Solid Substrate Room Temperature Phosphorescence Research Articles

Determination of trace human chorionic gonadotropin by using multiwall carbon nanotubes as phosphorescence labeling reagent

Taking advantage of the cutting effect of the strong oxidation of benzoyl peroxide [(C6H5CO)2O2] on the end of multiwall carbon nanotubes (MWNTs) to obtain water-soluble multiwall nanotubes (MWNTs’) and the spiking effect of polyacrylamide (PA) on the room temperature phosphorescence (RTP) of MWNTs’, a new phosphorescent labeling reagent, MWNTs’–PA, has been developed in this study. The product β-AbHCG–MWNTs’–PA obtained by MWNTs’–PA labeling human chorionic gonadotropin-β-subunit three-dimensional core monoclonal antibody (β-AbHCG) not only could maintain good RTP characteristics of MWNTs’ but also could take specific immunoreaction with β-HCG to form β-HCG– β-AbHCG–MWNTs’–PA, resulting in the increase of MWNTs’ RTP signal. Thus, a new solid substrate room temperature phosphorescence immunoassay (SSRTPIA) for the determination of β-HCG has been established. The limits of detection (LODs) of the new method were 0.021pgspot−1 for the direct way at 447/615nm (λexmax/λemmax) and 0.016pgspot−1 for the sandwich way at 447/614nm (λexmax/λemmax). This sensitive, accurate, and precise method was used to determine β-HCG and diagnose human diseases by the direct way or the sandwich way, with the results coinciding with those obtained by chemiluminescence immunoassay. Meanwhile, the mechanisms of MWNTs’ labeling β-AbHCG and determining β-HCG are also discussed.

A specific Tween-80-Rhodamine S-MWNTs phosphorescent reagent for the detection of trace calcitonin

The present study proposed a simple sensitive and specific immunoassay for the quantification of calcitonin (CT) in human serum with water-soluble multi-walled carbon nanotubes (MWNTs). The COOH group of MWNTs could react with the NH group of rhodamine S (Rhod.S) molecules to form Rhod.S-MWNTs, which could emit room temperature phosphorescence (RTP) on acetate cellulose membrane (ACM) and react with Tween-80 to form micellar compound. Tween-80-Rhod.S-MWNTs (TRM), as a phosphorescent labelling reagent, could dramatically enhance the RTP signal of the system. The developed TRM phosphorescent reagent was used to label anti-calcitonin antibody (AbCT) to form the TRM-AbCT labelling product, which could take high specific immunoreaction with CT, and the ΔIp (= Ip2−Ip1, Ip2 and Ip1 were the phosphorescence intensity of the test solution and the blank sample, respectively) of the system was linear to the content of CT. Hence, a new solid substrate room temperature phosphorescence immunoassay (SSRTPIA) was established for the determination of CT in human serum. This sensitive (limit of quantification (LOQ) was 8.0×10−14gmL−1), accurate, selective and precise method has been applied to determine CT in human serum and predict primary osteoporosis and fractures, with the results in good agreement with those obtained by chemiluminescence immunoassay (CLIA). Simultaneously, the structure of MWNTs was characterized with scanning electron microscopy (SEM) and infrared spectroscopy (IR), and the reaction mechanisms of both labelling AbCT with TRM and SSRTPIA for the determination of trace CT were discussed.

A Promising CdSe@CdS-Quantum Dots-Cysteine for the Determination of Trace IgE by Solid Substrate Room Temperature Phosphorescence Immunoassay

The labelling reagent CdSe@CdS-QDs-Cys (QDs-Cys) with the grain diameter of 4.5nm was synthesized by modifying CdSe@CdS quantum dots (QDs) with cysteine (Cys). At the same time, QDs-Cys-Ab(IgE), a phosphorescent quantum dot probe, was developed based on the labelling reaction between -COOH of QDs-Cys and -NH(2) of goat anti human IgE antibody (Ab(IgE)). This probe with excellent biocompatibility and high specificity could not only emit strong and stable room temperature phosphorescence (RTP), but also could carry out specific immunoassay (IA) with immunoglobulin E (IgE), causing the RTP of the system to sharply enhance. Thus, a new solid substrate room temperature phosphorescence immunoassay (SSRTPIA) for the determination of IgE was established. The limit of quantification (LOQ) of the method was 0.12fg spot(-1), corresponding concentration was 3.0 × 10(-13)gmL(-1) and sampling quantity was 0.40μL spot(-1). This highly selective, sensitive and accurate SSRTPIA has been applied to determine IgE in biological samples and diagnose diseases, and the results agreed well with those obtained by enzyme-link immunoassay (ELISA). Meanwhile, the mechanisms of QDs-Cys labelling Ab(IgE) and the determination of IgE by SSRTPIA were 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.

Solid substrate-room temperature phosphorimetry for the determination of trace lead using p-nitro-phenyl-fluorone-multi-wall carbon nanotubes–Tween-80 micellae compound and diagnosis about human diseases

The structures of multi-wall carbon nanotubes (MWNTs) were modified by H 2SO 4–HNO 3 and H 2SO 4–H 2O 2, respectively. The corresponding products were water-soluble MWNTs-A and MWNTs-B. According to the experiment, it was found that MWNTs-B could emit stable solid substrate-room temperature phosphorescence (RTP) on the surface of paper with Ag + as perturber. Under the conditions of 70 °C and 15 min, MWNTs-B can react with Tween-80 and p-nitro-phenyl-fluorone (R) to form R-MWNTs-B–Tween-80 micellae compound, which could emit RTP of R and MWNTs-B on the surface of paper, respectively. Pb 2+ could cause the RTP of R and MWNTs-B enhanced sharply, respectively. Δ I p is directly proportional to the content of Pb 2+. A new solid substrate-room temperature phosphorimetry (SS-RTP) for the determination of trace Pb 2+ has been established based on R-MWNTs-B–Tween-80 micellae compound containing double luminescent molecule. The detection limit of this method were 0.035 ag Pb 2+ spot −1 (8.8 × 10 −17 g Pb 2+ ml −1, MWNTs-B) and 0.028 ag Pb 2+ spot −1 (7.1 × 10 −17 g Pb 2+ ml −1, R). This method is of high sensitivity, good selectivity, high precision and accuracy. It could be applied to determine trace Pb 2+ in serum samples at wavelength of 453.7/623.0 nm (R) or 475.9/645.0 nm (MWNTs-B) with satisfactory results, showing that SS-RTP has flexibility and utility value. Simultaneously, this method can be used to diagnose human diseases. The reaction mechanism for the determination of trace Pb 2+ by SS-RTP based on R-MWNTs-B–Tween-80 micellae compound containing double luminescent molecule was also discussed.

Study on the phosphorescence characterizations of palmatine chloride on the solid substrate and its interaction with ctDNA

The spectroscopic characterizations of solid substrate room temperature phosphorescence (SS-RTP) of palmatine (Pal) have been studied. Strong RTP signal at 615 nm can be induced on filter paper in the presence of TIAc. The interaction between calf thymus DNA (ctDNA) and Pal has been investigated at pH 6.90 using fluorescence, UV–vis, SS-RTP and cyclic voltammogram spectroscopy. Strong binding affinity of Pal with DNA is revealed from the absorption and fluorescence studies in the liquid state. With the addition of ctDNA, the fluorescence intensity of Pal is enhanced greatly and UV–vis spectra show no apparent hypochromicity and red shift, which indicates that Pal intercalates into ctDNA bases. However, this conclusion could not explain the phenomena from fluorescence polarization and denatured DNA measurements, which indicate that groove binding is at least the main binding mode. Binding constant and binding site size have been calculated to be 2.57 × 10 4 L/mol and 0.16 based on Scatchard plot from fluorescence titration data. Groove binding has also been supported by phosphorescence lifetime and anion quenching experiments. Above studies demonstrate that there should exist intercalative binding and groove binding in the interaction of Pal and DNA. Furthermore, cyclic voltammogram study suggests that electrostatic binding exists at the same time exactly. Taken together, the binding model obtained in this study is mixed-mode.

Determination of trace formaldehyde by solid substrate-room temperature phosphorescence quenching method based on the rose bengal–potassium bromate–Tween-80 system

A new method for the determination of trace formaldehyde by solid substrate-room temperature phosphorescence quenching method has been proposed. It is based on the facts that rose bengal (R) can emit intense and stable room temperature phosphorescence on the solid substrate of filter paper (SS-RTP). Potassium bromate (KBrO 3) can oxidize R, which causes the quenching of RTP. In the presence of HCHO, it can react with KBrO 3 to form Br 2 and Br 2 can oxidize R, which causes smart quenching of RTP. The phosphorescence intensity (Δ I p) is directly proportional to the concentration of HCHO. In the presence of Tween-80, the Δ I p will be increased to 9.1 times higher than that without it. The linear range of this method is 0.016–1.6 fg spot −1 (corresponding concentration: 0.040–4.0 pg ml −1, 0.40 μl spot −1) with the detection limit of 4.5 ag spot −1 (corresponding concentration: 1.1 × 10 −14 g ml −1). The regression equation for working curve is Δ I p = 136.6 + 28.28 m HCHO fg spot −1 ( r = 0.9935, n = 6). This method is sensitive, simple, rapid and has been applied to the determination of trace formaldehyde in real samples with satisfactory results. The mechanism of determination of trace formaldehyde by SS-RTP quenching method based on the rose bengal–KBrO 3–Tween-80 system is also discussed.

Determination of trace arsenic(V) by catalytic solid substrate-room temperature phosphorescence quenching method

In the H 2SO 4 medium and in the presence of dodecylbenzene sulfonic acid sodiumsalt (DBS), dimethyl yellow (R) could emit strong and stable solid substrate room temperature phosphorescence (RTP) on filter paper. And NaIO 4 could oxidize R to cause the RTP quenching. Arsenic(V) could catalyze the reaction of NaIO 4 oxidizing R, which caused the RTP sharply quenching. The reducing value of phosphorescence intensity (Δ I p) for the system with DBS is 3.3 times higher than that without DBS. Moreover, the Δ I p is proportional to the concentration of As(V). Based on the facts above, a new RTP quenching method for the determination of trace As(V) has been established.

Determination of Trace Arsenic by Solid Substrate‐Room Temperature Phosphorescence Quenching Method Based on the Catalyzed Reaction of H2O2 Oxidizing 9‐Hydroxy‐2,3,4,9‐tetrahydro‐1,10‐anthraquinone

AbstractA new solid substrate‐room temperature phosphorescence (SS‐RTP) quenching method for the determination of trace As(V) has been developed, based on the facts that 9‐hydroxy‐2,3,4,9‐tetrahydro‐1,10‐anthraquinone (R) can emit intense and stable SS‐RTP on solid substrate, and α,α′‐dipyridyl can activate As(V) catalysis of the reaction of H2O2 oxidizing R to non‐phosphorescence compound R′, which can cause the sharp quenching of SS‐RTP. Under the optimum condition, the relationship between the ΔIp of the emitting intensity and 1.60–160 fg·spot−1 As(V) (corresponding concentration:0.0040–0.40 ng·mL−1, sample volume:0.4 µL·spot−1) conformed to Beer′ law. The regression equation of working curve can be expressed as ΔIp20.46+0.5492cAs(V) (fg·spot−1) (r=0.9995, n=6). The limit detection (LD) is 0.27 fg·spot−1 [As(V) corresponding concentration:6.8×10−13 g·mL−1, n=11]. The samples containing 0.0040 and 0.40 ng·mL−1 As(V) were repeatedly determined for 11 times. RSD are 3.0% and 2.7% respectively. The SS‐RTP mechanism was also discussed. R was synthesized in this paper. Meanwhile, the structure was determined by NMR, IR , mass spectra and elemental analysis.

Solid Substrate-Room Temperature Phosphorescence Method for the Determination of Trace Mn(II) Based on Oxidizing Reaction of Hydrogen Peroxide Using α,α′-Bipyridine as Sensitizer

A new solid substrate-room temperature phosphorescence (SS-RTP) method for the determination of trace manganese (II) has been established. It bases on the fact that fullerol (R) emits strong and stable room temperature phosphorescence (RTP) on filter paper substrate. H2O2 can oxidize R to cause the SS-RTP quenching. But manganese (II) can obstruct H2O2 to oxidize R, and enhance the RTP of R. alpha,alpha'-Bipyridine (Bipy) can sensitize the RTP. After adding Bipy, the DeltaI(p) enhances 7 times than that without Bipy. Under the optimum conditions, the linear dynamic range of this method is 0.016-1.12 pg spot(-1) with a detection limit (L.D.) of 4.6 fg spot(-1) (m(Mn(2+) is the absolute mass of Mn(2+)), and the regression equation of working curve is DeltaI(p)=25.20 + 63.55 m(Mn(2+) (pg spot(-1)), n=6, r=0.9983. For 0.016 and 1.12 pg spot(-1) Mn(2+), RSDS are 4.3 and 4.8%, respectively (n=7). This method has been applied to the determination of trace manganese (II) in actual sample with high sensitivity and good selection. And the reaction mechanism of SS-RTP is discussed.

Determination of alkaline phosphatase based on affinity adsorption solid-substrate room temperature phosphorimetry using rhodamine 6G–dibromoluciferin luminescent nanoparticle to label lectin and prediction of diseases

In the presence of heavy atom perturber LiAc, the silicon dioxide nanoparticle containing rhodamine 6G (R) and dibromoluciferin (D) (R-D-SiO 2) can emit strong and stable solid-substrate room temperature phosphorescence signal of R (λ ex/λ em = 481/648 nm) and D (λ ex/λ em = 457/622 nm) on the surface of acetyl cellulose membrane (ACM). R-D-SiO 2 is used to label triticum vulgare lectin (WGA). Then two types of affinity adsorption reactions, R-D-SiO 2-WGA- alkaline phosphatase (ALP) (direct method) and WGA-ALP-WGA-R-D-SiO 2 (sandwich method), are carried out on ACM. The conditions and the analytical characteristics for the determination of ALP using affinity adsorption solid-substrate room temperature phosphorimetry (AA-SS-RTP) were studied. For a 0.40-μl drop of sample, results show that the detection limits of the sandwich method are 0.16 ag spot −1(457/622 nm) and 0.17 ag spot −1(481/648 nm), and the detection limits of the direct method are 0.41 ag spot −1 (457/622 nm) and 0.44 ag spot −1 (481/648 nm). The contents of ALP in human serum correlated well with those obtained by enzyme-linked immunoassay. This study shows that AA-SS-RTP whether by the sandwich method or the direct method, can combine very well the characteristics of both high sensitivity of SS-RTP and specificity of the immunoreaction. Simultaneously, whether the phosphorescence excitation/emission wavelength of either R or D in R-D-SiO 2 is chosen to determine ALP, this can promote the agility and widen the adaptability of AA-SS-RTP.

Determination of Trace Bismuth by a Solid Substrate Room Temperature Phosphorescence Quenching Method Based on Anionic Polymeric Acryclic Acid Lead Particles Containing Luminescent Eosine Molecules

Luminescent particles of Anionic Polymeric Acryclic Acid Lead (Pb(PAA)2) which containing eosine(HFInBr4), Eosine nanomicroball of anionic polypropylene acid lead contained luminophores (short for E.N.PAA.L.C.L), were synthesized by a sol‐gel method, using anionic polymeric acryclic acid sodium (PAANa) as the precursor and Pb2+ as the precipitant. NH4Ac‐HAc can react with the Pb2+ in E.N.PAA.L.C.L, causing it to decompose into aqueous soluble components. E.N.PAA.L.C.L‐ NH4Ac‐HAc can emit strong and stable solid substrate room temperature phosphorescence (SS‐RTP) on filter paper, and bismuth, mercury or iodine can cause a decrease in phosphorescence intensity. Based on the facts above, a new method for the determination of trace bismuth by an SS‐RTP quenching method was established. The linear range of this method was 0.01–0.20(pg spot−1) (4.0×10−12 g ml−1) of Bi3+, with a detection limit (LD) of 0.0016 pg spot−1, and the regression equation of the working curve was ΔIp=61.01+237.8 mBi3+ (pg spot−1), r=0.9992. This method was applied to the determination of trace bismuth in human hair and well water samples with satisfactory results. The mechanism of SS‐RTP emission was also discussed.

Affinity Adsorption Solid Substrate‐Room Temperature Phosphorimetry for the Determination of Alkaline Phosphatase

In the presence of Pb(Ac)2, the silicon dioxide nanoparticle containing rhodamine 6G (R‐SiO2) can emit strong and stable solid substrate‐room temperature phosphorescence (SS‐RTP) signal on the surface of acetyl cellulose membrane (ACM) at λex/λem=482/649 nm. It was found in the research that specific affinity adsorption reaction between triticum vulgare lectin (WGA) (which was labeled with luminescent silicon dioxide nanoparticle) and alkaline phosphatase (AP) can be carried out on the surface of ACM. The product of the reaction can emit stronger SS‐RTP signal. A new method of SS‐RTP for the determination of AP was established, based on an affinity adsorption reaction between AP and WGA labeled with nanoparticles containing rhodanime 6G luminescent molecules. The linear range of this WGA‐AP‐WGA‐R‐SiO2 method is 1.00–360.00 ag AP spot−1 (sample volume: 0.40 µL spot−1, corresponding concentration range: 2.50–900.00 fg mL−1). The regression equation of working curve is ΔIp=16.24+0.8856 mAP (ag spot−1), r=0.9993. Detection limit of this method calculated by 3Sb/k is 0.14 ag spot−1. After 11‐fold replicate measurements, RSD are 3.9% and 3.1% for the systems containing 1.00 and 360.00 ag AP spot−1, respectively. Compared with R‐SiO2‐WGA‐AP method (detection limit: 0.45 ag spot−1, corresponding concentration range: 2.00–320.00 ag spot−1), the sensitivity of WGA‐AP‐WGA‐R‐SiO2 method was obviously improved and the linear range was wider. The sensitivity, accuracy, and precision of this method are high. It has been successfully applied to determine AP in human serum.

Determination of Trace Copper by Solid Substrate–Room Temperature Phosphorescence Quenching Method Based on Lead Carboxymethyl Cellulose [Pb(CMC)2] Particles Containing Luminescent Salicyl Fluorones Molecules

Luminescent particles of lead carboxymethyl cellulose [Pb(CMC)2] that contain luminescent salicyl fluorones (SAF) {[Pb(CMC)2]‐SAF} were synthesized by sol‐gel method, using sodium carboxymethyl cellulose (NaCMC) as precursor and Pb2+ as precipitator. [Pb(CMC)2]‐SAF can emit intense and stable solid substrate–room temperature phosphorescence (SS‐RTP) on filter paper. EDTA (ethylenediaminetetraacetic acid) can chelate the Pb2+ in [Pb(CMC)2]‐SAF, causing it to decompose into aqueous soluble components PbY2–, CMC–, and SAF, and these components can react with Cu2+ to form [Cu(CMC)2]‐SAF, causing decrease of phosphorescence intensity. Based on the facts above, a new method for the determination of trace mercury by SS‐RTP quenching method was established. This method has been applied to the determination of trace copper in human hair and tea samples with satisfactory results.

Determination of trace selenium by solid substrate-room temperature phosphorescence enhancing method based on potassium chlorate oxidizing phenyl hydrazine-1,2-dihydroxynaphthalene-3,6-disulfonic acid system

A new method for the determination of trace selenium based on solid substrate-room temperature phosphorimetry (SS-RTP) has been established. This method was based on the fact that in HCl–KCl buffer solution, potassium chlorate could oxidize phenyl hydrazine to form chloridize diazo-ion after being heated at 100 °C for 20 min, and then the diazo-ion reacted with 1,2-dihydroxynaphthalene-3,6-disulfonic acid to form red azo-compound which could emit strong room temperature phosphorescence (RTP) signal on filter paper. Selenium could catalyze potassium chlorate oxidizing the reaction between phenyl hydrazine and 1,2-dihydroxynaphthalene-3,6-disulfonic acid, which caused the sharp enhancement of SS-RTP. Under the optimum condition, the relationship between the phosphorescence emission intensity (Δ I p) and the content of selenium obeyed Beer's law when the concentration of selenium is within the range of 1.60–320 fg spot −1 (or 0.0040–0.80 ng ml −1 with a sample volume of 0.4 μl). The regression equation of working curve can be expressed as Δ I p = 13.12 + 0.4839 C Se(IV) (fg spot −1) ( n = 6), with correlation coefficient r = 0.9991 and a detection limit of 0.28 fg spot −1 (corresponding to a concentration range of 7.0 × 10 −13 g ml −1 Se(IV), n = 11). After 11-fold measurement, R.S.D. were 2.8 and 3.5% for the samples containing 0.0040 and 0.80 ng ml −1 of Se(IV), respectively. This accurate and sensitive method with good repeatability has been successfully applied to the determination of trace selenium in Chinese wolfberry and egg yolk with satisfactory results. The mechanism of the enhancement of phosphorescence was also discussed.

Determination of trace lead by solid substrate room temperature phosphorescence enhancing method based on heavy atom effect and dissoluble manganese supramolecule containing rhodamine 6G luminescent particles

Dissoluble manganese supramolecule containing rhodamine 6G luminescent particles (M 2) are synthesized, based on dissoluble manganese supramolecule (M 1) doping rhodamine 6G (R.6G), by crystalline method. The particle diameters of M 1 and M 2 determined by ETM are both of micron degree. M 1 and M 2 can emit solid substrate room temperature phosphorescence (SS-RTP) on filter paper. The transition probability from the singlet state (S 1) to triplet state (T 1) of the luminescent molecules was greatly enhanced, based on the increment of luminescent molecules for each spot and the heavy atom effect of certain amount of Pb 2+. As a result, the phosphorescence intensity ( I p) of M 2 was increased sharply, and the enhancing value of phosphorescence intensity (Δ I p) is directly proportional to the concentration of Pb 2+. Thus, a new method of SS-RTP enhancing for the determination of trace lead is established based on manganese supramolecule containing rhodamine 6G luminescent particles. The linear range of this method is 0.0040–0.400 pg spot −1 of Pb 2+ (corresponding concentration, 0.01–1.0 ng mL −1; sample volume, 0.4 μL spot −1), with a detection limit (LD) of 0.0011 pg spot −1 (corresponding concentration, 2.8 × 10 −12 g mL −1 of Pb 2+, n = 11). For the working solutions containing 0.0040 and 0.40 ng mL −1 of Pb 2+, they were determined repeatedly for seven times, respectively. The R.S.D.s were 3.2 and 3.8%, respectively. This method has good repeatability, sensitivity and high precision. It has been applied to the determination of trace lead in human hair and tea samples with satisfactory results.

Study on spectroscopic characterization of Pd porphyrin and its interaction with ctDNA

The fluorescence and solid substrate room temperature phosphorescence (SS-RTP) properties of Pd(II) meso-tetrakis (4- N-methyl-pyridiniumyl) porphyrin (Pd(II)TMPyP) were studied. The factors influencing the SS-RTP emission, such as filter type, inorganic salt sort, drying temperature, pre-drying time and drying time were investigated in detail. Strong SS-RTP signal can be induced on the slow speed filter paper in the presence of the external inorganic salt, Ca(NO 3) 2, with the maximum excitation and emission wavelengths at 421 nm and 675 nm, respectively. The interaction between calf thymus DNA (ctDNA) and Pd(II)TMPyP was investigated at pH 7.2 using SS-RTP, fluorescence and UV–vis spectroscopy. The SS-RTP intensity of Pd(II)TMPyP was enhanced efficiently with the increasing amount of ctDNA. This phenomenon demonstrates that the intercalated porphyrin is shielded by ctDNA to avoid collision quenching. This result was supported by SS-RTP lifetime measurement, SS-RTP anion quenching experiment and fluorescence polarization measurement. Furthermore, with the addition of ctDNA, the UV–vis spectra of Pd(II)TMPyP shows apparent hypochromicity (40%) at the Soret maximum of 417 nm and a red shift of Δ λ = 15 nm, also indicating that Pd(II)TMPyP intercalates into ctDNA bases. The binding constant of Pd(II)TMPyP to ctDNA was calculated to be 4.41 × 10 5 L/mol based on the derivative McGhee–von Hippel plots.

Determination of trace molybdenum by solid substrate-room temperature phosphorescence quenching method based on catalytic effect of H 2O 2 on formation of ion association complex [Rhod.B] +·B[(C 6H 6) 4] −

A new solid substrate-room temperature phosphorescence (SS-RTP) quenching method for the determination of trace molybdenum has been established. The SS-RTP can be quenched by H 2O 2 oxidizing [Rhod.B] +·B[(C 6H 6) 4] − ion association complex, which is formed of Rhod.B reacting with NaB(C 6H 6) 4 and [Rhod.B] +·B[(C 6H 6) 4] − ion association complex can emit strong and stable room temperature phosphorescence on filter paper substrate, while molybdenum can catalyze H 2O 2 to oxidize [Rhod.B] +·B[(C 6H 6) 4] − ion association complex to quench the SS-RTP sharply in HCl medium, heated at 90 °C for 10 min. Based on the facts above, a new method for the determination of trace molybdenum has been proposed. When using PVA–H 3BO 3–NaOH to modify the surface of filter, the results showed that Δ I p of the system enhanced 1.5 times than that of unmodified. The linear range of this method is 1.6–160 ag spot −1 (the sample volume: 0.40 μl spot −1), and the regression equation of working curve is Δ I p = 18.23 + 0.8935 m Mo(VI) ag spot −1, n = 6, r = 0.9980. The detection limit is 0.34 ag spot −1 (corresponding concentration: 8.5 × 10 −16 g ml −1). This method has been successfully applied to the determination of trace molybdenum in actual samples with special feature such as wide linear range, high sensitivity, good repeatability, high selectivity and so on. Meanwhile, the mechanism of catalysis reaction is also discussed.

Determination of DNA by solid substrate room temperature phosphorescence enhancing method based on the Morin·SiO 2 luminescent nanoparticles–Pd system as a phosphorescence probe

Sodium carbonate (Na 2SiO 3) as the precursor, was mixed with Morin organic dye to synthesize silicon dioxide luminescent nanoparticles containing Morin (Morin·SiO 2) by sol–gel method. The particle sizes of SiO 2·nH 2O and Morin·SiO 2 were both 50 nm, measured with TEM (transmission electron microscope). Morin·SiO 2 modified by HS–CH 2COOH could be dissolved by water. In the HMTA (hexamethylenetetramine)–HCl buffer solution, Pd 2+ could coordinate with Morin in Morin·SiO 2 to form complex Pd 2+–Morin·SiO 2, which could emit phosphorescence on polyamide membrane. And DNA (deoxyribonucleic acid) could cause a sharp enhancement of the room temperature phosphorescence (RTP) intensity of complex Pd 2+–Morin·SiO 2. Thus a new method of solid substrate room temperature phosphorescence (SS-RTP) enhancing for the determination of DNA was established based on the Morin·SiO 2 luminescent nanoparticles–Pd system as a phosphorescence probe. The Δ Ip is directly proportional to the content of DNA in the range of 4.00–1000.0 fg spot −1 (corresponding concentration: 0.010–2.50 ng ml −1). The regression equation of working curve was Δ Ip = 21.13 + 0.2076m DNA (fg spot −1) ( r = 0.9990) and the detection limit was 0.61 fg spot −1 (corresponding concentration: 1.5 pg ml −1). This method had a wide linear range, high sensitivity, convenience, rapidity and only a little sample was needed. Samples containing 0.10 and 25.0 ng ml −1 DNA were measured repeatedly for 11 times and RSDs were 3.2 and 4.1% ( n = 11), respectively, which indicated that the method had a good repeatability. Disturbance of common ions, such as Mg 2+, K +, and Ca 2+, was small, and there was no disturbance in the presence of protein and RNA. This method has been applied to the determination of DNA in nectar successfully.

Determination of trace silver by solid substrate-room temperature phosphorescence quenching method based on double catalytic system of meta-nitrophenyfluorone-polyoxyethylene-chromium-potassium bromate-β-cyclodextrin

A new solid substrate-room temperature phosphorescence (SS-RTP) quenching method for the determination of trace silver has been established. It is based on the fact that when using Mg 2+ as ion perturber and β-CD as surfactant, the system of meta-nitrophenyfluorone (R)-polyoxyethylene-Cr(III) can emit strong and stable room temperature phosphorescence signal on filter paper whose surface is modified by polyvinyl alcohol (PVA)-H 3BO 3-NaOH. Ag(I) can catalyze KBrO 3 oxidizing R-PEO-Cr(III) system which causes the quenching of SS-RTP. The reducing value of phosphorescence intensity (Δ I p) is directly proportional to the concentration of Ag(I) in the range of 3.2–160 ag spot −1 (corresponding concentration: 2.43 fg ml −1, the sample volume: 0.40 μl spot −1) with a detection limit (LD) of 0.97 ag spot −1. The regression equation of working curve can be expressed as Δ I p = 13.92 + 0.3089 m A g + (ag spot −1) ( r = 0.9983, n = 6). This method has many advantages, such as a wide linear dynamic range, high sensitivity, good repeatability and selectivity. It has been applied to the determination of trace silver in real samples with satisfactory results. What is more, the mechanism of SS-RTP quenching method based on Ag(I) catalyzing KBrO 3 oxidizing meta-nitrophenyfluorone has also been discussed.