Fluorescent Mesoporous Silica Nanoparticles Research Articles

Optimized Epigallocatechin Gallate Delivery and Adipogenesis Inhibition through Fluorescent Mesoporous Nanocarriers.

Epigallocatechin gallate (EGCG), a naturally occurring compound known for its multiple health benefits including antioxidant, anti-inflammatory, cancer preventive, and weight management effects, faces challenges due to its inherent instability and limited bioavailability. To address these limitations, our study pioneers an investigation into the unique behavior of EGCG, revealing its degradation into epicatechin (EGC) and gallic acid (GA) during the drug delivery process. In this research, we use fluorescent mesoporous silica nanoparticles (FMSNs) as a sophisticated delivery system for EGCG. This innovative approach aims to not only enhance the stability of EGCG but also regulate its sustained release dynamics to enable prolonged cellular activity. To comprehensively evaluate our novel delivery strategy, we performed assays to assess both the antioxidant potential and its impact on lipid inhibition using Oil Red O. The results not only underscore the potential of FMSN-based nanocarriers for efficient EGCG delivery but also reveal groundbreaking insights into its enzymatic degradation, a previously unexplored facet. This research substantially advances our understanding of EGCG's behavior during delivery and offers a promising avenue for improving its therapeutic efficacy and expanding its applications in health management.

Facile synthesis of fluorescent mesoporous nanocarriers with pH-sensitive controlled release of naturally derived dieckol

Dieckol is a marine polyphenol found in the brown algae Ecklonia cava and has been actively studied because it has various biological activities such as antioxidant, anti-inflammatory, and antibacterial. Herein, fluorescent mesoporous silica nanoparticles (FMSNs) were synthesized for the efficient delivery of naturally derived Die molecules. The Die-loaded FMSNs (FMSNs-Die) were further coated with polyethylene glycol (PEG) and graphene oxide (GO) nanosheets, termed as FMSNs-Die@PEG and FMSNs-Die@PEG@GO, respectively. The release kinetics was investigated using Fickian-type exponential and Kosmeyer-Peppas relaxation models. Overall, the FMSN-based nanocarriers exhibited a faster release at pH 4.5 than at pH 7.4. The release rate at pH 7.4 decreased in the following order: FMSNs-Die > FMSNs-Die@PEG > FMSNs-Die@PEG@GO. In contrast, the release rate at pH 4.5 exhibited a somewhat different order of FMSNs-Die@PEG ≥ FMSNs-Die > FMSNs-Die@PEG@GO. Notably, the difference of the release rates at these pH values was most pronounced for the PEG-coated FMSNs, signifying the strong pH-responsive release behavior of Die molecules. Within the pH ranges (pH 4.5 – 7.4), double-layer-coated FMSNs exhibited the significantly delayed release rates as compared to coating-free and single-layer-coated analogs. Our nanocarriers demonstrated pH-sensitive controlled release of Die, suggesting as a smart drug delivery system for natural product-derived drugs.

Effects of Methoxyfenozide-Loaded Fluorescent Mesoporous Silica Nanoparticles on Plutella xylostella (L.) (Lepidoptera: Plutellidae) Mortality and Detoxification Enzyme Levels Activities.

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.

Imaging Intracellular Drug/siRNA Co-Delivery by Self-Assembly Cross-Linked Polyethylenimine with Fluorescent Core-Shell Silica Nanoparticles.

Multifunctional theranostic nanomaterial represents one type of emerging agent with the potential to offer both sensitive diagnosis and effective therapy. Herein, we report a novel drug/siRNA co-delivery nanocarrier, which is based on fluorescent mesoporous core-shell silica nanoparticles coated by cross-linked polyethylenimine. The fluorescent mesoporous core-shell silica nanoparticles can provide numerous pores for drug loading and negative charged surface to assemble cross-linked polyethylenimine via electrostatic interaction. Disulfide cross-linked polyethylenimine can be absorbed on the surface of silica nanoparticles which provide the feasibility to bind with negatively charged siRNA and release drug “on-demand”. In addition, the hybrid nanoparticles can be easily internalized into cells to realize drug/siRNA co-delivery and therapeutic effect imaging. This work would stimulate interest in the use of self-assembled cross-linked polyethylenimine with fluorescent mesoporous core-shell silica nanoparticles to construct multifunctional nanocomposites for tumor therapy.

Nanotechnology and Conventional Techniques to Detect Latent Fingerprints on Surfaces

Abstract: This review paper centers around the use of legal science in dormant unique mark identification by the utilization of particular nanomaterials and their advantages concerning the nature of finger impression pictures. The use of measurable science in the discovery of the idle unique finger impression The benefits and significant aftereffects of studies directed on inert finger impression recognition with different nanomaterials which incorporate metal nano-particles, metallic oxide nanoparticles, semiconductor quantum specks, carbon dabs, polymer dabs, fluorescent silica nanoparticles, fluorescent mesoporous silica nanoparticles, fluorescent silica nanoparticles, formed polyelectrolyte spots, accumulation prompted outflow brilliant atom joined nanomaterials and phenomenal earth fluorescence nanoparticles are basically talked about. A portion of the nanomaterials utilized for idle finger impression discovery didn't bring about great quality finger impression pictures and these detriments are featured. Keywords: Nanotechnology, Nanomaterials, latent fingerprint, fluorescence

Polyethylenimine Functionalized Ultrasmall Mesoporous Silica Nanoparticles for siRNA Delivery

AbstractSmall interfering RNA (siRNA) for gene therapy has attracted great attention. However, due to easy degradation and inaccessibility to the cells, the gene silencing efficiency is not always satisfactory. To overcome this hurdle, developing an excellent nanocarrier to deliver siRNA into cancer cells is crucial. Fluorescent mesoporous silica nanoparticles are considered to be a superb nanocarrier for siRNA delivery systems because of its negligible toxicity and good biocompatibility. Herein, we developed an efficient fluorescent ultrasmall mesoporous silica nanocarrier for siRNA loading and delivery. The ultrasmall nanocarriers with polyethylenimine coating have a uniform size of about 10 nm. We find that the amino groups on polyethylenimine can protect siRNA from being degraded. Based on the fluorescence observation, we show that polyethylenimine‐coated mesoporous silica nanocarrier loaded with siRNA can be uptake by 293T cells. Importantly, we also prove that siRNA can be delivered into 293T cells by our nanocarrier and subsequently inhibit the expression of related genes. The study provides insights into the development of nonviral fluorescence nanocarriers for siRNA delivery, which have important implications for targeted cancer therapy.

Revealing the Phagosomal pH Regulation and Inflammation of Macrophages after Endocytosing Polyurethane Nanoparticles by A Ratiometric pH Nanosensor.

The effect of the intracellular pH of macrophages after taking up biodegradable polymer nanoparticles (NPs) on immunomodulating functions has not been explored so far. Previous studies have demonstrated that biodegradable polyurethane (PU) NPs exhibit immunosuppressive activity. Yet, the intracellular mechanism is not clearly understood. In this study, a uniquely designed pH nanosensor is employed for tracking the intracellular pH value of macrophages to reveal the intracellular journey of PU NPs and to clarify the intracellular pH effect on the corresponding inflammatory response. First, fluorescent mesoporous silica nanoparticles (FRMSNs) is used to detect the pH change in macrophages after endo/phagocytosis of PU NPs. Second, PU is coated on the external surface of FRMSNs to examine the intracellular trafficking process of PU in the macrophages. The results show that the majority of PU-coated FRMSNs remain to stay at the cytosol-early endosome/phagosome regions. The intracellular pH value and other supporting results show that the immune response of PU NPs may be correlated to their internalization journey. The retardation in the degradation process of the PU NPs may intervene with the lysosome activity and repress the immunostimulatory effect, which contributes to the low immune response of PU NPs.

STING Activator c-di-GMP-Loaded Mesoporous Silica Nanoparticles Enhance Immunotherapy Against Breast Cancer

Reversing the immunosuppressive tumor microenvironment (TME) is a strategic initiative to sensitize cancer immunotherapy. Emerging evidence shows that cyclic diguanylate monophosphate (c-di-GMP or cdG) can induce the stimulator of interferon genes (STING) pathway activation of antigen-presenting cells (APCs) and upregulate expression of type I interferons (IFNs) to enhance tumor immunogenicity. In vitro anionic cdG revealed fast plasma clearance, poor membrane permeability, and inadequate cytosolic bioavailability. Therefore, we explored a comprehensive "in situ vaccination" strategy on the basis of nanomedicine to trigger robust antitumor immunity. Rhodamine B isothiocyanate (RITC) fluorescent mesoporous silica nanoparticles (MSN) synthesized and modified with poly(ethylene glycol) (PEG) and an ammonium-based cationic molecule (TA) were loaded with negatively charged cdG via electrostatic interactions to form cdG@RMSN-PEG-TA. Treatment of RAW 264.7 cells with cdG@RMSN-PEG-TA markedly stimulated the secretion of IL-6, IL-1β, and IFN-β along with phospho-STING (Ser365) protein expression. In vivo cdG@RMSN-PEG-TA enhanced infiltration of leukocytes, including CD11c+ dendritic cells, F4/80+ macrophages, CD4+ T cells, and CD8+ T cells within the tumor microenvironment (TME), resulting in dramatic tumor growth inhibition in 4T1 breast tumor-bearing Balb/c mice. Our findings suggest that a nanobased platform can overcome the obstacles bare cdG can face in the TME. Our approach of an in situ vaccination using a STING agonist provides an attractive immunotherapy-based strategy for treating breast cancer.

Indoxacarb-loaded fluorescent mesoporous silica nanoparticles for effective control of Plutella xylostella L. with decreased detoxification enzymes activities.

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. 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. 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.

Functionalized mesoporous silica nanoparticles for innovative boron-neutron capture therapy of resistant cancers

Treatment resistance, relapse and metastasis remain critical issues in some challenging cancers, such as chondrosarcomas. Boron-neutron capture therapy (BNCT) is a targeted radiation therapy modality that relies on the ability of boron atoms to capture low energy neutrons, yielding high linear energy transfer alpha particles. We have developed an innovative boron-delivery system for BNCT, composed of multifunctional fluorescent mesoporous silica nanoparticles (B-MSNs), grafted with an activatable cell penetrating peptide (ACPP) for improved penetration in tumors and with gadolinium for magnetic resonance imaging (MRI) in vivo. Chondrosarcoma cells were exposed in vitro to an epithermal neutron beam after B-MSNs administration. BNCT beam exposure successfully induced DNA damage and cell death, including in radio-resistant ALDH+ cancer stem cells (CSCs), suggesting that BNCT using this system might be a suitable treatment modality for chondrosarcoma or other hard-to-treat cancers.

Preparation and Characterization of Carboxyl Functionalized Fluorescent Mesoporous Silica Nanoparticles Containing 8-Hydroxyquinolinate Zinc Complexes

Fluorescent mesoporous silica nanoparticles functionalized with carboxyl group (Znq-CMS-COOH) were successfully synthesized by in situ formation route of 8-hydroxyquinolinate zinc complexes in channels of mesoporous silica nanoparticles and post-grafting of carboxyl group on the surface. Moreover, the particle size and structural properties of Znq-CMS-COOH were characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS). Fourier transform infrared spectroscopy (FT-IR), UV-vis spectrometer, fluorescence spectrometer and nitrogen adsorption-desorption measurements. The obtained results suggest that the Znq-CMS-COOH presents the uniform spherical shape with the mean diameter of about 85 nm and the obvious wormhole arrangement mesoporous. In addition, the Znq-CMS-COOH possesses green fluorescence with the emission peaks at 495 nm. So the Znq-CMS-COOH, which is beneficial to further modification and tracing, might be a great potential carrier for applying in drug delivery system in the future.

In Situ Synthesis of Fluorescent Mesoporous Silica\u2013Carbon Dot Nanohybrids Featuring Folate Receptor-Overexpressing Cancer Cell Targeting and Drug Delivery

HighlightsA one-pot method was developed for the preparation of fluorescent mesoporous silica nanoparticles–carbon dots (MSNs–CDs) nanohybrid.The MSNs–CDs nanohybrid showed stable and bright yellow emission, excellent biocompatibility, and specific targeting capability toward folate receptor-overexpressing cancer cells and can be applied as fluorescence imaging-guided drug carriers for effectively delivering anticancer drugs to tumor sites.

Identifying a Membrane-Type 2 Matrix Metalloproteinase-Targeting Peptide for Human Lung Cancer Detection and Targeting Chemotherapy with Functionalized Mesoporous Silica.

Membrane-type 2 matrix metalloproteinase (MT2-MMP) is critical for the aggressive lung tumor growth, progression, and metastasis. Here, to obtain the peptides in binding specifically to MT2-MMP, a phage-displayed 12 peptide library was used and the affinity of peptides toward MT2-MMP was identified by multitest methods. The results showed that a specific MT2-MMP-targeting peptide with the sequence of HHRLHSAPPPQA (MT2-AF5p) exhibited a high specificity and strong affinity against lung tumors. To further achieve specific targeting and precise therapeutic effects, MT2-AF5p was conjugated onto fluorescent mesoporous silica nanoparticles (FMSN-NH2) and loaded with doxorubicin (DOX) to construct a chemotherapeutic drug-targeting delivery system (DOX-loaded FMSN@MT2-AF5p). The DOX-loaded FMSN@MT2-AF5p achieved a boost in DOX release in an acidic environment. Most importantly, FMSN@MT2-AF5p efficiently targeted the tumor area, as seen in the fluorescent imaging ex vivo. The novel peptide-functionalized nanoparticles with a good biocompatibility are promising for clinical use as a precise targeting nanodrug for lung cancer diagnosis and therapy.

Preparation of zwitterionic polymers functionalized fluorescent mesoporous silica nanoparticles through photoinduced surface initiated RAFT polymerization in the presence of oxygen

Abstract Mesoporous silicon nanoparticles (MSNs) have gradually developed into the multi-functional platforms in biomedical fields for their properties of high specific surface areas, regular mesoporous structure, low toxicity, chemical inert and facile functionalization. MSNs based fluorescent nanoprobes have been extensively investigated previously and many effective methods have been devoted to simplify the fabrication process. In this work, the MSNs based fluorescent polymer composites were prepared by a facile and effective reversible addition−fragmentation chain-transfer (RAFT) polymerization with the assistance by visible light irradiation, which could conduct in the presence of oxygen without complicated deoxygenation steps. A series of characterization techniques were employed to determine the successful synthesis of our preconceived MSNs-co-poly(MPC–AcFl) composites. Besides, the bright green fluorescence was observed in live L929 cells through CLSM, and cell viability evaluation was revealed that these as prepared composites were nearly no damage to cells. Combined with all the above results, the as prepared MSNs-co-poly(MPC–AcFl) composites should promising fluorescent nanoprobes for biomedical applications. Owing to the good monomer adoptability, the photoinduced oxygen tolerance RAFT polymerization could also be expanded for surface modification and construction of multifunctional composites.

Temperature-sensitive copolymer-coated fluorescent mesoporous silica nanoparticles as a reactive oxygen species activated drug delivery system

In this study, a temperature and ROS-responsive drug delivery system ROSP@MSN based on mesoporous silica nanoparticles has been designed and synthesized by taking advantage of 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl acrylate modified polymers (ROSP) as “nano-valve”, which can respond selectively to cancer exclusive microenvironment and implement targeted drug release. Due to the superior temperature-sensitive properties of ROSP, ROSP@MSN could achieve cargo loading in cold water, and subsequently close the pore by raising temperature to obtain ROSP@MSN@DOX. Upon the stimulus of ROS, ROSP@MSN@DOX shows good release performance at physiological conditions. The cytotoxicity study demonstrates that the cell viability is about 80% after Hela cells are treated with ROSP@MSN at a concentration of 100 μg/mL for 24 h, exhibiting the good biocompatibility of ROSP@MSN. Furthermore, after treated with ROSP@MSN@DOX at a concentration of 100 μg/mL for 24 h, the viability of Hela cells is reduced to 40.5%; Control experiments demonstrate that, when Hela cells are pretreated with active oxygen scavenger, cell viability is about 65.3% due to the significant decrease of intracellular reactive oxygen species. Therefore, the therapeutic nanocarrier with effective encapsulation and release capacity in particular situation is a great candidate for the new drug delivery platform for targeted cancer therapy.

A comparison between sphere and rod nanoparticles regarding their in vivo biological behavior and pharmacokinetics

In recent years, spherical nanoparticles has been studied extensively on biomedical applications including bioimaging and biosensing, diagnostics and theranostics, but the effect of the shape of nanoparticles has received little attention. In the present study, we designed three different shaped fluorescent mesoporous silica nanoparticles (MSNs), long rod nanoparticles (NLR), short rod nanoparticles (NSR), and spherical nanoparticles (NS) to systematically examine their behavior in vivo after oral administration. The results of the ex vivo optical imaging study in mice indicated that rod nanoparticles had a longer residence time in the gastrointestinal compared with spherical nanoparticles. The in vivo biodistribution showed that all the orally administered MSNs were mainly taken up by the liver, and kidney. NLR had a great capacity to overcoming rapid clearance by the RES and exhibited a longer circulation in the blood than NSR and NS. During renal excretion, the spherical nanoparticles were cleared faster than rod nanoparticles. In addition, it was also found that MSNs can be degraded in vivo and NSR were degraded faster than NLR and NS probably owing to their higher specific surface area. The pharmacokinetic results demonstrated that nifedipine(NI)-loaded NLR had a higher bioavailability than NI-loaded NSR and NS.

Cellular Interactions and Formation of an Epithelial "Nanocoating-Like Barrier" with Mesoporous Silica Nanoparticles.

Oral mucosa as the front-line barrier in the mouth is constantly exposed to a complex microenvironment with multitudinous microbes. In this study, the interactions of mesoporous silica nanoparticles (MSNs) with primary human gingival epithelial cells were analyzed for up to 72 h, and their diffusion capacity in the reconstructed human gingival epithelia (RHGE) and porcine ear skin models was further assessed at 24 h. It was found that the synthesized fluorescent mesoporous silica nanoparticles (RITC-NPs) with low cytotoxicity could be uptaken, degraded, and/or excreted by the human gingival epithelial cells. Moreover, the RITC-NPs penetrated into the stratum corneum of RHGE in a time-dependent manner, while they were unable to get across the barrier of stratum corneum in the porcine ear skins. Consequently, the penetration and accumulation of RITC-NPs at the corneum layers of epithelia could form a “nanocoating-like barrier”. This preliminary proof-of-concept study suggests the feasibility of developing nanoparticle-based antimicrobial and anti-inflammatory agents through topical application for oral healthcare.

Anti-CD155 and anti-CD112 monoclonal antibodies conjugated to a fluorescent mesoporous silica nanosensor encapsulating rhodamine 6G and fluorescein for sensitive detection of liver cancer cells.

A novel method for sensitive detection of liver cancer cells using anti-CD155 and anti-CD112 monoclonal antibodies conjugated to ultrabright fluorescent mesoporous silica nanoparticles (FMSNs) encapsulating Rhodamine 6G and fluorescein was developed. The diameter of the obtained nanoparticles was 90 nm, and the quantum yield was 69%. Because the emission of fluorescein has a high degree of overlap with the excitation of Rhodamine 6G, and these two dyes were sufficiently close to each other on the nanoparticles, fluorescence resonance energy transfer can occur between these two dyes. This transfer not only maintains the original feature of the nanochannels and the skeletal network of the silica weakening the inner filtering of the dye, but also makes the excitation peak of the nanoparticles wider and increases the useful load amount of the dye. Because the wider Stokes shifts weaken the interference of excitation, the detection sensitivity is enhanced at the same time. The NaIO4 oxidation method does not use a cross-linker but rather uses covalent immobilization of the monoclonal antibodies on the FMSNs. This method can maintain the activity of the monoclonal antibodies more easily than the glutaraldehyde method. These advantages ensure that the nanosensor has high sensitivity and specificity for detecting liver cancer SMMC-7721 and HHCC cells. The in vivo imaging experiment also ensured that the biosensor can target tumor tissue in mice.

Aptamer/Graphene Quantum Dots Nanocomposite Capped Fluorescent Mesoporous Silica Nanoparticles for Intracellular Drug Delivery and Real-Time Monitoring of Drug Release.

Great challenges in investigating the release of drug in complex cellular microenvironments necessitate the development of stimuli-responsive drug delivery systems with real-time monitoring capability. In this work, a smart drug nanocarrier based on fluorescence resonance energy transfer (FRET) is fabricated by capping graphene quantum dots (GQDs, the acceptor) onto fluorescent mesoporous silica nanoparticles (FMSNs, the donor) via ATP aptamer for real-time monitoring of ATP-triggered drug release. Under extracellular conditions, the fluorescence of FMSNs remains in the "off" state in the low ATP level which is unable to trigger the release of drug. Once specifically recognized and internalized into the target tumor cells by AS1411 aptamer, in the ATP-rich cytoplasm, the conformation switch of the ATP aptamer causes the shedding of the GQDs from the nanocarriers, leading to the release of the loaded drugs and consequently severe cytotoxicity. Simultaneously, the fluorescence of FMSNs turns "on" along with the dissociation of GQDs, which allows real-time monitoring of the release of drug from the pores. Such a drug delivery system features high specificity of dual-target recognition with AS1411 and ATP aptamer as well as high sensitivity of the FRET-based monitoring strategy. Thus, the proposed multifunctional ATP triggered FRET-nanocarriers will find potential applications for versatile drug-release monitoring, efficient drug transport, and targeted cancer therapeutics.

Local pH tracking in living cells.

Continuous and simultaneous 3D single-particle movement and local pH detection in HeLa cells were demonstrated for the first time by combining fluorescent mesoporous silica nanoparticles (FMSNs) and a single-particle tracking (SPT) technique with a precision of ∼10 nm. FMSNs, synthesized by the co-condensation of both pH-sensitive and reference dyes with a silica/surfactant source, allow long-term reliable ratiometric pH measurements with a precision better than 0.3 pH unit because of their excellent brightness and stability. pH variation in the surrounding area of FMSNs during endocytosis was monitored in real-time. Acidification and low mobility of FMSNs were observed at the early endocytic stage, whereas basification and high mobility of FMSNs were observed at the late stage. Our results indicate that it is possible to monitor local pH changes in the environments surrounding nanoparticles during the cellular uptake process of FMSNs, which provides much needed information for designing an efficient drug delivery nanosystem.