Strong Fluorescence Intensity Research Articles

A “sense-and-treat” ELISA using zeolitic imidazolate framework-8 as carriers for dual-modal detection of carcinoembryonic antigen

Enzyme-linked immunosorbent assay (ELISA) has been widely used in the area of biological analysis, while there are still some challenges getting in the way to ensure both excellent sensitivity and reliable accuracy. To overcome these obstacles, we simulated the “smart” sense-and-treat carriers in a drug delivery system to fabricate an improved ELISA, employing zeolitic imidazolate framework-8 (ZIF-8) as the carrier to deliver the tracer agent carbon dots (CDs) and the “drug” thymolphthalein (TP), which was referred to as a “sense-and-treat” ELISA. In the “sense” part, the strong fluorescence intensity of CDs could be observed directly to achieve the sensitive detection of the target. In the “treat” part, after stimulation of alkaline solution, TP was released from ZIF-8 carriers and generated a color change with an obvious absorption, which was beneficial for increasing the sensitivity of this ELISA due to the high loading of the TP. Finally, we took carcinoembryonic antigen (CEA) as a model and performed dual-modal detection using this improved “sense-and-treat” ELISA to accomplish quantitative determinations sensitively and accurately. In addition, the results indicated by the two parts kept good concordance, which could demonstrate the reliable accuracy of this ELISA.

Fluorescent aptasensor for ofloxacin detection based on the aggregation of gold nanoparticles and its effect on quenching the fluorescence of Rhodamine B.

This paper proposes the idea of building a fluorescent biosensor for ofloxacin (OFL) determination in aqueous and milk samples by label-free OFL-specific aptamer, gold nanoparticles (AuNPs) and Rhodamine B (RB). In the absence of OFL, AuNPs are coated with OFL aptamer and maintain dispersed in the high concentration of NaCl. The dispersed AuNPs could reduce the strong fluorescence intensity of RB efficiently. By contrast, in the presence of OFL, OFL is combined with aptamer to form stable compounds, causing the aptamers separated from the surface of AuNPs, thus AuNPs would be exposed in the solution. And the aggregated AuNPs will not quench the fluorescence intensity of RB. Through the distinction of the fluorescence intensity, the concentration of OFL could be detected in aqueous and milk samples quantitatively. The convenient and specific fluorescent assay for OFL is established with a linear range (R = 0.9907) from 20 to 300 nM and a detection limit of 1.66 nM in aqueous solution, and a linear range (R = 0.9963) from 20 to 300 nM and a detection limit of 4.61 nM (1.66 μg/L) in milk samples. With the good sensitivity and selectivity, this biosensor has good application potential to detect OFL in food and environmental samples.

Polycarbonate-Based Nanoparticles with Aggregation-Induced Emission (AIE): Synthesis and Application for Cell Imaging

The fluorescent nanoparticles with aggregation-induced emission have caused tremendous research interest. In this work, the polycarbonates-based fluorescent nanoparticles with aggregation-induced emission (AIE) have been prepared by a facile and efficient approach of ring-opening polymerization and click chemistry. The tetraphenylethylene moieties that feature the AIE characteristics can be facilely grafted onto the polymer main chain by click reaction between azide-terminated tetraphenylethene derivative and alkyne-bearing amphiphilic block copolymer poly(ethylene glycol)-block-poly(5-methyl-5-propargylxycarbonyl-1,3-dioxane-2-one). The resulted tetraphenylethylene substituted block copolymers possess amphiphilic properties and are able to self-assemble into fluorescent polymeric nanoparticles. Based on cellular imaging experiments, we demonstrated that these fluorescent nanoparticles have great potential for cells imaging applications due to their attractive properties including strong fluorescence intensity, great water dispersibility, excellent biocompatibility and high cellular uptake efficiency.

Tissue-Specific Metabolite Profiling on the Different Parts of Bolting and Unbolting Peucedanum praeruptorum Dunn (Qianhu) by Laser Microdissection Combined with UPLC-Q/TOF⁻MS and HPLC⁻DAD.

Background: Qianhu is a traditional Chinese medicine. It is thought that Qianhu roots will harden after bolting and not be suitable for medicinal purposes. Bolting Qianhu and unbolting Qianhu are referred to as “Xiong Qianhu” and “Ci Qianhu,” respectively. In this study, the properties, microscopic and chemical characteristics of Ci Qianhu and Xiong Qianhu roots were compared using fluorescence microscopy, laser microdissection coupled with ultra-high-performance liquid chromatography-quadrupole/time-of-flight mass spectrometry, and high-performance liquid chromatography with diode-array detection. Results: Microscopy results showed that the area of secondary xylem in the root increased after bolting, with the cork and secretory canals showing strong fluorescence intensity. A total of 34 peaks, mostly pyranocoumarins, were identified in the tissues of Ci Qianhu and Xiong Qianhu. The secretory canals contained the highest variability of coumarins, whereas the secondary xylem contained the least coumarins. Moreover, seven coumarins, especially the pyran- coumarin, decreased after bolting. Generally, both before and after bolting, coumarin level was the highest in the bark, followed by the middle part, and the lowest in the inner part. Conclusion: Thus, it was indicated that the area of secondary xylem increased after bolting, however the coumarin variant and content decreased in the secondary xylem of Qianhu. The result shows that the quality of Qianhu decreases after bolting, which supports the viewpoint that Xiong Qianhu is not suitable for medicinal use.

Development of a dual-wavelength fluorescent nanoprobe for in vivo and in vitro cell tracking consecutively.

Many imaging probes have been developed for a wide variety of imaging modalities. However, no optical imaging probe could be utilized for both microscopic and whole animal imaging. To fill the gap, the dual-wavelength fluorescent imaging nanoprobe was developed to simultaneously carry both visible-range fluorescent dye and near-infrared (NIR) dye. Emission scan confirms that the nanoprobe exhibits two separate peaks with strong fluorescent intensity in both visible and NIR ranges. Furthermore, the dual-wavelength fluorescent nanoprobe has high photostability and colloidal stability, as well as long shelf-life. In vitro cell culture experiments show that the nanoprobe has the ability to label different types of cells (namely, esophageal, prostate, fibroblast and macrophage cell) for fluorescent microscope imaging. More importantly, cell tracking experiments confirm that cell migration and distribution in various organs can be tracked in real time using in vivo whole-body NIR imaging and in vitro microscopic imaging, respectively.

Corncob residues as carbon quantum dots sources and their application in detection of metal ions

Carbon quantum dots (CQDs) have been attracting extensive attention due to their chemical inertness, high water solubility, size effect, non-toxicity, photoluminescence reaction, photo-induced electron transfer, and tunable light emissions, among other attributes. In the study, the CQDs were synthesized using a simple, green, energy-saving, and efficient hydrothermal method from corncob residues (CRs) obtained after hemicelluloses pre-extraction of corncobs, and the enzymatically hydrolyzed corncob residues (EHCRs). The resultant CQDs were characterized and their applications in detection of metal ions were investigated. The results showed that CRs and EHCRs were good sources for CQDs; the nitrogen doping improved the fluorescence intensity and stability of CQDs; the nitrogen-doped CQDs from EHCRs (E-N-CQDs) exhibited the strongest fluorescence compared with other CQDs; the E-N-CQDs had a strong emission at a wavelength of 414 nm and an optimal excitation wavelength of 318 nm, the strongest fluorescence intensity was found at pH 10.0; the E-N-CQDs were the most sensitive to Fe(III) with the detection limit of 0.75 μmol L−1, which was much lower than the concentration of Fe(III) in human blood (7.52 − 11.82 mmol L−1). The developed E-N-CQDs concept may provide a novel method for the detection of Fe(III) in human blood.

Single nucleotide recognition using a probes-on-carrier DNA chip.

Following the sequencing of the human genome, SNP analysis of individual patients has become essential for achieving the best drug response and ensuring optimal care. In this study, we developed a cost-effective probes-on-carrier DNA chip for the detection of SNPs. Our chips harbored three different probes against the TP53 gene, and were capable of detecting wild-type TP53 and SNPs such as rs121912651 and rs11540652. Four cell lines were used to validate the specificity of probe hybridization. Strong fluorescence intensity was observed in hybridized spots based on hybridization for perfect base pairing between complementary strands, whereas significantly lower fluorescence (p<0.05) was observed in nonhybridized spots. These hybridization results indicated that the probes-on-carrier chip is suitable for SNP genotyping.

The sentinel lymph node biopsy in penile carcinoma guided by multispectral separate-merge guided surgery device

Objective To explore the method and clinical value of sentinel lymph node biopsy for penile carcinoma guided by multispectral separate-merge guided surgery device(MGS). Methods The clinical data of 7 patients with sentinel lymph node biopsy of penile cancer guided by MGS from April 2017 to April 2018 were analyzed retrospectively at First Hospital of Shanxi Medical University. They were 62-78 years old, with an average age of 65 years. All of carcinoma was located in the glans or coronal sulcus, which diameter was 1.0-3.5 cm, with an average of 2.5 cm. Three cases of inguinal lymph nodes could be non-palpable and the others palpable. All patients were injected 0.25 ml (2.5 mg/ml) of indocyanine green solution with 1 ml syringe at 12, 4, 6 and 9 points in the proximal normal skin of penile tumors. Immediately, the imaging probe was aligned with the injection point to observe the dynamic changes of fluorescence image on MGS display. Results There were 14 sides of groin in 7 patients, except for 1 side without images, other 13 sides developed well. The images displayed by MGS include visible image, fluorescent image and merged image, and the merged image was green pseudo color. According to the dynamic changes of the image, it could be divided into five parts: injection point, penile body, pubic symphysis, inguinal region and sentinel lymph node. In 13 well-developed sides, fluorescence gradually disappeared in other parts about 15 minutes after injection, and the location of sentinel lymph nodes was determined in vitro by gradually consolidating and fixing the fluorescence images in the inguinal region. The lymph node-like tissue with strong fluorescence intensity was observed immediately after the skin incision. There was a clear boundary between the lymph node-like tissue and the surrounding tissue. Along this boundary, lymph nodes were separated, ligated, excised. No lymph nodes were found on the undetected side. Postoperative pathology confirmed that lymph nodes were located by fluorescence imaging in vitro and traced by fluorescence imaging in vivo, the coincidence rate was 100%. There were residual fluorescent tissues on three sides and lymphatic vessels were removed. Conclusions MGS-assisted intraoperative fluorescence imaging could improve the doctor's visual depth so that physicians can real-time, dynamic, accurate in vitro location and in vivo tracking of sentinel lymph nodes of penile cancer. Key words: Penile carcinoma; Sentinel lymph node biopsy; Fluorescence image; Indocyanine green; Image guided

Enhancing the efficiency of the Pichia pastoris AOX1 promoter via the synthetic positive feedback circuit of transcription factor Mxr1

BackgroundThe methanol-regulated AOX1 promoter (PAOX1) is the most widely used promoter in the production of recombinant proteins in the methylotrophic yeast Pichia pastoris. However, as the tight regulation and methanol dependence of PAOX1 restricts its application, it is necessary to develop a flexible induction system to avoid the problems of methanol without losing the advantages of PAOX1. The availability of synthetic biology tools enables researchers to reprogram the cellular behaviour of P. pastoris to achieve this goal.ResultsThe characteristics of PAOX1 are highly related to the expression profile of methanol expression regulator 1 (Mxr1). In this study, we applied a biologically inspired strategy to reprogram regulatory networks in P. pastoris. A reprogrammed P. pastoris was constructed by inserting a synthetic positive feedback circuit of Mxr1 driven by a weak AOX2 promoter (PAOX2). This novel approach enhanced PAOX1 efficiency by providing extra Mxr1 and generated switchable Mxr1 expression to allow PAOX1 to be induced under glycerol starvation or carbon-free conditions. Additionally, the inhibitory effect of glycerol on PAOX1 was retained because the synthetic circuit was not activated in response to glycerol. Using green fluorescent protein as a demonstration, this reprogrammed P. pastoris strain displayed stronger fluorescence intensity than non-reprogrammed cells under both methanol induction and glycerol starvation. Moreover, with single-chain variable fragment (scFv) as the model protein, increases in extracellular scFv productivity of 98 and 269% were observed in Mxr1-reprogrammed cells under methanol induction and glycerol starvation, respectively, compared to productivity in non-reprogrammed cells under methanol induction.ConclusionsWe successfully demonstrate that the synthetic positive feedback circuit of Mxr1 enhances recombinant protein production efficiency in P. pastoris and create a methanol-free induction system to eliminate the potential risks of methanol.

Enhanced biosynthesis of CdS nanoparticles through Arabidopsis thaliana phytochelatin synthase-modified Escherichia coli with fluorescence effect in detection of pyrogallol and gallic acid

In this work, CdS nanoparticles (CdS NPs) biosynthesized through Arabidopsis thaliana phytochelatin synthase-modified Escherichia coli (CdS/AtPCS1-E. coli) with fluorescence (FL) performance for detection of pyrogallol and gallic acid was investigated. Through expression of the AtPCS1 gene inside E. coli cells by pET28b vector, biosynthesis of CdS NPs was greatly enhanced due to generation of phytochelatins (PCs, (γ-Glu-Cys)n-Gly, n ≥ 2) for efficient capture of Cd2+. The expression of AtPCS1 and concentration of glutathione (GSH) and PCs were detected by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and high performance liquid chromatography (HPLC), respectively. The morphology and component were checked through scanning electron microscope (SEM), transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS). FL effect with different experimental conditions were examined. In addition, it is also applied to determination of pyrogallol and gallic acid. These results revealed that multifunctional PCs could effectively facilitate biosynthesis of CdS NPs with higher yield, better distribution and lower cost while stronger FL intensity could be obtained for quantitative analysis.

Polylactide/poly(butylene adipate‐co‐terephthalate)/rare earth complexes as biodegradable light conversion agricultural films

Rare earth europium(III) complex with α‐thenoyltrifluoroacetone and triphenylphosphine oxide (Eu (TTA)3(TPPO)2, shortened as EuTT) was synthesized in this paper, then blended with polylactide (PLA) and poly(butylene adipate‐co‐terephthalate) (PBAT) to prepare the biodegradable agricultural films. Through the optical performance, mechanical properties, and other research, the results showed that the rare earth complex could convert the sun's ultraviolet light to red light when doped polymer. Moreover, the relative intensity ratio of 5D0/7F2 to 5D0/7F1 of PLA/PBAT/EuTT film could reach 3.79, which implied that the film had strong fluorescence intensity and high color purity. The highest tensile strength of the film could reach 36.7/25.2 MPa, and the elongation at break was 462.8/483.0% in the machine and in the transverse direction when the added amount of Eu (TTA)3(TPPO)2 was 0.1 wt%. The tensile strength of the film was 33.3/20.1 MPa, and the elongation at break could reach 535.8/413.6% when the added amount of Eu (TTA)3(TPPO)2 was increased up to 0.3 wt%. Gel permeation chromatography showed that the Eu (TTA)3(TPPO)2 could cause depolymerization of polylactide, resulting in a decrease in the molecular weight of PLA. Furthermore, the crystallization ability of PLA was also improved. In this paper, the biodegradable films exhibited excellent ultraviolet light conversion ability and mechanical properties.

Synthesis and characterization of chromone-based ligand and its fluorescence property towards Zn2+

Zinc (Zn) is a type of element that are commonly found in the Earth’s environment and may be originated either naturally from the environment or produced by human activities. Zn has been identified as a hazardous metal which can give harmful effects to human health and Earth’s environment. Therefore, it is very important to develop a simplest method which does not require laborious work in order to detect Zn metal ions. Ligand of AFCMSH was synthesized by the mean of reflux reaction between 2-amino-3-formylchromone (AFC) and 4methylbenzenesulfonylhydrazide (MSH). The molecular structure of the ligand in the ground state was optimized using density functional theory (DFT/B3LYP) method with 6-311G(d,p) basis set. Characterization of ligand was conducted using spectroscopic techniques such as Fourier Transform Infra-Red spectroscopy (FT-IR), Gas Chromatography Mass Spectrometry (GC-MS), Nuclear Magnetic Resonance spectroscopy (NMR) and Ultraviolet-visible spectroscopy (UV-VIS). Meanwhile the fluorescence property of ligand in the presence of metal cations was recorded using Fluorescence Spectrophotometer. Ligand shows almost no fluorescence property in the presence of various metal ions except for Zn2+ ion when observed under UV light. Interestingly, ligand exhibits a remarkable fluorescence response by giving yellow-green fluorescence with strong fluorescence intensity in the emission spectrum at 501nm at excitation of 375 nm upon addition of one equivalent of Zn2+.

Successful engraftment after cord blood transplantation from an HLA‐homozygous donor (homo‐to‐hetero cord blood transplantation) in a primary myelofibrosis patient with broad HLA antibodies

Donor-specific human leukocyte antigen (HLA) antibodies are a significant risk factor for graft failure in cord blood transplantation (CBT). Although there are several treatments to decrease HLA antibodies, such as platelet transfusion, plasma exchange, rituximab, and bortezomib, their effectiveness has not been established. We herein report the case of a primary myelofibrosis (PMF) patient with broad HLA antibodies who underwent CBT from an HLA-homozygous donor in which the alleles were matched only in the host-versus-graft direction (homo-to-hetero CBT). The cord blood was killer cell immunoglobulin-like receptor (KIR) ligand matched. She received a reduced-intensity conditioning regimen. We used tacrolimus and mycophenolate mofetil as prophylaxis against graft-versus-host disease (GVHD). The neutrophils engrafted on Day 31. A chimerism analysis with fluorescence in situ hybridization of peripheral blood cells showed 99.9% donor type on Day 33. She developed only mild acute skin GVHD and chronic skin GVHD. This case indicates the usefulness of homo-to-hetero CBT in a patient with broad HLA antibodies with a strong mean fluorescence intensity, which is a significant risk factor for graft failure. Further studies are necessary to determine the risk of GVHD and to elucidate the association between KIR ligand incompatibility and graft failure in homo-to-hetero CBT.

Printable Monodisperse All‐Inorganic Perovskite Quantum Dots: Synthesis and Banknotes Protection Applications

AbstractAll‐inorganic perovskite quantum dots (PQDs) have drawn great attention recently, which are newcomer materials for banknotes protection. Herein, CsPbX3 (X = Cl, Br, I) PQDs are synthesized via one‐step hot‐injection method. It is interesting to find that the fluorescent colors can be tuned over wide visible spectra region of 506 and 636 nm by changing the ratio of halide ions. Then, the PQDs with strong fluorescence intensity, narrow full width at half maximum of 15–35 nm, and high quantum yields of 86.6% are formulated as fluorescent anticounterfeiting inks. Finally, the designable patterns are successfully printed on paper, polyethylene terephthalate, and banknotes by multiple printing techniques, including screen printing, inkjet printing, and roll‐to‐roll printing. The desired printed patterns are colorless under visible light but exhibit bright red, green, and cyan color outputs when exposed to 365 and 254 nm light. Moreover, the polydimethylsiloxane film of PQDs still emits bright color outputs even after 60 days. The excellent dual‐modal fluorescent properties make PQDs potential candidates in the field of banknotes protection.

3-Formylpyrazolo[1,5- a]pyrimidines as Key Intermediates for the Preparation of Functional Fluorophores.

A one-pot route for the regioselective synthesis of 3-formylpyrazolo[1,5- a]pyrimidines 4a-k in good yields through a microwave-assisted process is provided. The synthesis proceeds via a cyclocondensation reaction between β-enaminones 1 with NH-3-aminopyrazoles 2, followed by formylation with an iminium salt moiety (Vilsmeyer-Haack reagent). These N-heteroaryl aldehydes 4 were successfully used as strategic intermediates for the preparation of novel functional fluorophores with yields up to 98%. The structures of the products obtained and regioselectivity of the reactions were determined on the basis of NMR measurements and X-ray diffraction analysis. Since pyrazolo[1,5- a]pyrimidines (PPs) 3 have shown an important fluorescence, photophysical properties of four 2-methylderivatives substituted at position 7 with different acceptor (A) or donor (D) groups were investigated. The compounds evaluated exhibited large Stokes shift in different solvents, but only the substituted p-methoxyphenyl (4-An) showed a strong fluorescence intensity with quantum yields up to 44% due to its greater ICT. Therefore, hybrid systems based on pyrazolo[1,5- a]pyrimidines could be used as fluorescent probes to detect biologically or environmentally relevant species.

Ultrasensitive fluorescent detection of nucleic acids based on label-free enzymatic-assisted cascade signal amplification

A simple and homogenous label-free fluorescent method based on target-triggered and enzymatic-assisted isothermal cascade signal amplification was established for nucleic acid detection. This amplification method consists of two circuits that depend on polymerase and nicking endonuclease. In the presence of a target, a hairpin probe was opened to initiate the polymerization and nicking reaction, producing target analogues and G-rich sequences, and releasing the original target DNA. The released target and produced target analogues then trigger a new amplification cycle. Large amounts of G-rich sequences were generated through this cascade amplification process. The fluorogenic dye thioflavin T (ThT) specifically recognized G-rich sequences to form a G-quadruplex/ThT complex, which induced a strong fluorescence intensity. The approach was ultrasensitive for nucleic acid detection, and the detection limit was as low as 5.6 fM. The system discriminates single-nucleotide mutations in DNA and provides a promising strategy for nucleic acid detection in complex biological samples. This simple, label-free and ultrasensitive approach is a promising tool for biomedical research and clinical diagnostics.

Facile fabrication of luminescent hyaluronic acid with aggregation-induced emission through formation of dynamic bonds and their theranostic applications

Aggregation-induced emission (AIE) is an abnormal phenomenon, which has been extensively explored for various applications. Taken advantage of the unique AIE feature, a number of luminescent nanoprobes with strong fluorescence intensity could thus be fabricated through different strategies; however, the fabrication of AIE-active carbohydrate polymers is still challenge owing to the poor solubility of carbohydrate polymers in most of organic solvents. In this work, a rather facile strategy has been developed for fabricating AIE-active sodium hyaluronate (Sh) through the formation of dynamic phenyl borate between the phenylboronic acid groups of AIE dye (An-B(OH)2)) and Sh in a “one-pot” route. This reaction could occur under low temperature, air atmosphere and in the present water. The physicochemical properties, biocompatibility, biological imaging and drug delivery performance of the final An-Sh fluorescent organic nanoparticles (FNPs) were confirmed by different characterization techniques. Results suggested that An-Sh FNPs possess high water dispersibility, strong fluorescence, and good biocompatibility. These excellent properties make An-Sh FNPs great potential for biological imaging and controlled drug delivery applications. In conclusion, we have developed a facile one-pot strategy for the preparation of AIE-active FNPs through the formation of dynamic bonds in rather mild experimental conditions. The outstanding properties and performance of An-Sh FNPs make them promising candidates for biological imaging and controlled drug delivery applications.

Fluorometric aptasensing of the neonicotinoid insecticide acetamiprid by using multiple complementary strands and gold nanoparticles.

A fluorometric aptamer-based assay was developed for ultrasensitive and selective determination of the neonicotinoid insecticide acetamiprid. The method is based on the use of an aptamer against acetamiprid, multiple complementary strands (CSs), and gold nanoparticles (AuNPs). It is found that by using different CSs, the sensitivity and selectivity of the method is enhanced. On addition of acetamiprid to the aptamer, they will bind to each other and CS1-fluorescein (FAM)-labeled CS2 (as a dsDNA) will beformed. The FAM-labeled dsDNA does not bind to the AuNPs (as a strong quencher) and remains free in the environment, resulting in a strong fluorescence intensity. Without the introduction of acetamiprid, FAM-labeled CS2 binds to AuNPs directly and indirectly through hybridization with CS3 immobilized on the surface of the AuNPs. So, the fluorescence intensity of FAM-labeled CS2 is significantly quenched by AuNPs. The method can detect acetamiprid in the 5 to 50nM concentration range with a 2.8nM detection limit. The assay was applied to the determination of acetamiprid in spiked tap water where is gave recoveries that ranged between 95.4% and 94.4%. Graphical abstract (a) In the presence of acetamiprid, aptamer interacts with acetamiprid. The formation of aptamer/acetamiprid causes pairing of complementary strand 1 with FAM-labeled complementary strand, leading to a strong fluorescence intensity. (b) In the absence of acetamiprid, aptamer is hybridized with complementary strand 1. Thus, a very weak fluorescence signal is detected.

A selective fluorescent sensor for Cu(II) ion in ethanol and acetone based on BODIPY

A selective fluorescent sensor for Cu(II) ion in ethanol and acetone based on boradiazaindacene (BODIPY) has been studied. The selectivity towards Cu(II) ion is good over Ag(I), Cd(II), Fe(III), Hg(II), Ni(II), Pb(II), and Zn(II) ions, only Fe(III), Hg(II) and Ni(II) ions showed a slight interference. The solution showed strong fluorescence intensity after addition of triethanolamine, indicating that the Sensor 1-Cu(II) complex could be reversed by triethanolamine.

Protein coated gold nanoparticles as template for the directed synthesis of highly fluorescent gold nanoclusters

Bovine serum albumin (BSA) modified gold nanoparticles (AuNPs) was selected as template for the synthesis of AuNPs@gold nanoclusters (AuNCs) core/shell nanoparticles, in which BSA not only acted as dual functions agent for both anchoring and reducing Au3+ ions, but also was employed as a bridge between the AuNPs and AuNCs. Optical properties of AuNPs@AuNCs core/shell nanoparticles were studied using UV–visible and fluorescence spectroscopy. The prepared AuNPs@AuNCs core/shell nanoparticles exhibited sphere size uniformity with improved monodispersity, excellent fluorescence and fluorescent stability. Compared with AuNCs, AuNPs@AuNCs core/shell nanoparticles possessed large size and strong fluorescence intensity due to the effect of AuNPs as core. Moreover, the mechanism of the AuNPs induced fluorescence changes of the core/shell nanoparticles was first explored.