Protein-Gated Upconversion Nanoparticle-Embedded Mesoporous Silica Nanovehicles via Diselenide Linkages for Drug Release Tracking in Real Time and Tumor Chemotherapy

Two novel stimuli-responsive drug delivery systems (DDSs) were successfully created from bovine serum albumin- or myoglobin-gated upconversion nanoparticle-embedded mesoporous silica nanovehicles (UCNP@mSiO2) via diselenide (Se-Se)-containing linkages. More importantly, multiple roles of each scaffold of the nanovehicles were achieved. The controlled release of the encapsulated drug doxorubicin (DOX) within the mesopores was activated by triple stimuli (acidic pH, glutathione, or H2O2) of tumor microenvironments, owing to the conformation/surface charge changes in proteins or the reductive/oxidative cleavages of the Se-Se bonds. Upon release of DOX, the Förster resonance energy transfer between the UCNP cores and encapsulated DOX was eliminated, resulting in an increase in ratiometric upconversion luminescence for DOX release tracking in real time. The two protein-gated DDSs showed some differences in the drug release performances, relevant to structures and properties of the protein nanogates. The introduction of the Se-Se linkages not only increased the versatility of reductive/oxidative cleavages but also showed less cytotoxicity to all cell lines. The DOX-loaded protein-gated nanovehicles showed the inhibitory effect on tumor growth in tumor-bearing mice and negligible damage/toxicity to the normal tissues. The constructed nanovehicles in a spatiotemporally controlled manner have fascinating prospects in targeted drug delivery for cancer chemotherapy.

Cancer theranostic platforms based on injectable polymer hydrogels

Theranostic platforms that combine therapy with diagnosis not only prevent the undesirable biological responses that may occur when these processes are conducted separately, but also allow individualized therapies for patients. Polymer hydrogels have been employed to provide well-controlled drug release and targeted therapy in theranostics, where injectable hydrogels enable non-invasive treatment and monitoring with a single injection, offering greater patient comfort and efficient therapy. Efforts have been focused on applying injectable polymer hydrogels in theranostic research and clinical use. This review highlights recent progress in the design of injectable polymer hydrogels for cancer theranostics, particularly focusing on the elements/components of theranostic hydrogels, and their cross-linking strategies, structures, and performance with regard to drug delivery/tracking. Therapeutic agents and tracking modalities that are essential components of the theranostic platforms are introduced, and the design strategies, properties and applications of the injectable hydrogels developed via two approaches, namely chemical bonds and physical interactions, are described. The theranostic functions of the platforms are highly dependent on the architecture and components employed for the construction of hydrogels. Challenges currently presented by theranostic platforms based on injectable hydrogels are identified, and prospects of acquiring more comfortable and personalized therapies are proposed.

Mesoporous Silica Nanoparticles in Bioimaging

A biomedical contrast agent serves to enhance the visualisation of a specific (potentially targeted) physiological region. In recent years, mesoporous silica nanoparticles (MSNs) have developed as a flexible imaging platform of tuneable size/morphology, abundant surface chemistry, biocompatibility and otherwise useful physiochemical properties. This review discusses MSN structural types and synthetic strategies, as well as methods for surface functionalisation. Recent applications in biomedical imaging are then discussed, with a specific emphasis on magnetic resonance and optical modes together with utility in multimodal imaging.

Preparation and investigation of core-shell nanoparticles containing human interferon-α

Sustained release of active interferon-α (IFN-α) has been achieved from core-shell nanoparticles (NPs) prepared by aqueous precipitation of IFN-α-enriched human serum albumin (HSA-IFN-α) and layer-by-layer (L-b-L) by coating of the IFN-α NPs with poly(sodium-4-styrene) sulphonate (PSS) and chitosan (Chit). The concentration and the pH of HSA solution were optimized during the development of this method. Dynamic light scattering (DLS), zeta-potential, thermal analysis (differential scanning calorimetry (DSC) and termogravimetry (TG)), X-ray diffraction (XRD), IFN-α activity and morphology (transmission electron microscope (TEM)) studies were used to control the preparation and analyse the products. The dissolution kinetics of NPs was measured in vitro over 7 days in Hanson dissolution tester with Millex membrane. In vivo studies in Pannon white rabbit detected steady IFN-α plasma level for 10 days after subcutaneous injection administration of the HSA-IFN-α NPs. The IFN-α plasma concentration was detected by using the enzyme-linked immunosorbent assay (ELISA) method. In the present paper we discuss the preparation method, the optimization steps and the results of in vitro and in vivo release studies. It was established that 76.13% HSA-IFN-α are encapsulated in the core-shell NPs.

Magnetic Nanomaterials for Magnetically-Aided Drug Delivery and Hyperthermia

Magnetic nanoparticles have continuously gained importance for the purpose of magnetically-aided drug-delivery, magnetofection, and hyperthermia. We have summarized significant experimental approaches, as well as their advantages and disadvantages with respect to future clinical translation. This field is alive and well and promises meaningful contributions to the development of novel cancer therapies.

Glutathione-mediated mesoporous carbon as a drug delivery nanocarrier with carbon dots as a cap and fluorescent tracer

This work describes a novel and general redox-responsive controlled drug delivery-release nanocarrier with mesoporous carbon nanoparticles (MCNs) gated by customized fluorescent carbon dots (CDs). The modification of MCNs with a disulfide unit enables the system to be sensitive to intracellular glutathione (GSH). The CDs anchoring onto the surface of the MCNs via an electrostatic interaction block the mesopores and thus prevent the leakage of doxorubicin (DOX) loaded inside the channel of the MCNs. Upon the addition of GSH at the physiological environment, the integrity of the system is disrupted due to the dissociation of the disulfide bond; meanwhile stripping the CDs opens the gate and thus triggers the rapid release of the encapsulated DOX. The fluorescence of the CDs is quenched/'turned off' when linking to the MCNs, while it is restored/'turned on' when detaching the CDs from the surface of the MCNs. Thus the fluorescent CDs serve as both a controllable drug release gatekeeper and a fluorescent probe for the visualization of the drug delivery process. By combining these inherent capabilities, the present drug delivery system may be a promising route for designing custom-made visual controlled-release nanodevices specifically governed by in situ stimulus in the cells.

Phase-change material filled hollow magnetic nanoparticles for cancer therapy and dual modal bioimaging

To develop carriers for anti-cancer drug delivery, this study reports a biocompatible and thermal responsive controlled drug delivery system based on hollow magnetic nanoparticles (HMNPs). The system is constructed simply by filling the hollow interiors of HMNPs with a phase-change material (PCM), namely, 1-tetradecanol, which has a melting point of 38 °C. The system achieves near "zero release" of both hydrophobic paclitaxel (PTX) and hydrophilic doxorubicin hydrochloride (DOX) and precise "on" or "off" drug delivery in vitro to efficiently induce cell apoptosis. Furthermore, the system displays both infrared thermal imaging and magnetic resonance imaging properties. More importantly, the system demonstrates great potential for thermo-chemo combination cancer therapy in vivo when an alternating magnetic field is applied.

Core-shell-type magnetic mesoporous silica nanocomposites for bioimaging and therapeutic agent delivery

Advances in nanotechnology and nanomedicine offer great opportunities for the development of nanoscaled theranostic platforms. Among various multifunctional nanocarriers, magnetic mesoporous silica nanocomposites (M-MSNs) attract prominent research interest for their outstanding properties and potential biomedical applications. This Research News article highlights recent progress in the design of core-shell-type M-MSNs for both diagnostic and therapeutic applications. First, an overview of synthetic strategies for three representative core-shell-type M-MSNs with different morphologies and structures is presented. Then, the diagnostic functions of M-MSNs is illustrated for magnetic resonance imaging (MRI) applications. Next, magnetic targeted delivery and stimuli-responsive release of drugs, and effective package of DNA/siRNA inside mesopores using M-MSNs as therapeutic agent carriers are discussed. The article concludes with some important challenges that need to be overcome for further practical applications of M-MSNs in nanomedicine.

Molecular and supramolecular switches on mesoporous silica nanoparticles

This review summarizes the recent advances of molecular and supramolecular switches installed on mesoporous silica nanoparticles.

Silica-based nanoparticles: a versatile tool for the development of efficient imaging agents

In this review a selection of the most recent examples of imaging techniques applied to silica-based NPs for imaging is reported.

Fluoride ion sensing in aqueous medium by employing nitrobenzoxadiazole-postgrafted mesoporous silica nanoparticles (MCM-41)

A mesoporous silica-based inorganic-organic hybrid material (NBD-AP-MCM) has been designed and developed as a fluorescent chemosensor for the detection of fluoride in aqueous medium. The system was developed by covalently anchoring 7-nitro-2,1,3-benzoxadiazole (NBD) dye onto the surface of mesoporous silica nanoparticles, MCM-41. The system was characterized using several conventional analytical methods comprising spectroscopic, microscopic and thermo-gravimetric techniques. The sensory action of the material was investigated by carrying out steady state absorbance, fluorescence and time resolved fluorescence studies on the system in the absence and presence of several biologically and environmentally important anions in aqueous solution. The photophysical data of the present system (NBD-AP-MCM) have also been compared with the free dye (NBD) molecules. A significant decrease in the fluorescence quantum yield of the fluorophore in the hybrid material NBD-AP-MCM has been observed as compared to the unbound NBD. The decrease in fluorescence efficiency in the hybrid material is attributed to the aggregation caused quenching (ACQ) phenomenon. Interestingly, the system displays more than six-fold fluorescence enhancement in the presence of fluoride ions in aqueous solution. Enhancement of the fluorescence lifetime of the fluorescing moiety (NBD) has also been observed during fluorescence time-resolved studies. No significant optical changes have been observed with other commonly encountered anions rendering the present system highly selective towards fluoride detection. The fluorescence enhancement has been attributed to the cleavage of Si-O bonds due to the addition of fluoride. The silyl cleavage detaches the fluorophore from the solid support thereby making the fluorophore "free" in solution, which in turn recovers its original fluorescence which was decreased because of the aggregation on the solid silica support. Furthermore, the suitability of the present system in cellular imaging has also been demonstrated.

Synergetic gating of metal-latching ligands and metal-chelating proteins for mesoporous silica nanovehicles to enhance delivery efficiency

Stimuli-responsive drug delivery systems are highly desirable for improved therapeutic efficacy and minimized adverse effects of drugs. Mesoporous silica nanoparticles (MSNs) functionalized with pentadentate ligands, N-(3-trimethoxysilylpropyl)ethylenediamine triacetate (TSP-DATA), in the presence of metal ions with and without myoglobin (Mb)-containing surface-accessible histidine residues, were constructed for pH-triggered controlled release. The DATA ligands immobilized on the MSN pore outlets could encapsulate cargo within the pores by metal latching across pore openings, and release efficiency increased with the increase of surface density of the DATA ligands. The release efficiencies for the metal-chelating protein nanogates, through multiple-site binding of Mb with the metal-chelating ligands, were higher than those for the metal-latching ligand nanogates but were almost independent of surface density of the ligands investigated. Both the metal-latching ligands and the metal-chelating proteins played a synergetic role in gating MSNs for high-loading drug delivery and stimuli-responsive controlled release. The constructed Mb-Cu(2+)-gated MSN delivery system has promising applications in targeted drug therapy of tumors.