Fluorescent Nanoparticles Research Articles

Overcoming Barriers Associated with Oral Delivery of Differently Sized Fluorescent Core-Shell Silica Nanoparticles.

Oral delivery, while a highly desirable form of nanoparticle-drug administration, is limited by challenges associated with overcoming several biological barriers. Here, the authors study how fluorescent and poly(ethylene glycol)-coated (PEGylated) core-shell silica nanoparticles sized 5 to 50nm interact with major barriers including intestinal mucus, intestinal epithelium, and stomach acid. From imaging fluorescence correlation spectroscopy studies using quasi-total internal reflection fluorescence microscopy, diffusion of nanoparticles through highly scattering mucus is progressively hindered above a critical hydrodynamic size around 20nm. By studying Caco-2 cell monolayers mimicking the intestinal epithelia, it is observed that ultrasmall nanoparticles below 10nm diameter (Cornell prime dots, [C' dots]) show permeabilities correlated with high absorption in humans from primarily enhanced passive passage through tight junctions. Particles above 20nm diameter exclusively show active transport through cells. After establishing C' dot stability in artificial gastric juice, in vivo oral gavage experiments in mice demonstrate successful passage through the body followed by renal clearance without protein corona formation. Results suggest C' dots as viable candidates for oral administration to patients with a proven pathway towards clinical translation and may generate renewed interest in examining silica as a food additive and its effects on nutrition and health.

In vitro study: green synthesis and evaluation of MgO/C-dots/DOX phosphorescent nanocomposites for photodynamic/photocatalytic therapy of tumors

MgO nanoparticles (NPs) and carbon dots (C-dots) were synthesized by co-precipitation and hydrothermal techniques. In the next step, as-synthesized NPs were modified by C-dots. Then, polyethylene glycol (PEG) was conjugated with MgO/Cdots. Finally, Doxorubicin (Dox) as an anticancer drug was loaded on MgO/Cdots/PEG nanocomposites. The XRD pattern showed the characteristic peaks of C-dots and MgO. The FTIR spectrum showed that MgO/C-dots possessed the carboxyl functional groups, allowing DOX to be loaded onto MgO/C-dots/PEG through hydrogen bonds. The particle size of MgO, C-dots, MgO/C-dots, and MgO/C-dots/PEG/DOX was 20–30, 5–10, 30–40, and 100–130 nm, respectively, using TEM, DLS, and FESEM techniques. MgO, MgO/C-dots, and MgO/C-dots/DOX were fluorescent NPs when excited by a UV source. Anthracene and methylene blue were used as fluorescent probes to identify the reactive oxygen species (ROS) produced by UV excitation. The activity of MgO/C-dots and MgO/C-dots/DOX against colorectal cancer (C26) cells, after repeated 5-min illumination with both UV-light and red light LEDs, were measured by MTT assay. C26 cancer cells incubated with DOX-loaded MgO/C-dots and exposed to either wavelength (UV and red) killed ∼70% of cells. The green synthesized nanocomposites could act as anti-cancer photosensitizers probably by a photocatalytic mechanism.

A triple-signal strategy separated aptasensor for sensitive determination of aflatoxin B1 in peanut based on electrochemical and fluorescent dual-mode

It is necessary to develop accurate and sensitive AFB1 detection method due to its high toxicity of pathogenicity and carcinogenicity. The results of traditional single-mode AFB1 detection methods are easily affected by the test environment and human operation. Herein, an electrochemical and fluorescent dual-mode separated aptasensor was developed for detecting AFB1 with triple-signal readout. The AFB1 aptasensor was constructed by combining the Fc-labeled AFB1 aptamer with its complementary DNA (cDNA). Subsequently, the methylene blue (MB) was incorporated into dsDNA as another signal tag. In the presence of AFB1, the Fc tag approached to electrode surface, both of the cDNA and MB molecule released due to the interaction between AFB1 and its aptamer, resulting in “signal-on” and “signal-off” dual-signal strategy. There was a good linear relationship between the SWV electrochemical response signal and the logarithm of AFB1 concentration at 0.01–200 ng/mL (LOD 2.5 pg/mL, S/N = 3). Meanwhile, the released cDNA was designed to trigger hybridization chain reaction (HCR), and the HCR product was served as template for the formation of fluorescent copper nanoparticles (CuNPs). There was a good linear relationship between the fluorescent intensity of CuNPs and the logarithm of AFB1 concentration at 0.001–200 ng/mL (LOD 0.28 pg/mL, S/N = 3). The separated fluorescent method showed broadened linear range and lower LOD compared with SWV method, both up to 10-folds, which improved the detection sensitivity. The constructed dual-mode AFB1 aptasensor showed satisfactory selectivity, stability and reproducibility, and the good recoveries of real peanut samples indicated its practical application in food detection.

Semiconducting Polymer Dots Directly Stabilized with Serum Albumin: Preparation, Characterization, and Cellular Immunolabeling.

Semiconducting polymer dots (Pdots) are brightly fluorescent nanoparticles of growing interest for bioanalysis and imaging. A recurring challenge with these materials is obtaining robust physical and colloidal stability and low nonspecific binding. Here, we prepared and characterized Pdots with bovine serum albumin (BSA) as the stabilizing agent (BSA-Pdots) instead of a more conventionally used amphiphilic polymer, both without and with cross-linking of the protein using glutaraldehyde (BSA(GA)-Pdots) or disuccinimidyl glutarate. Characterization included fluorescence properties; colloidal stability as a function of pH, ionic strength, and solvent perturbation; shape retention and hardness; and nonspecific binding with common assay substrates, fixed cells, and live cells. These properties were contrasted with the same properties for amphiphilic polymer-stabilized Pdots and silica-coated Pdots. On balance, the BSA-stabilized Pdots were similar or more favorable in their properties, with BSA(GA)-Pdots being especially advantageous. Bioconjugation of the BSA-stabilized Pdots was possible using amine-reactive active-ester chemistry, including biotinylation and bioorthogonal functionalization for immunoconjugation via tetrazine-strained-alkene click chemistry. These approaches were used for selective fluorescent labeling of cells based on ligand-receptor and antibody-antigen binding, respectively. Overall, direct BSA stabilization is a very promising strategy for preparing Pdots with improved physical and colloidal stability, reduced nonspecific interactions, and utility for in vitro diagnostics and other bioanalyses and imaging.

Glutathione and bicarbonate nanoparticles improve mucociliary transport in cystic fibrosis epithelia.

Cystic fibrosis (CF) airway disease is characterized by thick mucus and impaired mucociliary transport (MCT). Loss of functional cystic fibrosis transmembrane receptor (CFTR) leads to acidification and oxidation of airway surface mucus. Replacing bicarbonate (HCO3 -) topically fails due to rapid reabsorption and neutralization, while the scavenging antioxidant, glutathione sulfhydryl (GSH), is also rapidly degraded. The objective of this study is to investigate GSH/NaHCO3 nanoparticles as novel strategy for CF airway disease. GSH/NaHCO3 poly (lactic-co-glycolic acid) nanoparticles were tested on primary CF (F508del/F508del) epithelial cultures to evaluate dose-release curves, surface pH, toxicity, and MCT indices using micro-optical coherence tomography. In vivo tests were performed in three rabbits to assess safety and toxicity. After 1week of daily injections, histopathology, computed tomography (CT), and blood chemistries were performed and compared to three controls. Fluorescent nanoparticles were injected into a rabbit with maxillary sinusitis and explants visualized with confocal microscopy. Sustained release of GSH and HCO3 - with no cellular toxicity was observed over 2weeks. Apical surface pH gradually increased from 6.54±0.13 (baseline) to 7.07±0.10 (24h) (p<0.001) and 6.87 ± 0.05 at 14 days (p<0.001). MCT, ciliary beat frequency, and periciliary liquid were significantly increased. When injected into the maxillary sinuses of rabbits, there were no changes to histology, CT, or blood chemistries. Nanoparticles penetrated rabbit sinusitis mucus on confocal microscopy. Findings suggest that GSH/NaHCO3 - nanoparticles are a promising treatment option for viscous mucus in CF and other respiratory diseases of mucus obstruction such as chronic rhinosinusitis.

A facile strategy to construct biocompatible fluorescent nanoparticles for intracellular bioimaging

Coumarins are widely used in many fields due to their excellent photostability, high fluorescence quantum yield and easy modification of the backbone, and its derivatives possess great technological potential especially in biomaterials field. However, many fluorescent materials constructed on the basis of coumarin skeletons have poor biocompatibility, which limits their application in the biomedical field, and the increasing demand for coumarin derivatives accelerates the research in biological and chemical synthesis to provide biocompatible and scalable materials of coumarins. In this work, we reported a facile strategy to construct fluorescent nanoparticles by using Stober method by incorporating silane-modified coumarin derivatives, and the polyvinylpyrrolidone (PVP) is introduced to enhance the biocompatibility of the material while obtaining homogeneous and stable fluorescent nanoparticles. Overall, this provides new ideas and methods for the preparation of simple and homogeneous fluorescent nanoparticles and the enhancement of biocompatibility.

Microfluidic-Assisted Formulation of ε-Polycaprolactone Nanoparticles and Evaluation of Their Properties and In Vitro Cell Uptake.

The nanoprecipitation method was used to formulate ε-polycaprolactone (PCL) into fluorescent nanoparticles. Two methods of mixing the phases were evaluated: introducing the organic phase into the aqueous phase dropwise and via a specially designed microfluidic device. As a result of the nanoprecipitation process, fluorescein-loaded nanoparticles (NPs) with a mean diameter of 127 ± 3 nm and polydispersity index (PDI) of 0.180 ± 0.009 were obtained. The profiles of dye release were determined in vitro using dialysis membrane tubing, and the results showed a controlled release of the dye from NPs. In addition, the cytotoxicity of the NPs was assessed using an MTT assay. The PCL NPs were shown to be safe and non-toxic to L929 and MG63 cells. The results of the present study have revealed that PCL NPs represent a promising system for developing new drug delivery systems.

Preparation and dynamic color-changing study of fluorescent polymer nanoparticles for individualized and customized anti-counterfeiting application

Preparing new fluorescent materials for individualized and customized anti-counterfeiting applications to meet needs from the rapid development of e-commerce is of great significance. This paper reports the preparation of dynamic color-changing fluorescent polymer nanoparticles (PNPs) by constructing a fluorescence resonance energy transfer (FRET) pair between aggregation-induced emission (AIE) structures and photochromic structures. At first, methyl methacrylate (MMA) was used as the main monomer and tetraphenylethylene (TPE, a typical AIE structure) modified methacrylate (TPE-MA) and photochromic spiropyran (SP) modified methacrylate (SP-MA) as minor monomers were copolymerized to obtain the ternary copolymer PMMA-TPE-SP. Then, two types of PNPs based on this terpolymer was prepared via the reprecipitation method, with and without the addition of an amphiphilic polymer as the surfactant. The photophysical study shows that the fluorescence color of PNPs dynamically changes from blue to light violet and finally to red under UV light irradiation, a process that can be reversed under visible light. The PNPs were alternately irradiated with UV light and visible light for 10 cycles, which proved their good photoswitching reproducibility. The PNPs prepared with addition of surfactant were found to have stronger fluorescence and better stability. Finally, the photochromic fluorescent inks were prepared based on these PNPs. Several anti-counterfeiting scenarios and modes were designed, exhibiting excellent photochromic behavior on cellulose paper, even after 120 days of long-term storage. With simple equipment, desirable anti-counterfeiting effects with dynamic fluorescence color changing was achieved. This study demonstrated a promising hard-to-imitate anti-counterfeiting encryption strategy, which can achieve multiple outputs with simple operation and can be personalized and customized as needed.

Simplified quantum chemistry methods to evaluate non‐linear optical properties of large systems

AbstractThis review presents the theoretical background concerning simplified quantum chemistry (sQC) methods to compute non‐linear optical (NLO) properties and their applications to large systems. To evaluate any NLO responses such as hyperpolarizabilities or two‐photon absorption (2PA), one should evidently perform first a ground state calculation and compute its response. Because of this, methods used to compute ground states of large systems are outlined, especially the xTB (extended tight‐binding) scheme. An overview on approaches to compute excited state and response properties is given, emphasizing the simplified time‐dependent density functional theory (sTD‐DFT). The formalism of the eXact integral sTD‐DFT (XsTD‐DFT) method is also introduced. For the first hyperpolarizability, 2PA, excited state absorption, and second hyperpolarizability, a brief historical review is given on early‐stage semi‐empirical method applications to systems that were considered large at the time. Then, we showcase recent applications with sQC methods, especially the sTD‐DFT scheme to large challenging systems such as fluorescent proteins or fluorescent organic nanoparticles as well as dynamic structural effects on flexible tryptophan‐rich peptides and gramicidin A. Thanks to the sTD‐DFT‐xTB scheme, all‐atom quantum chemistry methodologies are now possible for the computation of the first hyperpolarizability and 2PA of systems up to 5000 atoms. This review concludes by summing‐up current and future method developments in the sQC framework as well as forthcoming applications on large systems.This article is categorized under: Electronic Structure Theory &gt; Ab Initio Electronic Structure Methods Structure and Mechanism &gt; Molecular Structures Electronic Structure Theory &gt; Density Functional Theory Electronic Structure Theory &gt; Semiempirical Electronic Structure Methods

Charge transfer of 1,3,4‐oxadiazole derivative, its functional polymers and study of their different aggregation‐induced emission enhancement behaviors

AbstractIn this study, a symmetrical D‐π‐A‐π‐D initiator ViOXD, based on substituted amino donor (D) and 1,3,4‐oxadiazole acceptor (A), with rigid stilbene π‐bridge was synthesized. The photophysical investigation of ViOXD in solution and aggregate state showed its solvatochromic and aggregation‐caused quenching characteristics, because of its strong charge transfer and the formation of H‐aggregates, respectively. The introduction of peripheral polystyrene or carbazole‐containing PVPCz chains via atom transfer radical polymerization not only recovered the fluorescence of the ViOXD core, but also tuned its maximum emission wavelength in aggregate state, due to the stronger electron‐donating ability and better conjugation of PVPCz chains than polystyrene chains. On the other hand, the large conjugation length and symmetrical charge transfer from the ends to the cores of ViOXD facilitated the electronic delocalization and bestowed the end‐functionalized polymers with good fluorescence in aggregate state, which we have applied in cellular imaging by preparation of their fluorescent nanoparticles.

Design of a serum albumin sensitive probe for cell imaging and drug delivery by modifying a fluorescent agent

Protein-ligand interaction serves as a critical foundation for intramolecular charge transfer (ICT) probes to bind and recognize proteins. Many fluorescent agents are reported to have favorable protein binding abilities but lack protein sensitivity. Herein, a new serum albumin sensitive ICT probe (named MBD) was synthesized by modifying an existing fluorescent agent MPM. MBD not only inherited the favorable human serum albumin (HSA) binding ability of MPM but also newly obtained favorable serum albumin responsiveness. These properties were maintained after MBD formed a complex with water-soluble pillar[5]arene (WP5). Typical commercial drugs, fluorescent amino acids, fatty acids, and metal ions had negligible effects on the HSA responsiveness of the complex. The WP5-MBD complex possessed strong anti-interference ability in binding and recognizing HSA. Moreover, the WP5-MBD complex self-assembled into supramolecular fluorescent nanoparticles in solution. Such nanoparticles possessed good cell imaging and traceable drug delivery properties, which hold great potential for cancer treatment and diagnosis.

Development and evaluation of rosmarinic acid loaded novel fluorescent porous organosilica nanoparticles as potential drug delivery system for cancer treatment

Rosmarinic acid is a bioactive compound that possesses high anticancer activity, but its poor water-solubility and ineffective membrane permeability are the main causes of low bioavailability. This study aimed to improve these limitations by encapsulating rosmarinic acid in tetrasulfide-based porous organosilica nanoparticles to deliver it to cancer cells. To date, no reports on the use of these organosilica nanoparticles as a nanocarrier for rosmarinic acid. The synthesized nanoparticles were small, approximately 50 nm in size, with a high surface area of around 498.1 m2/g and an average pore diameter of 2.3 nm. Especially, fluorescent-labeled nanospheres were synthesized and further indicated the effective accumulation in the cytosol after 24 h incubation. In addition, the nanoparticles were non-toxic to human AGS gastric adenocarcinoma cells and mouse CT26 colon cancer cells within concentrations ranging from 0 to 240 μg/mL. Treatment with nanoparticles containing 140 μg/mL of rosmarinic acid resulted in the death of approximately 39.2 % of AGS cells and 36.9 % of CT26 cells after 72 h. Importantly, neither the silica nanospheres nor the rosmarinic acid-containing nanoparticles showed any significant toxic effects on HEK-293T and NIH-3T3 fibroblasts at the tested concentrations. These results suggested that the pharmacological effects of rosmarinic acid can be enhanced by encapsulating it into our novel synthesized biodegradable tetrasulfide-based porous organosilica nanoparticles.

AIE-active lysosome-targeted fluorescent organic nanoparticles for leucine aminopeptidase-activatable fluorescent imaging and precision photodynamic therapy potential

Leucine aminopeptidase (LAP) is a vital proteolytic enzyme, and its overexpression is often associated with many physiological diseases. Stimuli-activatable photosensitizer (PS) has invigorated photodynamic therapy (PDT) by selectively demolishing cancer cells. LAP can be utilized as a facile promoter for specifically activating PS to generate reactive oxygen (ROS) in cancer cells. Herein, we construct multifunctional amphiphilic AIE-active fluorescent organic nanoparticles BTL-Leus for imaging of endogenous LAP and precise PDT towards cancer cells. BTL-Leus enable sensitive, rapid and specific detection of LAP in aqueous solution, and can also serve as an efficient tool for high-throughput screening of LAP inhibitors. In addition, BTL-Leus were successfully applied to detect the real activities of endogenous LAP in human hepatoma cells (HepG2). BTL-Leus mainly accumulate in lysosomes by asialoglycoprotein receptor (ASGPR)-mediated endocytosis, then a large amount of ROS is generated under LAP stimuli and light exposure, which induced lysosomal membrane permeabilization (LMP) followed by cancer cell apoptosis. This research provides a novel and effective strategy for LAP-activatable fluorescent imaging and precision PDT potienal in living cancer cells.

Organotrialkoxysilanes Mediate the Syntheses of Fluorescent Gold Nanoparticles and TiO2‐Supported Ag−Ni Nanocatalysts for Selective Hydrazine Sensing and Decomposition

AbstractOrganotrialkoxysilanes enabled the controlled synthesis of mono‐metallic and bimetallic noble metal nanoparticles. 3‐Aminopropyltrimethoxysilane (3‐APTMS)‐treated gold cations were quickly (1 minute) transformed into gold nanoparticles (AuNPs) in the presence of 3‐glycidoxypropyltrimethoxysilane (3‐GPTMS). As made AuNPs demonstrated exceptional fluorescence properties with 15 % QY, and the blue fluorescence of nanomaterials is supported by CIE coordinates. Fluorescent gold nanoparticles were evaluated using UV‐ Visible spectroscopy, X‐ray photoelectron spectroscopy (XPS), zeta potential, X‐ray diffraction (XRD), fluorescence spectroscopy (FL), and transmission electron microscopy (TEM), mediated by the use of organotrialkoxysilanes, gold nanoparticles with an average particle size of 4–8 nm were produced, which could be helpful for the direct determination of hydrazine via fluorescence spectroscopy. The detection limit for hydrous hydrazine is 0.047 μM, with a linear range of 0.1–1 μM (R2=0.995). In addition, organotrialkoxysilanes were also used as templates for the stabilization and formation of supported TiO2 bimetallic Ag−Ni nanoparticles for use as photo‐nanocatalysts. TiO2‐supported bimetallic Ag−Ni nanocatalyst were characterized by field emission scanning electron microscope (FE SEM), EDX, elemental mapping, and the Brunauer‐Emmett‐Teller (BET) technique. Real‐time hydrazine decomposition was enabled by the as‐built heterogeneous support in the presence of sunlight.

Naphthalene Diimide-Based Orange Emitting Luminogen: A Fluorometric Probe for Thiol Sensing through the Click Reaction.

Fluorometric sensors have gained considerable attention in various fields, including environmental monitoring, biomedical research, and clinical diagnostics. This article delineates the fabrication of an orange emitting naphthalene diimide (NDI) derivative consisting of maleimide moiety (NDI-mal) for fluorometric sensing of thiols. Spherical shaped organic nanoparticles (∼100-150 nm) were constructed by NDI-mal in dimethyl sulfoxide (DMSO)/dimethylformamide (DMF)-water through J-type aggregation. NDI-mal displayed self-assembly driven aggregation-induced emission (AIE) through excimer formation at λem= 588 nm at fw = 99 vol % DMSO/DMF-water. Naphthyl residue at both terminals of NDI-mal facilitates intramolecular charge transfer (ICT) from the donor naphthyl residue to the acceptor NDI core. The fluorescence intensity of NDI-mal fluorescent organic nanoparticles (FONPs) got quenched in the presence of thiols due to thiol-maleimide adduct formation (Michael addition). NDI-mal FONPs selectively probed thiol functionalized small molecules (4-aminothiophenol), biomolecules (glutathione (GSH)), and proteins (reduced BSA) with high sensitivity having a limit of detection of 15.3 nM, 6.0 nM, and 9.2 ng/mL, respectively. Importantly, thiol sensing was selective against analogous small molecules, biomolecules, and proteins devoid of thiol moieties. Cellular imaging demonstrated selective diagnosis of cancer cells by NDI-mal FONPs through quenching of its emission upon interaction with thiols in B16F10 cells due to the high abundance of GSH in cancer cells compared to NIH3T3 cells. NDI-mal FONPs emitted their native fluorescence inside cells subjected to reactive oxygen species mediated thiol oxidation via Fenton's reaction. Notably, GSH-maleimide adduct formation by NDI-mal FONPs displayed notable therapeutic efficacy against cancer cells having ∼2.4-fold higher killing of B16F10 in comparison to NIH3T3 cells possibly through oxidative stress induced apoptosis owing to the depletion in the GSH level. Thus, NDI-mal AIE-gen successfully emerged as a selective and sensitive probe toward thiols through thiol-maleimide click chemistry with therapeutic ability against cancer cells in the absence of systematic intervention.

High-Quantum-Yield Ultrasmall Ln2O3 (Ln = Eu, Tb, or Dy) Nanoparticle Colloids in Aqueous Media Obtained via Photosensitization.

Fluorescent nanoparticles used in biomedical applications should be stable in their colloidal form in aqueous media and possess a high quantum yield (QY). We report ultrasmall Ln2O3 (Ln = Eu, Tb, or Dy) nanoparticle colloids with high QYs in aqueous media. The nanoparticles are grafted with hydrophilic and biocompatible poly(acrylic acid) (PAA) to ensure colloidal stability and biocompatibility and with organic photosensitizer 2,6-pyridinedicarboxylic acid (PDA) for achieving a high QY. The PAA/PDA-Ln2O3 nanoparticle colloids were nearly monodispersed and ultrasmall (particle diameter: ∼2 nm). They exhibited excellent colloidal stability with no precipitation after synthesis (>1.5 years) in aqueous media, very low cellular toxicity, and very high absolute QYs of 87.6, 73.6, and 2.8% for Ln = Eu, Tb, and Dy, respectively. These QYs are the highest reported so far for lanthanides in aqueous media. Therefore, the results suggest their high potential as sensitive optical or imaging probes in biomedical applications.

Cumulus expansion is impaired with advanced reproductive age due to loss of matrix integrity and reduced hyaluronan.

Reproductive aging is associated with ovulatory defects. Age-related ovarian fibrosis partially contributes to this phenotype as short-term treatment with anti-fibrotic compounds improves ovulation in reproductively old mice. However, age-dependent changes that are intrinsic to the follicle may also be relevant. In this study, we used a mouse model to demonstrate that reproductive aging is associated with impaired cumulus expansion which is accompanied by altered morphokinetic behavior of cumulus cells as assessed by time-lapse microscopy. The extracellular matrix integrity of expanded cumulus-oocyte complexes is compromised with advanced age as evidenced by increased penetration of fluorescent nanoparticles in a particle exclusion assay and larger open spaces on scanning electron microscopy. Reduced hyaluronan (HA) levels, decreased expression of genes encoding HA-associated proteins (e.g., Ptx3 and Tnfaip6), and increased expression of inflammatory genes and matrix metalloproteinases underlie this loss of matrix integrity. Importantly, HA levels are decreased with age in follicular fluid of women, indicative of conserved reproductive aging mechanisms. These findings provide novel mechanistic insights into how defects in cumulus expansion contribute to age-related infertility and may serve as a target to extend reproductive longevity.

The Facile Synthesis of Efficient Red‐Emissive Two‐Photon Carbon Dots for Real‐Time Cellular Imaging and High‐Resolution Deep‐Tissue Imaging

In recent years, the development of carbon dot‐based fluorescent nanoparticles for bioimaging applications has attracted the attention of the scientific community. However, many of these systems absorb and emit in the blue–green region of the electromagnetic spectrum, limiting their application in bioimaging. Herein, the facile design and development of highly efficient two‐photon excitable red‐emissive carbon dots are reported and their high performance in bioimaging applications is demonstrated. The importance of aromatic precursors in developing red‐emissive carbon dots is demonstrated. The optimized carbon dots are highly biocompatible and nontoxic, with remarkable photostability in cells under two‐photon near‐infrared excitation. The present study points to the great potential of two‐photon excitable red‐emissive carbon dot as an efficient bioimaging agent for cellular biolabeling, long‐term and real‐time cellular imaging, and high‐resolution deep‐tissue imaging in complex biological systems.

Optical, microstructural, and magnetic hyperthermia properties of green-synthesized Fe3O4/carbon dots nanocomposites utilizing Moringa oleifera extract and watermelon rinds

Cancer therapy with targeted-localized heating is one of the breakthroughs in the biomedical field. The incorporation of magnetic nanoparticles and fluorescent nanoparticles was one of the crucial issues for magnetic hyperthermia applications. This research investigates the magnetic hyperthermia properties of green-synthesized Fe3O4/CDs. Fe3O4 nanoparticles were synthesized using the coprecipitation method with Moringa oleifera leaf extract as a reducing agent and stabilizer. In contrast, CDs were synthesized using a hydrothermal method with watermelon rind waste as a carbon source. X-ray diffraction analysis confirmed the presence of cubic inverse spinel and a reduction in crystallite size with increasing CDs concentration. Transmission electron microscopy revealed particle size distributions of 9.7 nm for Fe3O4 and 7.5 nm for Fe3O4/CDs. Scanning electron microscopy showed that CDs were distributed on the surface of Fe3O4. The detection of characteristic FeO, CC, CO, and CO-C bonds indicated the presence of CDs on the surface of Fe3O4. Ultraviolet-visible spectroscopy spectra absorption peaks at 282 nm for CDs and 193 nm for Fe3O4. Photoluminescence spectra indicated shifts from 509 to 505 nm in excitation wavelength for both CDs and Fe3O4/CDs, situated within the green region of visible light. The vibrating sample magnetometer revealed that the nanocomposites displayed characteristics of soft ferromagnetic materials. Furthermore, the specific absorption rate (SAR) value of Fe3O4/CDs was found to be dependent on magnetization. The SAR value of Fe3O4/CDs decreased as the concentration of CDs increased, and the frequency and strength of the AMF increased. Therefore, these results can promote Fe3O4/CDs nanocomposites as a promising candidate for magnetic hyperthermia applications.

Biodistribution of Fluorescent Albumin Nanoparticles among Organs of Laboratory Animals after Intranasal and Peroral Administration.

Natural, environmental and engineered nanoparticles (NP) penetrate into cells by endocytosis and induce innate immunity. The behaviour of the nanomaterials both in vitro and in vivo should be assessed. Our goal was to study protein NP stability in biological fluids and distribution in organs of animals after intranasal and oral administration. Bovine serum albumin (BSA) was labelled with the fluorescent dye RhoB and NP were fabricated by nanoprecipitation. The fluorescent protein NPwere administered intranasally and orally in laboratory-outbred mice ICR and rabbits. RhoB-BSA NP distribution in organs was detected using spectrofluorometry and fluorescent microscopy. Innate immunity was evaluated using reverse transcription with random hexanucleotide primer and subsequent real-time PCR with specific fluorescent hydrolysis probes. The labelled BSA NP were shown to remain stable in blood sera and nasopharyngeal swabs for 5 days at +37 °C. In vivo the maximal accumulation was found in the brain in 2 days posttreatment without prevalent accumulation in olfactory bulbs. For the intestine, heart and liver, the BSA NP accumulation was similar in 1 and 2 days, whereas for kidney samples even decreased after 1 day. Both intranasal and peroral administration of RhoB-BSA NP did not induce innate immunity. Thus, after intranasal or oral instillation RhoB-BSA NP were found mainly in the brain and intestine without interferon gene expression.