Fabrication of FITC‐doped silica nanoparticles and study of their cellular uptake in the presence of lectins

Nanotechnology-Assisted Cell Tracking

The usefulness of nanoparticles (NPs) in the diagnostic and/or therapeutic sector is derived from their aptitude for navigating intra- and extracellular barriers successfully and to be spatiotemporally targeted. In this context, the optimization of NP delivery platforms is technologically related to the exploitation of the mechanisms involved in the NP–cell interaction. This review provides a detailed overview of the available technologies focusing on cell–NP interaction/detection by describing their applications in the fields of cancer and regenerative medicine. Specifically, a literature survey has been performed to analyze the key nanocarrier-impacting elements, such as NP typology and functionalization, the ability to tune cell interaction mechanisms under in vitro and in vivo conditions by framing, and at the same time, the imaging devices supporting NP delivery assessment, and consideration of their specificity and sensitivity. Although the large amount of literature information on the designs and applications of cell membrane-coated NPs has reached the extent at which it could be considered a mature branch of nanomedicine ready to be translated to the clinic, the technology applied to the biomimetic functionalization strategy of the design of NPs for directing cell labelling and intracellular retention appears less advanced. These approaches, if properly scaled up, will present diverse biomedical applications and make a positive impact on human health.

Design and synthesis of a new topical agent for halting blood loss rapidly: A multimodal chitosan-gelatin xerogel composite loaded with silica nanoparticles and calcium

Uncontrolled hemorrhage often causes death during traumatic injuries and halting exsanguination topically is a challenge. Here, an efficient multimodal topical hemostat was developed by (i) ionically crosslinking chitosan and gelatin with sodium tripolyphosphate for (ii) fabricating a robust, highly porous xerogel by lyophilization having 86.7 % porosity, by micro-CT and large pores ∼30 μm by SEM (iii) incorporating 0.5 mg synthesized silica nanoparticles (SiNPs, 120 nm size, -22 mV charge) and 2.5 mM calcium in xerogel composite that was confirmed by FTIR analysis with peaks at 3372, 986 and 788 cm^-1, respectively. XPS analysis displayed the presence of SiNPs (Si2p peak for silicon) and calcium (Ca2p1, Ca2p3 transition peaks) in the composite. Interestingly, in silico percolation simulation for composite revealed interlinked 800 μm long-conduits predicting excellent absorption capacity and validated experimentally (640 % of composite dry weight). The composite achieved >16-fold improved blood clotting in vitro than commercial Celox and Gauze through multimodal interaction of its components with RBCs and platelets. The composite displayed good platelet activation and thrombin generation activities. It displayed high compressive strength (2.45 MPa) and withstood pressure during application. Moreover, xerogel composite showed high biocompatibility. In vivo application of xerogel composite to lethal femoral artery injury in rats achieved hemostasis (2.5 min) significantly faster than commercial Celox (3.3 min) and Gauze (4.6 min) and was easily removed from the wound. The gamma irradiated composite was stable till 1.5 yr. Therefore, the xerogel composite has potential for application as a rapid topical hemostatic agent.

Multi-functional FITC-silica@gold nanoparticles conjugated with guar gum succinate, folic acid and doxorubicin for CT/fluorescence dual imaging and combined chemo/PTT of cancer

A novel type of multi-functional fluorescein isothiocyanate (FITC)-silica (SiO₂)@gold (Au) core-shell nanoparticles covered with folic acid (FA)-conjugated guar gum succinate (GGS) and doxorubicin (DOX) (FITC-SiO₂@Au-DOX-GGS-FA NPs) was prepared for imaging and therapy of cancer. The physicochemical properties of these NPs were analyzed with ¹H NMR, TEM and DLS. The FITC-SiO₂@Au-DOX-GGS-FA NPs exhibited the fluorescence and X-ray attenuation properties due to the presence of FITC-SiO₂@Au hybrid nanostructure. Due to acid-cleavable hydrazone bond between the DOX and NPs, the quantity of DOX delivered from the FITC-SiO₂@Au-DOX-GGS-FA NPs was increased at pH 5.6 than that at pH 7.4. Besides, the multi-functional NPs presented the improved cellular uptake by HeLa cells via FA-receptor-mediated endocytosis due to the existence of FA. The developed NPs also presented the improved cytotoxicity towards the HeLa cells due to its tumor-targetability and DOX/photothermal effect. These results suggested that the FITC-SiO₂@Au-DOX-GGS-FA NPs could be ideal for computed tomography (CT)/fluorescence dual imaging and combined chemo/photothermal therapy (PTT) of cancer.

Antitumor Effect of 131I-Labeled Anti-VEGFR2 Targeted Mesoporous Silica Nanoparticles in Anaplastic Thyroid Cancer

Anaplastic thyroid cancer (ATC) comprises approximately 2% of all thyroid cancers, and its median survival rate remains poor because of its resistance to conventional therapy. Vascular endothelial growth factor receptor (VEGFR)-targeted therapeutics-loaded mesoporous silica nanoparticles represent a major advance for angiogenesis imaging and inhibition in lethal cancers. In the present study, we aimed to assess whether ¹³¹I-labeled anti-VEGFR2 targeted mesoporous silica nanoparticles would have antitumor efficacy in an ATC tumor-bearing nude mouse model. Using in vitro and in vivo studies, we investigated the increased targeting ability and retention time in the anti-VEGFR2 targeted group using confocal microscopy and a γ counter. The tumor tissue radioactivity of the anti-VEGFR2 targeted group at 24 and 72 h after intratumoral injection was significantly higher than that of the non-targeted groups (all P < 0.05). Moreover, we found that radioactive accumulation was obvious even at 3 week post-injection in the anti-VEGFR2 targeted group via single-photon emission computed tomography/computed tomography, which was not seen at 3 day post-injection in the Na¹³¹I group. Meanwhile, compared with the non-targeted group, tumor growth in the targeted group was significantly inhibited, without causing apparent systemic toxic effects. Additionally, the median survival time in the targeted group (41 days) was significantly prolonged compared with that in the non-targeted (34 days) or Na¹³¹I (25 days) groups (both P < 0.01). Our data support the view that the as-developed ¹³¹I-labeled anti-VEGFR2 targeted mesoporous silica nanoparticles showed promising results in ATC tumor-bearing mouse model and such an approach might represent a novel therapeutic option for ATC.

Polymeric Nanocomplex Encapsulating Iron Oxide Nanoparticles in Constant Size for Controllable Magnetic Field Reactivity

The magnetic properties of nanoparticles make them ideal for using in various applications, especially in biomedical applications. However, the magnetic force generated by a single nanoparticle is low. Herein, we describe the development of nanocomplexes (size of 100 nm) of many iron oxide nanoparticles (IONPs) encapsulated in poly(lactic- co-glycolic acid) (PLGA) using the simple method of emulsion solvent evaporation. The response of the IONP-encapsulated PLGA nanocomplexes (IPNs) to an external magnetic field could be controlled by modifying the amount of IONPs loaded into each nanocomplex. In a constant size of IPNs, larger loading numbers of IONPs resulted in more rapid responses to a magnetic field. In addition, nanocomplexes were coated with a silica layer to facilitate the addition of fluorescent dyes. This allowed visualization of the responses of the IPNs to an applied magnetic field corresponding to the IONP loading amount. We envision that these versatile, easy-to-fabricate IPNs with controllable magnetism will have important potential applications in diverse fields.

Surface Engineered Ho3+ Incorporated Fluorescent Dye-Doped Bifunctional Silica Nanoparticles for Receptor Targeted Fluorescence Imaging and Potential Magnetic Resonance Imaging

The authors report Ho³⁺ ion incorporated and fluorescent dye-doped silica nanoparticles which are engineered to enable the imaging modalities of receptor targeted fluorescence imaging (FI) and magnetic resonance imaging (MRI). The silica nanoparticles synthesized through a modified Stöber method is luminomagnetic by virtue of the luminescence of organic dye fluorophore (FITC) and magnetism of Ho³⁺. The doping concentration of Ho³⁺ is estimated by inductively coupled plasma mass spectrometry (ICP-MS) as 0.97%. The presence of Ho³⁺ has a little effect on the luminescence intensity but impart strong paramagnetism of 27.217 emu/g at room temperature. The relaxivity measurements shown that the nanoparticles exhibit a longitudinal relaxivity (r₁) of 0.12 s^-1 mM^-1 and transverse relaxivity (r₂) of 26.96 s^-1 mM^-1, which makes the system potentially suitable for developing T2 MRI contrast agents based on holmium. The luminomagnetic nanoparticles were surface engineered through aminization and conjugated with folic acid (FA) to address the folate receptor targeted imaging of the cancer cells. The biocompatibility studies revealed no apparent toxicity even at higher doses of 750 μg/mL and at 48 h of incubation. The as prepared nanoparticles were demonstrated as a bioimaging probe in the in vitro receptor targeted fluorescence imaging of HeLa cells. The luminescence and magnetism together with biocompatibility enables the adaptability of the present system as a nano platform for potential bimodal imaging. Graphical Abstract ᅟ.

Nano-shape varied cerium oxide nanomaterials rescue human dental stem cells from oxidative insult through intracellular or extracellular actions

Cerium oxide nanomaterials (CeNMs), due to their excellent scavenging properties of reactive oxygen species (ROS), have gained great promise for therapeutic applications. A high level of ROS often degrades the potential of stem cells in terms of survivability, maintenance and lineage differentiation. Here we hypothesize the CeNMs may play an important role in protecting the capacity of stem cells against the oxidative insult, and the suppression mechanism of ROS level may depend on the internalization of CeNMs. We synthesized CeNMs with different directional shapes (aspect ratios) by a pH-controlled hydrothermal method, and treated them to stem cells derived from human dental pulp at various doses. The short CeNMs (nanoparticles and nanorods) were internalized rapidly to cells whereas long CeNMs (nanowires) were slowly internalized, which led to different distributions of CeNMs and suppressed the ROS levels either intracellularly or extracellularly under the H₂O₂-exposed conditions. Resultantly, the stem cells, when dosed with the CeNMs, were rescued to have excellent cell survivability; the damages in intracellular components including DNA fragmentation, lipid rupture and protein degradation were significantly alleviated. The findings imply that the ROS-scavenging events of CeNMs need special consideration of aspect ratio-dependent cellular internalization, and also suggest the promising use of CeNMs to protect stem cells from the ROS-insult environments, which can ultimately improve the stem cell potential for tissue engineering and regenerative medicine uses.

STATEMENT OF SIGNIFICANCE

Oxidative stress governs many stem cell functions like self-renewal and lineage differentiation, and the biological conditions involving tissue repair and disease cure where stem cell therapy is often needed. Here we demonstrate the unique role of cerium oxide nanomaterials (CeNMs) in rescuing stem cell survivability, migration ability, and intracellular components from oxidative stress. In particular, we deliver a novel finding that nano-morphologically varied CeNMs show different mechanisms in their scavenging reactive oxygen species either intracellularly or extracellularly, and this is related with their different cellular internalizations. We used human dental pulp stem cells for the model study and proved the CeNMs were effective in controlling ROS level by means of scavenging intracellularly or extracellularly, which ultimately led to improving the intact therapeutic potential of stem cells. This work touches an important biological issue of nanomaterial interactions with stem cells under the conditions related with oxidative stress and the resultant damage. The correlation of shape factor in therapeutic nanomaterials with stem cell interaction and the oxidative stress-related functions will provide informative ideas in the design of CeNMs for cellular therapy.

One-Pot Synthesis of Cy5-Encapsulated Photostable Fluorescent Silica Nanoparticles for Bioimaging

A new type of Cy5-encapsulated photostable fluorescent silica nanoparticles (FSNPs) bearing positive charges have been successfully fabricated by a reverse microemulsion synthesis in one-pot. The Cy5 dye containing four primary amines are embedded into silica via covalent bonds through a silane coupling agent (GPTMS), followed by co-condensation with tetraethylorthosilicate. The uniform-sized, spherical and monodispersed FSNPs have high fluorescence intensity and photostability. The FSNPs exhibit high stability, good biocompatibility as well as low cytotoxicity. These FSNPs can be internalized into live cells and thus fluorescently label the cells. This study provides a simple synthesis approach that can be applied to other water-soluble and amino-modified organic dye molecules for biological targeting and fluorescent cell imaging.

Metal mesh device sensor immobilized with a trimethoxysilane-containing glycopolymer for label-free detection of proteins and bacteria

Biosensors for the detection of proteins and bacteria have been developed using glycopolymer-immobilized metal mesh devices. The trimethoxysilane-containing glycopolymer was immobilized onto a metal mesh device using the silane coupling reaction. The surface shape and transmittance properties of the original metal mesh device were maintained following the immobilization of the glycopolymer. The mannose-binding protein (concanavalin A) could be detected at concentrations in the range of 10(-9) to 10(-6) mol L(-1) using the glycopolymer-immobilized metal mesh device sensor, whereas another protein (bovine serum albumin) was not detected. A detection limit of 1 ng mm(-2) was achieved for the amount of adsorbed concanavalin A. The glycopolymer-immobilized metal mesh device sensor could also detect bacteria as well as protein. The mannose-binding strain of Escherichia coli was specifically detected by the glycopolymer-immobilized metal mesh device sensor. The glycopolymer-immobilized metal mesh device could therefore be used as a label-free biosensor showing high levels of selectivity and sensitivity toward proteins and bacteria.

Simple coating with pH-responsive polymer-functionalized silica nanoparticles of mixed sizes for controlled surface properties

Different-sized silica nanoparticles (SiNPs) were functionalized by pH-responsive poly(2-(diisopropylamino)ethyl methacrylate) (PDP) via surface-initiated atom transfer radical polymerization (ATRP). The functionalized PDP-SiNPs were used to coat glass surfaces, polymeric nanofibers, and paper via simple coating methods such as dip, cast, and spray coating. A PDP-SiNPs mixture having different sizes was found to change the surface properties of the substrates remarkably, compared to one containing PDP-SiNPs with uniform sizes. High surface roughness was achieved with very little coating materials, which is beneficial from an economical point of view. Moreover, adsorption/desorption of PDP-SiNPs onto/from the substrates could be controlled by changing solution pH due to the protonation/deprotonation of the PDP. The surface properties of the coated substrates were analyzed by contact angle (CA) measurement, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). This inexpensive system provides a simple, quick, and effective approach to changing the surface properties of substrates that could be exploited for large-scale surface modification.