Search

A nanosurface molecular imprinted polymer nanoprobe (AuNC@MIP) for dichromate (Cr 2 O 7 2-) was synthesized by microwave irradiation, using gold nanoclusters (AuNC) as a nanosubstrate, Cr 2 O 7 2- as template molecule, 4-vinylpyridine (4-VP) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linking, and 2,2′-azobisisobutyronitrile (AIBN) as initiator. It was characterized by molecular spectral technique, electron microscope and X-ray photoelectron spectroscopy. The nanoprobe was found to exhibit a strong resonance Rayleigh scattering (RRS) effect at 370 nm. In the presence of diphenylcarbazide (DPC), the RRS-energy transfer (RRS-ET) was enhanced with the increase of Cr 2 O 7 2- concentration, and the RRS signal intensity at 370 nm was decreased linearly, with a linear range of 2.5–75 nmol/L Cr 2 O 7 2- and the limit of detection (LOD) of 2.47 nmol/L. Accordingly, a new RRS-ET method for the simple, sensitive and selective detection of trace Cr 2 O 7 2- was developed. As a comparison, the nanosurface MIP probes were prepared with different particle-size nanoparticle gold (AuNP) substrate and different functional monomers. [Display omitted] • Gold nanocluster surface molecularly imprinted polymers was synthesized using the microwave irradiation. • AuNC@MIP binding to Cr 2 O 7 2- produces resonance Rayleigh scattering-energy transfer effect (RRS-ET) strongly. • A new RRS nanoprobe for trace Cr 2 O 7 2- was established. • The RRS method is simple, highly sensitive and selective. [ABSTRACT FROM AUTHOR]

In pH 3.1 HCOOH-HCOONa buffer solution, liquid crystal 5CB was used as the probe to generate a strong resonance Rayleigh scattering (RRS) peak at 450 nm. Gold nanoparticles (AuNPs) could catalyse the reaction of phosphomolybdic acid (PMo)-formic acid (FA) to form phosphomolybdenum blue (PMoB), which caused the RRS strength of PMo at 450 nm to decrease linearly. Hg2+ could have an electrostatic substitution reaction with AuNPs, thereby inhibiting the catalytic effect of AuNPs, and the RRS peak was enhanced. In the range of 2.5 × 10−9 mol/L–4.5 × 10−8 mol/L Hg2+, as the concentration of Hg2+ increased, the catalytic effect of AuNPs gradually weakened, and the peak value of RRS at 450 nm (ΔI) was linearly increased. The regression equation is ΔI450nm = 27.988C−5.6159, and the detection limit is 1.0 nmol/L. The method has been used to detect Hg2+ in wastewater with satisfactory results. [ABSTRACT FROM AUTHOR]

At temperature of 75 °C, the ethanol-HAuCl4 reaction to generate gold nanoparticles is relatively slow (AuNPs), and the noble metal nanoparticles can catalyze this nanoreaction. Sulfite can reduce PdCl2-H2PtCl6 to generate PtPd nanoalloy (PtPd) and strong catalysis to generate red AuNPs, which has a strong RRS peak at 370 nm. When Victoria blue 4R (VB4R) is added, it produced a strong SERS peak at 1617 cm−1. We use SERS, RRS, absorption spectroscopy, electron microscopy, and other techniques to study the catalytic reaction of PtPd nanoalloy and propose a new mechanism for the nanoalloy catalytic reactions. When the SO32−concentration in the system gradually increases, the AuNPs produced by the catalytic reaction gradually increase and the RRS/SERS peak intensity increases linearly. Based on the nanoalloy catalytic amplification strategy, a new and sensitive RRS/SERS coupled dual-mode detection method for SO32− was constructed, with linear range of 0.13–12.1 μg·L−1 and a DL of 0.02 μg·L−1. [ABSTRACT FROM AUTHOR]

exhibited catalytic effect on the cracking reaction of double-stranded DNA (dsDNA) to form a short single-stranded DNA (ssDNA) that protected the nanogold (NG) to produce stable NGssDNA conjugate. The un-protected NG was aggregated to form NG aggregates (NGA) that appeared a resonance scattering (RS) peak at 542 nm. Unlike NGA, the NGssDNA exhibited a strong catalytic activity on the Cu2O particle reaction of Fehling reagent-glucose that can be monitored by RS technique at 608 nm. When theconcentration increased, the NGssDNA increased, and the RS intensity at 608 nm increased. The increased RS intensity ΔI608 nmwas linear to theconcentration in the range of 15–200 pmol L−1, with a regression equation of ΔI608 nm = 1.24 C + 4.6, and a detection limit of 5 pmol L−1. This new RS assay was applied to assayin water sample, with satisfactory results. [ABSTRACT FROM AUTHOR]

In pH 7.2 Tris-HCl buffer solution, the substrate strand DNA (SDNA) was hybridized to the enzyme strand DNA (EDNA) forming a double strand DNA (dsDNA). The SDNA in dsDNA could be cleaved by lead(II) to release a cleavaged single-stranded (ssDNA) that prevented the gold nanoparticles (AuNPs) from forming a stable AuNPs-ssDNA conjugate. The unconjugated AuNPs were aggregated to form AuNP aggregation (AuNPsA) that appeared as a resonance Rayleigh scattering (RS) peak at 532 nm. When the lead(II) concentration increased, the AuNPs-ssDNA increased, the AuNPsA decreased, the color changed from blue to red, and the RS intensity at 532 nm decreased. The decreased RS intensity ΔI 532 nm was linear to the lead(II) concentration in the range of 0.67–60 nmol/L, with a detection limit of 0.3 nmol/L. The AuNPs-ssDNA exhibited a strong catalytic effect on the reaction between chloroauric acid and vitamin C (VC) that can be detected by an RS method at 620 nm. When the lead(II) concentration increased, the intensity at 620 nm increased, and the increased intensity ΔI 620 nm was linear to the lead(II) concentration in the range of 1.33–120 pmol/L, with a detection limit of 0.5 pmol/L. The proposed method was applied to detect lead(II) in water samples, with satisfactory results. [ABSTRACT FROM AUTHOR]

Using citric acid (CA) and ethylenediamine (EDA) as precursors, stable nitrogen-doped carbon dots (CD) nanosols were prepared by microwave procedure and characterized in detail. It was found that CDNs catalyze ethanol (Et)-HAuCl4 to generate gold nanoparticles (AuNPs), which have strong surface plasmon resonance, Rayleigh scattering, (RRS) and a surface plasmon resonance (SPR) absorption (Abs) effect at 370 nm and 575 nm, respectively. Compled the new catalytic amplification indicator reaction with the specific As3+ aptamer reaction, a new RRS/Abs dual-mode aptamer sensor for the assay of trace As3+ was developed, based on the RRS/Abs signals increasing linearly with As3+ increasing in the ranges of 5–250 nmol/L and 50−250 nmol/L, whose detection limits were 0.8 nmol/L and 3.4 nmol/L As3+, respectively. This analytical method has the advantages of high selectivity, simplicity, and rapidity, and it has been successfully applied to the detection of practical samples. [ABSTRACT FROM AUTHOR]

Carbon monoxide (CO) is a commonly poisonous gas. It is important to detect CO in daily life. Herein, a new and sensitive surface enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) coupled di-mode method was developed for CO, based on gold nano-enzyme catalysis and gold nanoprobes. CO can react with HAuCl4 to generate gold nanoparticles (AuNPs) in pH 5.2 HAc-NaAc buffer. The generated AuNPs exhibited SERS activity at 1620 cm−1 in the presence of Vitoria blue B (VBB) molecular probes, and an RRS peak at 290 nm. Based on the AuNP bifunctional probes, the increased SERS and RRS intensities respond linearly with the concentration of CO in the range of 100–1500 ng/mL and 30–5230 ng/mL, respectively. To improve the sensitivity, the produced AuNPs were used as nano-enzyme catalysts for the new indicator reaction of HAuCl4-ethanol (En) to amplify the signal. The sensitive SERS method was coupled with the accurate RRS method to develop a sensitive and accurate SERS/RRS di-mode method for determination of 3.0–413 ng/mL CO, based on the AuNP-HAuCl4-En nanocatalytic reaction and its product of AuNPs as SERS and RRS bifunctional probes. [ABSTRACT FROM AUTHOR]

Carbon dots (CD) have excellent stability and fluorescence activity, and have been widely used in fluorescence methods. However, there are no reports about using CD as catalysts to amplify SERS signals to detect trace sulfate. Thus, preparing CD catalysts and their application in SERS sulfate-sensing are significant. In this article, highly catalytic N-doped carbon dots (CDN) were prepared by a hydrothermal procedure. CDN exhibited strong catalysis of the gold nanoparticle (AuNP) reaction between HAuCl4 and H2O2. Vitoria blue 4R (VB4R) has a strong SERS peak at 1614 cm−1 in the formed AuNP sol substrate. When Ba2+ ions were added, they were adsorbed on a CDN surface to inhibit the CDN catalytic activity that caused the SERS peak decreasing. Upon addition of analyte SO42−, a reaction with Ba2+ produced stable BaSO4 precipitate and CDN, and its catalysis recovered to cause SERS intensity increasing linearly. Thus, an SERS method was developed for the detection of 0.02–1.7 μmol/L SO42−, with a detection limit of 0.007 μmol/L. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new Au@MIP difunctional probe was prepared. • The indicator nanoreaction of HAuCl 4 -vanillin was studied. • The probe was not only recognized CAR but also catalyzed the AuNP nanoreaction. • A new SERS/RRS/Abs trimode analytical platform was developed. • The analytical platform was sensitive and selective. Although gold nanoparticle (AuNP) surface molecularly imprinted polymers (Au@MIP) were not fresh, this is of interest to spectral analysts due to their possession of high affinity for the target molecules, strong nanocatalysis to amplify the signals, and good stability to obtain accuracy. New avenues of molecular spectroscopy with straightforward, sensitivity and selectivity can be established using Au@MIP nanosol. In this article, a new carbendazim (CAR) Au@MIP nanocatalytic probe was prepared and the new Au@MIP-CAR-HAuCl 4 -vanillin (VAN) nano indicator reaction was constructed with in situ-generated AuNP as indicator, which with surface-enhanced Raman scattering (SERS), resonance Rayleigh scattering (RRS) and absorption (Abs) effects. Due to space constraints, these imprinted points show high selectivity in the recognition of CAR whose size and shape correspond to the template. The Au@MIP was sensitively detected CAR using SERS/RRS/Abs techniques, with determination range of 0.1–10, 1.5–17.5 and 9.0–30.0 nmol/L, the detection limits of 0.08, 1.0 and 5.0 nmol/L CAR respectively. In addition, the nanocatalytic mechanism was studied. [ABSTRACT FROM AUTHOR]

• Highly catalytic PdMOF and di-functional PdMOF@MIP probe were prepared. • The nanoprobe exhibits recognition of OTC and catalysis of HAuCl 4 -NaH 2 PO 2 to generate AuNPs. • The in situ generated AuNPs as indicator can be monitoring by SERS. • A trimode molecular spectral method for ultratrace oxytetracycline was established. • The SERS method is of simplicity, high sensitivity and selectivity. In this paper, a new Pd metal organic framework (PdMOF) surface molecularly imprinted polyaniline nanocatalytic probe (PdMOF@MIP) with dual functions of recognition and catalysis was synthesized. It is found that the PdMOF@MIP nanoprobe can not only identify OTC but also catalyze the new nanoreaction of NaH 2 PO 2 -HAuCl 4 to generate gold nanoparticles (AuNPs), and the generated AuNPs could be traced by surface-enhanced Raman scattering (SERS). When OTC specifically binds to PdMOF@MIP to generate PdMOF@MIP-OTC conjugate, its catalytic effect is weakened and the analytical signal is reduced linaerly. Accordingly, a new, highly sensitive, selective and simple SERS/RRS/Abs trimode detection platform for OTC was constructed. The linear range of SERS was 0.0625 ng/mL ∼ 1.75 ng/mL and the limit of detection was 0.015 ng/mL. This new nanocatalytic probe detection strategy can also be used for the selective detection of other antibiotics such as tetracycline and doxycycline, respectively. In addition, the nanocatalytic mechanism has been investigated. [ABSTRACT FROM AUTHOR]

A new gold nanosol SERS method for ultratrace atrazine by a difunctional surface molecular imprinted polymethacrylate probe. [Display omitted] • A new AuNP@MIP nanoprobe was prepared. • The nanoprobe not only has recognition function but also has catalytic function. • The new nano indicator reaction of glyoxal-HAuCl 4 is in situ generated AuNP. • A new SESR sensor platform was created for ultratrace ATZ. A new type of bifunctional nanosurface molecularly imprinted polymer nanoprobe (Au@MIP) was prepared using methacrylic acid as functional monomers respectively, gold nanoparticles (AuNP) as nanosubstrate. The Au@MIP nanoprobe not only has recognition function but also has catalytic function. The findings demonstrate that the AuNP@MIP nanoprobes, prepared with methacrylic acid as the functional monomer, very strongly catalyzed the new nano indicator reaction of glyoxal (GO)-HAuCl 4. In situ generated AuNP sol exhibits strong surface-enhanced Raman scattering (SESR) effects. After adding atrazine (ATZ), the signals were significantly boosted. As a result, a new SESR trimode sensor platform was created for ultratrace ATZ. The linear ranges for ATZ was 0.005–0.0625 nmol/L, with detection limits of 0.0012 nmol/L. Moreover, the SERS method was used to determine the content of ATZ in corn samples, achieving relative standard deviations (RSDs) of 6.53–9.57 % and recoveries of 96.4 %–108.2 %. [ABSTRACT FROM AUTHOR]

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%. [Display omitted] • A new SMIP was synthesized with nanosubstrate of MOF@AuNP. • The SMIP has recognition and catalytic amplification difunction. • A new HAuCl 4 -cysteine-SMIP nanocatalytic indicator reaction was discovered. • A new SERS/RRS/Abs trimode analytical platform was developed to determine malathion. [ABSTRACT FROM AUTHOR]

Highlights • CD Ca exhibited strong catalysis of nanogold reaction between HAuCl 4 and H 2 O 2. • PA binds with CD Ca to inhibit its nanocatalysis. • The intensity of the SERS peak at 1615 cm−1 is increased linearly with Na+ concentration increasing. • The SERS quantitative analysis method for Na+ has high sensitivity. Abstract The Ca-doped carbon dots (CD Ca) exhibited strong catalysis of HAuCl 4 -H 2 O 2 reaction to produce gold nanoparticle (AuNP), using Vitoria blue 4R (VB4r) as molecular probe, it appeared a strong surface enhanced Raman scattering (SERS) peak at 1615 cm−1 in the AuNP nanosol substrate. When catalyst CD Ca increased, the SERS peak enhanced linearly owing to AuNPs increasing, that is, the AuNP concentration is linear to SERS signal. Potassium pyroantimonate (PA) ligand can adsorb on CD Ca surface to inhibit the catalysis and cause the SERS peak decreasing. The analyte of Na+ reacts with PA to produce the stable precipitate of [Na 2 (PA)] and free CD Ca catalyst. The more Na+, the more CD Ca released, and the stronger SERS signal due to more AuNP substrate. Accordingly, a SERS quantitative analysis method for Na+ was developed based on CD Ca catalytic SERS reaction, with a linear range of 0.004–0.043 μmol/L, and a detection limit of 0.0019 μmol/L Na. [ABSTRACT FROM AUTHOR]

In 50 °C conditions, the gold nanoreaction of HAuCl 4 -H 2 O 2 is very slow, graphene oxide (GO) exhibited strong catalysis on the nanoreaction to form gold nanoparticles (AuNPs) with strong surface-enhanced Raman scattering (SERS) activity at 1614 cm −1 in the presence of molecular probes of Victoria Blue (VB4r). The SERS intensity increased with the GO increasing due to formation of more AuNPs. The ferritin antibody (Ab) can bind to GO surface to form Ab-GO that can inhibit the nanocatalysis. When ferritin (Ag) existed, the produced immunocomplexes of Ab-Ag are separated from the GO surface, which led to the recovery of GO catalysis. The enhanced SERS signal △I 1614cm-1 is linear to ferritin concentration in the range of 0.017–1.02 ng/mL. Accordingly, a new SERS quantitative analysis method was established for detection of ferritin, based on the regulating GO nanocatalysis. [ABSTRACT FROM AUTHOR]

The as-prepared gold nanoparticle (AuNP) exhibited strong catalysis of the nanoreaction between H 2 O 2 and HAuCl 4 to form gold nanoparticles (GNP) with nanoplasmonic surface-enhanced Raman scattering (SERS) at 1614 cm −1 , in the presence of Victoria blue B (VBB) molecular probes. Upon addition of the Pb 2+ aptamer, it adsorb on AuNP surface to inhibit the its nanocatalysis, and the SERS, surface plasmon resonance (SPR) absorption and resonance Rayleigh scattering (RRS) decreased due to the redox product of GNP nanoplasmonic effect decreasing. When Pb 2+ was added, the aptamer combined with it to form a very stable G-quadruplex and free AuNPs, which lead to the catalysis recovering, and the absorption, RRS and SERS intensity enhanced linearly. Hereby, a new and simple, sensitive and selective gold nanoplasmonic SERS platform was established for Pb 2+ , based on the aptamer-regulating GNP nanoplasmonic SPR effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new solvothermal procedure was used to prepare COFloaded gold nanocluster (AuCOF). • The AuCOF catalysis and stability were improved by loaded gold nanoclusters onto the COF. • The AuCOF catalyzed strongly the new nanogold indicator reaction of Au(III)-SO 3 2− with SERS and RRS effects. • A new Apt SERS quantitative method for the rapid determination of estradiol. A new covalent organic framework loaded gold nanocluster (AuCOF) was prepared by solvothermal procedure, using 1,3,5-benzenetricarboxaldehydeand p-phenylenediamine and chloroauric acid as precursor. It was found that the AuCOF exhibits strong catalysis of sulfite reduction of HAuCl 4 to form gold nanoparticles (AuNP) with surface enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) effects. The aptamer (Apt) of estradiol (E2) can be electrostatically adsorbed on the AuCOF surface to suppress its catalytic performance. While the Apt E2 can selectively bind to target molecule E 2 and desorb from the AuCOF surface to recover its catalysis. The SERS and RRS signals increased linearly with E 2 concentration increasing due to produce more AuNP indicator. The highly sensitive SERS method shows good linearity with E2 concentration in the range of 0.333–5.33nmol/L, and the detection limit was 0.150 nmol/L E2. This SERS method has been used for the determination of E2 in actual samples. In addition, the nanocatalytic mechanism and SERS quantitative analysis formula were studied. [ABSTRACT FROM AUTHOR]

With development of economy and society, there is an urgent need to develop convenient and sensitive methods for detection of Cu 2+ pollution in water. In this article, a simple and sensitive SERS sensor was proposed to quantitative analysis of trace Cu 2+ in water. The SERS sensor platform was prepared a common gold nanoparticle (AuNP)-SiO 2 sol substrate platform by adsorbing HSA, coupling with the catalytic reaction of Cu 2+ -ascorbic acid (H 2 A)-dissolved oxygen, and using label-free Victoria blue B (VBB) as SERS molecular probes. The SERS sensor platform response to the AuNP aggregations by hydroxyl radicals (•OH) oxidizing from the Cu 2+ catalytic reaction, which caused the SERS signal enhancement. Therefore, by monitoring the increase of SERS signal, Cu 2+ in water can be determined accurately. The results show that the SERS sensor platforms owns a linear response with a range from 0.025 to 25 μmol/L Cu 2+ , and with a detection limit of 0.008 μmol/L. In addition, the SERS method demonstrated good specificity for Cu 2+ , which can determined accurately trace Cu 2+ in water samples, and good recovery and accuracy are obtained for the water samples. With its high selectivity and good accuracy, the sensitive SERS quantitative analysis method is expected to be a promising candidate for determining copper ions in environmental monitoring and food safety. [ABSTRACT FROM AUTHOR]

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. MXene doped AuNCs catalyze nanogold reaction combined with aptamer constructed a SERS/RRS/Abs catalytic amplification platform for assay of ICP. [Display omitted] • MXeneTi 3 C 2 nanosheets was first time prepared with the microwave irradiation. • MXene@Au strongly catalyzed the new AuNP reaction of mandelic acid-HAuCl 4. • New fast, sensitive and accurate SERS/RRS amplification platform was constructed. • Organophosphorus pesticide isocarbophos be detected via SERS/RRS amplification platform. • The nanocatalysis mechanism of MXene@Au was investigated. [ABSTRACT FROM AUTHOR]

A new MXene supported Pd nanoparticles (Ti 3 C 2 @Pd) nanosol with good stability and strong catalysis was prepared by the two-step procedure. Experiment was found that Ti 3 C 2 @Pd could strongly catalyze the reduction of HAuCl 4 by H 2 O 2 to produce gold nanoparticles (AuNPs), with strong surface enhanced Raman scattering (SERS), resonance Rayleigh scattering (RRS) and surface plasmon resonance absorption (Abs). Coupled this new SERS/RRS/Abs trimode nanocatalytic indicator reaction with specific TNT polypeptide (PT TNT), a facile and selective trimode polypeptide biosensoring platform was established for the detection of ultratrace TNT, with a linear range of 1.1–66, 1.1–66 and 4.4–66 pmol/L TNT, and detection limit (DL) of 0.69, 0.97 and 3.36 pmol/L by SERS, RRS and Abs assay respectively. It has been used to detect TNT in wastewater and soil samples, with recovery of 98.7–106% and RSD of 6.22–8.77%. In addition, this biosensoring platform can be also used to assay glyphosate and estradiol, respectively. • MXeneTi 3 C 2 were rapidly prepared by microwave digestion procedure. • Ti 3 C 2 @Pd can strongly catalyze the reduction of HAuCl 4 by H 2 O 2 to produce AuNPs. • A SERS/RRS/Abs trimode biosensoring platform was established coupling AuNPs reaction with polypeptide. • The platform can be used to detect a variety of organic pollutants, such as TNT, GLY and E2. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Three liquid crystal molecules shown in this article can be arranged and assembled into rod-like nanoparticles in 65°C aqueous solution. • Liquid crystal molecules catalytic amplification Abs aptasensor for detecting OTC was established. • This method is fast, simple and low cost. [ABSTRACT FROM AUTHOR]

• A COF of MaBd was prepared by melamine (Ma) and p -benzaldehyde (Bd). • MaBd can strongly catalyze the GC-HAuCl 4 nanoreaction. • A SERS quantitative method was constructed coupled aptamer with nanoreaction. • The method has high sensitivity and selectivity, and low blank. A highly catalytic and stable covalent organic frameworks (COFs) of MaBd were prepared by the polycondensation of melamine (Ma) and p -benzaldehyde (Bd), and characterized by molecular spectra and electron microscopy. MaBd strongly catalyze the new indicator reaction between glycol (GC) and chloroauric acid to generate gold nanoparticles (AuNP) with strong RRS effect at 370 nm and surface enhanced Raman scattering (SERS) effect at 1617 cm−1 using Vitoria blue B (VBB) as molecular probes. Combining the MaBd nanocatalytic amplification reaction with highly selective aptamer (Apt) of glyphosate (GLY), a new, simple and highly sensitive SERS method was developed with a linear range of 0.003−0.07 nmol/L, and the detection limit of 0.002 nmol/L GLY. GLY in soil samples were analyzed by this SERS method, with relative standard deviation of 4.78–5.71 % and recovery of 92.3–105.3 %. [ABSTRACT FROM AUTHOR]

A fullerene carbon dot catalytic amplification-aptamer assay platform was fabricated for ultratrace As+3 utilizing SERS/RRS/Abs trifunctional Au nanoprobes. • C 60 was used as the precursor to prepare gold-doped carbon dots (CD Au). • CD Au strongly catalyzes the new AuNP reaction of fructose-HAuCl 4. • The AuNPs exhibits strong SERS/RRS/Abs effects. • The Apt-catalytic amplification platform was fast, convenient, sensitive and accurate. • The Apt-catalytic amplification platform can be used to detect As3+, Pb2+ and Hg2+. 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 Pb2+ and 2.0–12 μmol L−1 Hg2+, with DL of 0.80 nmol L−1 and 0.90 μmol L−1 respectively. [ABSTRACT FROM AUTHOR]