Silicon Quantum Dots: Synthesis, Encapsulation, and Application in Light-Emitting Diodes

Putative Adverse Outcome Pathway for Parkinson's Disease-like Symptoms Induced by Silicon Quantum Dots based on In Vivo/Vitro Approaches

Given the commercial proliferation of silicon quantum dots (SiQDs) and their inevitable environmental dispersal, this study critically examines their biological and public health implications, specifically regarding Parkinson's disease. The study investigated the toxicological impact of SiQDs on the onset and development of PD-like symptoms through the induction of ferroptosis, utilizing both in vivo [Caenorhabditis elegans (C. elegans)] and in vitro (SH-SY5Y neuroblastoma cell line) models. Our findings demonstrated that SiQDs, characterized by their stable and water-soluble physicochemical properties, tended to accumulate in neuronal tissues. This accumulation precipitated dopaminergic neurodegeneration, manifested as diminished dopamine-dependent behaviors, and escalated the expression of PD-specific genes in C. elegans. Importantly, the results revealed that SiQDs induced ferritinophagy, a selective autophagy pathway that triggered ferroptosis and resulted in PD-like symptoms, even exacerbating disease progression in biological models. These insights were incorporated into a putatively qualitative and quantitative adverse outcome pathway framework, highlighting the serious neurodegenerative risks posed by SiQDs through ferroptosis pathways. This study provides a multidisciplinary analysis critical for informing policy on the regulation of SiQDs exposure to safeguard susceptible populations and guiding the responsible development of nanotechnologies impacting environmental and public health.

Size-Tunable Band Structure and Optical Properties of Colloidal Silicon Nanocrystals Synthesized via Thermal Disproportionation of Hydrogen Silsesquioxane Polymers

Dodecane-capped silicon nanocrystals (NCs) were synthesized by using a low-temperature (800-1100 °C) polymer variant of traditional hydrogen silsesquioxane thermal disproportionation. Highly crystalline Si NCs having tunable diameters (3.0-6.7 nm) and thus photoluminescence (PL) peaks (1.68-1.29 eV) were attained via changes in the maximum annealing temperature. Modifications in the NC band structure with diameter were explored by comparison of emission with absorption spectra obtained from diffuse reflectance spectroscopy. Large apparent energy shifts between onsets and PL were noted, being significant for smaller NCs (≤∼4.0 nm). This, along with comparatively "softer" onsets, is commensurate with density of states elongation around PL peaks associated with increasing confinement predicted for indirect semiconductor nanostructures. Tauc analyses of absorption additionally revealed three distinguishable optical transitions in all NCs: attributed to indirect Γ25'-Δ1 in lower energy ranges (likely the emission progenitor), indirect Γ25'-L1 overtaken by quasi-direct Γ-X wave function mixing for NC diameters ≤∼4.0 nm within the midenergy regime, and direct Γ25'-Γ15 transitions at energies nearing and above ∼3 eV.

Targeted Biodegradable Near-Infrared Fluorescent Nanoparticles for Colorectal Cancer Imaging

Colorectal cancer (CRC) is the third leading cause of cancer death in the U.S., and early detection and diagnosis are essential for effective treatment. Current methods are inadequate for rapid detection of early disease, revealing flat lesions, and delineating tumor margins with accuracy and molecular specificity. Fluorescence endoscopy can generate wide field-of-view images enabling detection of CRC lesions and margins; increased signal intensity and improved signal-to-noise ratios can increase both speed and sensitivity of cancer detection. For this purpose, we developed targeted near-infrared (NIR) fluorescent silica nanoparticles (FSNs). We tuned their size to 50-200 nm and conjugated their surface with an antibody to carcinoembryonic antigen (CEA) to prepare CEA-FSNs. The physicochemical properties and biodegradable profiles of CEA-FSN were characterized, and molecular targeting was verified in culture using HT29 (CEA positive) and HCT116 (CEA negative) cells. CEA-FSNs bound to the HT29 cells to a greater extent than to the HCT116 cells, and smaller CEA-FSNs were internalized into HT29 cells more efficiently than larger CEA-FSNs. After intravenous administration of CEA-FSNs, a significantly greater signal was observed from the CEA-positive HT29 than the CEA-negative HCT116 tumors in xenografted mice. In F344-PIRC rats, polyps in the intestine were detected by white-light endoscopy, and NIR fluorescent signals were found in the excised intestinal tissue after topical application of CEA-FSNs. Immunofluorescence imaging of excised tissue sections demonstrated that the particle signals coregistered with signals for both CRC and CEA. These results indicate that CEA-FSNs have potential as a molecular imaging marker for early diagnosis of CRC.

Silicon-containing nanomedicine and biomaterials: materials chemistry, multi-dimensional design, and biomedical application

The invention of silica-based bioactive glass in the late 1960s has sparked significant interest in exploring a wide range of silicon-containing biomaterials from the macroscale to the nanoscale. Over the past few decades, these biomaterials have been extensively explored for their potential in diverse biomedical applications, considering their remarkable bioactivity, excellent biocompatibility, facile surface functionalization, controllable synthesis, etc. However, to expedite the clinical translation and the unexpected utilization of silicon-composed nanomedicine and biomaterials, it is highly desirable to achieve a thorough comprehension of their characteristics and biological effects from an overall perspective. In this review, we provide a comprehensive discussion on the state-of-the-art progress of silicon-composed biomaterials, including their classification, characteristics, fabrication methods, and versatile biomedical applications. Additionally, we highlight the multi-dimensional design of both pure and hybrid silicon-composed nanomedicine and biomaterials and their intrinsic biological effects and interactions with biological systems. Their extensive biomedical applications span from drug delivery and bioimaging to therapeutic interventions and regenerative medicine, showcasing the significance of their rational design and fabrication to meet specific requirements and optimize their theranostic performance. Additionally, we offer insights into the future prospects and potential challenges regarding silicon-composed nanomedicine and biomaterials. By shedding light on these exciting research advances, we aspire to foster further progress in the biomedical field and drive the development of innovative silicon-composed nanomedicine and biomaterials with transformative applications in biomedicine.

Quantum Dot-based Bio-conjugates as an Emerging Bioimaging Tool for Cancer Theranostic- A Review

Cancer is the most widely studied disorder in humans, but proper treatment has not yet been developed for it. Conventional therapies, like chemotherapy, radiation therapy, and surgery, have been employed. Such therapies target not only cancerous cells but also harm normal cells. Conventional therapy does not result in specific targeting and hence leads to severe side effects. The main objective of this study is to explore the QDs. QDs are used as nanocarriers for diagnosis and treatment at the same time. They are based on the principle of theranostic approach. QDs can be conjugated with antibodies via various methods that result in targeted therapy. This results in their dual function as a diagnostic and therapeutic tool. Nanotechnology involving such nanocarriers can increase the specificity and reduce the side effects, leaving the normal cells unaffected. This review pays attention to different methods for synthesising QDs. QDs can be obtained using either organic method and synthetic methods. It was found that QDs synthesised naturally are more feasible than the synthetic process. Top or bottom-up approaches have also emerged for the synthesis of QDs. QDs can be conjugated with an antibody via non-covalent and covalent binding. Covalent binding is much more feasible than any other method. Zero-length coupling plays an important role as EDC (1-Ethyl-3-Ethyl dimethylaminopropyl)carbodiimide is a strong crosslinker and is widely used for conjugating molecules. Antibodies work as surface ligands that lead to antigen- antibody interaction, resulting in site-specific targeting and leaving behind the normal cells unaffected. Cellular uptake of the molecule is done by either passive targeting or active targeting. QDs are tiny nanocrystals that are inorganic in nature and vary in size and range. Based on different sizes, they emit light of specific wavelengths. They have their own luminescent and optical properties that lead to the monitoring, imaging, and transport of the therapeutic moiety to a variety of targets in the body. The surface of the QDs is modified to boost their functioning. They act as a tool for diagnosis, imaging, and delivery of therapeutic moieties. For improved therapeutic effects, nanotechnology leads the cellular uptake of nanoparticles via passive targeting or active targeting. It is a crucial platform that not only leads to imaging and diagnosis but also helps to deliver therapeutic moieties to specific sites. Therefore, this review concludes that there are numerous drawbacks to the current cancer treatment options, which ultimately result in treatment failure. Therefore, nanotechnology that involves such a nanocarrier will serve as a tool for overcoming all limitations of the traditional therapeutic approach. This approach helps in reducing the dose of anticancer agents for effective treatment and hence improving the therapeutic index. QDs can not only diagnose a disease but also deliver drugs to the cancerous site.

Development of a biomimetic DNA delivery system by encapsulating polyethyleneimine functionalized silicon quantum dots with cell membranes

Quantum dots (QDs) are renowned for their remarkable optoelectronic properties, making them suitable for applications such as bioimaging and optoelectronics. However, their use in gene delivery has been restricted due to the low DNA loading capacity. This study aimed to develop a biomimetic DNA delivery system by encapsulating polyethyleneimine (PEI) functionalized silicon QDs (SiQDs) with cell membranes and evaluate its potential as a gene vector in vitro. To achieve this, hydrophilic dispersed silicon QDs (PQDs) were prepared through a one-pot hydrothermal reaction of PEI and 3-Aminopropyltrimethoxysilane (APTMS). Subsequently, red blood cell membrane (RBCM) encapsulated biomimetic QDs (CM-PQDs) was obtained through the extrusion method. The CM-PQDs exhibited higher DNA loading capacity and better stability than naked SiQDs. The CM-PQDs/DNA complex was effectively taken up by cells, as observed through the fluorescence characteristics of QDs themselves. Both CM-P10QDs (prepared with PEI10k) and CM-P25QDs (prepared with PEI25k) could deliver DNA into cells and express the reporter protein successfully. CM-P25QDs showed a higher transfection efficiency of 77.32% in 293 T cells and 47.11% in HeLa cells than SiQDs and CM-P10QDs. The results also indicated that cell membrane encapsulation could effectively reduce the cytotoxicity of SiQDs further. Therefore, the study concludes that CM-PQDs have the potential to serve as a safe and traceable biomimetic gene delivery system.

The electronic properties of boron-doped germanium nanocrystals films

Various doping concentrations of boron (B)-doped germanium nanocrystal (Ge NC) films were prepared using the plasma-enhanced chemical vapor deposition (PECVD) technique followed by thermal annealing treatment. The electronic properties of B-doped Ge NCs films combined with the microstructural characterization were investigated. It is worthwhile mentioning that the Hall mobilities [Formula: see text] of Ge NCs films were enhanced after B doping and reached to the maximum of 200 cm2 V-1, which could be ascribed to the reduction in surface defects states in the B-doped films. It is also important to highlight that the temperature-dependent mobilities [Formula: see text] exhibited different temperature dependence trends in the Ge NCs films before and after B doping. A comprehensive investigation was conducted to examine the distinct carrier transport properties in B-doped Ge NC films, and a detailed discussion was presented, focusing on the scattering mechanisms involved in the transport process.

Flexible Quantum Dot Light-Emitting Device for Emerging Multifunctional and Smart Applications

Quantum dot light-emitting diodes (QLEDs), owing to their exceptional performances in device efficiency, color purity/tunability in the visible region and solution-processing ability on various substrates, become a potential candidate for flexible and ultrathin electroluminescent (EL) lighting and display. Moreover, beyond the lighting and display, flexible QLEDs are enabled with endless possibilities in the era of the internet of things and artificial intelligence by acting as input/output ports in wearable integrated systems. Challenges remain in the development of flexible QLEDs with the goals for high performance, excellent flexibility/even stretchability, and emerging applications. In this paper, the recent developments of QLEDs including quantum dot materials, working mechanism, flexible/stretchable strategies and patterning strategies, and highlight its emerging multifunctional integrations and smart applications covering wearable optical medical devices, pressure-sensing EL devices, and neural smart EL devices, are reviewed. The remaining challenges are also summarized and an outlook on the future development of flexible QLEDs made. The review is expected to offer a systematic understanding and valuable inspiration for flexible QLEDs to simultaneously satisfy optoelectronic and flexible properties for emerging applications.

Emerging ultrasmall luminescent nanoprobes for in vivo bioimaging

Photoluminescence (PL) imaging has become a fundamental tool in disease diagnosis, therapeutic evaluation, and surgical navigation applications. However, it remains a big challenge to engineer nanoprobes for high-efficiency in vivo imaging and clinical translation. Recent years have witnessed increasing research efforts devoted into engineering sub-10 nm ultrasmall nanoprobes for in vivo PL imaging, which offer the advantages of efficient body clearance, desired clinical translation potential, and high imaging signal-to-noise ratio. In this review, we present a comprehensive summary and contrastive discussion of emerging ultrasmall luminescent nanoprobes towards in vivo PL bioimaging of diseases. We first summarize size-dependent nano-bio interactions and imaging features, illustrating the unique attributes and advantages/disadvantages of ultrasmall nanoprobes differentiating them from molecular and large-sized probes. We also discuss general design methodologies and PL properties of emerging ultrasmall luminescent nanoprobes, which are established based on quantum dots, metal nanoclusters, lanthanide-doped nanoparticles, and silicon nanoparticles. Then, recent advances of ultrasmall luminescent nanoprobes are highlighted by surveying their latest in vivo PL imaging applications. Finally, we discuss existing challenges in this exciting field and propose some strategies to improve in vivo PL bioimaging and further propel their clinical applications.

Facile synthesis of non-modified yellow emission silicon quantum dots and their visualization of hydrogen sulfide in living cells and onion tissues

Yellow fluorescent silicon quantum dots (y-SiQDs) with 22.2% fluorescence quantum yield were synthesized by a simple hydrothermal method using 3-glycidoxypropyl triethoxysilane (GOTS) and m-aminophenol. The excitation wavelength is 550 nm with an emission wavelength of 574 nm, which effectively avoids the interference of biological autofluorescence. Notably, the synthesis approach does not require any post-modification and the y-SiQDs can be directly used for hydrogen sulfide (H₂S) quantification due to static quenching. It exhibits high sensitivity and excellent selectivity for H₂S with a 0.2-10 μM (R² = 0.9953) linear range and detection limit of 54 nM. y-SiQDs have excellent stability and biocompatibility and can be used for H₂S imaging in living cells and onion tissues.

Nanomaterials for optical biosensors in forensic analysis

Biosensors are compact analytical devices capable of transducing a biological interaction event into a measurable signal outcome in real-time. They can provide sensitive and affordable analysis of samples without the need for additional laboratory equipment or complex preparation steps. Biosensors may be beneficial for forensic analysis as they can facilitate large-scale high-throughput, sensitive screening of forensic samples to detect target molecules that are of high evidential value. Nanomaterials are gaining attention as desirable components of biosensors that can enhance detection and signal efficiency. Biosensors that incorporate nanomaterials within their design have been widely reported and developed for medical purposes but are yet to find routine employment within forensic science despite their proven potential. In this article, key examples of the use of nanomaterials within optical biosensors designed for forensic analysis are outlined. Their design and mechanism of detection are both considered throughout, discussing how nanomaterials can enhance the detection of the target analyte. The critical evaluation of the optical biosensors detailed within this review article should help to guide future optical biosensor design via the incorporation of nanomaterials, for not only forensic analysis but alternative analytical fields where such biosensors may prove a valuable addition to current workflows.

Recent Advances in Hydrogels via Diels-Alder Crosslinking: Design and Applications

The Diels-Alder (DA) reaction is a promising tool for obtaining covalently crosslinked hydrogels due to its reaction bioorthogonality, the absence of by-products, and the application of mild conditions without a catalyst. The resulting hydrogels are in demand for use in various fields of materials science and biomedicine. While the dynamic nature of the cycloaddition of diene and dienophile has previously been used extensively for the fabrication of self-healing materials, it has only recently spread to the expansion of the functional properties of polymer gels for bioapplications. This review describes strategies and recent examples of obtaining hydrogels based on the DA reaction, demonstrating that the emerging functional properties go beyond self-healing. The types of classifications of hydrogels are listed, depending on the type of reaction and the nature of the components. Examples of obtaining hydrogels based on the normal and inverse electron-demand DA reaction, as well as the application of hydrogels for cell culture, drug delivery, injectable gels, and wound dressings, are considered. In conclusion, possible developmental directions are discussed, including the use of diene-dienophile pairs with a low temperature for the reversal of DA reaction, the modification of nanoparticles by diene and/or dienophile fragments, and new applications such as ink for 3D printing, sensing hydrogels, etc.

Quantum Dots and Their Interaction with Biological Systems

Quantum dots are nanocrystals with bright and tunable fluorescence. Due to their unique property, quantum dots are sought after for their potential in several applications in biomedical sciences as well as industrial use. However, concerns regarding QDs’ toxicity toward the environment and other biological systems have been rising rapidly in the past decade. In this mini-review, we summarize the most up-to-date details regarding quantum dots’ impacts, as well as QDs’ interaction with mammalian organisms, fungal organisms, and plants at the cellular, tissue, and organismal level. We also provide details about QDs’ cellular uptake and trafficking, and QDs’ general interactions with biological structures. In this mini-review, we aim to provide a better understanding of our current standing in the research of quantum dots, point out some knowledge gaps in the field, and provide hints for potential future research.

Sulfur quantum dots as a novel platform to design a sensitive chemiluminescence probe and its application for Pb2+ detection

The monitoring of Pb as a hazardous heavy metal element for the environment and human health is of high importance. In this study, a simple and sensitive chemiluminescence (CL) probe based on sulfur quantum dots (SQDs) was designed for the determination of Pb²⁺ . To the best of our knowledge, this is the first report about the analytical application of the CL method based on SQDs. For this purpose, SQDs were synthesized by a simple hydrothermal method and characterized by TEM, FT-IR, XPS and X-ray diffraction. Then, the direct chemiluminescence (CL) of SQDs elicited by common oxidants was investigated. The highest CL intensity was observed for the SQDs-KMnO₄ reaction, and its CL mechanism was studied. We indicated that the CL intensity of introduced system can be diminished as a result of interaction between Pb²⁺ and SQDs, and exploited this fact for designing a CL-based probe for the determination of Pb²⁺ . The CL intensity of SQDs-KMnO₄ reaction was linearly quenched by Pb²⁺ at the range of 50 to 2000 nM with a limit of detection as 16 nM (S/N=3). The probe was employed for the determination of Pb²⁺ in different water samples and the recovery results (95.2 to 102.8%) indicated the good analytical performance of the developed method.

Experimental Study of the Influence of CH4 and H2 on the Conformation, Chemical Composition, and Luminescence of Silicon Quantum Dots Inlaid in Silicon Carbide Thin Films Grown by Remote Plasma-Enhanced Chemical Vapor Deposition

Silicon carbide (SiC) has become an extraordinary photonic material. Achieving reproducible self-formation of silicon quantum dots (SiQDs) within SiC matrices could be beneficial for producing electroluminescent devices operating at high power, high temperatures, or high voltages. In this work, we use a remote plasma-enhanced chemical vapor deposition system to grow SiC thin films. We identified that a particular combination of 20 sccm of CH₄ and a range of 58-100 sccm of H₂ mass flow with 600 °C annealing allows the abundant and reproducible self-formation of SiQDs within the SiC films. These SiQDs dramatically increase the photoluminescence-integrated intensity of our SiC films. The photoluminescence of our SiQDs shows a normal distribution with positive skewness and well-defined intensity maxima in blue regions of the electromagnetic spectrum (439-465 nm) and is clearly perceptible to the naked eye.

Quantum Dots for Cancer-Related miRNA Monitoring

Quantum dots (QDs) possess exceptional optoelectronic properties that enable their use in the most diverse applications, namely, in the medical field. The prevalence of cancer has increased and has been considered the major cause of death worldwide. Thus, there has been a great demand for new methodologies for diagnosing and monitoring cancer in cells to provide an earlier prognosis of the disease and contribute to the effectiveness of treatment. Several molecules in the human body can be considered relevant as cancer markers. Studies published over recent years have revealed that micro ribonucleic acids (miRNAs) play a crucial role in this pathology, since they are responsible for some physiological processes of the cell cycle and, most important, they are overexpressed in cancer cells. Thus, the analytical sensing of miRNA has gained importance to provide monitoring during cancer treatment, allowing the evaluation of the disease's evolution. Recent methodologies based on nanochemistry use fluorescent quantum dots for sensing of the miRNA. Combining the unique characteristics of QDs, namely, their fluorescence capacity, and the fact that miRNA presents an aberrant expression in cancer cells, the researchers created diverse strategies for miRNA monitoring. This review aims to present an overview of the recent use of QDs as biosensors in miRNA detection, also highlighting some tutorial descriptions of the synthesis methods of QDs, possible surface modification, and functionalization approaches.

Gateway towards recent developments in quantum dot-based light-emitting diodes

Quantum dots (QDs), with their excellent photoluminescence, narrow emission linewidth, and wide color coverage, provide unrivaled advantages for advanced display technologies, enabling full-color micro-LED displays. It is indeed critical to have a fundamental understanding of how QD properties affect micro-LED display performance in order to develop the most energy-efficient display device in the near future. However, to take a more detailed look at the stability issues and passivation ways of QDs is essential for accelerating the commercialization of QD-based LED technologies. Knowing about the most recent breakthroughs in QD-based LEDs can give a good indication of how they might be used in shaping the future of displays. In this review, we discuss the characteristics of QD-based LEDs for the applications of display and lighting technologies. Various approaches for synthesis and the stability improvement of QDs are addressed in detail, along with recent advancements towards QD-based LED breakthroughs. Moreover, we summarize our latest research findings in QD-based LEDs, providing valuable information about the potential of QD-based LEDs for future display technologies.

Interactions of Si+(2PJ) and Ge+ (2PJ) with rare gas atoms (He-Rn): interaction potentials, spectroscopy, and ion transport coefficients

Accurate interatomic potentials were calculated for the interaction of a singly-charged silicon cation, Si⁺, with a single rare gas atom, RG (RG = Kr-Rn), as well as a singly-charged germanium cation, Ge⁺, with a single rare gas atom, RG (RG = He-Rn). The RCCSD(T) method and basis sets of quadruple-ζ and quintuple-ζ quality were employed; each interaction energy is counterpoise corrected and extrapolated to the basis set limit. The lowest electronic term (²P) of each cation was considered, and the interatomic potentials calculated for the diatomic terms that arise from these: ²Π and ²Σ⁺. Additionally, the interatomic potentials for the respective spin-orbit levels were calculated, and the effect on the spectroscopic parameters was examined. Variations in several spectroscopic parameters with the increasing atomic number of RG were examined. The presence of incipient chemical interaction was also examined via Birge-Sponer-like plots and various population analyses across the series. In the cases of heavier RG, these were consistent with a small amount of electron transfer from the heavier RG atom to the cation, rationalizing the spin-orbit splittings. This was also supported by the observed larger-than-expected spin-orbit splittings for the Si⁺-RG complexes. Finally, each set of RCCSD(T) potentials including spin-orbit coupling was employed to calculate transport coefficients for the cation moving through a bath of the RG. The calculated ion mobilities showed significant differences for the two atomic spin-orbit states, arising from subtle changes in the interaction potentials.

Concanavalin A-conjugated gold nanoparticle/silica quantum dot (AuNPs/SiQDs-Con A)-based platform as a fluorescent nanoprobe for the bioimaging of glycan-positive cancer cells

The glycan receptor is a glycosylphosphatidylinositol glycoprotein that is overexpressed on the surface of various cancer cells and has been utilized for wide applications. In the present work, the surface of citrate-capped gold nanoparticles (cit-AuNPs) was modified with mercaptopropionic acid (MPA) molecules to provide carboxylic groups for secondary functionalization with amine anchored-silica quantum dots (Si-NH₂ QDs) to produce cit-AuNPs-MPA/Si-NH₂ QDs fluorescent nanoparticles. Concanavalin A (Con A) molecules were attached through thiol-AuNP bonds to produce the final cit-AuNPs/MPA/Si-NH₂ QDs/Con A smart nanoparticles. The synthesized novel cit-AuNPs/MPA/Si-NH₂ QDs/Con A nanoparticles were utilized for the bioimaging of glycan-overexpressed breast cancer cells. Fluorescence microscopy and flow cytometry results revealed that the cit-AuNPs/MPA/Si-NH₂ QDs/Con A NPs can be efficiently taken up by cancer cells, with differentiating ability between overexpressed cancer cells and low-expressed normal cells. The cellular viability of the cit-AuNPs/MPA/Si-NH₂ QDs/Con A NPs was tested by the MTT test, proving their biocompatible nature at the 200 μg mL^-1 level. In conclusion, the fabricated cit-AuNPs/MPA/Si-NH₂ QDs/Con A NPs could be utilized for the bioimaging of MCF-7 cancer cells even in the clinical setting after proper in vivo validation.

Pharmaceutical Aspects of Nanocarriers for Smart Anticancer Therapy

Drug delivery to tumor sites using nanotechnology has been demonstrated to overcome the drawbacks of conventional anticancer drugs. Altering the surface shape and geometry of nanocomposites alters their chemical properties, which can confer multiple attributes to nanocarriers for the treatment of cancer and their use as imaging agents for cancer diagnosis. However, heterogeneity and blood flow in human cancer limit the distribution of nanoparticles at the site of tumor tisues. For targeted delivery and controlled release of drug molecules in harsh tumor microenvironments, smart nanocarriers combined with various stimuli-responsive materials have been developed. In this review, we describe nanomaterials for smart anticancer therapy as well as their pharmaceutical aspects including pharmaceutical process, formulation, controlled drug release, drug targetability, and pharmacokinetic or pharmacodynamic profiles of smart nanocarriers. Inorganic or organic-inorganic hybrid nanoplatforms and the electrospinning process have also been briefly described here.

Fluorescent nanoparticles as tools in ecology and physiology

Fluorescent nanoparticles (FNPs) have been widely used in chemistry and medicine for decades, but their employment in biology is relatively recent. Past reviews on FNPs have focused on chemical, physical or medical uses, making the extrapolation to biological applications difficult. In biology, FNPs have largely been used for biosensing and molecular tracking. However, concerns over toxicity in early types of FNPs, such as cadmium-containing quantum dots (QDs), may have prevented wide adoption. Recent developments, especially in non-Cd-containing FNPs, have alleviated toxicity problems, facilitating the use of FNPs for addressing ecological, physiological and molecule-level processes in biological research. Standardised protocols from synthesis to application and interdisciplinary approaches are critical for establishing FNPs in the biologists' tool kit. Here, we present an introduction to FNPs, summarise their use in biological applications, and discuss technical issues such as data reliability and biocompatibility. We assess whether biological research can benefit from FNPs and suggest ways in which FNPs can be applied to answer questions in biology. We conclude that FNPs have a great potential for studying various biological processes, especially tracking, sensing and imaging in physiology and ecology.

Silicon Quantum Dot-Polymer Fabry-Pérot Resonators with Narrowed and Tunable Emissions

Luminescent silicon nanoparticles have been widely recognized as an alternative for metal-based quantum dots (QDs) for optoelectronics partly because of the high abundance and biocompatibility of silicon. To date, the broad photoluminescence line width (often >100 nm) of silicon QDs has been a hurdle to achieving competitive spectral purity and incorporating them into light-emitting devices. Herein we report fabrication and testing of straightforward configuration of Fabry-Pérot resonators that incorporates a thin layer of SiQD-polymer hybrid/blend between two reflective silver mirrors; remarkably these devices exhibit up-to-14-fold narrowing of SiQD emission and achieve a spectral bandwidth as narrow as ca. 9 nm. Our polymer-based, SiQD-containing Fabry-Pérot resonators also provide convenient spectral tunability, can be prepared using a variety of polymer hosts and substrates, and enable rigid as well as flexible devices.

Ultrasensitive and visual detection of tetracycline based on dual-recognition units constructed multicolor fluorescent nano-probe

Ultrasensitive and visual detection of tetracycline antibiotic (TC) residues is of great significance to public health and environmental safety. A novel dual-response ratiometric fluorescent nano-probe (SiQDs-Cit-Eu) has been elaborately tailored for the determination and on-site visual assay of tetracycline, by grafting citric acid and europium (Eu³⁺) ions onto the surface of silicon quantum dots (SiQDs). The blue-emissive SiQDs (λ_em = 455 nm) fabricated by a one-step facile method act as both scaffold for coordination with Eu³⁺ ions and recognition unit for TC owing to the inner filter effect (IFE). The coordinate unsaturated red-fluorescent Eu³⁺ ions (λ_em = 617 nm) bond to the surface of SiQDs, serving as the specific recognition element for TC due to the antenna effect. In the presence of TC, the as-synthesized nano-probe exhibits double (λ_em = 455 and 617 nm) and reverse response signals which are accompanied by a marked color change from blue to purple, and then red, thus achieving ultra-high sensitivity with a detection limit of 7.1 nM and instant visual detection of TC in real samples (milk, honey, lake and river water). Furthermore, smartphone-assisted point-of-care testing platform is also constructed based on nano-probe-immobilized test paper by using the color scanning APP.

An Excess Electron Bound to Magnesium Halides and Basic Grignard Compounds (RMgX and RMgR, R = Me, Et, Ph; X = F, Cl, Br)

Grignard reagents are commonly used in organic synthesis, yet their ability to form stable anionic states has not been recognized thus far. In this work, representative examples of RMgF, RMgCl, and RMgBr molecules involving methyl, ethyl, and phenyl functional groups serving as R substituents are investigated regarding their equilibrium structures, adiabatic electron affinities, and vertical electron detachment energies of their daughter anions. The electronic stabilities determined for the negatively charged Grignard compounds are then compared to those predicted for their corresponding magnesium halides. The anions formed by RMgX (R = Me, Et, Ph; X = F, Cl, Br) molecules are found to be adiabatically electronically stable valence-bound systems characterized by relatively large vertical electron detachment energies spanning the 0.79–1.62 eV range. In addition, significant structural relaxation upon attachment of an excess electron is predicted for all Grignard compounds considered. Furthermore, the re-examination of the anions formed by magnesium halides resulted in recognizing them as valence-bound rather than dipole-bound anions, in contrast to the earlier interpretations.

Research advances in integrated theranostic probes for tumor fluorescence visualization and treatment

At present, cancer is obviously a major threat to human health worldwide. Accurate diagnosis and treatment are in great demand and have become an effective method to alleviate the development of cancer and improve the survival rate of patients. A large number of theranostic probes that combine diagnosis and treatment methods have been developed as promising tools for tumor precision medicine. Among them, fluorescent theranostic probes have developed rapidly in the frontier research field of precision medicine with their real time, low toxicity, and high-resolution merit. Therefore, this review focuses on recent advances in the development of fluorescent theranostic probes, as well as their applications for cancer diagnosis and treatment. Initially, small-molecule fluorescent theranostic probes mainly including tumor microenvironment-responsive fluorescent prodrugs and phototherapeutic probes were introduced. Subsequently, nanocomposite probes are expounded based on four types of nano-fluorescent particles combining different therapies (chemotherapy, photothermal therapy, photodynamic therapy, gene therapy, etc.). Then, the capsule-type "all in one" probes, which occupy an important position in theranostic probes, are summarized according to the surface carrier type. This review aims to present a comprehensive guide for researchers in the field of tumor-related theranostic probe design and development.

A critical review on quantum dots: From synthesis toward applications in electrochemical biosensors for determination of disease-related biomolecules

Fluorescent quantum dots (QDs), defined by a diameter size of <10 nm, have been the core concept of nanoscience and nanotechnology since their inception. QDs possess many unique structural, electrochemical and photochemical properties that render them a promising platform for sensing applications. These nanomaterials can greatly enhance the analytical performances of biosensors, namely detection limit, sensitivity and selectivity. QDs are being developed not only because of their ability for signal enhancement but also because of their high capacity for fuctionalization with bioreceptors. In this review, we summarize a basic knowledge of QDs before focusing on their application to sensing thus far followed by a discussion of future directions for research into the sensing field. Due to the nature of QDs, especially their ability to combine nanotechnology and biotechnology, they possess the potential to open a novel paradigm on early diagnosis of diseases using the electrochemical biosensors. Therefore, we try to give a comprehensive view of the role of these zero-dimensional (0D) nanomaterials in the designing electrochemical sensors for determination of disease-related biomolecules, including tumor markers, inflammatory biomarkers, depression markers and archetypal biomarker in diabetes diagnosis. Considering the high potential of QDs for the electrochemistry-based biosensing strategies, the authors suggest that more research is needed on understanding their electronic properties and why synthesis and surface modification methods can affect these properties.

Quantum dots as nanosensors for detection of toxics: a literature review

Great advances have been made in sensor-based methods for chemical analysis owing to their high sensitivity, selectivity, less testing time, and minimal usage of chemical reagents. Quantum Dots (QDs) having excellent optical properties have been thoroughly explored for variety of scientific applications wherein light plays an important role. In recent years, there have been an increasing number of publications on the applications of QDs as photoluminescent nanosensors for the detection of chemicals and biomolecules. However, there has been hardly any publication describing the use of QDs in the detection of various toxic chemicals at one place. Hence, a literature survey has been made on the applications of QDs as chemosensors for the detection of gaseous, anionic, phenolic, metallic, drug-overdose, and pesticide poison so as to open a new perspective towards the role of sensors in analytical toxicology. In this review, the QD-based analysis of biospecimens for poison detection in clinical and forensic toxicology laboratories is highlighted.