Strong Fluorescence Peak Research Articles

Yellow Emissive Carbon Dots - A Robust Nanoprobe for Highly Sensitive Quantification of Jaundice Biomarker and Mitochondria Targeting in Cancer Cells.

The abnormally high level of bilirubin (BR) in biofluids (human serum and urine) indicates a high probability of jaundice and liver dysfunction. However, quantification of BR as the Jaundice biomarker is difficult due to the interference of various biomolecules in serum and urine. To address this issue, we developed a fluorescence-based detection strategy, for which yellow emissive carbon dots (YCDs) were produced from a one-step solvothermal process using phloroglucinol and thionin acetate as chemical precursors. The as-fabricated YCDs exhibited a strong fluorescence peak at the wavelength of 542 nm upon excitation at 390 nm. We used YCDs for detecting BR through the fluorescence turn-off mechanism, unveiling the excellent sensitivity in the linear range of 0.5-12.5 μM with a limit of detection (LOD) of 9.62 nM, which was far below the clinically relevant range. The analytical nanoprobe also offered excellent detection specificity for quantifying BR in real samples. Moreover, the biocompatible fluorescent nanoprobe was successfully employed to target mitochondria in live cancer cells. A colocalization study confirmed that YCDs possessed the ability to target mitochondria and overlapped completely with MitoTracker Red. The developed nanoprobe of YCDs turned out to be straightforward in their synthesis, noninvasive, and can be utilized for biomedical sensors to diagnose the onset of jaundice as well as for mitochondria targeting.

High-contrast multicolour photoswitching based on dithienylethene Schiff base with a hydrazinylquinoline moiety

A new asymmetrical photochromic diarylethene DTE-HQo composed of a 2-hydrazinoquinoline moiety as the binding unit for ions and dithenylethene as a photoswitching trigger was reported. DTE-HQo displayed favourable photochromism upon irradiation with UV/vis light. Its fluorescent behaviour could be efficiently modulated by light, Zn2+, Cd2+ and HSO4−. The binding of Zn2+ induced a strong fluorescence peak at 510 nm in DTE-HQo due to the formation of a 1:2 complex [Zn2+ + 2DTE-HQo], resulting in a notable colour change from dark to intense white emission. Triggered by Cd2+, DTE-HQo formed a 1:1 complex [Cd2+ + DTE-HQo], leading to an enhanced emission intensity by 21-fold with an emission peak red-shifted from 461 nm to 514 nm. Unexpectedly, [Zn2+ + 2DTE-HQo] underwent hydrolysis when stimulated with water, generating a yellow-emitting complex [Zn2+ + DTE-HQo]. This color change easily distinguishes it from Cd2+ complex. Additionally, DTE-HQo showed high selectivity towards HSO4− and exhibited distinct “turn-on” fluorescence with a colour change from dark to bright blue upon stimulation. Moreover, the strong emission complexes of DTE-HQo with Zn2+, Cd2+ and HSO4− could be effectively quenched during the photocyclization process. Therefore, DTE-HQo can serve as an unimolecular multicolour photoswitching chemosensor, offering potential applications as a multifunctional probe for detecting Zn2+, Cd2+ and HSO4−.

A Ratiometric Fluorescence Amplification Using Copper Nanoclusters with o-Phenylenediamine Sensor for Determination of Mercury (II) in Natural Water

A simple and rapid method for determining mercury (II) has been developed using L-cysteine-capped copper nanocluster (CuNCs) with o-phenylenediamine (OPD) as the sensor. The characteristic fluorescence peak of the synthesized CuNCs was observed at 460 nm. The fluorescence properties of CuNCs were strongly influenced by the addition of mercury (II). Upon addition, CuNCs were oxidized to form Cu2+. Then, the OPD were rapidly oxidized by Cu2+ to form o-phenylenediamine oxide (oxOPD), as evidenced by the strong fluorescence peak at 547 nm, resulting in a decrease in the fluorescence intensity at 460 nm and an increase in the fluorescence intensity at 547 nm. Under optimal conditions, a calibration curve between the fluorescence ratio (I547/I460) and mercury (II) concentration was constructed with a linearity of 0–1000 µg L−1. The limit of detection (LOD) and limit of quantification (LOQ) were found at 18.0 µg L−1 and 62.0 µg L−1, respectively. The recovery percentage was in the range of 96.8–106.4%. The developed method was also compared with the standard ICP-OES method. The results were found to be not significantly different at a 95% confidence level (tstat = 0.365 < tcrit = 2.262). This demonstrated that the developed method could be applied for detecting mercury (II) in natural water samples.

Guava-fruit based synthesis of carbon quantum dots for spectrofluorometric quantitative analysis of risperidone in spiked human plasma and pharmaceutical dosage forms.

Autism is one of the most pressing issues facing the international community in recent years, particularly in Middle Eastern countries. Risperidone is a selective serotonin type 2 and dopamine type 2 receptor antagonist. It is the most administered antipsychotic medication in children with autism-related behavioral disorders. Therapeutic monitoring of risperidone may improve safety and efficacy in autistic individuals. The main objective of this work was to develop a highly sensitive green fitted method for the determination of risperidone in the plasma matrix and pharmaceutical dosage forms. Novel water-soluble N-carbon quantum dots were synthesized from guava fruit, a natural green precursor, and used for determination of risperidone based on quenching fluorescence spectroscopy phenomena. The synthesized dots were characterized by transmission electron microscopy and Fourier transform infrared spectroscopy. The synthesized N-carbon quantum dots exhibited aquantum yield of 26.12% and showed a strong emission fluorescence peak at 475 nm when excited at 380 nm. The fluorescence intensity of the N-carbon quantum dots decreased with increasing risperidone concentration, indicating that the fluorescence quenching was concentration dependent. The presented method was carefully optimized and validated according to the guidelines of ICH, and it demonstrated good linearity in a concentration range of 5-150 ng mL-1. With a LOD of 1.379 ng mL-1 and a LOQ of 4.108 ng mL-1, the technique was extremely sensitive. Due to the high sensitivity of the proposed method, it could be effectively used for the determination of risperidone in the plasma matrix. The proposed method was compared with the previously reported HPLC method in terms of sensitivity and green chemistry metrics. The proposed method proved to be more sensitive and compatible with the principles of green analytical chemistry.

MXene catalytic amplification-fluorescence/absorption dimode aptamer sensor for the detection of trace Pb2+ in milk.

Lead ion (Pb2+) is a toxic heavy metal, which is very harmful to organisms. Therefore, the establishment of a rapid, simple, and sensitive method is of great significance to food safety and human health. It was found that MXeneTi3C2 nanosheet (NS) has a strong catalytic effect on the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) via H2O2 to form the oxidized product (TMBOX); it has a strong fluorescence peak at 415 nm and an absorption (Abs) peak at 295 nm. The aptamer of Pb2+ (Aptpb) can be adsorbed on the surface of an NS to form MXene-Apt conjugates, which reduces its catalytic active sites and inhibits its catalytic activity. When the target Pb2+ is added, it specifically binds with Aptpb to release MXene NSs to enhance the dimode signals. Therefore, a new MXene catalytic fluorescence/absorption dimode aptamer biosenering platform was fabricated for the determination of trace Pb2+ in milk and water samples, with the fluorescence assay linear range (LR) of 5.0 × 10-2-2.0 nmol/L.

Systematic Microwave-Assisted Postsynthesis of Mn-Doped Cesium Lead Halide Perovskites with Improved Color-Tunable Luminescence and Stability

The metal doping at the Pb2+ position provides improved luminescence performance for the cesium lead halide perovskites, and their fabrication methods assisted by microwave have attracted considerable attention due to the advantages of fast heating and low energy consumption. However, the postsynthetic doping strategy of the metal-doped perovskites driven by microwave heating still lacks systematic research. In this study, the assembly of CsPbBr3/CsPb2Br5 with a strong fluorescence peak at 523 nm is used as the CsPbBr3 precursor, and through the optimization of the postsynthetic conditions such as reaction temperatures, Mn2+/Pb2+ feeding ratios, and Mn2+ sources, the optimum Mn2+-doped product (CsPb(Cl/Br)3:Mn) is achieved. The exciton fluorescence peak of CsPb(Cl/Br)3:Mn is blueshifted to 437 nm, and an obvious fluorescence peak attributing to the doped Mn2+ ions at 597 nm is obtained. Both the CsPbBr3 precursor and CsPb(Cl/Br)3:Mn have high PLQY and stability because there are CsPb2Br5 microcubic crystals to well disperse and embed the CsPbBr3 nanocrystals (NCs) in the precursor, and after Mn2+-doping, this structure is maintained to form CsPb(Cl/Br)3:Mn NCs on the surface of their microcrystals. The exploration of preparation parameters in the microwave-assisted method provides insights into the enhanced color-tunable luminescence of the metal-doped perovskite materials.

Improving photoluminescence, optical and electrical characteristics of PMMA films with gamma irradiation

Polymeric materials are macromolecules, essentially a combination of numerous repeated subunits. Polymers are innovative and advanced materials that currently have a strong impact on our daily lives. In recent years, polymer use has been prominent due to the materials’ distinctive properties; thus, they entered different fields of science, technology and industrial-biomedical applications.The improvement of photoluminescence, optical and electrical characteristics of non-conducting Poly(methyl methacrylate) (PMMA) films was studied. Upon gamma irradiation of various doses, the photophysical and electrical properties of PMMA films were investigated using photoluminescence spectroscopy, ultraviolet–visible (UV–vis) spectroscopy and the LCR Meter Bridge Circuit technique. The fluorescent response improved the photoluminescence (PL) spectral emission peaks according to gamma values. Strong fluorescence peaks appeared with the highest gamma dose. The UV–Vis results revealed a significant red-shift in the absorption edge as gamma doses increased. This shift exhibits a continuous decrease in the energy band gap values (from 3.50 to 2.60 eV for direct transition and from 3.05 to 1.55 eV for indirect transition). This was due to the formation of carbon clusters, which led to an increase in the electrical conductivity and improved the dielectric parameters of the irradiated PMMA films. Among a variety of measurements presented and discussed in the present study, the electrical measurements showed improved electrical characteristics of gamma-irradiated PMMA films.

Modulating visible-near-infrared reflectivity in ultrathin graphite by reversible Li-ion intercalation

Two-dimensional materials with optical turnability have wide prospect in related applications such as electrochromic coating and thermal camouflage. Here we report a Li-intercalated ultrathin graphite device with tunable visible-near-infrared reflectivity. After Li-ion intercalation, the Fermi surface of ultrathin graphite will move to a higher level, which prevents the interband optical transitions below it. Therefore, it is possible to change the absorptivity or emissivity of ultrathin graphite through reversible Li-ion intercalation, which accomplishes the modification to reflectivity indirectly. In our experiment, the strong fluorescence background and Peak shifts in Raman spectra, as well as the enlarged layer spacing in XRD spectra, together confirmed that Li-ions were successfully intercalated into the graphite layers. The relative reflectivity of ultrathin graphite increased sharply in a wide range from 460 nm to 1500 nm after complete Li-ion intercalation. At a typical near-infrared wavelength 1500 nm for instance, the relative reflectivity is 0.28 for pristine graphite while 0.70 for fully lithiated graphite. Such reversible intercalated modulation in visible-near-infrared reflectivity of ultrathin graphite might provide a new way to design electrochromic coating, thermal camouflage or radar stealth systems, which also promotes further understanding and optical applications of graphene and other 2D materials. • Systematic investigation into visible-near-infrared reflectivity modulation of intercalated ultrathin graphite. • The relative reflectivity of ultrathin graphite increased sharply in a wide wavelength range after Li-ion intercalation. • Such prominent modulation of ultrathin graphite might be ascribed to uplifted Fermi level in intercalated graphene layers.

A facile and sensitive fluorescence assay for glucose via hydrogen peroxide based on MOF-Fe catalytic oxidation of TMB

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)–H2O2 to produce the oxidation product TMBOX. The TMBOX fluorescent probe has a strong fluorescence peak at 405 nm. After optimizing the various conditions for the determination of H2O2 system and glucose system, the linear range of fluorescence determination of H2O2 was 0.75–7.5 μM, and the detection limit was 0.3 μM. Since H2O2 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.

Fluorescent detection mechanism of CO-releasing molecule-3: Competition of inter-/intra-molecular hydrogen bonds

The fluorescent detection mechanism of 2-(4-nitro-1,3-dioxoisoindolin-2-yl) acetic acid (CORM3-green) on CO-Releasing Molecule-3 (CORM-3) is theoretically studied. Upon reaction with CORM-3, the non-fluorescent CORM3-green is transferred to the keto form of 2-(4-amino-1,3-dioxoisoindolin-2-yl)acetic acid (PTI) to produce strong fluorescence peak located at 423 nm. This peak red-shifts to 489 nm, which is induced by the strengthening of intermolecular hydrogen bond (HB) between PTI and water molecules and attributed to the experimentally observed fluorescence emission at 503 nm. This result is dramatically different from previous reports that the experimental fluorescence corresponds to the proton transferred enol form of PTI. To illustrate this confusion, the calculated fluorescence peak of PTI-Enol is located at 689 nm, which is much larger than that of experimental result. This result excludes the occurrence of excited state intramolecular proton transfer (ESIPT). It is concluded that intermolecular HBs hinders the formation of intramolecular HB and the ESIPT of the keto form of PTI. This conclusion confirms that experimental Stokes shift of 113 nm is mainly caused by the intermolecular hydrogen bonding rather than by ESIPT process. This work proposes a reasonable explanation for the detection mechanism of CORM3-green and experimental fluorescence phenomenon.

Cell Membrane-Specific Fluorescent Probe Featuring Dual and Aggregation-Induced Emissions.

A cell membrane-specific fluorescent probe was prepared by conjugating a coumarin dye with a tetraphenylethene (TPE) derivative through an α,β-unsaturated ketone connection. The probe has two absorptions: one from the TPE moiety at 300 nm and a second one due to the coumarin moiety at 458.5 nm. The probe fluoresces at 470 nm in tetrahydrofuran (THF) solution. The probe exhibits a useful aggregation-induced emission (AIE) property. A gradual increase in the water content of a THF solution causes a significant decrease and 12 nm red shift in the fluorescence peak at 470 nm, giving rise to a new strong fluorescence peak at 591 nm at a 95% water content. The probe is hydrophobic with an AIE property and binds to cell membranes, resulting in 591 nm fluorescence upon implantation into cells. The probe possesses a long retention time despite the lack of a long, cell membrane-anchored hydrophobic alkyl chain, which is typical for traditional membrane-specific probes. Our probe also displays low cytotoxicity and excellent photostability.

Growth and fluorescence characteristics of Er:LuAG laser crystals

Er-doped Lu3Al5O12 (Er:LuAG) single crystals with various doping concentrations of 0.2, 0.5, 1.0, and 3.5 at% are grown by the Czochralski method. In the growth process, the cracking problem of this refractory crystal is overcome by a modified temperature field. Then, the lattice parameters and dopant segregation coefficient of as-grown boules are revealed. In addition to the structure and components, we mainly focus on the absorption and fluorescence spectra of Er:LuAG. Specifically, the absorption ranging from 250 to 1700 nm presents the characteristic energy-levels of the Er dopant. Using a 970 nm pump laser, strong fluorescence peaks are observed at 1532 nm, indicating Er:LuAG is an outstanding potential laser material in both the human eye-safe band and long air-path transmission. Notably, the best results were observed at an Er concentration of 1 at% with the highest luminescence intensity.

Landfill leachate treatment by coagulation/flocculation combined with microelectrolysis-Fenton processes

ABSTRACTLandfill leachate was pretreated by chemical flocculation with polyaluminum chloride (PAC) as a flocculant, and subsequently purified by the microelectrolysis-Fenton (MEF) process. Response surface methodology was employed to optimize the MEF process, and the optimal conditions were initial pH 3.20, H2O2 concentration 3.57 g/L, and Fe-C dosage 104.52 g/L. The PAC coagulation combined with MEF processes obtained a superior decontamination performance, and the predicted chemical oxygen demand (COD) and humic acids (HA) removal were respectively 90.27% and 93.79%. The strong fluorescence peak at 425 nm and the trapping experiment showed that was generated during MEF, which had a strong oxidation ability to degrade organic recalcitrant pollutants. The ultraviolet–visible spectra and three-dimensional excitation–emission matrices spectra (3D-EEMs) indicated that PAC coagulation could preferentially remove protein-like substances, while the MEF process was effective in destructing organic recalcitrant pollutants, especially humic-like and fulvic-like substances.

A sensitive fluorescence method for detection of E. Coli using rhodamine 6G dyeing.

Negatively charged bacteria combined with positively charged alkaline dye rhodamine 6G (Rh6G) in NaH2 PO4 -Na2 HPO4 buffer solution pH 7.4, by electrostatic interaction. The dyed bacteria exhibited a strong fluorescence peak at 552 nm and fluorescence intensity was directly linear to Escherichia coli (E. coli), Bacillus subtilis (B. subtilis) and Staphylococcus aureus (S. aureus) concentrations in the range of 7.06 × 10(4) to 3.53 × 10(7) , 4.95 × 10(5) to 2.475 × 10(8) and 32.5 to 16250 colony forming unit/mL (cfu/mL) respectively, with detection limits of 3.2 × 10(4) cfu/mL E. coli, 2.3 × 10(5) cfu/mL B. subtilis and 16 cfu/mL S. aureus, respectively. Samples were cultured for 12 h, after which the linear detection range for E. coli was 2 to 88 cfu/mL. This simple, rapid and sensitive method was used for the analysis of water and drinking samples. Copyright © 2015 John Wiley & Sons, Ltd.

Growth and spectroscopic properties of the 2.9 μm Tm,Ho:LuYAG laser crystals

Lu2.4Y0.6Al5O12 (LuYAG) crystals with three different doping concentrations of Tm3+ and Ho3+ were grown successfully by the Czochralski method. The crystals exhibit broad absorption band at 783nm and the full width at half maximum (FWHM) are about 11nm. Excited by 783nm laser diode (LD), strong fluorescence peaks are observed near 2.9μm, suggesting that the Tm3+ ions can act as the sensitizer for Ho3+ ions. The stimulated emission cross-sections at 2.911μm are calculated to be 5.49×10−18cm2, 3.11×10−18cm2, and 4.04×10−18cm2, respectively. Compared with the Tm,Ho:LuAG, and Tm,Ho:YAG crystals, the Tm,Ho:LuYAG crystal with 3at.% Tm3+ and 1at.% Ho3+ has a relatively longer lifetime 0.138ms for the upper level 5I6 and a shorter lifetime 7.25ms for the lower level 5I7, which is advantageous to the population inversion. These results indicate that the Tm,Ho:LuYAG crystal with 3at.% Tm3+ and 1at.% Ho3+ is a new potential candidate for realizing the 2.911μm laser output.

Aqueous Processing CdSe/TGA Quantum dots For Potential Bio-Medical Applications

ABSTRACTThe size-dependent optical properties of CdSe nanoparticles are desirable in bio-imaging and cell sorting applications because of their tunable photoluminescence in the visible range. Previous studies have already suggested that CdSe QDs could be utilized for pathogen detection by using suitable capping agents to make it biocompatible; however, systematic works on the effect of crystallite size and composition of the nanocrystals are scarce. The present research will be focused on the effect of CdSe crystal size and composition (pure and doped systems) to systematically evaluate its applicability in detecting pathogens, like Escherichia coli (E. coli). Highly luminescent water-soluble CdSe QDs were firstly synthesized in the aqueous phase, in the presence of thioglycolic acid (TGA) as a capping agent. CdSe/TGA molar ratios, reaction temperature, time, and pH were evaluated in order to optimizer the QDs optical properties. X-Ray diffraction (XRD) measurements confirmed the formation of CdSe exhibiting hexagonal structure with an estimated averaged crystallite size in the 4-6 nm range. Transmission electron microscopy (TEM) analyses evidenced the formation of CdSe nanocrystals with particle sizes between 3-5 nm. UV-Vis measurements showed a strong exciton peak between 390-400 nm with an estimated band gap of 2.64 eV (bulk: 1.74 eV); additionally, a strong fluorescence peak was observed between 500-550 nm using an excitation wavelength of 400 nm. Fourier Transform Infrared Spectroscopy (FT-IR) analyses suggested the actual functionalization of the CdSe surface with TGA functional groups. Preliminary results of the CdSe/TGA coupling with the selected bacteria, E. coli, are presented and discussed.

Analysis of fluorescence spectrum of petroleum-polluted water

In four ratio experiments, natural waters, sampled from the mountain reservoir and the sea water around Dalian city, were mixed with the sewage from petroleum refinery and petroleum exploitation plants. The fluorescence spectra of water samples containing only chromophoric dissolved organic matters(CDOM), samples containing only petroleum, and samples containing a mixture of petroleum and CDOM were analyzed, respectively. The purpose of this analysis is to provide a basis for determining the contribution of petroleum substances and CDOM to the total absorption coefficient of the petroleum-contaminated water by using fluorescence technique. The results showed that firstly, CDOM in seawater had three main fluorescence peaks at Ex: 225-230 nm/Em: 320-330 nm, Ex: 280 nm/Em: 340 nm and Ex: 225-240 nm/Em: 430-470 nm, respectively, and these may arise from the oceanic chlorophyll. CDOM in natural reservoir water had two main fluorescence peaks at EX: 240- 260 nm/Em: 420-450 nm and Ex: 310~350 nm/Em: 420--440 nm, respectively, and these may arise from the terrestrial sources; secondly, the water samples containing only petroleum extracted with n-hexane had one to three fluorescence spectral peaksat Ex: 220-240 nm/Em: 320-340 nm, Ex: 270-290 nm/Em: 310-340 nm and Ex: 220-235 nm/Em: 280-310 nm, respectively, caused by their hydrocarbon component; finally, the water samples containing both petroleum and CDOM showed a very strong fluorescence peak at Ex: 230-250 nm/Em: 320-370 nm, caused by the combined effect of CDOM and petroleum hydrocarbons.

Highly sensitive fluorescence and SERS detection of azide through a simple click reaction of 8-chloroquinoline and phenylacetylene.

In 0.19 mol/L acetic acid (HAc), a click reaction of 8-chloroquinoline/azide/phenylacetylene take places in aqueous solution without Cu(I) as a catalyst. 8-Chloroquinoline (CQN) exhibited a strong fluorescence peak at 430 nm that was quenched linearly as the concentration of azide increased from 20 to 1000 ng/mL. This quenching was due to consumption of CQN in the click reaction and a decrease in the number of efficiently excited photons due to the presence of triazole-quinoline ramification molecules with strong hydrophobicity. Using blue nanosilver sol as the substrate, CQN absorbed onto the surface of nanosilver particles, showing a strong surface-enhanced Raman scattering (SERS) peak at 1585 cm(-1) that decreased linearly as the azide concentration increased from 8 to 500 ng/mL; the detection limit was 4 ng/mL. Thus, two new, simple and sensitive fluorescence and SERS methods have been developed for the determination of azide via the click reaction.

Spectral Properties of K<sub>2</sub>PtCl<sub>6</sub>-KI-Protein Associated Particle Systems and its Application to Resonance Scattering Spectral Analysis

In suitable pH value of Walpole buffer solution and in the presence of surfactant Triton X-10 and alcohol, PtCl62- reacts with I- to form PtI62-. By means of the electrostatic and hydrophobic forces, proteins with positive charge, such as human serum albumin (HSA), bovine serum albumin (BSA), human immunoglobulin (IgG) and ovalbumin (OVA), associates with PtI62- to form stable [protein-(PtI6)n]m association particles which cause substantial enhancement of Rayleigh scattering and interface fluorescence. They produce three Rayleigh scattering peaks at 330 nm, 420 nm and 464 nm and a resonance scattering peak at 580 nm, among which the strongest peak is at 464 nm. The four kinds of protein association particle system all exhibit a strong fluorescence peak at 466 nm, while the HSA fluorescence peak at 360 nm was quenched with the formation of the association particle. The cause of the Rayleigh scattering peaks of the association particle system was considered in detail, and the relationship between the Rayleigh scattering and fluorescence of the association particle (the means diameter is about 470 nm) and the fluorescence quenching of HSA was interpreted. Under the optimal experimental conditions, there is a good linear relationship between the scattering intensity (I464 nm) and protein concentration in the range of 0.05~25μg/mL HSA, 0.05~25μg/mL BSA, 0.3~30μg/mL IgG and 0.1~16μg/mL OVA respectively, with a detection limit of 20 ng/mL HSA, 26 ng/mL BSA, 40 ng/mL IgG and 70 ng/mL OVA. This assay has been applied to the determination of the albumin of human serum samples with satisfactory results.

Unusual strong fluorescence of a hyperbranched phosphate: discovery and explanations

The unusual strong fluorescence of a hyperbranched molecule (3-hydroxyphenyl) phosphate (HHPP), which does not possess a rigid planar structure or obvious large π system, was discovered for the first time. The effects of the solvent polarity, pH value, concentration, and end group modification on the absorption and the fluorescence spectra of HHPP solutions were investigated. The terminal phenol groups and triphenyl phosphate (TPP) structures in HHPP were found to be responsible for two strong fluorescence peaks. The greatly enhanced fluorescence is explained by three factors. In particular, the special bridging effects of the phosphate groups in the hyperbranched molecules, which can form extended π electron systems, play an important role. It is suggested that the phosphate groups in the hyperbranched molecule could serve as effective bridging groups to connect various other fluorescence groups to form a new type of fluorescence molecule which does not have a rigid planar structure. In addition, the systematic colour changes with changing solvent polarity, mass concentration, and pH value make it a new potential probe in various applications.