Dye-doped silica nanoparticles: synthesis, surface chemistry and bioapplications

Targeted delivery of bee venom to A549 lung cancer cells by PEGylate liposomal formulation: an apoptotic investigation

This study focused on developing an optimal formulation of liposomes loaded with bee venom (BV) and coated with PEG (BV-Lipo-PEG). The liposomes were characterized using dynamic light scattering, transmission electron microscopy, and Fourier transform infrared spectroscopy. Among the liposomal formulations, F3 exhibited the narrowest size distribution with a low PDI value of 193.72 ± 7.35, indicating minimal agglomeration-related issues and a more uniform size distribution. BV-Lipo-PEG demonstrated remarkable stability over 3 months when stored at 4 °C. Furthermore, the release of the drug from the liposomal formulations was found to be pH-dependent. Moreover, BV-Lipo-PEG exhibited favorable entrapment efficiencies, with values reaching 96.74 ± 1.49. The anticancer potential of the liposomal nanocarriers was evaluated through MTT assay, flow cytometry, cell cycle analysis, and real-time experiments. The functionalization of the liposomal system enhanced endocytosis. The IC50 value of BV-Lipo-PEG showed a notable decrease compared to both the free drug and BV-Lipo alone, signifying that BV-Lipo-PEG is more effective in inducing cell death in A549 cell lines. BV-Lipo-PEG exhibited a higher apoptotic rate in A549 cell lines compared to other samples. In A549 cell lines treated with BV-Lipo-PEG, the expression levels of MMP-2, MMP-9, and Cyclin E genes decreased, whereas the expression levels of Caspase3 and Caspase9 increased. These findings suggest that delivering BV via PEGylated liposomes holds significant promise for the treatment of lung cancer.

Green hybrid coagulants for water treatment: An innovative approach using alum and bentonite clay combined with eco-friendly plant materials for batch and column adsorption

Textile industries contribute to water pollution through synthetic dye discharge. This study explores the use of natural bio-coagulants to remove acid dyes from wastewater, investigating factors like pH, coagulant dose, dye concentration, contact time, and temperature for optimal results. The optimum pH and coagulants capabilities of (CAAPP, CAAPH, CBAGL, CBAPP and CBAPH) were 3 (49.6 mg/g), 3 (42.5 mg/g), 3 (38.9 mg/g), 4 (35.7 mg/g), 4 (34.1 mg/g), and 4 (29.4 mg/g) respectively, while treating of selected BRF-221 dyes from water solution. The acidic range (3-4) was found to have the best pH for the maximal coagulation, and the optimal dose were found to be 0.05 g/50 mL. The equilibrium was attained within 45-60 min for all coagulants. After 60 min of shaking, the maximum coagulation capacities (21.9, 21.02, 16.5, 27.9, 25.3, and 23.4 mg/g) of several coagulant composites (CAAGL, CAAPP, CAAPH, CBAGL, CBAPP, CBAPH) were determined. The initial BRF-221 dye concentration in the range of 10-200 mg/L was considered as optimum for gaiting maximum elimination of dye using different coagulants. At a dye value of 100 mg/L of BRF-221, maximal coagulation capacities CAAGL (179.19 mg/g), CAAPP (166.06 mg/g), CAAPH (141.60 mg/g), and CBAGL (126.49 mg/g), CBAPP (113.9 mg/g), CBAPH (93.08 mg/g) were attained. The study found 35 °C to be the optimal temperature for maximum acid dye removal using bio-coagulants. Increasing temperature reduced coagulation capacity, indicating an exothermic process. Freundlich and Langmuir isotherms showed suitability for pseudo-first-order and pseudo-second-order kinetics in biosorption. Thermodynamic parameters were assessed for process feasibility. Effective coagulants demonstrated sensitivity to electrolyte variations. In column studies, adjusting parameters achieved maximum coagulation efficiency for removing BRF-221 dyes. The study successfully applied optimal parameters to remove real textile effluents at a practical scale. SEM, FT-IR, BET and XRD characterized coagulants, providing insights into stability and morphology.

Ultrabright fluorescent particles via physical encapsulation of fluorescent dyes in mesoporous silica: a mini-review

Harnessing the power of mesoporous silica to encapsulate organic fluorescent dyes has led to the creation of an extraordinary class of nanocomposite photonic materials. These materials stand out for their ability to produce the brightest fluorescent particles known today, surpassing even the luminosity of quantum dots of similar spectrum and size. The synthesis of these materials offers precise control over the shape and size of the particles, ranging from the nano to the multi-micron scale. Just physical encapsulation of the dyes opens new possibilities for mixing different dyes within individual particles, paving the way for nearly limitless multiplexing capabilities. Moreover, this approach lays the groundwork for the development of highly sensitive sensors capable of detecting subtle changes in temperature and acidity at the nanoscale, among other parameters. This mini-review highlights the mechanism of synthesis, explains the nature of ultrabrightness, and describes the recent advancements and future prospects in the field of ultrabright fluorescent mesoporous silica particles, showcasing their potential for various applications.

Tris-assisted one-step fabrication of functional carbon dots for specific folate receptor positive-expressed cancer cell imaging

Specific staining of cancer cells is momentous for cancer research. Nanoprobe with multivalent recognition is emerging as powerful tools for bioimaging, but the nonspecific cell uptake and complex functional modification procedures are still obstacles for specific detection and convenient synthesis. Carbon dots (CDs) with an intrinsic targeting ability, excellent optical properties and biocompatibility acquired from an efficient one-step fabrication procedure were urgently desired in specific cancer cells visualization. Herein, inspired by the interrelationships between interface and biomolecular mechanisms, we suggested that it was possible to construct CDs with the desired characteristics for folate receptor (FR) positive-expressed cancer cell imaging via rich hydroxyl groups Tris-assisted one-step hydrothermal treatment of folate acid (FA) and l-Arginine (L-Arg) precursors. The prepared small-sized F-CDs were equipped with abundant hydroxyl, pterin and negative charge surface, and possessed environmental friendliness, outstanding photostability and biocompatibility. Moreover, F-CDs had an intrinsic FR positive-expressed cancer cell targeting ability without any post-modification of the ligands. Rich hydroxyl groups play a vital role in endowing the optical properties and biological effects of F-CDs. F-CDs could be used as a promising candidate for FR-expressed cancer cell labeling and tracking. In addition, the caveolae-mediated endocytosis pathway of F-CDs was ascertained. More importantly, experimental results confirmed that the combination of physicochemical properties may provide an efficient strategy to overcome non-specific cell uptake interactions for cell labeling. Our strategy put forward a promising alternative to design fluorescent CDs for extensive chemical and biomedical applications.

Optimizing the performance of silica nanoparticles functionalized with a near-infrared fluorescent dye for bioimaging applications

Modified fluorescent nanoparticles continue to emerge as promising candidates for drug delivery, bioimaging, and labeling tools for various biomedical applications. The ability of nanomaterials to fluorescently label cells allow for the enhanced detection and understanding of diseases. Silica nanoparticles have a variety of unique properties that can be harnessed for many different applications, causing their increased popularity. In combination with an organic dye, fluorescent nanoparticles demonstrate a vast range of advantageous properties including long photostability, surface modification, and signal amplification, thus allowing ease of manipulation to best suit bioimaging purposes. In this study, the Stöber method with tetraethyl orthosilicate (TEOS) and a fluorescent dye sulfo-Cy5-amine was used to synthesize fluorescent silica nanoparticles. The fluorescence spectra, zeta potential, quantum yield, cytotoxicity, and photostability were evaluated. The increased intracellular uptake and photostability of the dye-silica nanoparticles show their potential for bioimaging.

Polydopamine-Coated Solid Silica Nanoparticles Encapsulating IR-783 Dyes: Synthesis and NIR Fluorescent Cell Imaging

We report a simple and efficient synthetic method for polydopamine (PDA)-coated solid silica nanoparticles (s-SiO2@PDA NPs) encapsulating anionic near-infrared (NIR) fluorescent dyes through physical adsorption. Despite the use of anionic NIR fluorescent dyes indocyanine green (ICG) and 2-[2-[2-chloro-3-[2-[1,3-dihydro-3,3-dimethyl-1-(4-sulfobutyl)-2H-indol-2-ylidene]-ethylidene]-1-cyclohexen-1-yl]-ethenyl]-3,3-dimethyl-1-(4-sulfobutyl)-3H-indolium (IR-783), they were successfully immobilized on anionic s-SiO2@PDA NP surfaces under acidic aqueous conditions. After embedding in the s-SiO2@PDA NPs, the fluorescence of ICG was almost quenched, while a diminished IR-783 fluorescence remained observable. The fluorescence intensity of IR-783 embedded in s-SiO2@PDA NPs remained almost constant over 2 weeks in a pseudobiological solution, with a slight reduction due to dye degradation and dye leakage from the s-SiO2@PDA NPs. Finally, the s-SiO2@PDA NPs encapsulating IR-783 were successfully used for NIR fluorescent imaging of African green monkey kidney cells.

An Unprecedented Metal Distribution in Silica Nanoparticles Determined by Single-Particle Inductively Coupled Plasma Mass Spectrometry

Metal-containing nanoparticles are now common in applications ranging from catalysts to biomarkers. However, little research has focused on per-particle metal content in multicomponent nanoparticles. In this work, we used single-particle inductively coupled plasma mass spectrometry (ICP-MS) to determine the per-particle metal content of silica nanoparticles doped with tris(2,2'-bipyridyl)ruthenium(II). Monodispersed silica nanoparticles with varied Ru doping levels were prepared using a water-in-oil microemulsion method. These nanoparticles were characterized using common bulk-sample methods such as absorbance spectroscopy and conventional ICP-MS, and also with single-particle ICP-MS. The results showed that averaged concentrations of metal dopant measured per-particle by single-particle ICP-MS were consistent with the bulk-sample methods over a wide range of dopant levels. However, the per-particle amount of metal varied greatly and did not adhere to the usual Gaussian distribution encountered with one-component nanoparticles, such as gold or silver. Instead, the amount of metal dopant per silica particle showed an unexpected geometric distribution regardless of the prepared doping levels. The results indicate that an unusual metal dispersal mechanism is taking place during the microemulsion synthesis, and they challenge a common assumption that doped silica nanoparticles have the same metal content as the average measured by bulk-sample methods.

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.

Greening the pathways: a comprehensive review of sustainable synthesis strategies for silica nanoparticles and their diverse applications

Silica nanoparticles (SiNPs) have emerged as a multipurpose solution with wide-ranging applications in various industries such as medicine, agriculture, construction, cosmetics, and food production. In 1961, Stöber introduced a ground-breaking sol-gel method for synthesizing SiNPs, which carried a new era of exploration both in academia and industry, uncovering numerous possibilities for these simple yet multifaceted particles. Inspite of numerous reported literature with wide applicability, the synthesis of these nanoparticles with the desired size and functionalities poses considerable challenges. Over time, researchers have strived to optimize the synthetic route, particularly by developing greener approaches that minimize environmental impact. By reducing hazardous chemicals, energy consumption, and waste generation, these greener synthesis methods have become an important focus in the field. This review aims to provide a comprehensive analysis of the various synthetic approaches available for different types of SiNPs. Starting from the Stöber' method, we analyze other methods as well to synthesis different types of SiNPs including mesoporous, core-shell and functionalized nanoparticles. With increasing concerns with the chemical methods associated for environmental issues, we aim to assist readers in identifying suitable greener synthesis methods tailored to their specific requirements. By highlighting the advancements in reaction time optimization, waste reduction, and environmentally friendly precursors, we offer insights into the latest techniques that contribute to greener and more sustainable SiNPs synthesis. Additionally, we briefly discuss the diverse applications of SiNPs, demonstrating their relevance and potential impact in fields such as medicine, agriculture, and cosmetics. By emphasizing the greener synthesis methods and economical aspects, this review aims to inspire researchers and industry professionals to adopt environmentally conscious practices while harnessing the immense capabilities of SiNPs.

Second Near-Infrared Macrophage-Biomimetic Nanoprobes for Photoacoustic Imaging of Neuroinflammation

Neuroinflammation is a significant pathological event involving the neurodegenerative process associated with many neurological disorders. Diagnosis and treatment of neuroinflammation in its early stage are essential for the prevention and management of neurological diseases. Herein, we designed macrophage membrane-coated photoacoustic (PA) probes (MSINPs), with targeting specificities based on naturally existing target-ligand interactions for the early diagnosis of neuroinflammation. The second near-infrared dye, IR1061, was doped into silica as the core and was encapsulated with a macrophage membrane. In vitro as well as in vivo, the MSINPs could target inflammatory cells via the inflammation chemotactic effect. PA imaging was used to trace the MSINPs in a neuroinflammation mouse model and showed a great targeted effect of MSINPs in the prefrontal cortex. Therefore, the biomimetic nanoprobe prepared in this study offers a new strategy for PA molecular imaging of neuroinflammation, which can enhance our understanding of the evolution of neuroinflammation in specific brain regions.

Silica nanoparticles: A review of their safety and current strategies to overcome biological barriers

Silica nanoparticles (SNP) have gained tremendous attention in the recent decades. They have been used in many different biomedical fields including diagnosis, biosensing and drug delivery. Medical uses of SNP for anti-cancer, anti-microbial and theranostic applications are especially prominent due to their exceptional performance to deliver many different small molecules and recently biologics (mRNA, siRNA, antigens, antibodies, proteins, and peptides) at targeted sites. The physical and chemical properties of SNP such as large specific surface area, tuneable particle size and porosity, excellent biodegradability and biocompatibility make them an ideal drug delivery and diagnostic platform. Based on the available data and the pre-clinical performance of SNP, recent interest has driven these innovative materials towards clinical application with many of the formulations already in Phase I and Phase II trials. Herein, the progress of SNP in biomedical field is reviewed, and their safety aspects are analysed. Importantly, we critically evaluate the key structural characteristics of SNP to overcome different biological barriers including the blood-brain barrier (BBB), skin, tumour barrier and mucosal barrier. Future directions, potential pathways, and target areas towards rapid clinical translation of SNP are also recommended.

Recent Advances in Biological Applications of Aptamer-Based Fluorescent Biosensors

Aptamers have been spotlighted as promising bio-recognition elements because they can be tailored to specific target molecules, bind to targets with a high affinity and specificity, and are easy to chemically synthesize and introduce functional groups to. In particular, fluorescent aptasensors are widely used in biological applications to diagnose diseases as well as prevent diseases by detecting cancer cells, viruses, and various biomarkers including nucleic acids and proteins as well as biotoxins and bacteria from food because they have the advantages of a high sensitivity, selectivity, rapidity, a simple detection process, and a low price. We introduce screening methods for isolating aptamers with q high specificity and summarize the sequences and affinities of the aptamers in a table. This review focuses on aptamer-based fluorescence detection sensors for biological applications, from fluorescent probes to mechanisms of action and signal amplification strategies.

Dual-color core-shell silica nanosystems for advanced super-resolution biomedical imaging

Fluorescent core-shell silica nanoparticles are largely employed in nanomedicine and life science thanks to the many advantages they offer. Among these, the enhancement of the stability of the fluorescent signal upon fluorophore encapsulation into the silica matrix and the possibility to combine in a single vehicle multiple functionalities, physically separated in different compartments. In this work, we present a new approach to the Stöber method as a two-cycle protocol for the tailored synthesis of dual-color fluorescent core-shell silicon dioxide nanoparticles (SiO2 NPs) using two commercial dyes as model. To facilitate the colloidal stability, the nanoparticle surface was functionalized with biotin by two approaches. The biotinylated nanosystems were characterized by several analytical and advanced microscopy techniques including Fourier transform infrared (FT-IR) spectroscopy, dynamic light scattering (DLS), UV-vis, transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Moreover, advanced super-resolution based on structured illumination was used for the imaging of the double-fluorescent NPs, both on a substrate and in the cellular microenvironment, at nanometric resolution 100 nm, in view of their versatile potential employment in fluorescence optical nanoscopy as nanoscale calibration tools as well as in biomedical applications as biocompatible nanosystems for intracellular biosensing with high flexibility of use, being these nanoplatforms adaptable to the encapsulation of any couple of dyes with the desired function.

Engineering Soluble Diketopyrrolopyrrole Chromophore Stacks from a Series of Pd(II)-Based Ravels

A strategy to engineer the stacking of diketopyrrolopyrrole (DPP) dyes based on non-statistical metallosupramolecular self-assembly is introduced. For this, the DPP backbone is equipped with nitrogen-based donors that allow for different discrete assemblies to be formed upon the addition of Pd(II), distinguished by the number of π-stacked chromophores. A Pd3 L6 three-ring, a heteroleptic Pd2 L2 L'2 ravel composed of two crossing DPPs (flanked by two carbazoles), and two unprecedented self-penetrated motifs (a Pd2 L3 triple and a Pd2 L4 quadruple stack), were obtained and systematically investigated. With increasing counts of stacked chromophores, UV/Vis absorptions red-shift and emission intensities decrease, except for compound Pd2 L2 L'2 , which stands out with an exceptional photoluminescence quantum yield of 51 %. This is extraordinary for open-shell metal containing assemblies and explainable by an intra-assembly FRET process. The modular design and synthesis of soluble multi-chromophore building blocks offers the potential for the preparation of nanodevices and materials with applications in sensing, photo-redox catalysis and optics.

Achieving photostability in dye-sensitized upconverting nanoparticles and their use in Fenton type photocatalysis

Dye sensitization is a promising approach to enhance the luminescence of lanthanide-doped upconverting nanoparticles. However, the poor photostability of near-infrared dyes hampers their use in practical applications. To address this, commercial IR820 was modified for improved photostability and covalently bonded to amine-functionalized silica-coated LnUCNPs. Two methods of covalent linking were investigated: linking the dye to the surface of the silica shell, and embedding the dye within the silica shell. The photostability of the dyes when embedded in the silica shell exhibited upconversion emissions from NaGdF4:Er3+,Yb3+/NaGdF4:Yb3+ nanoparticles for over four hours of continuous excitation with no change in intensity. To highlight this improvement, the photostable dye-embedded system was successfully utilized for Fenton-type photocatalysis, emphasizing its potential for practical applications. Overall, this study presents a facile strategy to circumvent the overlooked limitations associated with photodegradation, opening up new possibilities for the use of dye-sensitized lanthanide-doped upconverting nanoparticles in a range of fields.

Yb-Gd Codoped Hydroxyapatite as a Potential Contrast Agent for Tumor-Targeted Biomedical Applications

Recently, various nanomaterials based on hydroxyapatite (HAp) have been developed for bioimaging applications. In particular, HAp doped with rare-earth elements has attracted significant attention, owing to its enhanced bioactivity and imaging properties. In this study, the wet precipitation method was used to synthesize HAp codoped with Yb and Gd. The synthesized Ybx-Gdx-HAp nanoparticles (NPs) were characterized via various techniques to analyze the crystal phase, functional groups, thermal characteristics, and particularly, the larger surface area. The IR783 fluorescence dye and a folic acid (FA) receptor were conjugated with the synthesized Ybx-Gdx-HAp NPs to develop an effective imaging contrast agent. The developed FA/IR783/Yb-Gd-HAp nanomaterial exhibited improved contrast, sensitivity, and tumor-specific properties, as demonstrated by using the customized LUX 4.0 fluorescence imaging system. An in vitro cytotoxicity study was performed to verify the biocompatibility of the synthesized NPs using MTT assay and fluorescence staining. Photodynamic therapy (PDT) was also applied to determine the photosensitizer properties of the synthesized Ybx-Gdx-HAp NPs. Further, reactive oxygen species generation was confirmed by Prussian blue decay and a 2',7'-dichlorofluorescin diacetate study. Moreover, MDA-MB-231 breast cancer cells were used to evaluate the efficiency of Ybx-Gdx-HAp NP-supported PDT.

Silica nanoparticles for brain cancer

INTRODUCTION

Brain cancer is a debilitating disease with a poor survival rate. There are significant challenges for effective treatment due to the presence of the blood-brain barrier (BBB) and blood-tumor barrier (BTB) which impedes drug delivery to tumor sites. Many nanomedicines have been tested in improving both the survival and quality of life of patients with brain cancer with the recent focus on inorganic nanoparticles such as silica nanoparticles (SNPs). This review examines the use of SNPs as a novel approach for diagnosing, treating, and theranostics of brain cancer.

AREAS COVERED

The review provides an overview of different brain cancers and current therapies available. A special focus on the key functional properties of SNPs is discussed which makes them an attractive material in the field of onco-nanomedicine. Strategies to overcome the BBB using SNPs are analyzed. Furthermore, recent advancements in active targeting, combination therapies, and innovative nanotherapeutics utilizing SNPs are discussed. Safety considerations, toxicity profiles, and regulatory aspects are addressed to provide an understanding of SNPs' translational potential.

EXPERT OPINION

SNPs have tremendous prospects in brain cancer research. The multifunctionality of SNPs has the potential to overcome both the BBB and BTB limitations and can be used for brain cancer imaging, drug delivery, and theranostics. The insights provided will facilitate the development of next-generation, innovative strategies, guiding future research toward improved diagnosis, targeted therapy, and better outcomes in brain cancer patients.

An efficient and eco-compatible multicomponent synthesis of 2,4,5-trisubstituted imidazole derivatives using modified-silica-coated cobalt ferrite nanoparticles with tungstic acid

The aim of this study has been to offer a method for the synthesis of 2,4,5-trisubstituted imidazole derivatives based on green chemistry principles. Therefore, a one-pot multicomponent cyclocondensation reaction through aldehyde interaction with ammonium acetate and 1,2-diketone under solvent-free conditions was utilized as an eco-effective synthetic route using CoFe₂O₄@SiO₂@(-CH₂)₃OWO₃H NPs as the catalyst. The stabilized tungstic acid on 3-chloropropyl-anchored SiO₂-coated CoFe₂O₄ magnetic nanoparticles was designed, prepared, and applied as a recyclable heterogeneous acid catalyst to attain high product yield in a short reaction time. The nanocatalyst structure was confirmed using FT-IR, Raman, XRD, FE-SEM, EDX, VSM, and TGA techniques, and the organic product structures were examined by melting point, FT-IR and ¹H NMR analyses.

Biogenic Synthesis of Fluorescent Carbon Dots (CDs) and Their Application in Bioimaging of Agricultural Crops

Fluorescent nanoparticles have a transformative potential for advanced sensors and devices for point-of-need diagnostics and bioimaging, bypassing the technical burden of meeting the assay performance requirements. Carbon dots (CDs) are rapidly emerging carbon-based nanomaterials. Regardless of their fate, they will find increasing applications. In this study, a simple approach for synthesizing CDs from fruit peels was developed. The CDs were fabricated from Annona squamosa (L.) peels using a carbonization technique through microwave-assisted hydrothermal digestion at temperatures around 200 °C. Synthesized CDs were detected using a UV transilluminator for the preliminary confirmation of the presence of fluorescence. UV-Vis spectrophotometry (absorbance at 505 nm) analysis, zeta potential measurement (-20.8 mV), nanoparticles tracking analysis (NTA) (average size: 15.4 nm and mode size: 9.26 nm), photoluminescence, and Fourier transform infrared (FT-IR) analysis were used to identify the capping functional groups on the CDs. The total quantum yield exhibited was 8.93%, and the field emission scanning electron microscopy (FESEM) showed the size range up to 40 nm. The germinating mung bean (Vigna radiata (L.)) seeds were incubated with biogenically synthesized CDs to check the absorption of CDs by them. The fluorescence was observed under a UV-transilluminator in the growing parts of seeds, indicating the absorption of CDs during the germination, development, and growth. These fluorescent CDs could be used as a bioimaging agent. This novel method of synthesizing CDs was found to be eco-friendly, rapid, and cost-effective.

Ultrasmall silica nanoparticles in translational biomedical research: Overview and outlook

The exemplary progress of silica nanotechnology has attracted extensive attention across a range of biomedical applications such as diagnostics and imaging, drug delivery, and therapy of cancer and other diseases. Ultrasmall silica nanoparticles (USNs) have emerged as a particularly promising class demonstrating unique properties that are especially suitable for and have shown great promise in translational and clinical biomedical research. In this review, we discuss synthetic strategies that allow precise engineering of USNs with excellent control over size and surface chemistry, functionalization, and pharmacokinetic and toxicological profiles. We summarize the current state-of-the-art in the biomedical applications of USNs with a particular focus on select clinical studies. Finally, we illustrate long-standing challenges in the translation of inorganic nanotechnology, particularly in the context of ultrasmall nanomedicines, and provide our perspectives on potential solutions and future opportunities in accelerating the translation and widespread adoption of USN technology in biomedical research.

DNA-Immobilized Fluorescent Polystyrene Nanoparticles as Probes with Tunable Detection Limits

DNA-immobilized nanoparticle probes show high target specificity; thus, they are employed in various bioengineering and biomedicine applications. When the nanoparticles employed are dye-loaded polymer particles, the resulting probes have the additional benefit of biocompatibility and versatile surface properties. In this study, we construct DNA-immobilized fluorescent polystyrene (PS) nanoparticles through controlled surface reactions. PS nanoparticles with surface carboxyl groups are utilized, and amine-functionalized dye molecules and capture DNAs are covalently immobilized via a one-pot reaction. We show that the surface chemistry employed allows for quantitative control over the number of fluorescent dyes and DNA strands immobilized on the PS nanoparticle surfaces. The nanoparticles thus prepared are then used for DNA detection. The off state of the nanoprobe is achieved by hybridizing quencher-functionalized DNAs (Q-DNAs) to the capture DNAs immobilized on nanoparticle surfaces. Target-DNAs (T-DNAs) are detected by the displacement of the prehybridized Q-DNAs. The nanoprobes show successful detection of T-DNAs with high sequence specificity and long-term stability. They also show excellent detection sensitivity, and the detection limit can be tuned by adjusting the capture DNA-to-dye ratio.

Silica nanoparticle remodeling under mild conditions: versatile one step conversion of mesoporous to hollow nanoparticles with simultaneous payload loading

A binary mixture of mesoporous silica nanoparticles plus organic polyammonium additive (dye or drug) is cleanly converted upon mild heating into hollow nanoparticles. The remodeled nanoparticle shell is an organized nanoscale assembly of globular additive/silica subunits and cancer cell assays show that a loaded drug additive is bioavailable.

Fluorescent silica nanoparticles as an internal marker in fruit flies and their effects on survivorship and fertility

Tracking and differentiating small insects at the individual levels requires appropriate marking materials because of their small size. This study proposes and investigates the use of fluorescent silica nanoparticles (FSNPs) as an internal marker owing to their good optical properties and biocompatibility. FSNPs were prepared using the water-in-oil reverse microemulsion technique with Rubpy dye as a fluorophore. The obtained particles were spherical, monodispersed in nanosize and exhibited bright orange luminescence under ultraviolet (UV) light. Internal marking was accomplished in fruit flies (Drosophila melanogaster) through feeding. The result shows that the fruit flies exhibit bright luminescence in their abdomen when exposed to UV light. The marking persistence duration of FSNPs in the fruit fly bodies is longer than those of other fluorescent dyes. Fruit flies fed with FSNPs have a longer lifespan than those fed with Rubpy dye. There was no difference in fertility and negative geotaxis response among the treatment and control groups. These findings demonstrate that FSNPs can be used as an internal marker in fruit flies, and are possibly applied with other small insects with a translucent abdomen.

Dye-sensitized lanthanide containing nanoparticles for luminescence based applications

Due to their exceptional luminescent properties, lanthanide (Ln) complexes represent a unique palette of probes in the spectroscopic toolkit. Their extremely weak brightness due to forbidden Ln electronic transitions can be overcome by indirect dye-sensitization from the antenna effect brought by organic ligands. Despite the improvement brought by the antenna effect, (bio)analytical applications with discrete Ln complexes as luminescent markers still suffers from low sensitivity as they are limited by the complex brightness. Thus, there is a need to develop nano-objects that cumulate the spectroscopic properties of multiple Ln ions. This review firstly gives a brief introduction of the spectral properties of lanthanides both in complexes and in nanoparticles (NPs). Then, the research progress of the design of Ln-doped inorganic NPs with capping antennas, Ln-complex encapsulated NPs and Ln-complex surface functionalized NPs is presented along with a summary of the various photosensitizing ligands and of the spectroscopic properties (excited-state lifetime, brightness, quantum yield). The review also emphasizes the problems and limitations encountered over the years and the solutions provided to address them. Finally, a comparison of the advantages and drawbacks of the three types of NP is provided as well as a conclusion about the remaining challenges both in the design of brighter NPs and in the luminescence based applications.

Optically traceable PLGA-silica nanoparticles for cell-triggered doxorubicin delivery

Fluorescent silica nanoparticles with a polymer shell of poly (D, L-lactide-co-glycolide) (PLGA) can provide traceable cell-triggered delivery of the anticancer drug doxorubicin (DOX), protecting the cargo while in transit and releasing it only intracellularly. PLGA with 50:50 lactide:glycolide ratio was grown by surface-initiated ring-opening polymerization (ROP) from silica nanoparticles of ca. 50 nm diameter, doped with a perylenediimide (PDI) fluorescent dye anchored to the silica structure. After loading DOX, release from the core-shell particles was evaluated in solution at physiological pH (7.4), and in human breast cancer cells (MCF-7) after internalization. The hybrid silica-PLGA nanoparticles can accommodate a large cargo of DOX, and the release in solution (PBS) due to PLGA hydrolysis is negligible for at least 72 h. However, once internalized in MCF-7 cells, the nanoparticles release the DOX cargo by degradation of the PLGA. Accumulation of DOX in the nucleus causes cell apoptosis, with the drug-loaded nanoparticles found to be as potent as free DOX. Our fluorescently traceable hybrid silica-PLGA nanoparticles with cell-triggered cargo release offer excellent prospects for the controlled delivery of anticancer drugs, protecting the cargo while in transit and efficiently releasing the drug once inside the cell.

pH-responsive silica nanoparticles for the treatment of skin wound infections

Chronic wounds are not only a burden for patients but also challenging for clinic treatment due to biofilm formation. Here, we utilized the phenomenon that chronic wounds possess an elevated local pH of 8.9 and developed pH-sensitive silica nanoparticles (SiNPs) to achieve a targeted drug release on alkaline wounds and optimized drug utility. Chlorhexidine (CHX), a disinfectant and antiseptic, was loaded into SiNPs as the model drug. The loaded CHX displayed a release 4 - 5 fold higher at pH 8.0 and 8.5 than at pH 6.5, 7.0 and 7.4. CHX-SiNPs furthermore exhibited a distinctive antibacterial activity at pH 8.0 and 8.5 against both Gram-negative and -positive bacterial pathogens, while no cytotoxicity was found according to cell viability analysis. The CHX-SiNPs were further formulated into alginate hydrogels to allow ease of use. The antibacterial efficacy of CHX-SiNPs was then studied with artificial wounds on ex vivo human skin. Treatment with CHX-SiNPs enabled nearly a 4-lg reduction of the viable bacterial cells, and the alginate formulated CHX-SiNPs led to almost a 3-lg reduction compared to the negative controls. The obtained results demonstrated that CHX-SiNPs are capable of efficient pH-triggered drug release, leading to high antibacterial efficacy. Moreover, CHX-SiNPs enlighten clinic potential towards the treatment of chronic wound infections. STATEMENT OF SIGNIFICANCE: A platform for controlled drug release at a relatively high pH value i.e., over 8, was established by tuning the physical structures of silica nanoparticles (SiNPs). Incorporation of chlorhexidine, an antimicrobial agent, into the fabricated SiNPs allowed a distinctive inhibition of bacterial growth at alkaline pHs, but not at acidic pHs. The efficacy of the SiNPs loaded with chlorhexidine in treating wound infections was further validated by utilizing ex vivo human skin samples. The presented work demonstrates clinic potential of employing alkaline pH as a non-invasive stimulus to achieve on-demand delivery of antimicrobials through SiNPs, showcasing a valuable approach to treating bacterial infections on chronic wounds.

A Multianalyte Electrochemical Genosensor for the Detection of High-Risk HPV Genotypes in Oral and Cervical Cancers

Infection with high-risk human papillomavirus (HPV) is a major risk factor for oral and cervical cancers. Hence, we developed a multianalyte electrochemical DNA biosensor that could be used for both oral and cervical samples to detect the high-risk HPV genotypes 16 and 18. The assay involves the sandwich hybridization of the HPV target to the silica-redox dye reporter probe and capture probe, followed by electrochemical detection. The sensor was found to be highly specific and sensitive, with a detection limit of 22 fM for HPV-16 and 20 fM for HPV-18, between the range of 1 fM and 1 µM. Evaluation with oral and cervical samples showed that the biosensor result was consistent with the nested PCR/gel electrophoresis detection. The biosensor assay could be completed within 90 min. Due to its simplicity, rapidity, and high sensitivity, this biosensor could be used as an alternative method for HPV detection in clinical laboratories as well as for epidemiological studies.

In silico study of substrate chemistry effect on the tethering of engineered antibodies for SARS-CoV-2 detection: Amorphous silica vs gold

The influence of the properties of different solid substrates on the tethering of two antibodies, IgG1-CR3022 and IgG1-S309, which were specifically engineered for the detection of SARS-CoV-2, has been examined at the molecular level using conventional and accelerated Molecular Dynamics (cMD and aMD, respectively). Two surfaces with very different properties and widely used in immunosensors for diagnosis, amorphous silica and the most stable facet of the face-centered cubic gold structure, have been considered. The effects of such surfaces on the structure and orientation of the immobilized antibodies have been determined by quantifying the tilt and hinge angles that describe the orientation and shape of the antibody, respectively, and the dihedrals that measure the relative position of the antibody arms with respect to the surface. Results show that the interactions with amorphous silica, which are mainly electrostatic due to the charged nature of the surface, help to preserve the orientation and structure of the antibodies, especially of the IgG1-CR3022, indicating that the primary sequence of those antibodies also plays some role. Instead, short-range van der Waals interactions with the inert gold surface cause a higher degree tilting and fraying of the antibodies with respect to amorphous silica. The interactions between the antibodies and the surface also affect the correlation among the different angles and dihedrals, which increases with their strength. Overall, results explain why amorphous silica substrates are frequently used to immobilize antibodies in immunosensors.

Fully Automated Computational Approach for Precisely Measuring Organelle Acidification with Optical pH Sensors

pH balance and regulation within organelles are fundamental to cell homeostasis and proliferation. The ability to track pH in cells becomes significantly important to understand these processes in detail. Fluorescent sensors based on micro- and nanoparticles have been applied to measure intracellular pH; however, an accurate methodology to precisely monitor acidification kinetics of organelles in living cells has not been established, limiting the scope of this class of sensors. Here, silica-based fluorescent microparticles were utilized to probe the pH of intracellular organelles in MDA-MB-231 and MCF-7 breast cancer cells. In addition to the robust, ratiometric, trackable, and bioinert pH sensors, we developed a novel dimensionality reduction algorithm to automatically track and screen massive internalization events of pH sensors. We found that the mean acidification time is comparable among the two cell lines (ΔT_MCF-7 = 16.3 min; ΔT_MDA-MB-231 = 19.5 min); however, MCF-7 cells showed a much broader heterogeneity in comparison to MDA-MB-231 cells. The use of pH sensors and ratiometric imaging of living cells in combination with a novel computational approach allow analysis of thousands of events in a computationally inexpensive and faster way than the standard routes. The reported methodology can potentially be used to monitor pH as well as several other parameters associated with endocytosis.

Silica Nanoparticle Acute Toxicity on Male Rattus norvegicus Domestica: Ethological Behavior, Hematological Disorders, Biochemical Analyses, Hepato-Renal Function, and Antioxidant-Immune Response

With extensive production and various applications of silica nanoparticles (SiNPs), there is a controversy regarding the ecotoxicological impacts of SiNPs. Therefore, the current study was aimed to assess the acute toxicity of silica nanoparticles in male Rattus norvegicus domestica after 24 and 96 h. Hematological, serum biochemical, stress biomarker, and immune-antioxidant parameters were addressed. Chemical composition, crystal structure, and the particle shape and morphology of SiNPs were investigated using XRD, FTIR, BET, UV-Vis, and SEM, while TEM was used to estimate the average size distribution of particles. For the exposure experiment, 48 male rats were divided into four groups (12 rat/group) and gavaged daily with different levels of zero (control), 5, 10, and 20 mg of SiNPs corresponding to zero, 31.25, 62.5, and 125 mg per kg of body weight. Sampling was carried out after 24 and 96 h. Relative to the control group, the exposure to SiNPs induced clear behavioral changes such as inactivity, lethargy, aggressiveness, and screaming. In a dose-dependent manner, the behavior scores recorded the highest values. Pairwise comparisons with the control demonstrated a significant (p < 0.05) decrease in hematological and immunological biomarkers [lysozymes and alternative complement activity (ACH50)] with a concomitant reduction in the antioxidant enzymes [catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD)] in all exposed groups to SiNPs. On the contrary, there was a noticeable increase in biochemical parameters (glucose, cortisol, creatinine, urea, low-density lipoproteins (LDL), high-density lipoproteins (HDL), total protein, and albumin) and hepato-renal indicators, including alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST), of all SiNP-exposed groups. It was observed that SiNPs induced acute toxicity, either after 24 h or 96 h, post-exposure of rats to SiNPs evidenced by ethological changes, hepato-renal dysfunction, hyperlipemia, and severe suppression in hematological, protein, stress, and immune-antioxidant biomarkers reflecting an impaired physiological status. The obtained outcomes create a foundation for future research to consider the acute toxicity of nanoparticles to preserve human health and sustain the environment.

Synthesis of novel silica encapsulated spiropyran-based thermochromic materials

A series of novel spiropyrans were synthesized through the condensation of substituted 3,3-dimethyl-2-methyleneindoline with different nitro-substituted o-hydroxy aromatic aldehydes. Indoles were initially substituted with a variety of alkanes and esters moieties. The substituted 3,3-dimethyl-2-methyleneindoline was then reacted with nitro-substituted o-hydroxy aromatic aldehydes to yield the respective spiropyrans. The synthesized novel spiropyrans were encapsulated in silica nano-shells to protect them from the effect of moisture and pH. The thermochromic behaviour of novel spiropyrans was studied by UV-visible spectroscopy. The thermally induced isomerization of spiropyran derivatives was carried out in a water/ethanol mixture. The thermal isomerization of spiro-heterocyclic (colourless form) to merocyanine (MC) (coloured form) was a discontinuous process and was observed in a temperature range of 5-60°C via UV-visible spectrometer. The absorption process occurs reversibly regardless of the heating/cooling sequence. The spiropyran derivatives, therefore, have a potential application for colorimetric temperature indication.

Polysorbate- and DNA-Mediated Synthesis and Strong, Stable, and Tunable Near-Infrared Photoluminescence of Plasmonic Long-Body Nanosnowmen

Direct photoluminescence (PL) from metal nanoparticles (NPs) without chemical dyes is promising for sensing and imaging applications since this offers a highly tunable platform for controlling and enhancing the signals in various conditions and does not suffer from photobleaching or photoblinking. It is, however, difficult to synthesize metal NPs with a high quantum yield (QY), particularly in the near-infrared (NIR) region where deep penetration and reduced light scattering are advantageous for bioimaging. Herein, we designed and synthesized Au-Ag long-body nanosnowman structures (LNSs), facilitated by polysorbate 20 (Tween 20). The DNA-engineered conductive junction between the head and body parts results in a charge transfer plasmon (CTP) mode in the NIR region. The junction morphology can be controlled by the DNA sequence on the Au core, and polythymine and polyadenine induced thick and thin junctions, respectively. We found that the LNSs with a thicker conductive junction generates the stronger CTP peak and PL signal than the LNSs with a thinner junction. The Au-Ag LNSs showed much higher intensities in both PL and QY than widely studied Au nanorods with similar localized surface plasmon resonance wavelengths, and notably, the LNSs displayed high photostability and robust, sustainable PL signals under continuous laser exposure for >15 h. Moreover, the PL emission from Au-Ag LNSs could be imaged in a deeper scattering medium than fluorescent silica NPs. Finally, highly robust PL-based cell images can be obtained using Au-Ag LNSs without significant signal change while repetitively imaging cells. The results offer the insights in plasmonic NIR probe design, and show that chemical dye-free LNSs can be a very promising candidate with a high QY and a robust, reliable NIR PL signal for NIR sensing and imaging applications.

Polymer Micro and Nanoparticles Containing B(III) Compounds as Emissive Soft Materials for Cargo Encapsulation and Temperature-Dependent Applications

Polymer nanoparticles doped with fluorescent molecules are widely applied for biological assays, local temperature measurements, and other bioimaging applications, overcoming several critical drawbacks, such as dye toxicity, increased water solubility, and allowing imaging of dyes/drug delivery in water. In this work, some polymethylmethacrylate (PMMA), polyvinylpyrrolidone (PVP) and poly(styrene-butadiene-styrene) (SBS) based micro and nanoparticles with an average size of about 200 nm and encapsulating B(III) compounds have been prepared via the reprecipitation method by using tetrahydrofuran as the oil phase and water. The compounds are highly hydrophobic, but their encapsulation into a polymer matrix allows obtaining stable colloidal dispersions in water (3.39 µM) that maintain the photophysical behavior of these dyes. Although thermally activated non-radiative processes occur by increasing temperature from 25 to 80 °C, the colloidal suspension of the B(III) particles continues to emit greenish light (λ = 509 nm) at high temperatures. When samples are cooling back to room temperature, the emission is restored, being reversible. A probe of concept drug delivery study was conducted using coumarin 6 as a prototype of a hydrophobic drug.

Advances and Challenges of Fluorescent Nanomaterials for Synthesis and Biomedical Applications

With the rapid development of nanotechnology, new types of fluorescent nanomaterials (FNMs) have been springing up in the past two decades. The nanometer scale endows FNMs with unique optical properties which play a critical role in their applications in bioimaging and fluorescence-dependent detections. However, since low selectivity as well as low photoluminescence efficiency of fluorescent nanomaterials hinders their applications in imaging and detection to some extent, scientists are still in search of synthesizing new FNMs with better properties. In this review, a variety of fluorescent nanoparticles are summarized including semiconductor quantum dots, carbon dots, carbon nanoparticles, carbon nanotubes, graphene-based nanomaterials, noble metal nanoparticles, silica nanoparticles, phosphors and organic frameworks. We highlight the recent advances of the latest developments in the synthesis of FNMs and their applications in the biomedical field in recent years. Furthermore, the main theories, methods, and limitations of the synthesis and applications of FNMs have been reviewed and discussed. In addition, challenges in synthesis and biomedical applications are systematically summarized as well. The future directions and perspectives of FNMs in clinical applications are also presented.

Multifunctional superparamagnetic nanoparticles with a fluorescent silica shell for the in vitro study of bio-nano interactions at the subcellular scale

Despite the high level of interest in bio-nano interactions, detailed intracellular mechanisms that govern nanoscale recognition and signalling still need to be unravelled. Magnetic nanoparticles (NPs) are valuable tools for elucidating complex intracellular bio-nano interactions. Using magnetic NPs, it is possible to isolate cell compartments that the particles interact with during intracellular trafficking. Studies at the subcellular scale rely heavily on optical microscopy; therefore, combining the advantages of magnetic recovery with excellent imaging properties to allow intracellular NP tracking is of utmost interest for the nanoscience field. However, it is a challenge to prepare highly magnetic NPs with a suitable fluorescence for the fluorescence imaging techniques typically used for biological studies. Here we present the synthesis of biocompatible multifunctional superparamagnetic multicore NPs with a bright fluorescent silica shell. The incorporation of an organic fluorophore in the silica surrounding the magnetic multicore was optimised to enable the particles to be tracked with the most common imaging techniques. To prevent dye loss resulting from silica dissolution in biological environments, which would reduce the time that the particles could be tracked, we added a thin dense encapsulating silica layer to the NPs which is highly stable in biological media. The synthesised multifunctional nanoparticles were evaluated in cell uptake experiments in which their intracellular location could be clearly identified using fluorescence imaging microscopy, even after 3 days. The magnetic properties of the iron oxide core enabled both efficient recovery of the NPs from the intracellular environment and the extraction of cell compartments involved in their intracellular trafficking. Thus, the NPs reported here provide a promising tool for the study of the processes regulating bio-nano interactions.

Modifying thin-film composite forward osmosis membranes using various SiO2 nanoparticles for aquaculture wastewater recovery

This paper describes the fabrication, modification, and evaluation of the performance of thin-film composite (TFC) forward osmosis (FO) membranes for lab-scale aquaculture wastewater recovery using various fumed silica (SiO₂) nanoparticles. The active polyamide (PA) layers of these membranes were novelly modified using different types of pretreated SiO₂ nanoparticles [virgin SiO₂, dried SiO₂, and 3-aminopropyltriethoxysilane (APTES)-modified SiO₂] and concentrations (0.05, 0,1, 0,2, and 0.4 wt%) to improve the membrane hydrophilicity with minimum particle agglomeration. Results show that the APTES-SiO₂ modified membrane had the highest water flux and selectivity, followed by the dried-SiO₂ modified membrane. The APTES coupling agent notably reduced the SiO₂ aggregation on the membrane surface and improved membrane hydrophilicity. Consequently, high permeate flux and an acceptable reverse solute flux were observed. The optimal SiO₂ concentration for PA modification was 0.1 wt% for all the nanoparticle types. The virgin and APTES-SiO₂ modified membranes were used for aquaculture wastewater recovery. The water recovery rate reached 47% in 84 h when using the APTES-SiO₂ modified membrane, while it reached only 26% in 108 h when using the virgin membrane. With a suitable design of the filtration apparatus and choice of draw solution (DS), the prepared novel TFC-FO membrane containing APTES-modified SiO₂ can be used for recycling aquaculture wastewater into the DS, which can then be reused for other purposes.

Role of Aqueous-Phase Calcination in Synthesis of Ultra-Stable Dye-Embedded Fluorescent Nanoparticles for Cellular Probing

Fluorescence imaging is a major driver of discovery in biology, and an invaluable asset in clinical diagnostics. To overcome quenching limitations of conventional fluorescent dyes and further improve intensity, nanoparticle-based constructs have been the subject of intense investigation, and within this realm, dye-doped silica-coated nanoparticles have garnered significant attention. Despite their growing popularity in research, fluorescent silica nanoparticles suffer from a significant flaw. The degradation of these nanoparticles in biological media by hydrolytic dissolution is underreported, leading to serious misinterpretations, and limiting their applicability for live cell and in vivo imaging. Here, the development of an ultra-stable, dye-embedded, silica-coated metal nanoparticle is reported, and its superior performance in long-term live cell imaging is demonstrated. While conventional dye-doped silica nanoparticles begin to degrade within an hour in aqueous media, by leveraging a modified liquid calcination process, this new construct is shown to be stable for at least 24 h. The stability of this metal-enhanced fluorescent probe in biologically relevant temperatures and media, and its demonstrated utility for cell imaging, paves the way for its future adoption in biomedical research.

Synthesis of Silica Nanoparticles with Physical Encapsulation of Near-Infrared Fluorescent Dyes and Their Tannic Acid Coating

This study reports a novel method for the synthesis of silica nanoparticles (NPs) encapsulating near-infrared (NIR) fluorescent dyes through physical adsorption. Although a NIR cationic fluorescent dye, oxazine 725 (OXA), has no chemical bonding moiety toward silica NPs such as the triethoxysilyl group, the dyes were successfully incorporated into silica NPs without denaturation under the mild reaction conditions. Next, tannic acid (TA) molecules were coated in the presence of Fe³⁺ on the particle surface for the functionalization of silica NPs encapsulating OXA (OXA@SiO₂ NPs). The TA coating on the surface of OXA@SiO₂ NPs was confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy. The TA coating significantly contributed to the resistance improvement against photobleaching and leakage of the dyes in the NPs. Furthermore, the obtained TA-coated silica NPs encapsulating OXAs (OXA@SiO₂@TA NPs) were used for the fluorescence imaging of African green monkey kidney (COS-7) cells, and it was shown that the fluorescence originated from OXA@SiO₂@TA NPs was clearly observed in the COS-7 cells.

Study of the effect of the introduction of Tris(bipyridine)ruthenium(II) chloride into silicon dioxide particles by spectrofluorometry methods

The Stoeber reaction was used to grow silica microparticles in the presence of the fluorescent dye Tris(bipyridine)ruthenium (II) chloride. The diameter of the obtained particles varies from about 150 to 280 nm depending on the dye concentration. Using spectrofluorometry methods, concentration quenching of fluorescence of dye solutions was studied before and after growing the microparticles. It was found out that the concentration quenching of fluorescence decreases significantly after its incorporation into the silicon dioxide microparticles upon excitation in the short-wavelength region of the spectrum.