Self-assembly of manganese doped zinc sulfide quantum dots/CTAB nanohybrids for detection of rutin

Preparation of Nitrogen and Sulfur Co-Doped Fluorescent Carbon Dots from Cellulose Nanocrystals as a Sensor for the Detection of Rutin

The poor water solubility, large particle size, and low accessibility of cellulose, the most abundant bioresource, have restricted its generalization to carbon dots (CDs). Herein, nitrogen and sulfur co-doped fluorescent carbon dots (N, S-CDs) were hydrothermally synthesized using cellulose nanocrystals (CNC) as a carbon precursor, exhibiting a small particle size and excellent aqueous dispersion. Thiourea was selected as a nitrogen and sulfur dopant to introduce abundant fluorescent functional groups into N, S-CDs. The resulting N, S-CDs exhibited nanoscale size (6.2 nm), abundant functional groups, bright blue fluorescence, high quantum yield (QY = 27.4%), and high overall yield (16.2%). The excellent optical properties of N, S-CDs endowed it to potentially display a highly sensitive fluorescence "turn off" response to rutin. The fluorescence response for rutin allowed a wide linear range of 0-40 mg·L^-1, with a limit of detection (LOD) of 0.02 μM, which revealed the potential of N, S-CDs as a rapid and simple sensing platform for rutin detection. In addition, the sustainable and large-scale production of the N, S-CDs in this study paves the way for the successful high-value utilization of cellulose.

Inorganic-inorganic nanohybrids for drug delivery, imaging and photo-therapy: recent developments and future scope

Advanced nanotechnology has been emerging rapidly in terms of novel hybrid nanomaterials that have found various applications in day-to-day life for the betterment of the public. Specifically, gold, iron, silica, hydroxy apatite, and layered double hydroxide based nanohybrids have shown tremendous progress in biomedical applications, including bio-imaging, therapeutic delivery and photothermal/dynamic therapy. Moreover, recent progress in up-conversion nanohybrid materials is also notable because they have excellent NIR imaging capability along with therapeutic benefits which would be useful for treating deep-rooted tumor tissues. Our present review highlights recent developments in inorganic-inorganic nanohybrids, and their applications in bio-imaging, drug delivery, and photo-therapy. In addition, their future scope is also discussed in detail.

Preparation of galactose oxidase functional phosphorescent quantum dots and detection of D-galactose

Environmental friendly nano biosensor can improve the detection performance of traditional biomolecular sensors and have important application value in practical applications. In this study, a kind of room temperature phosphorescence (RTP) quantum dots (QDs) (GOX RTP QDs) nanobiosensor was prepared by mineralization at room temperature (25 °C), using galactose oxidase (GOX) as template, which improved the catalytic ability of traditional GOx to D-Galactose. The specific enzyme substrate reaction between GOx and D-Galactose and photoinduced electron transfer (Piet) were used to detect the RTP of D-galactose. The linear range of D-galactose detection is 0.02-0.8 mM, and the detection limit of the method is 0.008 mM. This method is based on the RTP property of QDs, which can effectively avoid the interference of background fluorescence of biological samples, and does not need complex sample pretreatment process. Therefore, this method is more suitable for the quantitative detection of D-Galactose in biological samples.

A covalent triazine framework as an oxidase mimetic in the luminol chemiluminescence system: application to the determination of the antioxidant rutin

It is found that a covalent triazine framework (CTF-1) (that was prepared from 1,4-dicyanobenzene) exhibits oxidase-like activity toward the oxidation of luminol with dissolved oxygen in alkaline condition to produce intense blue chemiluminescence (CL). The reaction follows Michaelis-Menten kinetics and shows strong specificity for luminol. Reactive oxygen species including ¹O₂, ^•OH and O₂^•- are testified to be involved in the reaction and responsible for the CL. The reaction was applied to the determination of the radical-scavenging activity of antioxidants, with rutin, kaempferol and ferulic acid serving as model scavengers. A sensitive CL method was developed for the determination of rutin based on its inhibitory effect on the reaction. The CL system gave a linear response to the concentration of rutin in the range of 0.03-0.25 μmol·L^-1 with a limit of detection of 0.015 μmol·L^-1. The practicability of the method was demonstrated by successful determination of rutin in tablets and in Flos Sophorae Immaturus. Graphical Abstract.

-Phosphorescent Mesoporous Surface Imprinting Microspheres: Preparation and Application for Transferrin Recognition from Biological Fluids

The relationship between the thickness of surface molecularly imprinted polymers (MIPs) and specific recognition performance of transferrin (Trf) as well as the quantitative relation between the grafting amount of Mn-ZnS room-temperature phosphorescence (RTP) quantum dots (QDs) (short for PQDs) and RTP signals for recognition of Trf was analyzed in this study. Based on analysis results, RTP protein mesoporous imprinting microspheres (SiO₂-PQDs-MIPs) with high specificity and strong interference resistance were developed using a mesoporous SiO₂ nanomaterial that can create more three-dimensional precise recognition sites as the matrix and using PQDs with strong resistance to background fluorescence interference as the luminescent materials. A discriminatory analysis of Trf was realized by the phosphorescence quenching principle based on light quenching caused by the photoinduced electron transfer. The concentration range, limit of detection, relative standard deviation, and imprinting factor of Trf detection under pH 7.4 are 0.05-1.0 μM, 0.014 μM, 3.23%, and 3.09, respectively. Although the sensing signals of SiO₂-PQDs-MIPs for proteins are based on the phosphorescence of PQDs, they are particularly suitable for specific recognition and accurate quantitative detection of proteins in biological fluids. Research conclusions are expected to realize high-efficiency recognition of target proteins in actual biological samples.

Polyphenol oxidase/gold nanoparticles/mesoporous carbon-modified electrode as an electrochemical sensing platform for rutin in dark teas

In the communication, by virtue of the excellent conductivity and great surface area of mesoporous carbon (FDU-15), the enhanced conductivity of Au NPs, and the good electrochemical response of polyphenol oxidase (PPO) to rutin, a PPO/AuNPs/FDU-15-modified electrode was used as a candidate for the determination of rutin in dark teas with satisfactory results.

By virtue of great surface area of mesoporous carbon, enhanced conductivity of AuNPs, and good electrochemical response of polyphenol oxidase to rutin, a PPO/AuNPs/FDU-15-modified electrode was used for the determination of rutin in dark teas.

Molecular imprinting based on phosphorescent resonance energy transfer for malachite green detection in fishes and water

Room temperature phosphorescent quantum dots combined with molecular imprinting technology for the highly selective detection of malachite green (MG) in fish and water.

Single-sensing-unit 3D quantum dot sensors for the identification and differentiation of mucopolysaccharides

Principle of Mn–ZnS⁺ QDs 3D sensors used to identify and differentiate MPSs.

“Design of novel WO3/CB nanohybrids” An affordable and efficient electrochemical sensor for the detection of multifunctional flavonoid rutin

A CB/WO₃ nanohybrid-modified SPCE was applied for the electrochemical determination of rutin.

Sensitive prostate specific antigen quantification using dihydrolipoic acid surface-functionalized phosphorescent quantum dots

Herein, high-quality Mn-doped ZnS quantum dots (QDs) have been synthesized using a facile approach directly in aqueous media. The surface of the obtained QDs was further modified by cap-exchange of the native cysteine shell with dihydrolipoic acid (DHLA) ligands resulting in nanocrystals with high water-stability having an intense phosphorescent signal. Covalent bioconjugation of the DHLA-coated nanoparticles with an anti-IgG antibody was then carried out. Interestingly the QD immunoprobe (QD-labelled antibodies) maintained an intense phosphorescence emission, without any significant spectral-shift (as compared to the free QDs). Coupling of an asymmetric flow field flow fractionation technique to an elemental mass spectrometry detection enabled the accurate determination of the efficiency of the bioconjugation reaction. The obtained nanoparticle-antibody bioconjugate was then applied to develop a quantitative sandwich-type phosphorescent immunoassay for Prostate Specific Antigen (PSA), and a limit of detection (LOD) of 17 pg mL^-1 of PSA was achieved and allow to quantify such biomarker in samples within clinically relevant levels. Finally, the assay was validated for the quantification of PSA in the cellular media of prostate cancer cells. Obtained results proved the robustness of the proposed immunoassay based on long-lived phosphorescence measurements against eventual photoluminescent interferences significantly affecting the conventional short-lived fluorescence detection.

Enhanced photo-electrochemical response of reduced graphene oxide and C3N4 nanosheets for rutin detection

Herein, a sensitive photo-electrochemical sensor based on C₃N₄ and reduced graphene oxide nanosheets modified glassy carbon electrode (C₃N₄-RGO/GCE) has been fabricated for the detection of rutin under UV light illumination. In C₃N₄-RGO catalyst, RGO not only works as a template but also promotes electron transfer, meanwhile, C₃N₄ acts as a photocatalyst. Benefiting from the superior electron transfer capacity and efficient UV light effect of the C₃N₄-RGO catalyst, we get a photo-electrochemical sensor for the rutin detecting with a low detection limit of 1.78×10^-9molL^-1 and an excellent linear range of 5×10^-9-1.4×10^-4molL^-1. Meanwhile, the achieved C₃N₄-RGO/GCE demonstrated nice selectivity, good reproducibility as well as reliable stability. Moreover, compared with the electrochemical determination, the C₃N₄-RGO electrode provides a new way for rutin detection by photo-electrochemical method with a promising UV light responsive result.

Study of the interaction of flavonoids with 3-mercaptopropionic acid modified CdTe quantum dots mediated by cetyltrimethyl ammonium bromide in aqueous medium

Flavonoids are polyphenols that help the maintenance of health, aiding the prevention of diseases. In this work, CdTe QDs coated with 3-mercaptopropionic acid (3MPA), with an average size of 2.7nm, were used as photoluminescence probe for flavonoids in different conditions. The interaction between 14 flavonoids and QDs was evaluated in aqueous dispersions in the absence and in the presence of cetyltrimethylammonium bromide (CTAB). To establish a relationship between photoluminescence quenching and the concentration of flavonoids, the Stern-Volmer model was used. In the absence of CTAB, the linear ranges for quercetin, morin and rutin were from 5.0×10^-6molL^-1 to 6.0×10^-5molL^-1 and from 1.0×10^-5molL^-1 to 6.0×10^-4molL^-1 for kaempferol. The sensibility of the Stern-Volmer curves (K_s) indicated that quercetin interacts more strongly with the probe: K_{s quercetin}>K_{s kaempferol}>K_{s rutin}>K_{s morin}. The conjugation extension in the 3 rings, and the acidic hydroxyl groups (positions 3'and 4') in the B-ring enhanced the interaction with 3MPA-CdTe QDs. The other flavonoids do not interact with the probe at 10^-5molL^-1 level. In CTAB organized dispersions, K_{s 3-hydroxyflavone}>K_{s 7-hydroxyflavone}>K_{s flavona}>K_{s rutin} in the range from 1.0×10^-6molL^-1 to 1.2×10^-5molL^-1 for flavones and of 1.0×10^-6molL^-1 to 1.0×10^-5molL^-1 for rutin. Dynamic light scattering, conductometric measurements and microenvironment polarity studies were employed to elucidate the QDs-flavonoids interaction in systems containing CTAB. The quenching can be attributed to the preferential solubility of hydrophobic flavonoid in the palisade layer of the CTAB aggregates adsorbed on the surface of the 3MPA CdTe QDs.

Equilibrium and kinetics study on removal of arsenate ions from aqueous solution by CTAB/TiO2 and starch/CTAB/TiO2 nanoparticles: a comparative study

We present a comparative study on the efficacy of TiO₂ nanoparticles for arsenate ion removal after modification with CTAB (N-cetyl-N,N,N-trimethyl ammonium bromide) followed by coating with starch biopolymer. The prepared nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), thermogravimetry, scanning electron microscopy (SEM) and electron dispersive X-ray analysis (EDX). The removal efficiency was studied as a function of contact time, material dose and initial As(V) concentration. CTAB-modified TiO₂ showed the highest arsenate ion removal rate (∼99% from 400 μg/L). Starch-coated CTAB-modified TiO₂ was found to be best for regeneration. For a targeted solution of 400 μg/L, a material dose of 2 g/L was found to be sufficient to reduce the As(V) concentration below 10 μg/L. Equilibrium was established within 90 minutes of treatment. The sorption pattern followed a Langmuir monolayer pattern, and the maximum sorption capacity was found to be 1.024 mg/g and 1.423 mg/g after starch coating and after CTAB modification, respectively. The sorption mechanisms were governed by pseudo second order kinetics.

A two-dimensional sensing device based on manganese doped zinc sulfide quantum dots for discrimination and identification of common sugars

A Mn-doped ZnS QD 2D sensor for identification and separation of common sugars.

Detection of tumor marker miRNA21 based on phosphorescent resonance energy transfer of Mn–ZnS QDs

Since miRNA21 is a marker of many human tumors, trace detection of miRNA21 contributes to early tumor diagnosis.

Detection of phosphate based on phosphorescence of Mn doped ZnS quantum dots combined with cerium(iii)

A simple and rapid room-temperature phosphorescence (RTP) sensor for phosphate detection was developed on the basis of Ce³⁺ modulated mercaptopropionic acid (MPA)-capped Mn-doped ZnS quantum dots (QDs).

Self-assembly of phosphorescent quantum dots/boronic-acid-substituted viologen nanohybrids based on photoinduced electron transfer for glucose detection in aqueous solution

We synthesized boronic-acid-substituted viologens (BBV) and designed a glucose sensor based on room-temperature phosphorescence (RTP) quantum dots (QDs) and BBV.

Boronic acid based imprinted electrochemical sensor for rutin recognition and detection

An electrochemical sensor based on boronic acid affinity and molecular imprinted polymer specific binding was developed for rutin dual-recognition and sensitive detection.

Construction of biomolecular sensors based on quantum dots

At this post-genomic era, the focus of life science research has shifted from life genetic information to general biofunctions. Biomolecular sensors based on QDs will play an important role in the identification and detection of biomolecules.

Room-temperature phosphorescence logic gates developed from nucleic acid functionalized carbon dots and graphene oxide

Room-temperature phosphorescence (RTP) logic gates were developed using capture ssDNA (cDNA) modified carbon dots and graphene oxide (GO). The experimental results suggested the feasibility of these developed RTP-based "OR", "INHIBIT" and "OR-INHIBIT" logic gate operations, using Hg(2+), target ssDNA (tDNA) and doxorubicin (DOX) as inputs.

Ion-unquenchable and thermally "on-off" reversible room temperature phosphorescence of 3-bromoquinoline induced by supramolecular gels

Ion-unquenchable and thermally on-off reversible room temperature phosphorescence (RTP) can be induced by entrapping 3-bromoquinoline (3-BrQ) into supramolecular gels formed by the self-assembly of a sorbitol derivative (DBS). In comparison with conventional substrates inducing RTP, the gel state 3-BrQ/DBS can produce strong RTP due to the efficient restriction of the vibration of 3-BrQ. Notably, the rather inconvenient deoxygenation is no longer necessary in the preparation of 3-BrQ/DBS gels. The produced RTP was found to be very fast to reach stable, not depending on the standing time. As a reference, in the liquid state of 3-BrQ/sodium deoxycholate (NaDC), stable RTP can be observed after standing for 5 h. The investigation of RTP quenching indicates that the mechanism of RTP induced by DBS gels mainly involves the microenvironment in which 3-BrQ is located. 3-BrQ was entrapped in the hydrophobic 3D network structure of DBS gels, thereby restricting the motion and collision of 3-BrQ and avoiding RTP quenching and additionally quenching by ions. Furthermore, the RTP of 3-BrQ/DBS gels show an excellent "on-off" effect at 10 or 80 °C. This indicates that the solid DBS gel is beneficial for the preparation of RTP sensor devices.

Application of BSA-bioconjugated phosphorescence nanohybrids in protein detection in biofluids

In this study, a cross-linking agent 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) was used to link QDs and bovine serum albumin (BSA) to form a nanohybrid BSA–Mn-ZnS Room-Temperature Phosphorescence (RTP) biosensor.