) in water with satisfactory results.

Nanogold exhibits strong catalytic effect on the slow reaction between glucose and Fehling reagent at 70 degrees C. The production of Cu(2)O particles have two stronger resonance scattering (RS) peaks at 390 nm and 505 nm. The catalytic effect of nanogold-labeled goat anti-human IgG (AuIgG) on the reaction was investigated with the RS technique. Coupled the immunoreaction and the immunonanogold catalytic reaction and centrifugal technique, a highly sensitive and selective RS method was developed for the detection of immunoglobulin G (IgG) as a model. With the concentration of IgG increased, the RS intensity at 505 nm decreased. The decreased intensity at 505 nm DeltaI(505)(nm) was proportional to IgG concentration in the range of 0.13-53.3 ng mL(-1), with a detection limit of 0.04 ng mL(-1) IgG. This new immunonanogold-catalytic Cu(2)O-particle RS bioassay was applied to the determination of IgG in serum sample, with high sensitivity, good selectivity, and low cost.

Gold nanoparticles in diameter of 10 nm were used to label rabbit anti-human chorionic gonadotrophin (RhCG) antiserum to obtain a resonance scattering spectral probe (AuRhCG) for human chorionic gonadotrophin (hCG). The immunoreaction between AuRhCG and hCG take place to form hCG-AuRhCG immunocomplex in pH 5.0 citric acid-Na(2)HPO(4) buffer solution. The immunocomplex solutions were centrifuged to obtain the supernatant solution. The AuRhCG in the supernatant solution exhibited strong catalytic effect on the particle reaction between Ag(+) and hydroquinone to produce gold-silver composite particles in pH 3.4 citric acid-trisodium citrate buffer solution. There is a stronger resonance scattering (RS) peak at 423 nm for the particles. With the addition of hCG, the AuRhCG in the supernatant solution decreased, and the RS intensity at 423 nm decreased. The decreased RS intensity DeltaI(423 nm) was proportional to the concentration of hCG in the range of 2.5-208.3 mIU/mL with a detection limit of 0.83 mIU/mL. This method has been applied to the determination of hCG in urine samples, with satisfactory results.

Gold nanoparticles in size of about 10nm was used to label goat anti-human complement 3 (anti-C3) to obtain a sensitive and selective immunoresonance scattering spectral probe for C3. It was based on the immune reaction between labeled anti-C3 and C3 in the pH 5.6 Na(2)HPO(4)-citric acid buffer solutions and in presence of polyethylene glycol (PEG). The resonance scattering (RS) intensity at 560nm enhanced greatly with C3. Well linear relationships between the enhanced RS intensity ( big up tri, openI(RS)) and the C3 concentration in the range of 8.33-200ngml(-1) were obtained, with a detection limit of 2.8ngml(-1) and the limit of quantification 8.51ngml(-1) for C3. The convenient and selective and sensitive assay was applied to quantification of C3 in human sera, with satisfactory results.

A gold-labeled immunoresonance scattering spectral probe for trace prealbumin (PA) was prepared by using gold nanoparticles in size of 9.0nm to label goat anti-human prealbumin polyclonal antibody. The immune reaction between the gold-labeled antibody and prealbumin took place in pH 7.6 Na(2)HPO(4)-NaH(2)PO(4) buffer solution. In the presence of polyethylene glycol PEG-10000, the labeled gold nanoparticles were released and aggregated which brought the resonance scattering intensity (I(RS)) at 580nm to enhance greatly. The DeltaI(RS) is proportional to the prealbumin concentration in the range from 16.67 to 666.67ng/mL, with a detection limit of 4.1ng/mL. This simple, sensitive and selective assay was applied to determination of prealbumin in human plasma, with satisfactory results.

Yellow silver nanoparticles in water phase were prepared by microwave synthesis method. Study found that there is a fluorescence peak at 465 nm and a strongest resonance scattering peak at 460 nm for the nanoparticles. The resonance scattering intensity at 465 nm I(460 nm). fluorescence intensity at 465 nm F(465)(nm) and absorbance at 455 nm A(455 nm) were found linear to the concentration c(Ag) in the range from 0 to 3.5x10(-4)mol/L Ag, with linear regression equation for I(460 nm)=48.1x10(4) c(Ag)+3.69 and F(465 nm)=28.7x10(4)c(Ag)+3.50 and A(455 nm)1.23x10(4)c(Ag)+0.01, their regression coefficient for 0.9976, 0.9954 and 0.9957, respectively. When the c(Ag) was over 3.5x10(-4)mol/L, the resonance scattering peak and fluorescence peak of 465 nm take place red-shift and display luminescence quenching, but the absorption peak place does not change and the absorption intensity enhances. The paper reports the spectral properties of silver nanoparticles in water phase, and offers the principle of interface luminescence electron to state the luminescence effect of silver nanoparticles.

The Ag cluster in solution has been prepared by a microwave high-pressure procedure. There is a maximum resonance Rayleigh scattering (RRS) peak at 425 nm (7.06 x 10(14) Hz) and a smaller RRS peak at 850 nm (1/2 x 7.06 x 10(14) Hz) by synchronous scattering at lambda(ex) = lambda(em). It is a nonlinear optical medium. When scattering the emission wavelength (lambda(em)) as the excited wavelength (lambda(ex)) at 425 nm (7.06 x 10(14) Hz), a maximum RRS peak was observed at 425 nm (7.06 x 10(14) Hz). A 1/2 fraction scattering peak at 850 nm (1/2 x 7.06 x 10(14) Hz) was also investigated. When lambda(ex) is at 850 nm (3.53 x 10(14) Hz), a frequency-doubling scattering peak at 425 nm is observed, and a RRS peak is displayed at 850 nm (3.53 x 10(14) Hz). When the lambda(ex) is two times longer than the maximum RRS wavelength (the strongest wavelength of pump band lambda(pb)) of an atomic cluster, a nonlinear scattering frequency-doubling peak (lambda(pb)) exhibits at half of the lambda(ex), which is stronger than the RRS peak. This phenomenon is defined as pump effect.

A new catalytic kinetic method has been proposed for the determination of Se from 8.0x10(-9) to 8.0x10(-8) M, using the fact that Se(IV) can catalyze the slow reaction between KClO(3) and phenylhydrazine sulfate (PH) in 0.1 M H(2)SO(4) solution at 100 degrees C. The reduction product of ClO(3)(-), Cl(-), reacts with Ag(+) to form (AgCl)(n) nanoparticles. The nanoparticles exhibit a maximum resonance scattering spectral peak at 470 nm. The intensity of resonance scattering light at 470 nm is linear with respect to the Se concentration, using the fixed-reaction time procedure. The factors influencing the determination of Se were examined. This catalytic resonance scattering spectral method has been applied to the analysis of Se in real samples, with satisfactory results.

A novel resonance scattering spectral method has been proposed for the determination of trace amounts of chlorides in the range of 2 x 10(-7)-8 x 10(-6) mol/l. It was based on the photochemical reaction system of AgNO3-NaCl-sodium oxalic to form the (AgCl)nucleus (n)(Ag)shell (s) nanoparticle. There is a strongest resonance scattering peak at 470 nm and a maximum absorption peak at 425 nm. The concentration of chlorides is proportional to the intensity of resonance scattering at 470 nm. The nonlinear resonance scattering peaks of the nanoparticle system have been also considered, according to the theory of the interaction between the surface electron of nanoparticle and the incidence photon.