Li-Hong Zhang

A colorimetric probe for online analysis of sulfide based on the red shifts of longitudinal surface plasmon resonance absorption resulting from the stripping of gold nanorods

A gold nanorods (GNRs) nonaggregation-based colorimetric probe has been developed for the detection of S(2-) based on that the longitudinal surface plasmon resonance absorption wavelength (LPAW) of GNRs red shifts (Δλ) and the color of the solution distinctly changes on account of the faster stripping of GNRs along longitudinal axis than transverse axis in the process of GNRs reacting with S(2-) ions to form Au(2)S complexes on the GNRs surfaces. The GNRs probe exhibits highly sensitive and selective response toward S(2-) with a wide linear range from 10.0 to 10000.0 μM. The proposed colorimetric probe can be used to visibly detect S(2-) in water samples on line in 15 min with the results agreeing well with those of the optical sensor, showing its great practicality. Moreover, the detection mechanism of the probe is also discussed.

BSA-protected gold nanoclusters as fluorescent sensor for selective and sensitive detection of pyrophosphate

Gold nanoclusters (AuNCs) protected by bovine serum albumin (BSA) can emit red photoluminescence under illumination by ultraviolet light. The luminescence of the BSA–AuNCs was quenched when Cu2+ chelated with glycine in the BSA chain and generated BSA–AuNCs–Cu2+, while the luminescence of the BSA–AuNCs restored when pyrophosphate ion (P2O74−, PPi) was added and chelated with Cu2+, resulting in Cu2+ being removed from the surface of BSA–AuNCs. Bearing this in mind, herein we present a novel BSA–AuNCs–Cu2+ fluorescent sensor for PPi detection. This environmentally-friendly, simple, rapid and selective fluorescent sensor possesses a wide linear range (0.16–78.1 μM) and a high sensitivity (the limit of detection (LD) is 0.083 μM), which could also determine PPi in the effluent of copper plating with the results consistent with those obtained by absorptiometry. Furthermore, the morphologies of BSA–AuNCs, BSA–AuNCs–Cu2+ and BSA–AuNCs–Cu2+-PPi were characterized by high resolution transmission electron microscopy (HRTEM). The mechanism of the proposed assay for PPi detection has been discussed.

Ultra-sensitive non-aggregation colorimetric sensor for detection of iron based on the signal amplification effect of Fe3+ catalyzing H2O2 oxidize gold nanorods

Fe(3+) can catalyze H2O2 to oxidize along on the longitudinal axis of gold nanorods (AuNRs), which caused the aspect ratio of AuNRs to decrease, longitudinal plasmon absorption band (LPAB) of AuNRs to blueshift (Δλ) and the color of the solution to change obviously. Thus, a rapid response and highly sensitive non-aggregation colorimetric sensor for the determination of Fe(3+) has been developed based on the signal amplification effect of catalyzing H2O2 to oxidize AuNRs. This simple and selective sensor with a wide linear range of 0.20-30.00 μM has been utilized to detect Fe(3+) in blood samples, and the results consisted with those obtained by inductively coupled plasma-mass spectroscopy (ICP-MS). Simultaneously, the mechanism of colorimetric sensor for the detection of Fe(3+) was also discussed.

Research on the spectral properties of luminescent carbon dots.

This paper is trying to research the developing status of carbon dots (CDs), and the results show that the simple, rapid and high yield synthetic methods for CDs and the application of CDs in biological science and analysis field will certainly become an inevitable development trend in the future. The CDs obtained by microwave possess excellent optical properties including UV-Vis absorption, fluorescence and room temperature phosphorescence. Under the conditions of 30 °C and 10 min, the fluorescence signal (F) of CDs not only could be enhanced by hexadecyltrimethylammonium bromide (CTAB), Triton X-100, Na(2)S, Na(2)C(2)O(4) and NH(3).H(2)O, but also could be quenched by sodium dodecyl sulfate, KBrO(3), K(2)S(2)O(8), NaIO(4), ascorbic acid, NaBH(4), HNO(3), HCl, H(2)SO(4), CH(3)COOH and most metal ions, with the λ(em)(max) blue or red shifting in varying degrees, indicating the potential values of CDs in analytical application. Besides, the sensitive response of F to pH showed the promise of developing a new pH sensor with CDs.

Non-aggregation based label free colorimetric sensor for the detection of Cu2+ based on catalyzing etching of gold nanorods by dissolve oxygen

A label-free non-aggregation colorimetric sensor has been designed for the detection of Cu(2+), based on Cu(2+) catalyzing etching of gold nanorods (AuNRs) along longitudinal axis induced by dissolve oxygen in the presence of S2O3(2-), which caused the aspect ratio (length/width) of AuNRs to decrease and the color of the solution to distinctly change. The linear range and the detection limit (LD, calculated by 10 Sb/k, n=11) of this sensor were 0.080-4.8 µM Cu(2+) and 0.22 µM Cu(2+), respectively. This sensor has been utilized to detect Cu(2+) in tap water and human serum samples with the results agreeing well with those of inductively coupled plasma-mass spectroscopy (ICP-MS), showing its remarkable practicality. In order to prove the possibility of catalyzing AuNRs non-aggregation colorimetric sensor for the detection of Cu(2+), the morphological structures of AuNRs were characterized by high resolution transmission electron microscopy (HRTEM) and the sensing mechanism of colorimetric sensor for the detection of Cu(2+) was also discussed.

A highly sensitive coupling technique for the determination of trace quercetin based on solid substrate room temperature phosphorimetry and poly (vinyl alcohol) complex imprinting

Al(3+) could react with quercetin (Q) to form [AlQ](3+) complex which could be used as a template for the preparation of poly (vinyl alcohol)-[AlQ](3+) complex imprinting (PVA-C-I). The [AlQ](3+) not only had good matching ability and selectivity with the cavity of PVA-C-I, but also could react with the fluorescein isothiocyanate anion (FITC(-)) on the outside of cavity by electrostatic interaction to form ion-association complex [AlQ](3+)·[(FITC)(-)](3). The ion-association complex could emit strong and stable room temperature phosphorescence (RTP) on polyamide membrane (PAM) and the ΔI(p) of the system had linear relationship with the content of Q, showing the highly selective identification of PVA-C-I to Q. Thus, a new coupling technique for the determination of trace Q based on solid substrate room temperature phosphorimetry and poly (vinyl alcohol) complex imprinting (PVA-C-I-SSRTP) was established. The linear range and limit of detection (LOD) of this method were 0.010-2.0 (×10(-12) g mL(-1)) and 2.0×10(-14) g mL(-1), respectively, showing wide linear range and high sensitivity of PVA-C-I-SSRTP. This method was used to determine the content of Q in waste water, and the results are consistent with those by spectrofluorimetry. Meanwhile, the mechanism for the determination of Q using PVA-C-I-SSRTP was also discussed.

Determination of trace gastrin and diagnosis of human diseases using CdTe quantum dots labelled gastrin antibodies as phosphorescence sensors.

CdTe quantum dots (CdTe-QDs) can emit strong and stable room temperature phosphorescence (RTP) via the perturbation effect of a Pb(2+) ion on the surface of a nitrocellulose membrane (NCM). CdTe-QDs-Ab(GAS), the product of CdTe-QDs labelled gastrin antibodies (Ab(GAS)), can not only maintain good RTP characteristics, but can also be used as a RTP sensor and carry out highly specific immunoreactions with gastrin (GAS) to form GAS-Ab(GAS)-CdTe-QDs causing the ΔI(p) of the system to sharply enhance. Thus, a new solid substrate room temperature phosphorescence immunoassay (SSRTPIA) for the determination of GAS was established based on the linear relativity between the ΔI(p) of the system and the content of GAS. The limit of quantification (LOQ) of this method was 0.43 fg spot(-1) with the corresponding concentration being 1.1 × 10(-12) g mL(-1) and sampling quantity being 0.40 per spot(-1). This highly specific, accurate, selective and sensitive RTP sensor has been applied to the determination of GAS in biological samples and the diagnosis of diseases, and the results agreed well with those obtained by radioimmunometric assay (RIA). Meanwhile, the mechanism of SSRTPIA for the determination of GAS using CdTe-QDs-Ab(GAS) as the RTP sensor was discussed.

Fullerol-fluorescein isothiocyanate phosphorescent labeling reagent for the determination of glucose and alkaline phosphatase

The active -OH group in fullerol (F-ol) could react with the dissociated -COOH group in fluorescein isothiocyanate (FITC) to form F-ol-(FITC)(n), which could emit room temperature phosphorescence (RTP) signal of F-ol and FITC on acetate cellulose membrane (ACM), respectively. Their RTP signals were enhanced by N,N-dimethylaniline (DMA). The labeling reaction between the -NCS group of FITC in DMA-F-ol-(FITC)(n) and the -NH2 group in wheat germ agglutinin (WGA) produced DMA-F-ol-(FITC)(n)-WGA, which could further take affinity adsorption (AA) reaction with bioactive substances (BS), such as glucose and alkaline phosphatase (AP), to produce DMA-F-ol-(FITC)(n)-WGA-BS. Both of these two products could maintain the good RTP characteristics of F-ol and FITC. Based on the facts above, a new phosphorescent labeling reagent, DMA-F-ol-FITC, was developed, and a new affinity adsorption solid substrate room temperature phosphorimetry (AASSRTP) for the determination of BS was established. This method was applied to the determination of BS in human serum and the diagnosis of diseases, with the results agreeing very well with those of enzyme-linked immunosorbent assay (ELISA). The mechanism of DMA-F-ol-(FITC)(n) labeling of WGA and AASSRTP for the determination of BS is discussed.

Design of highly sensitive phosphorescence sensor for determination of procaterol hydrochloride based on inhibition of KClO3 oxidation fluorescein isothiocyanate.

Procaterol hydrochloride (Prh) can inhibit KClO3 oxidation of fluorescein isothiocyanate (FITC) to form a non-phosphorescent compound, which causes room temperature phosphorescence (RTP) of FITC in the system to enhance sharply the linear relationship between ∆Ip and the Prh content. Thus, a rapid response and highly sensitive phosphorescence sensor for the determination of Prh has been developed based on the inhibiting effect of Prh on KClO3 oxidation of FITC. This simple, high sensitivity (detection limit (LD) calculated by 3Sb /k was 0.019 fg/spot, sample volume 0.40 µl, corresponding concentration 4.8 × 10(-14) g ml(-1) ) and selective sensor with a wide linear range (0.080-11.20 g/spot) has been applied to detect Prh in blood samples, and the results were consistent with those obtained by high-performance liquid chromatography (HPLC). Simultaneously, the mechanism of the phosphorescence sensor for the detection of Prh was also investigated using infrared spectroscopy.

Design of a highly sensitive fluorescent sensor and its application based on inhibiting NaIO4 oxidizing rhodamine 6G

A novel fluorescent sensor has been designed for the determination of terbutaline sulfate (TBS). It was validated by determining the selectivity, linearity, accuracy and precision of analysis. All of the experiments presented in this work were based on the inhibition of NaIO4 oxidizing rhodamine 6G (Rh 6G), which led to a large enhancement of the fluorescence signal. The limit of detection (LOD: 5.8 × 10−12 g mL−1) of this sensor was evaluated and compared with other methods, indicating a better sensitivity for TBS determination using this technique. It has been applied successfully to determine TBS in human serum and urine samples due to the high sensitivity of the sensor. The linear range was from 0.026 to 5.2 ng mL−1, allowing a wide determinable range of TBS. Meanwhile, the mechanism of this sensor was also discussed.