Detection of biological mercaptan by DNA functionalized room temperature phosphorescent quantum dot nanocomposites

In this study, green low-toxicity Mn-doped Zns (Mn-Zns) room-temperature phosphorescent (RTP) quantum dots (QDs) (PQDs) nanocomposites (DNA-PQDs) were prepared under the optimal conditions by using single-stranded DNA (PS-C-ssDNA) rich of cytosine C and Thioguanine G (PS) as the template. DNA-PQDs interact with Ag⁺ to form AgN bonds and further produce C-Ag⁺-C conjugates. As a result, DNA-PQDs cluster together and induce the phosphorescent exciton energy transfer (PEET), resulting in quenching of room-temperature phosphorescent of DNA-PQDs. Nevertheless, Ag⁺ tends to form AgS bonds with biological mercaptan when it is added in, so that Ag⁺ falls from C-Ag⁺-C. DNA-PQDs changed from aggregation to looseness and RTP is recovered accordingly. On this basis, RTP detection of biological mercaptan is realized. Since this sensor system has RTP properties based on DNA-PQDs, it is very applicable to detection of mercaptan compounds in biological fluids.

-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.

Preparation of DNA functional phosphorescent quantum dots and application in melamine detection in milk

Bio-functionalization of quantum dots (QDs) is of important value in practical applications. With single-stranded DNA (ssDNA) rich in thymine T and thioguanine G taken as the template, a new-type nanocomposite material (ssDNA-PQDs) synthesized from low-toxicity T-ssDNA functionalized Mn–ZnS and room-temperature phosphorescent (RTP) QDs (PQDs) was prepared in this paper by optimizing synthesis conditions, and these ssDNA-PQDs could emit orange RTP signals at 590 nm. As these ssDNA-PQDs are rich in T sequences and T sequences can bond with melamine through the hydrogen-bond interaction, ssDNA-PQDs experience aggregation, thus causing phosphorescent exciton energy transfer (PEET) between ssDNA-PQDs of different particle sizes and their RTP quenching. Based on this principle, an RTP detection method for melamine was established. The linear range and detection limit of the detection method are 0.005–6 mM and 0.0016 mM respectively. As this method is based on the RTP nature of ssDNA-PQDs, it can avoid disturbance from background fluorescence and scattered light of the biological fluid, and it is very suitable for melamine detection in the biological fluid milk.

Preparation of phosphorescent quantum dots taking single-stranded DNA as a template and their application to melamine detection in milk.

Detection of resveratrol by phosphorescence quantum dots without conjunction and mutual impact exploration

In this study, a convenient and sensitive method for the detection of resveratrol was established based on phosphorescence quenching of resveratrol for MPA-capped Mn:ZnS QDs. The quenching intensity was in proportion to the concentration of resveratrol within a certain range. Under optimal conditions, the present assay was valid for detecting resveratrol in the range from 0.03 μM to 14 μM with a detection limit of 0.01 μM. The mechanism of action was also explored, and its application in actual samples was also demonstrated with satisfactory results. This study aims to provide a convenient method for the detection of resveratrol.

“Turn on” room-temperature phosphorescent biosensors for detection of hyaluronic acid based on manganese-doped ZnS quantum dots

Biosensors based on excellent optical properties of quantum dots (QDs) nanohybrids are efficient for biological detection. In this work, a room-temperature phosphorescent (RTP) PDAD–Mn–ZnS QDs biosensor was constructed with poly(diallyldimethylammonium chloride) (PDAD) as the modifier of MPA-capped Mn–ZnS QDs, and used to detect hyaluronic acid (HA). The newly-added HA induced severe electrostatic interaction with PDAD–Mn–ZnS QDs, leading to the aggregation between PDAD–Mn–ZnS QDs and HA and thereby enhancing RTP. The enhancement of RTP was proportional to the HA concentrations within certain ranges. On this basis, a high-performance HA sensor was built and this sensor had a detection limit of 0.03 μg mL⁻¹ and a detection range of 0.08–2.8 μg mL⁻¹. This proposed RTP sensor can avoid interferences from the background fluorescence or scattering light of the matrix that are encountered in spectrofluorometry. Thus, this biosensor is potentially suitable for detection of HA in real samples without complicated pretreatment.

Fabricating PDAD–Mn–ZnS QDs nanohybrids as a facile room-temperature phosphorescent biosensor for detection of hyaluronic acid.

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.

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.

Room-temperature phosphorescence probe based on Mn-doped ZnS quantum dots for the sensitive and selective detection of selenite

Selenite was selectively and sensitively detected based on the room-temperature phosphorescence quenching of Mn–ZnS QDs caused by HSe⁻ from the reaction of selenite and glutathione.

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.