Dot Nanohybrid Research Articles

Gold–Graphene Quantum Dot Hybrid Nanoparticle for Smart Diagnostics of Prostate Cancer

Prostate cancer is one of the most prevalent cancers afflicting men worldwide, often detected at advanced stages, leading to increased mortality rates. Addressing this challenge, we present an innovative approach employing electrochemical biosensing for early-stage prostate cancer detection. This study used Indium–Tin Oxide (ITO) as a substrate and a deposited gold–graphene quantum dot (Au–GQD) nanohybrid to establish electrochemical sensing platforms for DNA-hybridization assays. A capturing DNA probe, PCA3, was covalently immobilized on the surface of the Au–GQDs and deposited electrochemically onto the ITO electrode surface. The Au–GQDs enabled the capturing of the target PCA3 biomarker probe. The sensor achieved a limit of detection (LoD) of up to 211 fM and presented a linear detection range spanning 1 µM to 100 fM. A rapid 5-min response time was also achieved. The tested shelf life of the pre-immobilized sensor was approximately 19 ± 1 days, with pronounced selectivity for its intended target amidst various interferants. The sensing device has the potential to revolutionize prostate cancer management by facilitating early-stage detection and screening with enhanced treatment efficacy.

Synergistic effect of silver nanoparticles decorated graphene quantum dots nanohybrids reinforced polyaniline ternary nanocomposites on optical, thermal, and dielectric properties

ABSTRACT In situ synthesized graphene quantum dots (GQDs) decorated with green synthesized AgNPs (AgNPs@GQDs) hybrid nanofillers reinforced polyaniline (PANI) ternary nanocomposites was synthesized by in situ polymerization. The UV-Vis spectroscopy showed the presence of AgNPs at 402 nm in AgNPs@GQDs hybrid nanofillers, and a charge transfer complex was formed between PANI matrix and AgNPs@GQDs hybrid nanofillers. The direct optical band gap of the ternary nanocomposites calculated from UV-Vis analysis is found to be 3.085 eV, which indicates the ternary nanocomposite may be used for solar cell applications. The Fourier transfer infrared (FTIR) spectroscopy represented the occurrence of interphase interactions between the ternary nanocomposites. The X-ray diffraction (XRD) data showed the positions and intensities of the hybrid nanofillers and PANI matrix. The morphology of the ternary nanocomposites was confirmed by scanning electron microscopy (SEM). The thermogravimetric analysis (TGA) attributed to the thermal degradation of the ternary nanocomposites. The cyclic voltammetry (CV) showed the oxygen reduction potential of the ternary nanocomposites. Photoluminescence (PL) activity of the ternary nanocomposites was confirmed by fluorescence spectroscopy. The AC conductivity of the ternary nanocomposites significantly increases as compared to pure PANI due to the presence of uniformly distributed hybrid nanofillers within PANI matrix.

Charge transfer dynamics in graphene quantum dot-porphyrin derivative nanohybrids appraised via experimental and theoretical calculations

This article is designed to unveil the electronic and spectroscopic property changes of electron withdrawing/releasing group substituted porphyrins, in porphyrin-graphene quantum dot nanohybrids via experimental and computational calculations. Herein, amino, methyl, fluoro & nitro derivatives of meso substituted Tetraphenylporphyrin referred as TAPP, TMPP, TFPP & TNPP respectively, are synthesized from the corresponding benzaldehydes. Charge transfer dynamics of their nanohybrid systems with graphene quantum dots are investigated by electronic spectroscopy, steady state fluorescence and lifetime decay analysis. Negative Gibb's free energy change and dynamic quenching constants stipulate a photoinduced electron transfer with dynamic quenching mechanism within the nanohybrids under scrutiny. Further the computational calculations with the aid of optimized geometries, scatter plots and energy decomposition analysis reflect the same experimental observations. Both experimental and computational studies show that the electron withdrawing group substituted porphyrins have higher interaction with GQD than the electron releasing group substituted porphyrins.

Ratiometric fluorescence detection of Hg2+ based on gold nanocluster/carbon quantum dots nanohybrids.

Ratiometric fluorescence sensing methods are widely used in analysis and detection due to their high sensitivity and stability. In this work, a ratiometric fluorescence method for sensitive detection of Hg2+ was established using a gold nanoclusters/carbon quantum dots (AuNCs/CQDs) nanohybrid probe. The AuNCs/CQDs nanohybrids probe were simply constructed by mixing blue-light-emitting gold nanoclusters (AuNCs) with an orange-emissive carbon quantum dots (CQDs). The probe had two fluorescence emission peaks at 434 nm and 561 nm when the excitation wavelength was 375 nm. With the addition of Hg2+, the fluorescence at 434 nm decreased and the fluorescence at 561 nm remained unchanged; the fluorescence intensity ratio Δ(F434/F561) and Hg2+ concentration have a good linear relationship in the range of 8.32 × 10-7 to 7.69 × 10-5 mol L-1, and the limit of detection (LOD) is 3.58 × 10-7 mol L-1. The method was applied in the detection of Hg2+ in cosmetics and wastewater, and has potential applications for detecting Hg2+ in other samples.

DNA Linked Mixed-Dimensional Heterostructures: The Designing, Nanoscale Control and Device Applications of Tmdc-Quantum Dot Nanohybrids

DNA Linked Mixed-Dimensional Heterostructures: the Designing, Nanoscale Control and Device Applications of TMDC-Quantum Dot Nanohybrids Kai Chen,a Teymour Talha-Dean,b Tingting Zheng, a Stoichko Dimitrov, a Jan Mol b and Matteo Palma a aDepartment of chemistry, Queen Mary University of London, London E1 4NS, United Kingdom bDepartment of Physics, Queen Mary University of London, London E1 4NS, United KingdomThe construction of mixed-dimensional heterostructures is a promising approach for the development of biosensing and optoelectronic systems and devices. The accurate nanoscale control of the heterostructures interface is a key challenge, for instance to tune the distance between the individual components and their stoichiometry, that in turn affect their electronic coupling. In this regard, DNA can be a powerful structural and functional linker for nano-hybrids assembly, due to its tunability down to sub-nanometer control.Our current interest is focused on the fabrication of TMDC-based nanohybrids using double stranded (ds) DNA as both a linker and templating moiety. In particular, we recently employed three different approaches to functionalize the surface of MoS2 nanoflakes and assembled 0D (quantum dots)/2D (MoS2 flakes) hybrids using DNA as a connection moiety (see figure).[1] DNA allowed us to control the distance between QDs and MoS2 with sub-nanoscale accuracy, allowing the fine tuning of the electronic coupling between the two nanostructures.We will further discuss the construction of mixed-dimensional nanohybrids i) via the use different DNA nanotechnology strategies, and ii) for the fabrication of responsive optoelectronic devices. [1] T. Talha-Deam, K. Chen, G. Mastroianni, F. Gesuele, J. Mol and M. Pamla. “Nanoscale Control of DNA-Linked MoS2-Quantum Dot Heterostructures”. Bioconjugate Chemistry, 2022, DOI: 10.1021/acs.bioconjchem.2c00285

SERS monitoring of photoinduced-enhanced oxidative stress amplifier on Au@carbon dots for tumor catalytic therapy

Currently, artificial enzymes-based photodynamic therapy (PDT) is attractive due to its efficient capacity to change the immunosuppressive tumor microenvironment (TME). It is of great significance to study the therapeutic mechanism of novel artificial enzymes in TME through a monitoring strategy and improve the therapeutic effect. In this study, Au@carbon dots (Au@CDs) nanohybrids with a core-shell structure are synthesized, which not only exhibit tunable enzyme-mimicking activity under near-infrared (NIR) light, but also excellent surface-enhanced Raman scattering (SERS) properties. Therefore, Au@CDs show a good capability for monitoring NIR-photoinduced peroxidase-like catalytic processes via a SERS strategy in tumor. Moreover, the Au@CDs deplete glutathione with the cascade catalyzed reactions, thus elevating intratumor oxidative stress amplifying the reactive oxygen species damage based on the NIR-photoinduced enhanced peroxidase and glutathione oxidase-like activities, showing excellent and fast PDT therapeutic effect promoted by photothermal property in 3 min, finally leading to apoptosis in cancer cells. Through SERS monitoring, it is further found that after removing the NIR light source for 33 min, the reactive oxygen species (ROS) activity of the TME is counteracted and eliminated due to the presence of glutathione. This work presents a guidance to rationally design of artificial enzyme for ROS-involved therapeutic strategies and a new spectroscopic tool to evaluate the tumor catalytic therapy.

Highly sensitive and selective electrochemical aptasensor with gold-aspartic acid, glycine acid-functionalized and boron-doped graphene quantum dot nanohybrid for detection of α-amanitin in blood

Poisonous mushroom may cause fatal harm to human and animal, but its rapid detection still faces a great challenge. The paper reports synthesis of gold-aspartic acid, glycine acid-functionalized and boron-doped graphene quantum dot nanohybrid (AGB-GQD@Au) for the electrochemical detection of α-amanitin. AGB-GQD was prepared by pyrolysis and then reacted with chloroauric acid to produce gold nanoparticles. AGB-GQD@Au offers 12.5 nm-sized particles and Schottky heterojunction, improving the catalytic activity. AGB-GQD@Au connected with hairpin DNA and thionine by Au–S bonds was used as redox probe for electrochemical detection of α-amanitin coupled with one target-induced DNA cycle amplification strategy. α-Amanitin specifically hybridizes with aptamer in duplex DNA to release auxiliary strand DNA. The released DNA triggers one DNA cycle process and brings one redox probe to the electrode surface. By the DNA cycle, one target brings many redox probes to the electrode surface, producing a significant signal amplification. The detection signal was further enhanced by the catalysis of AGB-GQD@Au towards redox of thionine. Differential pulse voltammetric current increases linearly with the increasing α-amanitin in the range from 4 to 4 × 105 fM with the detection limit of 1.2 fΜ (S/N = 3). The analytical method provides advantages of sensitivity, selectivity and repeatability. It has been successfully applied in electrochemical detection of α-amanitin in blood.

Ag@CDs nanohybrid: Fabrication, design of a multi-mode chemosensory probe for selective Fe3+ detection and logic gate operation

In this study, we propose a unique use of silver–carbon dot nanohybrid (Ag@CDs) with an average size of 16 nm as a multi-mode sensor for the selective detection of Fe3+ and the construction of logic gates based on these unique detection properties. The Ag NPs exhibit colourimetric sensing and fluorescence quenching in response to Fe3+ in the concentration range of 10–100 ppm, with the carbon dots acting as the fluorescent entity. Surprisingly, the nanohybrid was shown to have excellent sensitivity to Fe3+, resulting in aggregation and formation of yellowish-brown clumps. When the reaction mixture was treated with Fe3+, there was a discernible change in the colour of the assay mixture and fluorescence quenching. That is, the Ag@CDs acted as a calorimetric and fluorescence multi-mode sensor. Even in interfering groups in the natural river water sample, the produced nanohybrid displayed good selectivity towards Fe3+, with a minimum LOD of 0.76 ppm. Further, we constructed an advanced logic system, IMP-OR gate, by using additional inputs - ascorbic acid and urea.

TRAIL/S-layer/graphene quantum dot nanohybrid enhanced stability and anticancer activity of TRAIL on colon cancer cells

Tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL), known as a cytokine of the TNF superfamily, is considered a promising antitumor agent due to its ability to selectively induce apoptosis in a wide variety of cancer cells. However, failure of its successful translation into clinic has led to development of nano-based platforms aiming to improve TRAIL therapeutic efficacy. In this regard, we fabricated a novel TRAIL-S-layer fusion protein (S-TRAIL) conjugated with graphene quantum dots (GQDs) to benefit both the self-assembly of S-layer proteins, which leads to elevated TRAIL functional stability, and unique optical properties of GQDs. Noncovalent conjugation of biocompatible GQDs and soluble fusion protein was verified via UV–visible and fluorescence spectroscopy, size and ζ-potential measurements and transmission electron microscopy. The potential anticancer efficacy of the nanohybrid system on intrinsically resistant cells to TRAIL (HT-29 human colon carcinoma cells) was investigated by MTT assay and flow cytometry, which indicated about 80% apoptosis in cancer cells. These results highlight the potential of TRAIL as a therapeutic protein that can be extensively improved by taking advantage of nanotechnology and introduce S-TRAIL/GQD complex as a promising nanohybrid system in cancer treatment.

Electrochemical detection of omethoate and acetamiprid in vegetable and fruit with high sensitivity and selectivity based on pomegranate-like gold nanoparticle and double target-induced DNA cycle signal amplification

The study reports synthesis of gold-graphene quantum dot nanohybrid via reduction of chloroauric acid with arginine and aspartic acid-functionalized graphene quantum dot (Arg/Asp-GQD). The Arg/Asp-GQD-Au offers pomegranate-like architecture and Schottky heterojunction and was used for construction of electrochemical sensor for detection of omethoate and acetamiprid coupled with double target-induced DNA cycles. Target molecule hybridizes with aptamer DNA in duplex DNA to release auxiliary strand DNA. This triggers the DNA cycle and brings one redox probe to electrode surface. By the DNA cycle, one target molecule can transfer many redox probes to electrode surface and produces a significant signal amplification. The detection signal was enhanced by catalysis of Arg/Asp-GQD-Au toward redox of these probes due to its excellent catalytic activity. Differential pulse voltammetric peak current linearly increases with increasing target concentration between 5 × 10−14 and 5 × 10−10 M with detection limit of 1.67 × 10−14 Μ (S/N = 3) for omethoate and between 1 × 10−14 and 5 × 10−10 M with detection limit of 3.33 × 10−15 M (S/N = 3) for acetamiprid. The proposed method provides a much better sensitivity and selectivity and was successfully applied to detection of omethoate and acetamiprid in vegetable and fruit.

Highly Sensitive and Selective Electrochemical Aptasensor with Gold-Aspartic Acid, Glycine Acid-Functionalized and Boron-Doped Graphene Quantum Dot Nanohybrid for Detection of Α-Amanitin in Blood

Highly Sensitive and Selective Electrochemical Aptasensor with Gold-Aspartic Acid, Glycine Acid-Functionalized and Boron-Doped Graphene Quantum Dot Nanohybrid for Detection of Α-Amanitin in Blood

Bifunctional Magnetic Zncdse/Zns Quantum Dot Nano-Hybrid Based Lateral Flow Immunoassay for Ultrasensitive and Quantitative Streptomycin and Dihydrostreptomycin Detection in Animal-Derived Foods

Bifunctional Magnetic Zncdse/Zns Quantum Dot Nano-Hybrid Based Lateral Flow Immunoassay for Ultrasensitive and Quantitative Streptomycin and Dihydrostreptomycin Detection in Animal-Derived Foods

Sn(IV) porphyrin-biotin decorated nitrogen doped graphene quantum dots nanohybrids for photodynamic therapy

Photodynamic therapy (PDT) is a minimally invasive therapeutic procedure for cancer treatment. This study focuses on the synthesis, photophysicochemical properties, and PDT activity of Sn (IV) porphyrin (2), when linked to biotin decorated nitrogen doped graphene quantum dots (B-NGQDs). The porphyrin complex 2 was conjugated through an ester bond to B-NGQDs to form 2-B-NGQDs. Singlet oxygen quantum yield increased for 2 when linked to B-NGQDs to form 2-B-NQGDs. The dark toxicity and photodynamic therapy studies were conducted for 2, NGQDs and their conjugates using MCF-7 breast cancer cells. The cell viability for dark toxicity of all the compounds was above 90%, and 2-B-NGQDs showed high PDT activity at a concentration of 40 µg/mL with cell viability of 22%.

Enhanced Nonlinear Photoluminescence of Au–Carbon Dot Nanohybrids Produced by Photocatalytic Reduction of Au(III) Ions

Enhanced Nonlinear Photoluminescence of Au–Carbon Dot Nanohybrids Produced by Photocatalytic Reduction of Au(III) Ions

One step production of Se doped carbon dots for rapid sensing of tetracycline in real water sample

In the present decade, the utilization of antibiotics at augmented rate has caused harmful environmental pollution. The resistance rate of bacteria against antibiotics has become faster due to excessive employment of antibiotics. Therefore, it is mandatory to develop a new, sustainable and environment friendly nanohybrid system which can easily detect antibiotic especially tetracycline. It is prevalently found drug pollutant which can easily contaminate food, aquatic species and human health. While keeping all the facts during consideration, a simple and one step scheme is followed for the development of selenium supported carbon dots (Se@CDs) nano hybrids by utilizing commonly available natural sugars such as sucrose, fructose and glucose as a reducing and stabilizing agent. The CDs were prepared from the waste coconut husk. The developed nano-hybrid exhibits excellent optical and emission properties which suggest their further applications. Additionally, different analytical studies have been carried out to evaluate their physicochemical properties. Due to their outstanding analytical behavior, they have been successfully utilized in the sensitive and specific detection of tetracycline (TC) in presence of different interfering ions. The glucose derived Se@CDs shows maximum quenching effect towards TC. The value of detection limit and binding constant were found to be 155 nM and 517 nM −1 . Further, their recovery studies have been carried out in different real samples. The obtained findings suggest that the developed Se@CDs can be successfully explored in biological fields. • Development of Se doped carbon dots have been carried out by using three natural reducing sugars. • Different analytical techniques have been performed to evaluate the physicochemical properties of prepared Se@CDs nanohybrid. • The developed glucose derived Se@CDs have been found highly effective in the fluorescence quenching of tetracycline. • The value of detection limit of G-Se@CDs for tetracycline sensing was found to be 155 nM.

A highly sensitive SERS platform based on small-sized Ag/GQDs nanozyme for intracellular analysis

The small-sized plasmonic nanoparticles are easily internalized by cells and organelles, but usually possess poor surface-enhanced Raman scattering (SERS) activity, restricting their promising applications for intracellular SERS analysis. To break the current bottleneck of intracellular SERS application, herein, a uniform and small-sized (ca. 10 nm) core–shell Ag/oxidized graphene quantum dots (o-GQDs) nanohybrids have been prepared. The Ag/o-GQDs inherit unique features with parallel-interlaced stacking of o-GQDs as capping agent, possess the increasing and broadening plasmon adsorption and display a unique edge state charge transfer (CT) resonance in the long-wavelength region of visible light, enabling the enhanced electromagnetic (EM) and CT effect for superior SERS sensitivity at lower energy. Further, the Ag/o-GQDs demonstrate excellent biocompatibility and highly efficient nanozymatically catalytic activity, which are first put forward to integrate efficient SERS with Ag/o-GQDs nanozyme to catalyze peroxidase-like reaction for accurate sensing of the intracellular H2O2 at the subcellular level. Moreover, the Ag/o-GQDs nanozyme-catalyzed reactive oxygen species (ROS) generation and the cancer cell multisubcellular-targeting capability provide a promising strategy for the synergistically catalytic therapy specifically toward tumors. This study illustrates a significant route to design an efficient small-sized noble metal/carbon nanozymatic SERS substrate, and demonstrates an exciting potential for ultrasensitive SERS bioanalysis at the subcellular level.

Unique insights into photocatalytic VOCs oxidation over WO3/carbon dots nanohybrids assisted by water activation and electron transfer at interfaces

Internal electric field (IEF) at heterojunction interfaces can separate photoexcited charge carriers and promote photocatalytic performance. Here we have modified WO3 nanoplates with carbon dots (CDs) and constructed an interfacial IEF directing from CDs to WO3 with assistance of their remarkably different work functions. Such electric field drove photoexcited electrons to transport towards CDs and retained photoexcited holes to stay at WO3, achieving electron/hole spatial separation. H2O preferred chemisorption on the five-coordinated W atoms of WO3 with an elongated H-O bond and bent H-O-H angle, which allowed the activation of H2O and favorable production of ·OH radicals. The WO3/CDs (WC1) showed a superior photocatalytic activity for visible-light photooxidation of HCHO and CH3COCH3 with CO2 production rate of 411 and 188 μmol g–1 h–1, respectively, outperforming most of WO3-based photocatalysts. The enhanced photocatalytic performance correlated with the IEF-induced charge separation, favorable ·OH production and VOCs chemisorption. Our work confirms the role of CDs cocatalyst in the photocatalytic oxidation of VOCs, which will inspire enthusiasm to develop more advanced heterojunction photocatalysts involving carbon nanomaterials.

Temperature-responsive polymer-tethered Zr-porphyrin MOFs encapsulated carbon dot nanohybrids with boosted visible-light photodegradation for organic contaminants in water

Zirconium-based porphyrin metal–organic frameworks (MOFs) have attracted extensive attention in the photocatalysis because of their considerable specific surface area, powerful visible light efficiency and semiconductor properties. However, the rapid charge recombination and self-aggregation limit their applications. Here, porphyrin-based Zr-MOF (PCN-222) nanohybrids (CDs@PCN-222@PNIPAM) as an efficient hydrophilic photocatalyst were fabricated by encapsulating various carbon dots (CDs) into PCN-222 nanopores with surface wettability modification by catechol-terminated thermo-responsive PNIPAM having various chain lengths. Due to the electron collecting effect of the nitrogen-doped CDs (N-CDs) and their synergistic effect with PCN-222, the photocatalytic performance of the prepared nano-hybrid photocatalyst were significantly improved. Furthermore, the introduction of hydrophilic polymer with moderate molecular weight effectively enhanced the transfer efficiency of photo-generated charges and the surface wettability of photocatalyst, and improved the water dispersibility of catalyst so that effectively promotes the enrichment and catalytic conversion of water-soluble target pollutants around the active site of the photocatalyst. The removal efficiency of RhB and tetracycline (TC) under visible light irradiation reached almost 100 % and 90.93 % in just 20 min, respectively. In addition, polymer-functionalized Zr-MOF-based nanohybrids revealed an interesting temperature-response switching behavior for the photocatalysis. The study on the catalytic mechanism and degradation pathways of TC showed that the h+ plays a major role in the degradation process, and other reactive species are also involved in the further mineralization of pollutants. This work provides a new insight for the functional modification of MOFs and the design of high efficiency photocatalyst.

Sensitive electrochemiluminescent detection of telomerase activity based on nicking enzyme assisted signal amplification

Herein, an ultrasensitive biosensor for the detection of telomerase activity was constructed by utilizing gold@Carbon dots nanohybrids (Au@CDs) as a high efficiency electrochemiluminescence (ECL) emitter and nicking enzyme assisted signal amplification (NESA) technology. Firstly, the self-enhanced Au@CDs was synthesized from the reduction of HAuCl4 with carbon dots (CDs), which served as reductant and stabilizer. The prepared hybrids exhibited significant enhancement in the ECL emission compared to the single CDs. Enhanced sensitivity was thus achieved by using these Au@CDs as ECL labels. Next, an isothermal amplification with nicking enzyme (Nb.BbvcI)-assisted recycle was employed to convert a small amount of telomerase to numerous output signal DNA (sDNA). The obtained sDNA was then linked with Au@CDs and immobilized on a capture DNA (cDNA), and connected to the working electrode through oligonucleotide hybridization, resulting in a quantitative ECL reading. As a consequence, by employment of the dual signal amplification strategy, the proposed biosensor exhibited excellent sensitivity for telomerase activity detection with a detection limit down to 1 HeLa cell, which is comparable or even better than the most reported methods. The method also displayed a wide linear response ranges and good reproducibility. This work not only expanded the application of high-efficiency ECL indicators Au@CDs, but also offered a novel PCR-free ECL sensing platform for detecting telomerase activity that is helpful for real-time monitoring, point-of-care testing and on-site analysis.

A ratiometric fluorescent probe for pH detection based on Ag2S quantum dots-carbon dots nanohybrids.

In this study, a novel ratiometric fluorescent nanoprobe for pH monitoring has been developed by synthesizing red fluorescent Ag2S quantum dots (Ag2S QDs) and green fluorescent carbon dots (CDs) nanohybrids (Ag2S CDs) in one pot using CDs as templates. The nanoprobe exhibits dual-emission peaks at 500 and 670 nm under a single-excitation wavelength of 450 nm. The red fluorescence can be selectively quenched by increasing pH, while the green fluorescence is an internal reference. Therefore, the change of the relative fluorescence intensity (I500/I670) in the ratiometric Ag2S CDs probes can be used for pH sensing. The results revealed that I500/I670 of Ag2S CDs probes was linearly related to pH variation between pH 5.4 and 6.8. Meanwhile, the Ag2S CDs probes possessed a good reversibility along with pH changing between 5.0 and 7.0 without any interruption from common metal ions, proteins and other interferences.