Biocompatible Quantum Dots Research Articles

A novel carbon quantum dot (CQD) synthesis method with cost-effective reactants and a definitive indication: Hot bubble synthesis (HBBBS)

Carbon quantum dots (CQDs) are carbon-based biocompatible quantum dots that have low toxicity, are more soluble in water, have broad application areas, and the surface modification of these can be performed easily. In this study, we present a new CQD synthesis method with cost-effective reactants that can be easily found in laboratories are used. Besides, there is a definitive indication (bubble) for CQD production, unlike the other methods in the literature. The purification method of the CQDs was also optimized in this study. In the beginning of the synthesis, 3 times centrifugation (x3 CF) of the mixture was performed and the optimization of the purification method indicated that x3 CF before 3 days of dialysis membrane tubing (x3 CF & 3 DM) resulted in the formation of the purest CQDs. The characterization of the CQDs was done utilizing UV–VIS spectrophotometer, Fourier Transfer Infrared Spectroscopy (FT-IR), Zetasizer, fluorescence microscopy, Dynamic Light Scattering (DLS), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), and Transmission Electron Microscopy (TEM). It was concluded that the CQD formation depends on the mixing of sulphuric acid:acetone (2:1) ratio in a hot (140-165 °C) and an inert environment, and bubble coverage of the mixture surface(30-60 s). The bubble formation due to the reaction between sulphuric acid and pure acetone at high temperatures gives the developed method’s name of “Hot Bubble Synthesis” (HBBBS).

Quantum-Inspired Macromolecular Design: Harnessing Quantum Dots for Enhanced Polymer Functionality in Drug Delivery

Quantum dots (QDs) have emerged as transformative nanomaterials in drug delivery due to their unique optical and electronic properties, such as tunable fluorescence, high surface area and size-dependent emission in pharmaceutical origin. When integrated with polymers, this hybrid system offers enhanced functionality for targeted, controlled and stimuli-responsive drug delivery. This review focuses on the synthesis and application of quantum dot-polymer composites in drug delivery, emphasizing their ability to improve drug targeting, sustained release and real-time imaging in therapeutic applications. The multifunctionality of these systems enables personalized medicine approaches, particularly in cancer therapy and neurological disorders. Despite their promising potential, concerns related to toxicity and scalability pose significant challenges for their widespread clinical use. Ongoing research efforts are focused on developing more biocompatible QDs, optimizing the design of polymer-QD hybrids and addressing regulatory hurdles. This review, we believe, provides a comprehensive analysis of current advancements in quantum dot-based drug delivery systems and outlines future directions to overcome the existing limitations and enhance clinical applicability. The integration of quantum dots with polymers represents a significant leap forward in the field of nanomedicine, offering the potential for highly efficient, precise and safe drug delivery platforms.

Thermally assisted optical processes in InP/ZnS quantum dots.

The utilization of InP-based biocompatible quantum dots (QDs) necessitates a comprehensive understanding of the structure-dependent characteristics influencing their optical behavior. The optimization of core/shell QDs for practical applications is of particular interest due to their reduced toxicity, enhanced photostability, and improved luminescence efficiency. This optimization involves analyzing thermally activated processes involving exciton and defect-related energy levels. This study investigates water-soluble colloidal InP/ZnS QDs with varying shell thicknesses and stabilizing coatings using temperature-dependent optical absorption (OA) and photoluminescence (PL). Our results indicate that all samples experience temperature-induced shifts in exciton absorption and luminescence peaks due to interactions with acoustic phonons. Despite the wide size distribution of nanocrystals, the halfwidth of the bands remains constant. We observe a temperature-dependent Stokes shift in InP/ZnS QDs, revealing the fine structure of exciton states across different configurations. Furthermore, our findings demonstrate common mechanisms underlying PL thermal quenching in these QDs, regardless of the shell thickness or coating type. Specifically, defect-related emissions arise from localized energy levels at the core/shell interface. At the same time, exciton PL quenching primarily occurs through thermally activated electron migration from the InP core to the ZnS shell. Overall, our study highlights the potential for tailoring the temperature response of InP/ZnS QDs by adjusting shell thickness, offering opportunities to optimize their performance for specific applications.

УЛЬТРАМАЛІ КВАНТОВІ ТОЧКИ: ОСОБЛИВОСТІ СИНТЕЗУ, ОПТИЧНІ ВЛАСТИВОСТІ ТА ПЕРСПЕКТИВИ ПРАКТИЧНОГО ВИКОРИСТАННЯ (ОГЛЯД)

In recent years, interest in ultra-small (on the order of 2 nm) quantum dots (QDs) has increased. This subset of CTs includes clusters of magic sizes corresponding to a certain, clearly defined number of atoms. Ultrasmall CTs are characterized by unique properties - sharp absorption of light and almost complete surface luminescence. They are promising for a variety of applications, ranging from dye-sensitized solar cells, white light LEDs, and biomedical sensing due to their controllable electronic structure and large specific surface area. In this review, modern methods of synthesis of ultrasmall quantum dots are considered: the method of high-temperature organic synthesis, the method of hot injection, sonochemical synthesis of QDs of magical sizes, etc. Ultra-small quantum dots are used in solar cells. Due to their large surface-to-volume ratio, compared to traditional materials, they have a higher absorption efficiency, meaning they can convert a higher percentage of incident light into electricity. In contrast to the traditional production of solar cells based on organic solutions, which require high-temperature processing or an inert atmosphere during sputtering, and also have low stability in the open air, a method of processing solar cells with a solution containing PbS/ZnO is proposed. of nanocrystals in open air and at room temperature. Ultrasmall quantum dots are used in medicine due to their unique properties. Overall, they have several advantages over traditional imaging and sensing tools, such as higher brightness, longer fluorescence lifetimes, and tunable emission spectra. Current research is focused on increasing the stability and biocompatibility of quantum dots and developing new methods for their inclusion in various biomedical applications.

A coumarin-modified graphene quantum dot-based luminogen for the detection of cysteine in aqueous media.

A biocompatible fluorescence sensor for cysteine detection receives wide appreciation recently, because of its importance in the medical field. Functionalized graphene quantum dots (GQDs) are recently emerging biocompatible quantum dots, which are considered as suitable candidates for biomolecule detection. Motivated by this concept, here we have developed a versatile fluorescent probe based on 3-aminocoumarin (AMC) functionalized GQDs for the detection of cysteine (Cys). Modification on GQD with AMC resulted in a stable fluorescent probe with an enhancement in quantum yield of about 84% and 40 nm redshift in emission peak compared with bare GQD. The modified GQD is then used for the sensitive and selective detection of cysteine in aqueous media. The detection of Cys within the linear range of 50 nM to 1.5 μM was achieved with a detection limit (LOD) of 0.86 nM. Here, the AMC-GQD exhibit a turn-off fluorescence sensing behavior. The quenching mechanism was also explored. The sensing process follows dynamic quenching mechanism, which is attributed to the photoinduced charge transfer from AMC-GQD to Cys. The Stern-Volmer plot, energy-level alignment obtained from cyclic voltammetry measurements and density functional theory predictions give a valid proof for this. Furthermore, the sensor was applied efficiently to the determination of Cys in real water samples.

Current Advances in the Biomedical Applications of Quantum Dots: Promises and Challenges.

Quantum dots (QDs) are a type of nanoparticle with exceptional photobleaching-resistant fluorescence. They are highly sought after for their potential use in various optical-based biomedical applications. However, there are still concerns regarding the use of quantum dots. As such, much effort has been invested into understanding the mechanisms behind the behaviors of QDs, so as to develop safer and more biocompatible quantum dots. In this mini-review, we provide an update on the recent advancements regarding the use of QDs in various biomedical applications. In addition, we also discuss# the current challenges and limitations in the use of QDs and propose a few areas of interest for future research.

Quantum dots: The cutting-edge nanotheranostics in brain cancer management.

Quantum dots (QDs) are semiconductor nanocrystals possessing unique optoelectrical properties in that they can emit light energy of specific tunable wavelengths when excited by photons. They are gaining attention nowadays owing to their all-around ability to allow high-quality bio-imaging along with targeted drug delivery. The most lethal central nervous system (CNS) disorders are brain cancers or malignant brain tumors. CNS is guarded by the blood-brain barrier which poses a selective blockade toward drug delivery into the brain. QDs have displayed strong potential to deliver therapeutic agents into the brain successfully. Their bio-imaging capability due to photoluminescence and specific targeting ability through the attachment of ligand biomolecules make them preferable clinical tools for coming times. Biocompatible QDs are emerging as nanotheranostic tools to identify/diagnose and selectively kill cancer cells. The current review focuses on QDs and associated nanoformulations as potential futuristic clinical aids in the continuous battle against brain cancer.

Bright, Magnetic NIR-II Quantum Dot Probe for Sensitive Dual-Modality Imaging and Intensive Combination Therapy of Cancer.

Improving the effectiveness of cancer therapy will require tools that enable more specific cancer targeting and improved tumor visualization. Theranostics have the potential for improving cancer care because of their ability to serve as both diagnostics and therapeutics; however, their diagnostic potential is often limited by tissue-associated light absorption and scattering. Herein, we develop CuInSe2@ZnS:Mn quantum dots (QDs) with intrinsic multifunctionality that both enable the accurate localization of small metastases and act as potent tumor ablation agents. By leveraging the growth kinetics of a ZnS shell on a biocompatible CuInSe2 core, Mn doping, and folic acid functionalization, we produce biocompatible QDs with high near-infrared (NIR)-II fluorescence efficiency up to 31.2%, high contrast on magnetic resonance imaging (MRI), and preferential distribution in 4T1 breast cancer tumors. MRI-enabled contrast of these nanoprobes is sufficient to timely identify small metastases in the lungs, which is critically important for preventing cancer spreading and recurrence. Further, exciting tumor-resident QDs with NIR light produces both fluorescence for tumor visualization through radiative recombination pathways as well as heat and radicals through nonradiative recombination pathways that kill cancer cells and initiate an anticancer immune response, which eliminates tumor and prevents tumor regrowth in 80% of mice.

Elucidating the Size-dependent FRET Efficiency in Interfacially Engineered Quantum Dots Attached to PBSA Sunscreen.

Applying sunscreen on human skin provides photoprotection against the harmful ultraviolet (UV) radiation of the sun. Sunscreen absorbs UV radiations and dissipates the absorbed energy through various radiative and nonradiative pathways. The attachment of functionalized quantum dots (QDs) to the sunscreen component is a novel idea to enhance the absorption cross-section of UV radiations. Therefore, the attachment of the sunscreen component to the ligand functionalized biocompatible QDs and the absorbed energy transfer from sunscreen to the QDs could work as a model system to overall improve the efficiency of the sunscreen. This study elucidates the mechanism of size-dependent Förster resonance energy transfer (FRET) efficiency and its rate between 2-phenylbenzimidazole-5-sulfonic acid (PBSA) and mercaptoacetic acid (MAA) functionalized CdS QDs. In the PBSA-QDs dyad, the PBSA (donor) dissipates UV-absorbed energy to the CdS QDs (acceptor). Following excitation at 306 nm, the steady-state photoluminescence (SSPL) and time-resolved photoluminescence (TRPL) techniques measurements demonstrate that both the nonradiative energy transfer efficiency and rate are QDs size-dependent in addition to donor-acceptor distance, and suggest that bigger sized-QDs result in an increase of the FRET efficiency.

Controlled membrane interactions by lipid coated quantum dots

Quantum Dots (QDs) are being employed in a wide range of biological application due to their superior fluorescence characteristics. Biocompatibility of QDs is usually achieved by exchange of as-synthesized surface ligands with ligands that impart the particle with water solubility properties. An alternative approach for surface functionalization is ligand adsorption. This approach is based on weak interactions between the alkane chains of the as-synthesized surface ligands and a hydrophobic element of an adsorbed ligand with a functional head group/s.

Correction: Exploring the photoexcited electron transfer dynamics in artificial sunscreen PBSA-coupled biocompatible ZnO quantum dots

Correction for ‘Exploring the photoexcited electron transfer dynamics in artificial sunscreen PBSA-coupled biocompatible ZnO quantum dots’ by Muhammad Mubeen et al., New J. Chem., 2022, 46, 9526–9533, https://doi.org/10.1039/D2NJ01153K.

Facile Development of Biocompatible Nitrogen-Doped Carbon Quantum Dots for Efficient Photocatalytic Removal of Dyes

Facile Development of Biocompatible Nitrogen-Doped Carbon Quantum Dots for Efficient Photocatalytic Removal of Dyes

Advances in quantum dots as diagnostic tools.

Quantum dots (QDs) are crystalline inorganic semiconductor nanoparticles a few nanometers in size that possess unique optical electronic properties vs those of larger materials. For example, QDs usually exhibit a strong and long-lived photoluminescence emission, a feature dependent on size, shape and composition. These special optoelectronic properties make them a promising alternative to conventional luminescent dyes as optical labels in biomedical applications including biomarker quantification, biomolecule targeting and molecular imaging. A key parameter for use of QDs is to functionalize their surface with suitable (bio)molecules to provide stability in aqueous solutions and efficient and selective tagging biomolecules of interest. Researchers have successfully developed biocompatible QDs and have linked them to various biomolecule recognition elements, i.e., antibodies, proteins, DNA, etc. In this chapter, QD synthesis and characterization strategies are reviewed as well as the development of nanoplatforms for luminescent biosensing and imaging-guided targeting. Relevant biomedical applications are highlighted with a particular focus on recent progress in ultrasensitive detection of clinical biomarkers. Finally, key future research goals to functionalize QDs as diagnostic tools are explored.

Roles of cation efflux pump in biomineralization of cadmium into quantum dots in Escherichia coli

Cadmium (Cd) is a typical and widely present toxic heavy metals in environments. Biomineralization of Cd ions could alleviate the toxicity and produce valuable products in certain waste streams containing selenite. However, the impact of the intrinsic Cd(II) efflux system on the biotransformation process remains unrevealed. In this work, the significance of the efflux system on Cd biomineralization was evaluated by constructing engineered Escherichia coli strains, including ΔzntA with suppressed Cd(II) efflux system and pYYDT-zntA with strengthened Cd(II) efflux system. Compared to the wild type (WT), 20% more Cd ions were accumulated in ΔzntA and 17% less were observed in pYYDT-zntA in the presence of selenite as determined by inductively coupled plasma atomic emission spectrometer. Through combination with X-ray absorption fine structure analysis, it was discovered that 50% higher production of CdSxSe1−x quantum dots (QDs) was achieved in the ΔzntA cells than that in the WT cells. Moreover, the ΔzntA cells exhibited the same viability as the WT cells and the pYYDT-zntA cells because accumulated Cd ions were transformed into biocompatible QDs. In addition, the biosynthesized QDs had a uniform particle size (3.82 ± 0.53 nm) and a long fluorescence lifetime (45.6 ns), which could potentially be utilized for bio-imaging. These results not only elucidate the significance of Cd(II) efflux system in the biotransformation of Cd ions and selenite, but also provide a promising way to recover Cd and Se as valuable products in certain waste streams.

Zebrafish imaging and two-photon fluorescence imaging using ZnSe quantum dots* *Project supported by the National Natural Science Foundation of China (Grant Nos. 61774062 and U20A20206), the Science and Techology Program of Guangzhou City, China (Grant No. 2019050001), and the Natural Science Foundation of Guangdong Province, China (Grant Nos. 2018A030313854 and 2016A030308010).

This study is to report a ZnSe quantum dot with a large two-photon absorption cross section and good biocompatibility, which can be used in bioimaging. Fluorescence emission at 410 nm is observed in the quantum dot under 760-nm laser excitation. These biocompatible quantum dots exhibit a two-photon cross-section of 9.1 × 105 GM (1 GM = 10−50 cm4⋅s/photon). Two-photon excited laser scanning microscopic images show that cells co-cultured with ZnSe quantum dots are found in the blue channel at a fluorescence intensity that is 14.5 times that of control cells not co-cultured with quantum dots. After incubating zebrafish larvae with ZnSe quantum dots for 24 h, the fluorescence intensity of the yolk sac stimulated by ultraviolet light is 2.9 times that of the control group. The proposed material shows a great potential application in biological imaging.

Proteome Mediated Synthesis of Biocompatible Green Fluorescence Cerium Oxide Quantum Dots with Enhanced Antioxidant Activity

Biocompatibility of quantum dots make good candidature for in vivo and in vitro diagnostic applications. In this study biocompatible cerium oxide quantum dots (CeO2 QDs) were synthesized from proteome of Justicia adhatoda leaf using simple aqueous protocol. Synthesized cerium oxide nanoparticle possessed green colored fluorescence under UV light. Quantum yield of CeO2 QDs was found to be 31.13% and were stable for 3 month at 4 °C. The band gap was found to be 3.26 eV which was higher than the band gap of bulk material i.e., 3.19 eV. The concentration of synthesized CeO2 QDs was determined as 165.96 ppm. These quantum dots were also characterized using an UV-Vis spectroscopy, Fourier Transform Infra-red Spectroscopy (FT-IR) and Transmission Electron Microscopy (TEM) respectively. It displayed distinct absorbance peak at 380 nm under UV-Visible spectrum. TEM images showed monodispersity of 2–5 nm spherical shaped CeO2 QDs and higher degree of crystallinity was observed by the pattern of selected area electron diffraction. In FTIR, the stretching observed at 621.65 cm–1 is assigned to Ce-O which confirmed the CeO2QDs formation. In view of biocompability, synthesized CeO2QDs were also characterised in reference to cell toxicity. Generated CeO2QDs has not showed any toxicity to J774A.1, Raw 264.7 and 3T3 cell lines in vitro cell viability assay. Significant enhancement in antioxidant activity of synthesized cerium oxide nanoparticles was observed from bulk material. This process offers plenty of advantages such as simple protocol, mild environment operation, potential for large scale commercial production of biocompatible CeO2QD. These QDs might find potential applications in both in vitro and in vivo diagnostics.

Retraction: A facile cation exchange-based aqueous synthesis of highly stable and biocompatible Ag2S quantum dots emitting in the second near-infrared biological window.

Retraction of 'A facile cation exchange-based aqueous synthesis of highly stable and biocompatible Ag2S quantum dots emitting in the second near-infrared biological window' by Rijun Gui et al., Dalton Trans., 2014, 43, 16690-16697, DOI: 10.1039/C4DT00699B.

Utilization of waste tea leaves as bio-surfactant in CdS quantum dots synthesis and their cytotoxicity effect in breast cancer cells

Green technology for nanoparticles synthesis is considered to be of great significance in biomedical applications. Recently, low dimensional semiconductor cadmium sulfide (CdS) quantum dots (QDs) have raised great attention due to their optical properties and wide usage in biomedical studies. In our present work, we demonstrate a simple green synthesis route for CdS QDs production using waste matured tea leaves (mother leaf) as bio-surfactant that are a waste product of the tea leaf industry and not suitable for drinking. The structural and morphological analysis showed waste tea leaf derived CdS QDs range from 2.5 to 4 nm in particle size with a cubic crystalline structure. Interestingly, these CdS QDs exhibit strong fluorescence emission with maximum around 670 nm. We explored the cytotoxic effect of waste tea leaf mediated CdS QDs (MT-CdS QDs) in breast cancer cell lines and compared their viability with standard drug - cisplatin. Our experimental studies strongly suggest that MT-CdS QDs exhibits cytotoxic effect on breast cancer cells and their performance was compared with standard drug cisplatin. To further understand the role of MT-CdS QDs towards cytotoxicity, the fluorescence microscopy and flow cytometry analysis were carried out. The flow cytometry results reveal that MT-CdS QDs induces cell death as it arrests the cell cycle at S phase as well as G2/M phase. Further the apoptosis mechanism was confirmed with the expression of anti-apoptotic and apoptotic proteins. These studies explored that waste tea leaves have dual advantage – both in controlling the particle size of CdS QDs as well as facilitates their cytotoxicity effect in breast cancer cell death. Therefore, it is anticipated that the utilization of MT-CdS QDs produced from waste tea leaves as bi-functional drug and delivery vehicle in cancer treatment will be a promising approach. Also, this is a simple and circular economic route for producing biocompatible QDs at low-cost, which could simultaneously benefit tea and biomedical industries.

Water Transfer of Oil-Soluble ZnAgInSe/ZnS Quantum Dots by DHLA-PEG-Suc-cRGD Ligands for Tumor Targeted Bio-Imaging.

Semiconductor quantum dots have attracted increasing attention, owing to their unique optical and electrical properties compared to traditional organic fluorescent dyes. However, one of the main obstacles impeding their biological applications is their biocompatibility. Hence, in this work, for achieving biocompatible quantum dots, oil-soluble ZnAgInSe/ZnS quantum dots without highly toxic heavy metals were selected, and four kinds of biocompatible thiols (dihydrolipoic acid, L-cysteine, N-acetyl-L-cysteine and glutathione) were explored as their water transfer agents. Among them, dihydrolipoic acid was found to be more favorable for achieving strongly fluorescent water-soluble quantum dots. Based on this observation, a tumor targeted ligand, namely dihydrolipoic acid-poly(ethylene glycol)-succinic anhydride-cyclic arginine-glycine-aspartate, was designed to further enhance their tumor targeting ability. By means of in vitro cell and in vivo mice experiments, dihydrolipoic acid-poly(ethylene glycol)-succinic anhydride-cyclic arginine-glycine-aspartate stabilized ZnAgInSe/ZnS quantum dots were confirmed to have a high affinity for αvβ₃ integrin receptor-positive U87MG tumor. This study demonstrates the versatility of highly fluorescent, broadly emissive ZnAgInSe/ZnS quantum dots for multi-scale biomedical optical imaging.

Chitosan-Based Carbon Quantum Dots for Biomedical Applications: Synthesis and Characterization.

Rapid development in medicine and pharmacy has created a need for novel biomaterials with advanced properties such as photoluminescence, biocompability and long-term stability. The following research deals with the preparation of novel types of N-doped chitosan-based carbon quantum dots. Nanomaterials were obtained with simultaneous nitrogen-doping using biocompatible amino acids according to Green Chemistry principles. For the carbon quantum dots synthesis chitosan was used as a raw material known for its biocompability. The nanomaterials obtained in the form of lyophilic colloids were characterized by spectroscopic and spectrofluorimetric methods. Their quantum yields were determined. Additionally the cytotoxicity of the prepared bionanomaterials was evaluated by XTT (2,3-Bis-(2-methoxy-4-nitro5-sulfophenyl)-2H-tetrazolium-5-carboxanilide salt) method. Our results confirmed the formation of biocompatible quantum dots with carbon cores exhibiting luminescence in visible range. Performed studies showed that modification with lysine (11.5%) and glutamic acid (7.4%) had a high impact on quantum yield, whereas functionalization with amino acids rich in S and N atoms did not significantly increase in fluorescence properties. XTT assays as well as morphological studies on human dermal fibroblasts confirmed the lack of cytotoxicity of the prepared bionanomaterials. The study shows chitosan-based quantum dots to be promising for biomedical applications such as cell labelling, diagnostics or controlled drug delivery and release systems.