Silica–Quantum Dot Nanomaterials as a Versatile Sensing Platform

Simple and Cost-Effective Quantum Dot Chemodosimeter for Visual Detection of Biothiols in Human Blood Serum

An emission "turn-off" chemodosimeter for the naked-eye detection of biothiols using silica-overcoated cadmium selenide quantum dots is developed. Hole scavenging by the thiol group of cysteine, homocysteine, or glutathione on interaction with quantum dots resulted in an instant and permanent emission quenching under physiologically relevant conditions. Also, the emission suppression is so specific that thiols and substituted thiols (methionine and cystine) can easily be distinguished. A pilot experiment for the visual detection of serum thiols in human blood was also conducted. Densitometry analysis proved the potential of this system as a new methodology in clinical chemistry and research laboratories for routine blood and urine analyses using a simple procedure. This method enables one to visually distinguish biothiols and oxidized biothiols, whose ratio plays a crucial role in maintaining "redox thiol status" in the blood.

A Mesoporous Magnetic Fe3O4/BioMOF-13 with a Core/Shell Nanostructure for Targeted Delivery of Doxorubicin to Breast Cancer Cells

In the current project, magnetic Bio-MOF-13 was used as an efficient carrier for the targeted delivery and controlled release of doxorubicin (DOX) to MDA-MB-231 cells. Magnetic Bio-MOF-13 was prepared by two strategies and compared to determine the optimal state of the structure. In the first path, Bio-MOF-13 was grown in situ on the surface of Fe3O4 nanoparticles (core/shell structure), while in the second method, the two presynthesized materials were mixed together (surface composite). Core/shell structure, among prepared nanocomposites, was chosen for biological evaluation due to its favorable structural features like a high accessible surface area and pore volume. Also, it is highly advantageous for drug release due to its ability to selectively release DOX in the acidic pH of breast cancer cells, while preventing any premature release in the neutral pH of the blood. Drug release from the carrier structure is precisely controlled not only by pH but also by an external magnetic field, guaranteeing accurate drug delivery at the intended location. Confocal microscopy and flow cytometry assay clearly confirms the increase in drug concentration in the MDA-MB-231 cell line after external magnet applying. This point, along with the low toxicity of the carrier components, makes it a suitable candidate for injectable medicine. According to MTT results, the percentage of viable MDA-MB-231 cells after treatment with 10 μL of DOX@Fe3O4/Bio-MOF-13 core/shell composite in different concentrations, in the presence and absence of magnetic field is 0.87 ± 0.25 and 2.07 ± 0.15, respectively. As a result, the DOX@Fe3O4/Bio-MOF-13 core/shell composite was performed and approved for targeted drug delivery and magnetic field-assisted controlled release of DOX to the MDA-MB-231 cell line.

Protective potential of naringenin and its nanoformulations in redox mechanisms of injury and disease

Increasing evidence suggests that elevated intracellular levels of reactive oxygen species (ROS) play a significant role in the pathogenesis of many diseases. Increased intracellular levels of ROS can lead to the oxidation of lipids, DNA, and proteins, contributing to cellular damage. Hence, the maintenance of redox hemostasis is essential. Naringenin (NAR) is a flavonoid included in the flavanones subcategory. Various pharmacological actions have been ascribable to this phytochemical composition, including antioxidant, anti-inflammatory, antibacterial, antiviral, antitumor, antiadipogenic, neuro-, and cardio-protective activities. This review focused on the underlying mechanism responsible for the antioxidative stress properties of NAR and its' nanoformulations. Several lines of in vitro and in vivo investigations suggest the effects of NAR and its nanoformulation on their target cells via modulating signaling pathways. These nanoformulations include nanoemulsion, nanocarriers, solid lipid nanoparticles (SLN), and nanomicelle. This review also highlights several beneficial health effects of NAR nanoformulations on human diseases including brain disorders, cancer, rheumatoid arthritis, and small intestine injuries. Employing nanoformulation can improve the pharmacokinetic properties of NAR and consequently efficiency by reducing its limitations, such as low bioavailability. The protective effects of NAR and its' nanoformulations against oxidative stress may be linked to the modulation of Nrf2-heme oxygenase-1, NO/cGMP/potassium channel, COX-2, NF-κB, AMPK/SIRT3, PI3K/Akt/mTOR, BDNF, NOX, and LOX-1 pathways. Understanding the mechanism behind the protective effects of NAR can facilitate drug development for the treatment of oxidative stress-related disorders.

QD:Puf Nanohybrids Are Compatible with Studies in Cells

Colloidal semiconductor quantum dots (QD), as well as other nanoparticles, are useful in cell studies as fluorescent labels. They may also be used as more active components in various cellular assays, serving as sensors or effectors. However, not all QDs are biocompatible. One of the main problems is their outer coat, which needs to be stable and to sustain hydrophilicity. Here we show that purpose-designed CdSe QDs, covered with a Puf protein, can be efficiently accumulated by HeLa cells. The uptake was measurable after a few hours of incubation with nanoparticles and most of the fluorescence was localised in the internal membrane system of the cell, including the endoplasmic reticulum and the Golgi apparatus. The fluorescence properties of QDs were mostly preserved, although the maximum emission wavelength was slightly shifted, and the fluorescence lifetime was shortened, indicating partial sensitivity of the QDs to the cell microenvironment. QD accumulation resulted in a decrease in cell viability, which was attributed to disturbance of endoplasmic reticulum performance.

Mesoporous Silica Nanoparticles in Chemical Detection: From Small Species to Large Bio-Molecules

A recompilation of applications of mesoporous silica nanoparticles in sensing from the last five years is presented. Its high potential, especially as hybrid materials combined with organic or bio-molecules, is shown. Adding to the multiplying effect of loading high amounts of the transducer into the pores, the selectivity attained by the interaction of the analyte with the layer decorating the material is described. Examples of the different methodologies are presented.

Recent achievements and advances in optical and electrochemical aptasensing detection of ATP based on quantum dots

The design and fabrication of high sensitive and selective biosensing platforms areessential goals to precisely recognize biomaterials in biological assays. In particular, determination of adenosine triphosphate (ATP) as the main energy currency of the cells and one of the most important biomolecules in living organisms is a pressing need in advanced biological detection. Recently, aptamer-based biosensors are introduced as a new direct strategy in which the aptamers (Apts) directly bind to the different targets and detect them on the basis of conformational changes and physical interactions. They can also be conjugated to optical and electronic probes such as quantum dot (QD) nanomaterials and provide unique QD aptasensing platforms. Currently, these Apt-based biosensors with excellent recognition features have attracted extensive attention due to the high specificity, rapid response and facile construction. Therefore, in this review article, recent achievements and advances in aptasensing detection of ATP based on different detection methods and types of QDs are discussed. In this regard, the optical and electrochemical aptasensors have been categorized based on detection methods; fluorescence (FL), electrochemiluminescence (ECL) and photoelectrochemical (PEC) and they have been also divided to two main groups based on QDs; metal-based (M-based) and carbon-based (C-based) materials. Then, their advantages and limitations have been highlighted, compared and discussed in detail.

Synthesis and Application of Silica-Coated Quantum Dots in Biomedicine

Quantum dots (QDs) are semiconductor nanoparticles with outstanding optoelectronic properties. More specifically, QDs are highly bright and exhibit wide absorption spectra, narrow light bands, and excellent photovoltaic stability, which make them useful in bioscience and medicine, particularly for sensing, optical imaging, cell separation, and diagnosis. In general, QDs are stabilized using a hydrophobic ligand during synthesis, and thus their hydrophobic surfaces must undergo hydrophilic modification if the QDs are to be used in bioapplications. Silica-coating is one of the most effective methods for overcoming the disadvantages of QDs, owing to silica's physicochemical stability, nontoxicity, and excellent bioavailability. This review highlights recent progress in the design, preparation, and application of silica-coated QDs and presents an overview of the major challenges and prospects of their application.

Recent applications of quantum dots in optical and electrochemical aptasensing detection of Lysozyme

Lysozyme (Lyz) is a naturally occurring enzyme that operates against Gram-positive bacteria and leads to cell death. This antimicrobial enzyme forms the part of the innate defense system of nearly all animals and exists in their somatic discharges such as milk, tears, saliva and urine. Increased Lyz level in serum is an important indication of several severe diseases and so, precise diagnosis of Lyz is an urgent need in biosensing assays. Up to know, various traditional and modern techniques have been introduced for Lyz determination. Although the traditional methods suffer from some significant limitations such as time-consuming, arduous, biochemical screening, bacterial colony isolation, selective enrichment and requiring sophisticated instrumentation or isotope labeling, some new modern approaches like aptamer-based biosensors (aptasensors) and quantum dot (QD) nanomaterials are the main goal in Lyz detection. Electrochemical and optical sensors have been highlighted because of their adaptability and capability to decrease the drawbacks of common methods. Using an aptamer-based biosensor, sensor selectivity is enhanced due to the specific recognition of the analyte. Thereby, in this review article, the recent advances and achievements in electrochemical and optical aptasensing detection of Lyz based on different QD nanomaterials and detection methods have been discussed in detail.

Doped-carbon dots: Recent advances in their biosensing, bioimaging and therapy applications

As a fascinating class of fluorescent carbon dots (CDs), doped-CDs are now sparked intense research interest, particularly in the diverse fields of biomedical applications due to their unique advantages, including low toxicity, physicochemical, photostability, excellent biocompatibility, and so on. In this review, we have summarized the most recent developments in the literature regarding the employment of doped-CDs for pharmaceutical and medical applications, which are published over approximately the past five years. Accordingly, we discuss the toxicity and optical properties of these nanomaterials. Beyond the presentation of successful examples of the application of these multifunctional nanoparticles in photothermal therapy, photodynamic therapy, and antibacterial activity, we further highlight their application in the cellular labeling, dual imaging, and in vitro and in vivo bioimaging by use of fluorescent-, photoacoustic-, magnetic-, and computed tomography (CT)-imaging. The potency of doped-CDs was also described in the biosensing of ions, small molecules, and drugs in biological samples or inside the cells. Finally, the advantages, disadvantages, and common limitations of doped-CD technologies are reviewed, along with the future prospects in biomedical research. Therefore, this review provides a concise insight into the current developments and challenges in the field of doped-CDs, especially for biological and biomedical researchers.

Molecularly Imprinted Polymer-Quantum Dot Materials in Optical Sensors: An Overview of Their Synthesis and Applications

In the last decades analytical methods have focused on the determination of target analytes at very low concentration levels. This has been accomplished through the use of traditional analytical methods that usually require high reagent consumption, expensive equipment and long pretreatment steps. Thus, there is a demand for simple, rapid, highly selective and user-friendly detection procedures. Quantum dots (QDs) are semiconductor fluorescent nanomaterials with unique optoelectronic properties that have shown great potential for the development of fluorescence probes. Besides, the combination of QDs with molecularly imprinted polymer (MIPs), synthetic materials with selective recognition, have been proposed as useful materials in the development of optical sensors. The resulting MIP-QDs optical sensors integrate the advantages of both techniques: the high sensitivity of QDs-based fluorescence sensors and the high selectivity of MIPs. This review gives a brief overview of the strategies for the synthesis of MIPs-QDs based optical sensors, highlighting the modifications in the synthesis procedure that improve the sensor performance. Finally, a revision of recent applications in sensing and bioimaging is presented.