Fluorescent Quantum Dots Research Articles

Quantum Dot-Based Immunoassays: Unraveling Sensitivity Discrepancies and Charting Future Frontiers.

The 2023 Nobel Prize in Chemistry honors the groundbreaking contributions of Alexei Ekimov, Louis Brus, and Moungi Bawendi to the field of quantum dots (QDs). In this spirit, we developed a direct competitive QD fluorescence immunoassay (dc-QD-FLISA) to detect aristolochic acid type I (AAI), a potent carcinogen found in herbal remedies. Unexpectedly, the dc-QD-FLISA exhibited lower sensitivity than that of an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA), contrary to our initial expectations. This discrepancy in the sensitivity prompted a comprehensive analysis of the entire experimental process. We propose that steric hindrance between QDs and antigen-binding sites on antibodies may significantly diminish the binding efficiency, reducing sensitivity within the dc-QD-FLISA method. Furthermore, issues such as buffer conditions, antibody handling, and separation methods are also contributing factors. We recommend site-directed QD modification and stringent consideration of the experimental conditions. This study not only provides insights into QD-based immunoassays but also highlights the need for future advancements in immunoassay technology in terms of augmenting sensitivity and specificity, potentially revolutionizing disease diagnosis, biomarker discovery, and biomedical research.

Synergism Variation between intracellular Glutathione, phycocyanin and SOD in microalgae by carbon quantum dot fluorescence

Based on the use of CQDs as fluorescent probe and covalent coupling method to detect biological molecules with amino groups, to deeply analysis and detect the metabolism of Microcystis aeruginosa. The metabolic changes of carboxyl biomolecules in Microcystis aeruginosa were analyzed by covalent coupling method, including GSH, phycocyanin and SOD enzyme. The changes of GSH content and its correlation between phycocyanin, SOD were analyzed. The content of phycocyanin and SOD reached the maximum on the 65th day, and GSH was more sensitive to the growth and metabolism of microalgae. GSH plays an important role in reducing the external oxidative damage of microalgae cells. The synthesis of glutathione (GSH), GSH/GSSG mutual transformation, the production of phytochelating peptide (PC), the ASA-GSH cycle, and other physiological processes are interconnected. These interactions are crucial for preserving the antioxidant properties of microalgae and regulating redox-sensitive signal transduction.

On‐Patient Temporary Medical Record for Accurate, Time‐Sensitive Information at the Point of Care

AbstractAccurate medical recordkeeping is important for personal and public health. Conventional forms of on‐patient medical information, such as medical alert bracelets or finger‐markings, may compromise patient privacy because they are readily visible to other people. Here, the development of an invisible, temporary, and easily deployable on‐patient medical recordkeeping system is reported. Information is stored in unique patterns of spatially distributed near‐infrared (NIR) fluorescent quantum dots (QDs), which are delivered to the skin using dissolvable microneedle arrays. The patterns are invisible to the naked eye but detectable with an infrared camera, which can extract information with >98% accuracy using automated pattern recognition software. By encapsulating NIR QDs in an FDA‐approved biodegradable polymer, biodegradation rates can be tuned so that the encoded medical information can be conveyed in both a spatial and temporal manner, with some components fading within 100 days and others persisting for 6 months. This may be particularly useful for administering a series of vaccinations or treatments by indicating if enough time has passed for the patient to receive the next dose. Importantly, this system contains no personal information, does not require connection to a centralized database, and is not visible to the naked eye, ensuring patient privacy.

Harnessing fluorescent carbon quantum dots from natural resource for advancing sweat latent fingerprint recognition with machine learning algorithms for enhanced human identification.

Nowadays, it is fascinating to engineer waste biomass into functional valuable nanomaterials. We investigate the production of hetero-atom doped carbon quantum dots (N-S@MCDs) to address the adaptability constraint in green precursors concerning the contents of the green precursors i.e., Tagetes erecta (marigold extract). The successful formation of N-S@MCDs as described has been validated by distinct analytical characterizations. As synthesized N-S@MCDs successfully incorporated on corn-starch powder, providing a nano-carbogenic fingerprint powder composition (N-S@MCDs/corn-starch phosphors). N-S@MCDs imparts astounding color-tunability which enables highly fluorescent fingerprint pattern developed on different non-porous surfaces along with immediate visual enhancement under UV-light, revealing a bright sharp fingerprint, along with long-time preservation of developed fingerprints. The creation and comparison of latent fingerprints (LFPs) are two key research in the recognition and detection of LFPs, respectively. In this work, developed fingerprints are regulated with an artificial intelligence program. The optimum sample has a very high degree of similarity with the standard control, as shown by the program's good matching score (86.94%) for the optimal sample. Hence, our results far outperform the benchmark attained using the conventional method, making the N-S@MCDs/corn-starch phosphors and the digital processing program suitable for use in real-world scenarios.

Lemon peel-based fluorescent carbon quantum dots as a functional filler in polyvinyl alcohol-based films for active packaging applications

Carbonation of agro-waste into high-value-added products is becoming a promising strategy for producing functional active materials and for reducing landfills. Carbon quantum dots (CQDs) are of great attention due to their non-toxic, antibacterial, antioxidant, fluorescent, and other functional properties. The current study demonstrated the hydrothermal synthesis of dried lemon peel-based carbon quantum dots (LCQDs) and their incorporation in polyvinyl alcohol for developing active films. The developed LCQDs exhibit excellent fluorescence, antioxidant, and antibacterial activities against S. aureus, B. cereus, S. enterica, L. monocytogenes, and E. coli. Interestingly, as confirmed by FE-SEM and FTIR, LCQDs showed excellent compatibility with PVA-based films. The mechanical and water vapor barrier properties were improved by adding 3% LCQDs to the PVA film, which also resulted in improved UVC (99.9%), UVB (99.9%) and UVA (99.1%) blocking effects. Additionally, PVA film containing 3% LCQDs showed 98.9% radical scavenging activity by ABTS method and was 100% effective against S. aureus and S. enterica. Therefore, 3% LCQDs-incorporated PVA films could have excellent potential as active food packaging materials.

Biomimetic synthesis of RPL14B-based CdSe quantum dots for the detection of heavy metal copper ions.

In the present study, an Escherichia coli-expressed yeast ribosomal protein was used as a template for synthesizing RPL14B-based CdSe quantum dots in vitro via the quasi-biosynthesis strategy at low temperature. The synthetic bionic RPL14B-based CdSe quantum dots were characterized using TEM, HRTEM, and EDX spectra, and the results showed that the synthesized quantum dots were CdSe quantum dots with a crystal face spacing of 0.21 and 0.18 nm. The biomimetic method-synthesized quantum dots exhibited the characteristics of a uniform particle size, good dispersion, and strong photobleaching resistance. Moreover, the fluorescence of the RPL14b-based CdSe quantum dots could be specifically quenched using Cu2+ in a linear range of 0.2-10 μM. Finally, these RPL14b-based CdSe quantum dots can be used for the specific detection of heavy metal copper ions in addition to other applications in biological analyses.

Green synthesis of lactic acid and carbon dots using food waste and seashell waste

Novel utilisation of seashell waste in lactic acid fermentation, showcasing fluorescent carbon quantum dots synthesised from cell biomass.

Assembly-fission synthesized fluorescent sulfur quantum dots combined with tyrosinase catalytic oxidation for selective detection of p-aminophenol in water samples

A SQD combined tyrosinase oxidation “ON–OFF” platform constructed for p-AP detection with low cost, high selectivity, convenience and high sensitivity.

A brief review on the nanomaterials-based detection of CKD biomarkers

Chronic kidney disease (CKD) imposes a significant worldwide medical burden, exacerbated by the often limited efficacy of current treatments. The future prevention and management of CKD critically rely on early detection and effective intervention. Nanomaterials (NMs), such as fluorescence carbon dots (CDs), quantum dots (QDs), and metal-based NMs, emerge as unique and highly sensitive probe materials expected to play a substantial role in the precise identification of CKD biomarkers. NMs’ design makes it possible to manage properties including size, shape, charge, and targeting ligands, which enhances the biological compatibility and availability of medicines. Consequently, the rise of NMs in medicine has brought about fresh approaches to CKD diagnosis. This review explores the utility of the NMs for the rapid identification of CKD biomarkers.

Open system massive synthesis of narrow-band blue and green fluorescent graphene quantum dots and their application in water sensing

PG-derived graphene quantum dots (GQDs) were obtained with 99.4% product yield and exhibited narrow-band blue fluorescence with a high quantum yield.

Green transformation of biomass-derived Indian gooseberry into fluorescent intrinsic nitrogen-functionalized carbon quantum dots for real-time detection of vitamin B2 in the nanomolar range

Selective and specific detection of vitamin B2 with a fluorescent nanoprobe synthesized using a green methodology.

Green synthesis of fluorescent carbon quantum dots from bagasse: inhibition of calcium sulphate scales

The conversion of biomass waste generated in large amounts to value-added materials and energy can reduce environmental pollution, atmospheric CO2 emissions and waste disposal costs in a circular economy.

Recent Advancements in Biomedical Research on Fluorescent Carbon Quantum Dots

Recent Advancements in Biomedical Research on Fluorescent Carbon Quantum Dots

Recent advancements towards the green synthesis of carbon quantum dots as an innovative and eco-friendly solution for metal ion sensing and monitoring

An overview of the importance of green chemistry in synthesizing fluorescent carbon quantum dots as an effective tool for metal ion sensing is discussed. Various synthesis methods and mechanisms involved in metal ion sensing using CQDs are presented.

A portable smartphone platform based on fluorescent carbon quantum dots derived from biowaste for on-site detection of permanganate

A schematic illustration of the synthesis pathway of CQDs and their application in MnO4− sensing based on a smartphone-assisted platform is shown.

Operando time and space-resolved liquid-phase diagnostics reveal the plasma selective synthesis of nanographenes.

Coupling atmospheric-pressure low-temperature plasmas to electrochemical reactors enables the generation of highly reactive species at plasma-liquid interfaces. This type of plasma electrochemical reactor (PEC) has been used to synthesize fluorescent nitrogen-doped graphene quantum dots (NGQDs), which are usable for multifunctional applications in a facile, simple, and sustainable way. However, the synthesis mechanism remains poorly understood, as well as the location of synthesis. To research these issues, we present an in situ diagnostics study on liquid phase chemistry during the PEC synthesis of NGQDs from chitosan. Monitoring of the photoluminescence and UV-VIS absorption at different depths in the reaction medium during plasma treatment reveals that the NGQD production initiates at the plasma-liquid interface but its completion and/or accumulation occurs at a few millimetres depth below the interface, where the liquid ceases to flow convectively, as determined by particle image velocimetry. Our study provides insights into the plasma synthesis of fluorescent GQDs/NGQDs from carbon precursors that may prove useful for achieving the scalability of PEC processes up to continuous-flow or array reactors.

Aminopropyl triethoxy silane capped ZnO quantum dots for highly selective dopamine

Quantum dots (QDs) can be used as labels with fluorescent nanoprobes and ZnO QDs have band gap over 4 eV with a large 60 meV exciton binding energy. Capped ZnO presents high quantum efficiency and surface enhancement in biochemical analysis and ultrasensitive detection of biomaterials and proteins. This work reported the synthesis of ZnO QDs capped with different agents of 3-aminopropyl triethoxy silane (APTES), tetraethyl orthosilicate (TEOS) and dimethyl sulfoxide (DMSO) from nonaqueous medium. ZnO QDs were characterized by different techniques of UV-vis absorption spectra, fluorescent emission spectra, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Zeta potential and high-resolution transmission electron microscopy (HRTEM). Photoluminescence (PL) emissions illustrated that APTES capped ZnO QDs have the highest PL intensity and applied as an optical sensor for dopamine (DA) determination in an aqueous solution and real serum samples. The visible luminescence of ZnO may result from either the recombination of a delocalized electron with a deeply trapped hole or the recombination of a delocalized hole with a deeply trapped electron. Zeta potential values showed that the surface potentials of - 4.23, -7.70, -14, -1.94 mV for uncapped ZnO, DMSO, APTES capped, TEOS capped ZnO QDs, respectively. The fluorescence quenching observed in ZnO QDs primarily stemmed from electron transfer between the ZnO QDs and two variants of dopamine: reduced dopamine acting as electron donors and oxidized dopamine-quinone serving as electron acceptors. APTES capped ZnO QDs probe exhibited a linear dynamic range from 6.2 – 0. 195 nM of DA with correlation coefficient (R2) of 0.99, limit of detection (LOD) of 0.2 nM and a sensitivity of 406.6 µM-1.

Photo-controllable azobenzene microdroplets on an open surface and their application as transporters.

The control of droplet motion is a significant challenge, as there has been no simple method for effective manipulation. Utilizing light for the control of droplets offers a promising solution due to its non-contact nature and high degree of controllability. In this study, we present our findings on the translational motion of pre-photomelted droplets composed of azobenzene derivatives on a glass surface when exposed to UV and visible light sources from different directions. These droplets exhibited directional and continuous motion upon light irradiation and this motion was size-dependent. Only droplets with diameters less than 10 μm moved with a maximum velocity of 300 μm min-1. In addition, the direction of the movement was controllable by the direction of the light. The motion is driven by a change in contact angle, where UV or visible light switched the contact angle to approximately 50° or 35°, respectively. In addition, these droplets were also found to be capable carriers for fluorescent quantum dots. As such, droplets composed of photoresponsive molecules offer unique opportunities for designing novel light-driven open-surface microfluidic systems.

Effect of pH on Swelling Ratio and Fluorescence of Quantum Dots (QDs) Based Hydrogel (CuInS2/ZnS QDs)

Effect of pH on Swelling Ratio and Fluorescence of Quantum Dots (QDs) Based Hydrogel (CuInS2/ZnS QDs)

Living Materials Based Dynamic Information Encryption via Light-Inducible Bacterial Biosynthesis of Quantum Dots.

Microbial biosynthesis, as an alternative method for producing quantum dots (QDs), has gained attention because it can be conducted under mild and environmentally friendly conditions, distinguishing it from conventional chemical and physical synthesis approaches. However, there is currently no method to selectively control this biosynthesis process in a subset of microbes within a population using external stimuli. In this study, we have attained precise and selective control over the microbial biosynthesis of QDs through the utilization of an optogenetically engineered Escherichia coli (E. coli). The recombinant E. coli is designed to express smCSE enzyme, under the regulation of eLightOn system, which can be activated by blue light. The smCSE enzymes use L-cysteine and Cd2+ as substrates to form CdS QDs. This system enables light-inducible bacterial biosynthesis of QDs in precise patterns within a hydrogel for information encryption. As the biosynthesis progresses, the optical characteristics of the QDs change, allowing living materials containing the recombinant E. coli to display time-dependent patterns that self-destruct after reading. Compared to static encryption using fluorescent QD inks, dynamic information encryption based on living materials offers enhanced security.