Li-Ping Lin

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.

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.

Catalytic solid substrate–room‐temperature phosphorimetry detection for trace cadmium with Cd2+–3.5‐generation polyamidoamine dendrimer–Tween‐80 complex

3.5-Generation polyamidoamine dendrimers (3.5-G-D) emitted strong and stable room-temperature phosphorescence (RTP) on filter paper when Pb2+ was used as a heavy atom perturber. The RTP signal of 3.5-G-D was sharply enhanced upon the formation of 3.5-G-D-Tween-80 micelle compound. The complex Cd2+ -3.5-G-D-Tween-80, generated in the coordination reaction between Cd2+ and the tertiary amidocyanogen on the outer layer of 3.5-G-D in 3.5-G-D-Tween-80 micelle compound, could catalyze KBrO3 to oxidize 3.5-G-D in 3.5-G-D-Tween-80, which caused the sharp quenching of the RTP signal of the system. The phosphorescence intensity change (ΔI(p) ) of the system had a linear relationship with the content of Cd2+. Thus a new catalytic solid substrate-room-temperature phosphorimetry (SS-RTP) for the determination of trace cadmium has been established. This highly selective and sensitive method has been applied to determine trace cadmium in biological samples with a limit of detection (LD) of 1.2 ag per spot (when the sample volume was 0.4 μL per spot, the corresponding concentration was 3.0 × 10(-15)  g mL(-1) ), the results agreeing with those obtained by atomic absorption spectrometry. The mechanism of catalytic SS-RTP for the determination of trace cadmium was also discussed.

Analysis application in biological field and prediction of human diseases with dual luminescence molecular of 3.5-generations polyamidoamine dendrimers–porphyrin

A new phosphorescence-labelling reagent (3.5-G-D-P labelling reagent) was developed, based on 3.5-generation polyamidoamine dendrimers (3.5-G-D) as internal acceptor to capture porphyrin (P) molecular. In the disturber of heavy atom, 3.5-G-D-P could emit room temperature phosphorescence (RTP) of 3.5-G-D and P on the surface of polyamide membrane (PAM), respectively. Products (3.5-G-D-P-WGA) of 3.5-G-D-P labelling triticum vulgaris lectin (WGA) could emit strong and stable RTP signal on the surface of PAM, and it also could take specific affinity adsorption reaction (AA) with alkaline phosphatase (ALP). The product of the AA reaction (3.5-G-D-P-WGA-ALP) could keep the RTP characteristics of 3.5-G-D-P very well, and the DeltaI(p) of the system was linear correlation to the content of ALP. The DeltaI(p) of the system with Tween-80 was once for P and twice for 3.5-G-D more than that without Tween-80. Thus, the affinity adsorption solid substrate-room temperature phosphorimetry (AA-SS-RTP) for the determination of trace ALP has been established using Tween-80-3.5-G-D-P to label WGA. The detection limit (LD) of this method was 0.12fgspot(-1) for 3.5-G-D and 0.18fgspot(-1) for P with direct method, 0.14fgspot(-1) for 3.5-G-D and 0.17fgspot(-1) for P with sandwich method, respectively, and the sensitivity was obviously high. This research showed that either using 3.5-G-D or P excitation/emission wavelength to determine the content of ALP in human serum, the results were coincided with ELISA, and the flexibility of AA-SS-RTP was obviously improved and the applicability was wider. Meanwhile, the reaction mechanism of determining ALP by direct method AA-SS-RTP was discussed.

Fullerol-fluorescein isothiocyanate-concanavalin agglutinin phosphorescent sensor for the detection of alpha-fetoprotein and forecast of human diseases

Based on the reaction of the active -OH group in fullerol (F) with the dissociated -COOH group in fluorescein isothiocyanate (FITC) to form an F-FITC and the enhanced effect of N, N-dimethylaniline (DMA) on phosphorescence signal of F-FITC, a new phosphorescent labeling reagent (DMA-F-FITC) was developed. Whats more, a phosphorescent sensor for the determination of alpha-fetoprotein variant (AFP-V) has been designed via the coupling technique of the high sensitivity for affinity adsorption-solid substrate-room temperature phosphorimetry (AA-SS-RTP) with the strong specificity reaction between DMA-F-FITC-Con A and AFP-V. The DMA-F-FITC increased the number of luminescent molecules in the biological target which improved the sensitivity of phosphorescent sensor. The proposed sensor was responsive, simple, selective and sensitive, and it has been applied to the determination of trace AFP-V in human serum and the forecast of human diseases using phosphorescence emission wavelength of F or FITC, with the results agreed well with those obtained by enzyme-linked immunoassay (ELISA). Meanwhile, the mechanisms for the labeling reaction and the sensing detection of AFP-V were discussed.