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This review covers strategies to prepare high-performance emissive polymer nanomaterials, combining very high brightness and photostability, to respond to the drive for better imaging quality and lower detection limits in fluorescence imaging and sensing applications. The more common approaches to obtaining high-brightness nanomaterials consist of designing polymer nanomaterials carrying a large number of fluorescent dyes, either by attaching the dyes to individual polymer chains or by encapsulating the dyes in nanoparticles. In both cases, the dyes can be covalently linked to the polymer during polymerization (by using monomers functionalized with fluorescent groups), or they can be incorporated post-synthesis, using polymers with reactive groups, or encapsulating the unmodified dyes. Silica nanoparticles in particular, obtained by the condensation polymerization of silicon alcoxides, provide highly crosslinked environments that protect the dyes from photodegradation and offer excellent chemical modification flexibility. An alternative and less explored strategy is to increase the brightness of each individual dye. This can be achieved by using nanostructures that couple dyes to plasmonic nanoparticles so that the plasmon resonance can act as an electromagnetic field concentrator to increase the dye excitation efficiency and/or interact with the dye to increase its emission quantum yield. [ABSTRACT FROM AUTHOR]

The diamond back moth, Plutella xylostella, causes severe damage at all crop stages, beside its rising resistance to all insecticides. The objective of this study was to look for a new control strategy such as application of insecticide-loaded carbon dot-embedded fluorescent mesoporous silica nanoparticles (FL-SiO2 NPs). Two different-sized methoxyfenozide-loaded nanoparticles (Me@FL-SiO2 NPs-70 nm, Me@FL-SiO2 NPs-150 nm) were prepared, with loading content 15% and 16%. Methoxyfenozide was released constantly from Me@FL-SiO2 NPs only at specific optimum pH 7.5. The release of methoxyfenozide from Me@FL-SiO2 NPs was not observed other than this optimum pH, and therefore, we checked and controlled a single release condition to look out for the different particle sizes of insecticide-loaded NPs. This pH-responsive release pattern can find potential application in sustainable plant protection. Moreover, the lethal concentration of the LC50 value was 24 mg/L for methoxyfenozide (TC), 14 mg/L for Me@FL-SiO2 NPs-70 nm, and 15 mg/L for Me@FL-SiO2 NPs-150 nm after 72 h exposure, respectively. After calculating the LC50, the results predicted that Me@FL-SiO2 NPs-70 nm and Me@FL-SiO2 NPs-150 nm exhibited better insecticidal activity against P. xylostella than methoxyfenozide under the same concentrations of active ingredient applied. Moreover, the activities of detoxification enzymes of P. xylostella were suppressed by treatment with insecticide-loaded NPs, which showed that NPs could also be involved in reduction of enzymes. Furthermore, the entering of FL-SiO2 NPs into the midgut of P. xylostella was confirmed by confocal laser scanning microscope (CLSM). For comparison, P. xylostella under treatment with water as control was also observed under CLSM. The control exhibited no fluorescent signal, while the larvae treated with FL-SiO2 NPs showed strong fluorescence under a laser excitation wavelength of 448 nm. The reduced enzyme activities as well as higher cuticular penetration in insects indicate that the nano-based delivery system of insecticide could be potentially applied in insecticide resistance management. [ABSTRACT FROM AUTHOR]

Water-repellent and anticorrosive superhydrophobic cotton fabrics were produced via an eco-friendly water-based coating with core–shell fluorescent silica nanoparticles (SiPs) and subsequent immersion in a mixture of two fluorine-free organosilanes (3-(aminopropyl)-trimethoxysilane and trimethoxy-(octadecyl)-silane). Transmission electron microscopy confirmed the spherical and core–shell structure of SiPs, and Fourier-transform infrared spectroscopy characterized their chemical composition. Scanning electron microscopy with energy-dispersive X-ray spectroscopy confirmed the high coating coverage even after realistic laundering cycles. In confocal laser scanning microscopy, the fluorescent core–shell SiPs were used as probes to characterize the coating coverage on the surface of the cotton fibers. The high fluorescent signal provided by the fluorescent core–shell SiP cores enabled their visualization over large surface areas of the modified cotton fibers, before and after several washing cycles. The hydrophobic property of the cotton fiber treatments was evaluated considering the type of particle coating (monolayer or hierarchization), covalent bond with silanes, and a final curing process. Monolayer coating with fluorescent core–shell SiPs and further silanization yielded cotton fibers with high hydrophobicity and excellent durability (tested up to 10 washing processes), maintaining water contact angle (WCA) values above 150°, repellency grade 3, and lower water uptake (165%) compared to pristine (600%) or silanized cotton fibers (340%). Principal component analysis showed that the silanization process increased the SiP-coated cotton fiber resistance to laundering sustaining nonwetting properties up to 10 washing cycles, which was not observed for SiP-coated fibers subjected to no silanization process. Additionally, the silanized and noncured SiP-coated fibers were tested against solvents and corrosive aqueous media, for which high resistance to toluene, chloroform, and strong acid was observed, with the maintenance of static and dynamic WCAs. Thus, this systematic study allowed us to verify the main factors associated with superior hydrophobicity and durability and achieve an optimized and less toxic approach that combines the deposition of fluorescent core–shell SiPs and binary silanization. [ABSTRACT FROM AUTHOR]

Rhodamine B can be used as a fluorophore to produce a fluorescent silica nanoparticles derived from geothermal sludge. The purpose of this research is to synthesize fluorescent silica nanoparticles (FSNP) modified with rhodamine B and cetyl trimethyl ammonium bromide (CTAB) using sol-gel method. Geothermal waste was used as a precursor and added with NaOH at 900C to generate sodium silicate. Rhodamine B, as the fluorescent dye were added with concentration variations ranging from 0.156 mg/g to 10 mg/g.CTAB was used as template and HCl 2N was applied as gelling catalyst with aging time of 18 hours. Characterization of FSNP was measured using spectrofluorometer to identify the fluorescent intensity, fourier transform infrared (FT-IR) to determine the functional group of FSNP, BraunerEmmett-Teller (BET) adsorption to calculate the specific area of the particles, X-ray diffraction (XRD) to analyze the crystallographic phases, and transmission electron microscopy (TEM) to analyze the surface morphology of the FSNP. FT-IR and fluorescent intensity results showed that FSNP with 2.5 mg/g of rhodamine B had the optimum characteristics. The FSNP was in amorphous phase with uniform pore distribution. BET analysis showed that the specific surface of the FSNP was 190.22 m2/g.

BACKGROUND Plutella xylostella L. is a cosmopolitan lepidopteron insect pest for numerous vegetables and crops. The extensive use of insecticides has resulted in the emergence of resistance in P. xylostella. Thus, development of innovative strategies to overcome the insecticide resistance and control P. xylostella effectively is highly desirable. Inspired by the concept and breakthrough of nanomedical strategies to treat multidrug resistance, nanotechnology may find potential application in overcoming or delaying insecticide resistance. RESULTS: Carbon dots‐embedded fluorescent mesoporous silica nanoparticles (FL‐SiO2 NPs) were successfully developed. Indoxacarb‐loaded nanoparticles (IN@FL‐SiO2 NPs) were facilely prepared with loading content of 24%. The release of indoxacarb from IN@FL‐SiO2 NPs was pH sensitive. IN@FL‐SiO2 NPs exhibited better insecticidal activity against P. xylostella than indoxacarb technical under the same doses of active ingredient applied. Moreover, the activities of detoxification enzymes including GST, CarE, and P450 of P. xylostella were suppressed by treatment with IN@FL‐SiO2 NPs. Furthermore, the entry of FL‐SiO2 NPs into the midgut of P. xylostella was confirmed by CLSM observation. CONCLUSIONS: Although there is no absolute correlation between the enzyme activity and resistance, the change in corresponding enzyme activity can afford valuable information on the resistance situation. IN@FL‐SiO2 NPs treated P. xylostella displayed higher mortality, along with decreased enzymes activities, which indicates that nano‐based delivery system of insecticide could be potentially applied in insecticide resistance management. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Development of multi-purpose probes for mass transport measurements is of importance to gain knowledge in diffusional behaviour in heterogeneous structures such as food, hygiene or pharamceuticals. By combining different techniques, such as Fluorescence Recovery After Photobleaching (FRAP) and Nuclear Magnetic Resonance Diffusometry (NMR-d), information of both local and global diffusion can be collected and used to gain insights on for example material heterogeneities and probe-material interactions. To obtain a FRAP-responsive probe, fluorescent silica particles were produced using fluorescent preconjugates added in a modified Stöber process. A NMR-d responsive moiety was introduced by derivatizing the fluorescent silica particles with polyethylene glycol. The particle size distributions were determined by dynamic light scattering and transmission electron microscopy and these measurements were compared to value extrapolated from diffusion measurements using FRAP and NMR-d. The good agreement between the FRAP and NMR-d measurements demonstrates the potential of multi-purpose probes for future applications concerning mass transport at local and global scale simultaneously. [ABSTRACT FROM AUTHOR]

Abstract Fluorescent silica nanoparticles (FSNPs) have attracted great interest for potential applications in biological and biomedical fields because they possess higher fluorescence quantum yield and better fluorescence stability as comparison with small organic fluorescent molecules. The encapsulation of covalent linkage with fluorescent organic dyes or fluorescent metal complexes has demonstrated to be the commonly adopted strategies for fabrication of FSNPs previously. However, it is still challengeable to obtain FSNPs based polymer composites with intensive fluorescence and good water dispersibility through a one-pot surface modification strategy. In this paper, we developed a facile method to fabricate novel FSNPs based polymer composites (PhE@MSNs-PEtOx) through introducing the aggregation-induced emission (AIE) dye (PhE-OH) and poly(2-ethyl-2-oxazoline) (PEtOx) onto mesoporous silica nanoparticles (MSNs) based on cationic ring opening polymerization (CROP). The resulting PhE@MSNs-PEtOx composites possess strong fluorescence emission, excellent hydrophilicity and biocompatibility. These features make the final FSNPs based polymer composites great potential for biomedical applications. Taken together, we have developed for the first time that FSNPs based polymer composites can be facilely prepared through the one-pot introduction of AIE dyes and hydrophilic PEtOx on MSNs. Moreover, the novel FSNPs based composites could also be utilized for other biomedical applications considered their properties. Graphical abstract Unlabelled Image Highlights • Surface modification of AIE-active silica nanoparticles • Surface-initiated cationic ring opening polymerization • Fluorescent nanomaterials with aggregation-induced emission feature • These fluorescent AIE-active silica nanomaterials are of great potential for biomedical applications. [ABSTRACT FROM AUTHOR]

We have synthesized and characterized of a series of single and multidye copolymerized nanoparticles with large to very large Stokes shifts (100 to 255 nm) for versatile applications as standalone or multiplexed probes in biological matrices. Nanoparticles were prepared via the Stöber method and covalently copolymerized with various combinations of three dyes, including one novel aminocyanine dye. Covalently encapsulated dyes exhibited no significant leakage from the nanoparticle matrix after more than 200 days of storage in ethanol. Across multiple batches of nanoparticles with varying dye content, the average yields and average radii were found to be highly reproducible. Furthermore, the batch to batch variability in the relative amounts of dye incorporated was small (relative standard deviations <2.3%). Quantum yields of dye copolymerized nanoparticles were increased 50% to 1000% relative to those of their respective dye-silane conjugates, and fluorescence intensities were enhanced by approximately three orders of magnitude. Prepared nanoparticles were surface modified with polyethylene glycol and biotin and bound to streptavidin microspheres as a proof of concept. Under single wavelength excitation, microsphere-bound nanoparticles displayed readily distinguishable fluorescence signals at three different emission wavelengths, indicating their potential applications to multicolor sensing. Furthermore, nanoparticles modified with polyethylene glycol and biotin demonstrated hematoprotective qualities and reduced nonspecific binding of serum proteins, indicating their potential suitability to in vivo imaging applications. [ABSTRACT FROM AUTHOR]

Nowadays, sole recognition of targeted species is not sufficient to quantify or recover it from environmental samples. Therefore, current challenge in the management of crucial species is to improve or design sensing probes which are able to recognize, quantify as well as recover it from various assays. Herein, a Schiff base chemosensor SB has been modulated to SB-Silt after incorporating hydrolysable units for its covalent grafting on silica surfaces. Interestingly, despite fluorogenic insensitivity of SB towards metallic species, SB-Silt was found to be highly efficient for the recognition and quantification of Zn 2+ ions. Furthermore, functionalization of nanosilica with SB-Silt produced a multi-functional nanoprobe SB@SNPs for monitoring Zn 2+ ions. The ‘turn ON’ fluorescence emission in SB-Silt and SB@SNPs (at 437 nm and 457 nm, respectively) in the presence of Zn 2+ ions enabled the detection upto 6.8 nM and 0.17 μM (LODs), respectively. The maximum adsorption capacity (Q m ) of SB@SNPs for Zn 2+ ions was determined to be 167.2 mg g −1 . Moreover, the SB-Silt-Zn 2+ conjugate (formed by the interaction of SB-Silt and Zn 2+ ions) exhibited a complete quenching of fluorescence (at 437 nm) accompanied with continuous red shifting of emission wavelength to 517 nm in the presence of hydrogen phosphate (upto 4 equiv.). Overall, the developed material is highly efficient, sensitive, selective, reusable and easily separable, and hence can be used as a multifunctional nanoprobe. [ABSTRACT FROM AUTHOR]

For the first time, a synthetic fluorescent antioxidant flavone analog was successfully anchored onto the surface of the APTES-modified mesoporous silica nanoparticles (NPs) through sulfonamide linkage. The surface chemistry and morphology of the flavone modified fluorescent silica ( FMFS ) NPs were studied in detail. The flavone moiety when attached onto the FMFS NP surface, imparted its characteristic fluorescence and antioxidant activities to these NPs. Moreover, the NPs are highly biocompatible as evidenced from their cytotoxicity assay on normal lung cell (L132). The fluorescence activity of these biocompatible NPs was further utilized to study their interaction with a biomolecule, BSA (Bovine Serum Albumin). It was interesting to note that the fluorescence behavior of FMFS NPs completely changed on their binding with BSA. On the other hand, the intrinsic fluorescence activity of BSA was also significantly modified due to its interaction with FMFS NPs. Thus, the sensing and detection of biomolecules like BSA in presence of FMFS NPs can be accomplished by monitoring changes in the fluorescence behavior of either FMFS NPs or BSA. Furthermore, these FMFS NPs retained their intrinsic fluorescence behavior in the cellular medium which opens up their possible use as biocompatible cell imaging agents in future. [ABSTRACT FROM AUTHOR]

Among the several types of inorganic nanoparticles available, silica nanoparticles (SNP) have earned their relevance in biological applications namely, as bioimaging agents. In fact, fluorescent SNP (FSNP) have been explored in this field as protective nanocarriers, overcoming some limitations presented by conventional organic dyes such as high photobleaching rates. A crucial aspect on the use of fluorescent SNP relates to their surface properties, since it determines the extent of interaction between nanoparticles and biological systems, namely in terms of colloidal stability in water, cellular recognition and internalization, tracking, biodistribution and specificity, among others. Therefore, it is imperative to understand the mechanisms underlying the interaction between biosystems and the SNP surfaces, making surface functionalization a relevant step in order to take full advantage of particle properties. The versatility of the surface chemistry on silica platforms, together with the intrinsic hydrophilicity and biocompatibility, make these systems suitable for bioimaging applications, such as those mentioned in this review.

A novel pyridyltriphenylamine-rhodamine dye PTRh and a pyridyltriphenylamine derivative PTO were synthesized and characterized by 1 H NMR and HRMS-MALDI-TOF. PTRh performed typical fluorescence resonance energy transfer (FRET) signal from pyridyltriphenylamine to rhodamine along with notable color change from green to rose when interacting with Hg 2+ in EtOH/H 2 O. And PTRh as a ratiometric probe for Hg 2+ based on FRET could achieve a very low detection limit of 32 nM and energy transfer efficiency of 83.7% in aqueous organic system. On the other hand, spectra properties of PTO in its aggregates, THF/H 2 O mixed solution and silica nanoparticles (Si-NPs) dispersed in water were investigated. And the results indicated PTO exhibited bright green fluorescence in solid state, and PTO was successfully encapsulated in silica matrix (30–40 nm), emitting bright blue fluorescence with 11.7% quantum yield. Additionally, living cell imaging experiments demonstrated that PTRh could effectively response to intracellular Hg 2+ and PTO-doped Si-NPs were well uptaken by MCF-7 breast cancer cells. It could be concluded that the chromophores are promising materials used as biosensors. [ABSTRACT FROM AUTHOR]

Among the several types of inorganic nanoparticles available, silica nanoparticles (SNP) have earned their relevance in biological applications namely, as bioimaging agents. In fact, fluorescent SNP (FSNP) have been explored in this field as protective nanocarriers, overcoming some limitations presented by conventional organic dyes such as high photobleaching rates. A crucial aspect on the use of fluorescent SNP relates to their surface properties, since it determines the extent of interaction between nanoparticles and biological systems, namely in terms of colloidal stability in water, cellular recognition and internalization, tracking, biodistribution and specificity, among others. Therefore, it is imperative to understand the mechanisms underlying the interaction between biosystems and the SNP surfaces, making surface functionalization a relevant step in order to take full advantage of particle properties. The versatility of the surface chemistry on silica platforms, together with the intrinsic hydrophilicity and biocompatibility, make these systems suitable for bioimaging applications, such as those mentioned in this review. [ABSTRACT FROM AUTHOR]

Prothioconazole (PTC) has been widely utilized for plant fungal disease control, but its metabolite prothioconazole-desthio (PTC-d) exhibits reproductive toxicity. In the present study, carbon quantum dot (CQD)-modified fluorescent double-hollow shelled mesoporous silica nanoparticles (FL-MSNs) loaded with PTC, referred to as PTC@FL-MSNs, were constructed with an average size of 369 nm and a loading capacity of 28.1 wt %, which could increase the antifungal efficiency of PTC. In addition, upright fluorescence microscope and UPLC-MS/MS studies showed that PTC@FL-MSNs could be effectively transported via root uptake and foliar spray in soybean plants. Compared to a 30% PTC dispersible oil suspension agent, the PTC@FL-MSN treatment group showed higher concentrations (leaves: 0.50 > 0.48 mg/kg), longer half-lives for degradation (leaves: 3.62 > 3.21 d; roots: 3.39 > 2.82 d), and fewer metabolites. These findings suggest that sustained pesticide release and toxicity reduction are potential applications for PTC nanofungicide delivery technology.

We describe the preparation of very bright and photostable fluorescent silica nanoparticles (SiNPs), with emission in the visible or in the near infrared (NIR). The nanoparticles can be prepared with diameters of 30–300 nm with low size dispersity, and incorporate perylenediimide (PDI) dyes modified with alkoxysilane groups that react with the silica structure. One of the dyes ( PDIvis ) emits in the green and the other ( PDInir ) in the NIR (with fluorescence quantum yields of 90% and 24%, respectively). Silica nanoparticles containing these dyes were efficiently internalized in HEK293 cells with low toxicity and reveled very high photostability, showing good potential for use as a platform for in vivo laser scanning bioimaging applications. The NIR emitting nanoparticles, in particular, can be used in multi-color imaging, even in cells expressing high levels of fluorescent proteins and/or co-stained with different fluorescent dyes (most of which commonly emit at wavelengths lower than the NIR). [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel assay method based on FRET between fluorescent SiNPs and AuNPs was developed. [•] The method was based on the conformation change of aptamer lead by target recognition. [•] The aptamer toward adenosine without modification was split into two fragments. [•] The method was label-free without the modification of fluorescent SiNPs or AuNPs. [•] The detection limit of adenosine was as low as 45nM with excellent specificity. [ABSTRACT FROM AUTHOR]

Fluorescent silica nanoparticles (FSNs) are prepared by incorporating dye into a mesoporous silica nanoparticle (MSN) synthesis procedure. FSNs containing sulforhodamine B, hydrophobically modified sulforhodamine B, and Cascade Blue hydrazide are made. The MSN-based FSNs do not leach dye under simulated physiological conditions and have strong, stable fluorescence. FSNs prepared with sulforhodamine B are compared to FSNs prepared with hydrophobically modified sulforhodamine B. The data indicate that FSNs prepared with sulforhodamine B are equally as stable but twice as fluorescent as particles made with hydrophobically modified sulforhodamine B. The fluorescence of a FSN prepared with sulforhodamine B is 10 times more intense than the fluorescence of a 4.5 nm core-shell CdSe/ZnS quantum dot. For diagnostic applications, a method to selectively and covalently bind antibodies to the surface of the FSNs is devised. FSNs that are functionalized with antibodies specific for Neisseria gonorrhoeae specifically bind to Neisseria gonorrhoeae in flow cytometry experiments, thus demonstrating the functionality of the attached antibodies and the potential of MSN-based FSNs to be used in diagnostic applications. [ABSTRACT FROM AUTHOR]

Abstract: Multifunctional fluorescent silica nanoparticles with phenylboronic acid tags were developed for labeling sialic acid on the surface of living cancer cells. In this paper, fluorescent silica nanoparticles (FSNPs) with strong and stable emission at 515nm were firstly prepared through a reverse microemulsion process, and then modified with highly selective phenylboronic acid (PBA) tags on their surface via an aqueous ‘thiol-ene’ click reaction. These nanoparticles had a hydrodynamic diameter of 92.6±9.1nm, and a bright fluorescence signal, which is 366 times higher than that of a single dye molecule. Meanwhile, these PBA-tagged FSNPs were found very stable in aqueous solution as well as in cell culture medium, verified by transmission electron microscopy, X-ray photoelectron spectroscopy and zeta potential analysis. The over-expressed sialic acid (SA) on the membrane of living HeLa cells was visualized in situ by a confocal laser scanning microscopy, ascribed to the specific interaction between PBA and SA. Thus, the PBA-FSBPs showed a great potential in probing SA expressed on living cells with high selectivity and sensitivity. [Copyright &y& Elsevier]

Water-soluble, highly fluorescent double-layered silica nanoparticles (FL-DLSN) have been successfully synthesized through a reverse (water-in-oil) microemulsion method. The microemulsion was prepared by mixing a surfactant (Brij35), co-surfactant, organic solvent, water, and fluorescein as an organic fluorophore. The sizes of the silica nanoparticles were successfully controlled in the reverse microemulsion using Brij35 by changing the water-to-Brij35 ratio and by adding HCl. Initially, tetraethylorthosilicate was hydrolyzed by adding NHOH as a catalyst and then polymerized to generate core fluorescent silica nanoparticles with fluorescein. 3-(Aminopropyl)triethoxysilane (APTS) was sequentially added into the reaction mixture, and reacted on the surface of pre-generated core silica nanoparticles to form the second layer in the form of a shell. The second silica layer that was derived from the condensation of APTS effectively protected the fluorescein dye within the silica matrix. This is a novel and simple synthetic approach to generate highly fluorescent, monodispersed silica nanoparticles by doping organic molecules into a silica matrix. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Nanoparticles (NPs) are considered a promising tool in the context of biofilm control. Many studies have shown that different types of NPs can interfere with the bacterial metabolism and cellular membranes, thus making them potential antibacterial agents; however, fundamental understanding is still lacking on the exact mechanisms involved in these actions. The development of NP-based approaches for effective biofilm control also requires a thorough understanding of how the chosen nanoparticles will interact with the biofilm itself, and in particular with the biofilm self-produced extracellular polymeric matrix (EPS). This work aims to provide advances in the understanding of the interaction between engineered fluorescent pluronic silica (PluS) nanoparticles and bacterial biofilms, with a main focus on the role of the EPS matrix in the accumulation and diffusion of the particles in the biofilm. It is demonstrated that particle surface chemistry has a key role in the different lateral distribution and specific affinity to the biofilm matrix components. The results presented in this study contribute to our understanding of biofilm-NP interactions and promote the principle of the rational design of smart nanoparticles as an important tool for antibiofilm technology.

Fluorescent silica nanoparticles (FSNPs) can provide high-intensity and photostable fluorescent signals as a probe for biomedical analysis. In this study, FSNPs hybridized with aggregation-induced emission (AIE) luminogens (namely FSNP-SD) were successfully fabricated by a surfactant-free sol-gel method. The FSNP-SD were spherical, monodisperse and uniform in size, with an average diameter of approximately 100 nm, and emitted strong fluorescence at the peak of 490 nm. The FSNP-SD selectively stained the cytoplasmic regions and were distributed in the cytoplasm. Moreover, they can stay inside cells, enabling the tacking of cells over a long period of time. The intracellular vesicles and multinucleated cells were increase gradually with the rise of FSNP-SD concentration. Both cell viability and survival only lost less than 20% when the cells were exposed to the high concentration of 100 µg/mL FSNP-SD. Additionally, the cell apoptosis and intracellular ROS assay indicated that FSNP-SD had no significant toxic effects at the maximum working concentration of 80 µg/mL. This study demonstrated that the FSNP-SD are promising biocompatible fluorescent probes for living cell imaging. [ABSTRACT FROM AUTHOR]

The use of fluorescent nanomaterials has gained great importance in the field of medical imaging. Many traditional imaging technologies have been reported utilizing dyes in the past. These methods face drawbacks due to non-specific accumulation and photobleaching of dyes. We studied the uptake and internalization of two different sized (30 nm and 100 nm) FITC labeled silica nanoparticles in Human umbilical vein endothelial cell line. These nanomaterials show high biocompatability and are highly photostable inside live cells for increased period of time in comparison to the dye alone. To our knowledge, we report for the first time the use of 30 nm fluorescent silica nanoparticles as efficient endothelial tags along with the well studied 100 nm particles. We also have emphasized the good photostability of these materials in live cells. [ABSTRACT FROM AUTHOR]

Abstract: The aim of the study was to develop an immobilized-antigen immunofluorescence glass slide system using fluorescent silica nanoparticles (FSNPs) for the detection of biomarkers to evaluate food functionality. A plain glass slide was first cleaned by treatment with piranha solution, after which C-reactive protein (CRP), a model antigen, was immobilized on the slide via procedures that exploited activation of the slide surface with 3-aminopropyltrimethoxysilane (APTMS) and glutaraldehyde, or 3-mercaptopropyltrimethoxysilane (MPTMS) and N-γ-maleimidobutyryloxysuccinimide ester (GMBS). Streptavidin-modified FSNPs that contained a fluorescent dye, dichlorotris(1,10-phenanthroline)ruthenium(II) hydrate, were conjugated with biotinylated monoclonal anti-rat CRP antibody to produce FSNP–antibody conjugates. The bioconjugate bound more effectively to the surface of slides that had been activated with APTMS before immobilization of the antigen than to those activated with MPTMS–GMBS. Specific binding of the coating antigen and bioconjugate to the slide surface was confirmed by fluorescence and atomic force microscopy. The fluorescence intensity due to formation of a complex between the antigen and bioconjugate increased gradually with increasing bioconjugate concentration up to 0.250mg/mL. [Copyright &y& Elsevier]

The use of fluorescent nanomaterials with good photostability and biocompatibility in live imaging of cells has gained increased attention. Even though several imaging techniques have been reported for mammalian cells, very limited literatures are available for nanomaterial based live imaging in plant system. We studied the uptake ability of two different nanomaterials, the highly photostable CdSe quantum dots and highly biocompatible FITC-labeled silica nanoparticles by rice seedlings which could provide greater opportunities for developing novel in vivo imaging techniques in plants. The effects of these nanomaterials on rice seed germination have also been studied for analyzing their phytotoxic effects on plants. We observed good germination of seeds in the presence of FITC-labeled silica nanoparticles whereas germination was arrested with quantum dots. The uptake of both the nanomaterials has been observed with rice seedlings, which calls for more research for recommending their safe use as biolabels in plants. [ABSTRACT FROM AUTHOR]

This paper presents the synthesis of organic dye molecules embedded silica nanoparticles by Stöber method and their applications as fluorescence probes in cell imaging. By modifying the surface of fluorescent silica nanoparticles (FSNs) with amino, biologically functionalized and monodisperse FSNs can be obtained. In this work, FSNs were conjugated with monoclonal anti-Carcinoembryonic Antigen (anti-CEA) antibody via covalent binding. The antibody-conjugated FSNs can be used to label the SPCA-1 cells successfully, demonstrating that the application of FSNs as fluorescence probes in fluorescence imaging and bioassay would be feasible. [ABSTRACT FROM AUTHOR]

Herein, the fluorescence resonance energy transfer (FRET) system composed of Zinc sulfide quantum dots (ZnS QDs) and fluorescent silica nanoparticles (FS) and the influence of bovine hemoglobin (BHb) on the system were studied using spectroscopy. UV–vis, SEM and XRD were used to characterize ZnS QDs. FT-IR spectroscopy, Zeta potential, DLS and fluorescence spectroscopy confirmed the synthesis of FS. The mechanism and efficiency of FRET in aqueous solution and BHb solution has been analyzed by fluorescence spectroscopy and Förster's non-radiative energy transfer theory, which implied that in the absence of BHb, there is dynamic quenching between ZnS QDs and FS. In the presence of BHb, it is static quenching. And BHb interfered with the stability of the ZnS QDs-FS FRET system and reduced FRET efficiency. Moreover, steady-state, synchronous fluorescence spectra and Raman spectroscopy showed that ZnS QDs caused an increase of hydrophilicity of the chromophore microenvironment, and FS may induce heme degradation to form fluorescent heme product, resulting in increased fluorescence intensity. This investigation will be significant in exploring the toxicity profile of ZnS QDs-FS FRET system for their in vivo. [Display omitted] • There was FRET phenomenon between ZnS QDs and FS. • BHb caused changes in the FRET mechanism between ZnS QDs and FS. • ZnS QDs induced an increase in the hydrophilicity of Tyr and Trp. • ZnS QDs affected the spin state of heme iron in BHb. • FS may induce heme degradation to form fluorescent heme product. [ABSTRACT FROM AUTHOR]

The exploration of fluorescent tools with distinguished optical properties and favorable biocompatibility is significant for biosensing and bioimaging. We herein present a host-guest interactions aided strategy for fabricating fluorescent silica nanoparticles (FSNPs), which is enabled by cyclodextrin (CD) supermolecules. Compared with conventional FSNPs, the modified products (are named as fluorophore@CD@SNPs) possess several advantages. First, the incorporated fluorophores can thoroughly get rid of their intrinsic aggregation due to CD's inclusion effect, and the fluorescence intensity of the obtained fluorophore@CD@SNPs can enhance 48-67%. The fluorophores can then be well-fixed by the host CD molecules. As a result, the leak rates of the incorporated fluorophores are only 15-17%, which is about 3 times lower than that of conventional ones (42-48%). Notably, the as-prepared fluorophore@CD@SNPs show observable less cytotoxicity as compared with their conventional counterparts, probably due to the substantially decreased leakage of the incorporated fluorophores. Because of prominent properties and versatile fabrication, the proposed fluorophore@CD@SNPs not only possess better performances for cell-imaging but are competent for ratiometric sensing of pH value at living cell using (indicator-reference) integrative silica NPs.

Rapid detection of Entamoeba histolytica based on fluorescent silica nanoparticle (FSNP) indirect immunofluorescence microscopy was evaluated. Silica nanoparticles were synthesized using Stöber's method, with their surface activated to covalently bind to, and immobilize, protein A. For biolabeling, FSNP was added to conjugated E. histolytica trophozoites with monoclonal anti-E. histolytica IgG1 for microscopic observation of fluorescence. Fluorescent silica nanoparticle sensitivity was determined with axenically cultured E. histolytica serially diluted to seven concentrations. Specificity was evaluated using other intestinal protozoa. Fluorescent silica nanoparticles detected E. histolytica at the lowest tested concentration with no cross-reaction with Entamoeba dispar, Entamoeba moshkovskii, Blastocystis sp., or Giardia lamblia. Visualization of E. histolytica trophozoites with anti-E. histolytica antibody labeled with fluorescein isothiocyanate (FITC) was compared with that using anti-E. histolytica antibody bioconjugated FSNP. Although FITC and FSNP produced similar results, the amount of specific antibody required for FITC to induce fluorescence of similar intensity was fivefold that for FSNP. Fluorescent silica nanoparticles delivered a rapid, simple, cost-effective, and highly sensitive and specific method of detecting E. histolytica. Further study is needed before introducing FSNP for laboratory diagnosis of amoebiasis., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: Tuberculosis is a public health problem worldwide, and new easy to perform diagnostic methods with high accuracy are necessary for optimal control of the disease. Recently, fluorescent silica nanoparticles (FSNP) has attracted immense interest for the detection of pathogenic microorganisms. The aim of this study was to detect Mycobacterium tuberculosis in clinical samples using bioconjugated FSNP compared with microscopic examination, polymerase chain reaction (PCR), nested PCR, and culture as the gold standard., Methods: In total, 152 sputum specimens were obtained from patients who were suspected to have pulmonary tuberculosis. All samples were examined by the four techniques described., Results: The assay showed 97.1% sensitivity (95% confidence interval [CI] 91-99.2) and 91.35% specificity (CI 78.3-97.1). Furthermore, assays using variable bacterial concentrations indicated that 100 colony forming units/mL of M. tuberculosis could be detected. There were no differences between the results obtained from two types of mouse monoclonal antibody against Hsp-65 and 16 KDa antigens., Conclusion: We performed this assay in a large number of clinical samples to confirm the diagnostic specificity and sensitivity of the test and can recommend its application for diagnosis of M. tuberculosis. We believe that this method is more convenient for routine diagnosis of M. tuberculosis in sputum and will be more easily applicable in the field, and with sufficient sensitivity.