Hybrid Mesoporous Nanocarriers Act by Processing Logic Tasks: Toward the Design of Nanobots Capable of Reading Information from the Environment

Here, we present the design of smart nanodevices capable of reading molecular information from the environment and acting accordingly by processing Boolean logic tasks. As proof of concept, we prepared Au-mesoporous silica (MS) nanoparticles functionalized with the enzyme glucose dehydrogenase (GDH) on the Au surface and with supramolecular nanovalves as caps on the MS surface, which is loaded with a cargo (dye or drug). The nanodevice acts as an AND logic gate and reads information from the solution (presence of glucose and nicotinamide adenine dinucleotide (NAD⁺)), which results in cargo release. We show the possibility of coimmobilizing GDH and the enzyme urease on nanoparticles to mimic an INHIBIT logic gate, in which the AND gate is switched off by the presence of urea. We also show that such nanodevices can deliver cytotoxic drugs in cancer cells by recognizing intracellular NAD⁺ and the presence of glucose.

Applications of mesoporous silica in biosensing and controlled release of insulin

The development of new oral insulin delivery systems could bring significant benefits to insulin-dependent patients due to the simplicity of the method, avoidance of pain caused by parenteral administration and maintenance of optimal therapeutic levels for a longer period. However, administration of such therapeutic proteins orally remains a challenge because insulin (Ins) is a very sensitive molecule and can be easily degraded under the existing pH conditions in the stomach and intestines. Moreover, due to the large size of insulin, intestinal epithelium permeability is very low. This could be improved by immobilizing insulin in the mesoporous silica pores (MSN), acting as a shield to protect the molecule integrity from the proteolytic degradation existing in the stomach and upper part of the small intestine. Due to the high adsorption capacity of insulin, biocompatibility, ease of functionalization with various organic and/or inorganic groups, high mechanical and chemical resistance, adjustable pore size and volume, MSN is considered an ideal candidate for the development of controlled release systems that are sensitive to various stimuli (pH, temperature) as well as to glucose. Modifying MSN surfaces by coating with various mucoadhesive polymers (chitosan, alginate, etc.) will also facilitate interaction with the intestinal mucus and improve intestinal retention time. Moreover, the development of glucose-responsive systems for achieving MSN-based self-regulated insulin delivery, decorated with various components serving as sensors - glucose oxidase (GOD_x) and phenylboronic acid (PBA) that can control the insulin dosage, avoiding overdose leading to serious hypoglycemia. MSN have also been tested for application as biosensors for glucose monitoring.

Near-infrared light triggered drug release from mesoporous silica nanoparticles

Stimuli triggered drug delivery systems enable controlled release of drugs at the optimal space and time, thus achieving optimal therapeutic effects. As one of the most important stimuli used in bioapplications, near-infrared (NIR) light possesses unique advantages such as deep tissue penetration with minimum auto-fluorescence & tissue scattering and high biosafety. Mesoporous silica nanoparticles (MSNs) are one of the most studied nanocarriers; apart from having a high surface area and large pore volume for loading of drugs, they can be easily functionalized with inorganic nanomaterials and stimuli responsive polymers or organic switch molecules, creating possibilities for designing complex stimuli triggered drug delivery systems. Considering the high tissue penetration depth of NIR light and the unique mesoporous structure of MSNs, NIR responsive inorganic nanoparticle functionalized MSNs can be further combined with stimuli responsive materials to form smart "nano-devices" for controlled drug delivery toward tumors, and to date much progress has been made. In this article, recent advances in the design of NIR triggered mesoporous silica drug delivery systems are systematically summarized and some outstanding studies are highlighted. We will also discuss the shortcomings, challenges and opportunities in the field.

Nucleoside Analogue-Based Supramolecular Nanodrugs Driven by Molecular Recognition for Synergistic Cancer Therapy

The utilization of nanotechnology for the delivery of a wide range of anticancer drugs has the potential to reduce adverse effects of free drugs and improve the anticancer efficacy. However, carrier materials and/or chemical modifications associated with drug delivery make it difficult for nanodrugs to achieve clinical translation and final Food and Drug Administration (FDA) approvals. We have discovered a molecular recognition strategy to directly assemble two FDA-approved small-molecule hydrophobic and hydrophilic anticancer drugs into well-defined, stable nanostructures with high and quantitative drug loading. Molecular dynamics simulations demonstrate that purine nucleoside analogue clofarabine and folate analogue raltitrexed can self-assemble into stable nanoparticles through molecular recognition. In vitro studies exemplify how the clofarabine:raltitrexed nanoparticles could greatly improve synergistic combination effects by arresting more G1 phase of the cell cycle and reducing intracellular deoxynucleotide pools. More importantly, the nanodrugs increase the blood retention half-life of the free drugs, improve accumulation of drugs in tumor sites, and promote the synergistic tumor suppression property in vivo.

Phase Engineering of Hydrophobic Meso-Environments in Silica Particles for Technical Performance Enrichment

Hexadecyltrimethylammonium bromide (CTAB) was utilized to template the growth of mesoporous silica particles via ammonia-catalyzed hydrolysis and condensation of tetraethoxysilane (TEOS) in the reaction solutions with varied volume fractions of ethanol ( f_R). The use of 9,10-bis(phenylethynyl) anthracene (BPEA) as a fluorescence probe unraveled a clear difference in interior structure between the CTAB micelles confined at different f_R. At f_R of 0.3, the confined CTAB micelles consisting of regularly and densely packed alkane chains, which created crystalline interiors, in which the doped BPEA molecules were effectively isolated in the monomeric form and well protected against aggressive attack from the surrounding environment. At f_R of 0.4 or 0.5, the confined CTAB micelles consisting of less regularly but densely packed alkane chains created glassy interiors, which enabled reversible aggregation of the doped BPEA in response to the surrounding environmental change, for instance, the ethanol content in the particle dispersion. At f_R of 0.6 or 0.7, the confined CTAB micelles consisting of loosely packed alkane chains created amorphous interiors, which offered sufficiently large free spaces to facilitate the material exchange with the surrounding environment, as evidenced by noticeable intake of the Pyronin Y molecules present in the particle dispersion. The revealed phase modulation of the interiors of surfactant micelles, confined in the pores of mesoporous particles, from crystalline to glassy and amorphous structures, which were scarcely reported in literature, will inspire rational design of mesoporous silica particles with desired technical performance according to the purposes of the practical application.

MSN-on-a-Chip: Cell-Based Screenings Made Possible on a Small-Molecule Microarray of Native Natural Products

Standard small-molecule microarrays (SMMs) are not well-suited for cell-based screening assays. Of the few attempts made thus far to render SMMs cell-compatible, all encountered major limitations. Here we report the first mesoporous silica nanoparticle (MSN)-on-a-chip platform capable of allowing high-throughput cell-based screening to be conducted on SMMs. By making use of a glass surface on which hundreds of MSNs, each encapsulated with a different native natural product, were immobilized in spatially defined manner, followed by on-chip mammalian cell growth and on-demand compound release, high-content screening was successfully carried out with readily available phenotypic detection methods. By combining this new MSN-on-a-chip system with small interfering RNA technology for the first time, we discovered that (+)-usniacin possesses synergistic inhibitory properties similar to those of olaparib (an FDA-approved drug) in BRCA1-knockdown cancer cells.

Tetraphenylethylene-Interweaving Conjugated Macrocycle Polymer Materials as Two-Photon Fluorescence Sensors for Metal Ions and Organic Molecules

A luminescent conjugated macrocycle polymer (CMP) with strong two-photon fluorescence property, namely, P[5]-TPE-CMP, is constructed from ditriflate-functionalized pillar[5]arene and a 1,1,2,2-tetrakis(4-ethynylphenyl)ethylene (TPE) linker through a Sonogashira-Hagihara cross-coupling reaction. Significantly, in sharp contrast with the corresponding conjugated microporous polymer without synthetic macrocycles, P[5]-TPE-CMP shows an outstanding stability against photobleaching and exhibits highly selective cation sensing capability toward Fe³⁺ at different excitation wavelengths (both UV and red-near-infrared regions). Meanwhile, its fluorescence could also be sufficiently quenched by 4-amino azobenzene, a frequently used organic dye that is certified to be carcinogenic, as compared with a group of common organic compounds. This work paves a new way for enhancing the properties of porous organic polymers through the introduction of supramolecular macrocycles like macrocyclic arenes.

Reversible Nanogate System for Mesoporous Silica Nanoparticles Based on Diels-Alder Adducts

The implementation of nanoparticles as nanomedicines requires sophisticated surface modifications to reduce the immune response and enhance recognition abilities. Mesoporous silica nanoparticles present extraordinary host-guest abilities and facile surface functionalization. These two factors make them ideal candidates for the development of novel drug-delivery systems, at the expense of increasing structural complexity. With this idea in mind, a system composed of triggerable and tunable silica nanoparticles was developed for application as drug-delivery nanocarriers. Diels-Alder cycloaddition adducts were chosen as thermal-responsive units that permitted the binding of gold nanocaps able to block the pores and allow the incorporation of targeting fragments. The capping efficiency was tested under different thermal conditions to give outstanding efficiencies within the physiological range and mild temperatures, as well as enhanced release under pulsing heating cycles, which showed the best release profiles.

AIEgen-Functionalized Mesoporous Silica Gated by Cyclodextrin-Modified CuS for Cell Imaging and Chemo-Photothermal Cancer Therapy

A novel multifunctional drug delivery system has been constructed by assembling per-6-thio-β-cyclodextrin-modified ultrasmall CuS nanoparticles (CD-CuS) onto fluorescent AIEgen-containing mesoporous silica nanoparticles (FMSN). The CD-CuS nanoparticles are anchored on the surface of benzimidazole-grafted FMSN, acting as a gatekeeper and photothermal agent. The prepared blue-emitting nanocomposite (FMSN@CuS) exhibits good biocompatibility and cell imaging capability. Anticancer drug doxorubicin hydrochloride (DOX) molecules are loaded into FMSN@CuS, and zero prerelease at physiological pH (7.4) and on-demand drug release at an acidic environment can be achieved due to the pH-responsive gate-opening of CD-CuS only at an acidic condition. The FMSN@CuS nanocomposite can generate obvious thermal effect after the exposure of 808 nm laser, which can also accelerate the DOX release. Meanwhile, the fluorescence intensity of DOX-loaded FMSN@CuS increases with the release of DOX, and the intracellular drug release process can be tracked according to the change of luminescence intensity. More importantly, DOX-loaded FMSN@CuS displays efficient anticancer effects in vitro upon 808 nm laser irradiation, demonstrating a good synergistic therapeutic effect via combining enhanced chemotherapy and photothermal therapy.

Multistimuli Responsive Core-Shell Nanoplatform Constructed from Fe3 O4 @MOF Equipped with Pillar[6]arene Nanovalves

An intelligent theranostic nanoplatform based on nanovalve operated metal-organic framework (MOF) core-shell hybrids, incorporating tumorous microenvironment-triggered drug release, magnetic resonance imaging (MRI) guidance, sustained release, and effective chemotherapy in one pot is reported. The core-shell hybrids are constructed by an in situ growth method, in which Fe₃ O₄ particles with superior abilities of MRI and magnetic separation form the core and UiO-66 MOF with high loading capacity compose the shell, and then are surface-installed with pillararene-based pseudorotaxanes as tightness-adjustable nanovalves. This strategy endows the system with the ability of targeted, multistimuli responsive drug release in response to pH changes, temperature variations, and competitive agents. Water-soluble carboxylatopillar[6]arene system achieved sustained drug release over 7 days due to stronger host-guest binding, suggesting that the nanovalve tightness further reinforces the desirable release of anticancer agent over a prolonged time at the lesion site.

Photochromism into nanosystems: towards lighting up the future nanoworld

The ability to manipulate the structure and function of promising nanosystems via energy input and external stimuli is emerging as an attractive paradigm for developing reconfigurable and programmable nanomaterials and multifunctional devices. Light stimulus manifestly represents a preferred external physical and chemical tool for in situ remote command of the functional attributes of nanomaterials and nanosystems due to its unique advantages of high spatial and temporal resolution and digital controllability. Photochromic moieties are known to undergo reversible photochemical transformations between different states with distinct properties, which have been extensively introduced into various functional nanosystems such as nanomachines, nanoparticles, nanoelectronics, supramolecular nanoassemblies, and biological nanosystems. The integration of photochromism into these nanosystems has endowed the resultant nanostructures or advanced materials with intriguing photoresponsive behaviors and more sophisticated functions. In this Review, we provide an account of the recent advancements in reversible photocontrol of the structures and functions of photochromic nanosystems and their applications. The important design concepts of such truly advanced materials are discussed, their fabrication methods are emphasized, and their applications are highlighted. The Review is concluded by briefly outlining the challenges that need to be addressed and the opportunities that can be tapped into. We hope that the review of the flourishing and vibrant topic with myriad possibilities would shine light on exploring the future nanoworld by encouraging and opening the windows to meaningful multidisciplinary cooperation of engineers from different backgrounds and scientists from the fields such as chemistry, physics, engineering, biology, nanotechnology and materials science.

Monosulfonicpillar[5]arene: Synthesis, Characterization, and Complexation with Tetraphenylethene for Aggregation-Induced Emission

A pillar[5]arene derivative with a hydrophilic sulfonic group, i.e., monosulfonicpillar[5]arene (MSP5), has been successfully synthesized for the first time, which exhibited strong binding affinity towards alcohol analogs. Significantly, fluorescent supramolecular ensemble was fabricated from the supramolecular complexation of MSP5 and a neutral guest with tetraphenylethene core. Enhanced fluorescent emission of this system can be detected both in dilute solution and the solid state, and its temperature and competitive guest multi-responsive properties suggest its promising application as a chemical sensor towards alcohol analogs, ethylenediamine, and temperature variations.

Mesoporous Silica and Organosilica Nanoparticles: Physical Chemistry, Biosafety, Delivery Strategies, and Biomedical Applications

Predetermining the physico-chemical properties, biosafety, and stimuli-responsiveness of nanomaterials in biological environments is essential for safe and effective biomedical applications. At the forefront of biomedical research, mesoporous silica nanoparticles and mesoporous organosilica nanoparticles are increasingly investigated to predict their biological outcome by materials design. In this review, it is first chronicled that how the nanomaterial design of pure silica, partially hybridized organosilica, and fully hybridized organosilica (periodic mesoporous organosilicas) governs not only the physico-chemical properties but also the biosafety of the nanoparticles. The impact of the hybridization on the biocompatibility, protein corona, biodistribution, biodegradability, and clearance of the silica-based particles is described. Then, the influence of the surface engineering, the framework hybridization, as well as the morphology of the particles, on the ability to load and controllably deliver drugs under internal biological stimuli (e.g., pH, redox, enzymes) and external noninvasive stimuli (e.g., light, magnetic, ultrasound) are presented. To conclude, trends in the biomedical applications of silica and organosilica nanovectors are delineated, such as unconventional bioimaging techniques, large cargo delivery, combination therapy, gaseous molecule delivery, antimicrobial protection, and Alzheimer's disease therapy.

Synthesis of rotaxanes and catenanes using an imine clipping reaction

Supramolecular chemistry and self-assembly provide a valuable chance to understand the complicated topological structures on a molecular level. Two types of classical mechanically interlocked molecules, rotaxanes and catenanes, possess non-covalent mechanical bonds and have attracted more attention not only in supramolecular chemistry but also in the fields of materials science, nanotechnology and bioscience. In the past decades, the template-directed clipping reaction based on imine chemistry has become one of the most efficient methods for the construction of functionalized rotaxanes and catenanes. In this review, we outlined the main progress of rotaxanes and catenanes using the template-directed clipping approach of imine chemistry. The review contains the novel topological structures of rotaxanes and catenanes, functions and applications.

Artificial Molecular Machines in Nanotheranostics

Due to their dynamic nature and excellent stimuli-responsiveness resulting from noncovalent driving forces, artificial molecular machines (AMMs) show great promise in cancer theranostics. In this Perspective, we introduce the potential applications of AMMs in controlled drug delivery, bioorthogonal catalysis, imaging, and cell membrane permeabilization, with the goal of enhancing cancer diagnosis and therapy. We expect this preliminary discussion will garner multidisciplinary interest from scientists to advance AMMs and to expand their future clinical applications.

Biobased polyelectrolyte multilayer-coated hollow mesoporous silica as a green flame retardant for epoxy resin

Here, we describe a multifunctional biobased polyelectrolyte multilayer-coated hollow mesoporous silica (HM-SiO₂@CS@PCL) as a green flame retardant through layer-by-layer assembly using hollow mesoporous silica (HM-SiO₂), chitosan (CS) and phosphorylated cellulose (PCL). The electrostatic interactions deposited the CS/PCL coating on the surface of HM-SiO₂. Subsequently, this multifunctional flame retardant was used to enhance thermal properties and flame retardancy of epoxy resin. The addition of HM-SiO₂@CS@PCL to the epoxy resin thermally destabilized the epoxy resin composite, but generated a higher char yield. Furthermore, HM-SiO₂ played a critical role and generated synergies with CS and PCL to improve fire safety of the epoxy resin due to the multiple flame retardancy elements (P, N and Si). This multi-element, synergistic, flame-retardant system resulted in a remarkable reduction (51%) of peak heat release rate and a considerable removal of flammable decomposed products. Additionally, the incorporation of HM-SiO₂@CS@PCL can sustainably recycle the epoxy resin into high value-added hollow carbon spheres during combustion. Therefore, the HM-SiO₂@CS@PCL system provides a practical possibility for preparing recyclable polymer materials with multi-functions and high performances.

Nanoscale metal–organic frameworks for drug delivery: a conventional platform with new promise

This review highlights recent advances made using nanoscale metal–organic frameworks (NMOFs) for designing cargo-delivery systems.

Multifunctional bacterial imaging and therapy systems

Advanced antibacterial materials are classified and introduced, and their applications in multimodal imaging and therapy are reviewed.

Facile surface functionalization of upconversion nanoparticles with phosphoryl pillar[5]arenes for controlled cargo release and cell imaging

A new organic–inorganic hybrid material based on upconversion nanoparticles and pillarenes is constructed for cargo controlled delivery and cell imaging.

Barium cation-responsive supra-amphiphile constructed by a new twisted cucurbit[15]uril/paraquat recognition motif in water

A new, strong, and barium cation-responsive host–guest recognition motif based on twisted cucurbit[15]uril and paraquat was established in water.

Inorganic Nanocrystals Functionalized Mesoporous Silica Nanoparticles: Fabrication and Enhanced Bio-applications

Mesoporous SiO2 nanoparticles (MSNs) are one of the most promising materials for bio-related applications due to advantages such as good biocompatibility, tunable mesopores, and large pore volume. However, unlike the inorganic nanocrystals with abundant physical properties, MSNs alone lack functional features. Thus, they are not sufficiently suitable for bio-applications that require special functions. Consequently, MSNs are often functionalized by incorporating inorganic nanocrystals, which provide a wide range of intriguing properties. This review focuses on inorganic nanocrystals functionalized MSNs, both their fabrication and bio-applications. Some of the most utilized methods for coating mesoporous silica (mSiO2) on nanoparticles were summarized. Magnetic, fluorescence and photothermal inorganic nanocrystals functionalized MSNs were taken as examples to demonstrate the bio-applications. Furthermore, asymmetry of MSNs and their effects on functions were also highlighted.

A Metal-Polyphenol Network Coated Nanotheranostic System for Metastatic Tumor Treatments

As a characteristic trait of most tumor types, metastasis is the major cause of the death of patients. In this study, a photothermal agent based on gold nanorod is coated with metal (Gd³⁺ )-organic (polyphenol) network to realize combination therapy for metastatic tumors. This nanotheranostic system significantly enhances antitumor therapeutic effects in vitro and in vivo with the combination of photothermal therapy (PTT) and chemotherapy, also can remarkably prevent the invasion and metastasis due to the presence of polyphenol. After the treatment, an 81% decrease in primary tumor volumes and a 58% decrease in lung metastasis are observed. In addition, the good performance in magnetic resonance imaging, computerized tomography, and photothermal imaging of the nanotheranostic system can realize image-guided therapy. The multifunctional nanotheranostic system will find a great potential in diagnosis and treatment integration in tumor treatments, and broaden the applications of PTT treatment.

Nucleic acid aptamer application in diagnosis and therapy of colorectal cancer based on cell-SELEX technology

Nucleic acid aptamers are a class of high-affinity nucleic acid ligands. They serve as “chemical antibodies” since their high affinity and specificity. Nucleic acid aptamers are generated from nucleic acid random-sequence using a systematic evolution of ligands by exponential enrichment (SELEX) technology. SELEX is a process of effectively selecting aptamers from different targets. A newly developed cell-based SELEX technique has been widely used in biomarker discovery, early diagnosis and targeted cancer therapy, particular at colorectal cancer (CRC). Combined with nanostructures, nano-aptamer-drug delivery system was constructed for drug delivery. Various nanostructures functionalized with aptamers are highly efficient and has been used in CRC therapeutic applications. In the present, we introduce a cell- SELEX technique, and summarize the potential application of aptamers as biomarkers in CRC diagnosis and therapy. And some characteristics of aptamer-targeted nanocarriers in CRC have been expatiated. The challenges and perspectives for cell-SELEX are also discussed.

Free-Blockage Mesoporous Anticancer Nanoparticles Based on ROS-Responsive Wetting Behavior of Nanopores

To achieve an excellent delivery effect of drug, stimuli-responsive nano "gate" with physical blockage units is usually constructed on the surface of the mesoporous silica nanocarriers (MSNs). In nature, the aquaporins in cell membrane can control the transport of water molecules by regulating the channel wettability, which is resulted from the conformational change of amino acids in the channel. Inspired by this phonomenon, herein a new concept of free-blockage controlled release system is proposed, which is achieved by controlling the wettability of the internal surface of nanopores on MSNs. Such a new system is different from the physical-blockage controlled release system, which bypasses the use of nano "gate" and overcomes the limitations of traditional physical blockage system. Moreover, further studies have shown that the system can selectively release the entrapped doxorubicin in human breast adenocarcinoma (MCF-7) cells triggered by intracellular reactive oxygen species (ROS) but not in normalhuman umbilical vein endothelial cells (HUVECs) containing ROS with low levels. The wettability-determined free-blockage controlled release system is simple and effective, and it can also be triggered by intracellular biological stimuli, which provides a new approach for the future practical application of drug delivery and cancer therapy.

Fluorescence Resonance Energy Transfer Systems in Supramolecular Macrocyclic Chemistry

The fabrication of smart materials is gradually becoming a research focus in nanotechnology and materials science. An important criterion of smart materials is the capacity of stimuli-responsiveness, while another lies in selective recognition. Accordingly, supramolecular host-guest chemistry has proven a promising support for building intelligent, responsive systems; hence, synthetic macrocyclic hosts, such as calixarenes, cucurbiturils, cyclodextrins, and pillararenes, have been used as ideal building blocks. Meanwhile, manipulating and harnessing light artificially is always an intensive attempt for scientists in order to meet the urgent demands of technological developments. Fluorescence resonance energy transfer (FRET), known as a well-studied luminescent activity and also a powerful tool in spectroscopic area, has been investigated from various facets, of which the application range has been broadly expanded. In this review, the innovative collaboration between FRET and supramolecular macrocyclic chemistry will be presented and depicted with typical examples. Facilitated by the dynamic features of supramolecular macrocyclic motifs, a large variety of FRET systems have been designed and organized, resulting in promising optical materials with potential for applications in protein assembly, enzyme assays, diagnosis, drug delivery monitoring, sensing, photosynthesis mimicking and chemical encryption.

Hybrid mesoporous silica nanocarriers with thermovalve-regulated controlled release

Mesoporous silica nanoparticles (MSNs) are excellent nanocarriers, featuring very high cargo capacity due to their large surface area and pore volume. The particle and pore dimensions can be accurately tuned, and both the internal and external surfaces allow versatile functionalization. We developed hybrid MSNs with diameters around 140 nm, with the external surface selectively modified with a temperature-responsive biocompatible copolymer to control cargo release. The nanoparticles feature either a polymer brush or a gel-like responsive shell, produced by grafting from RAFT polymerization of PEG-acrylate macromonomers. The hybrid nanoparticles have fluorescent molecules incorporated into the inorganic network providing excellent optical properties for traceability and imaging. The cargo release profiles are explained by a temperature-controlled "pumping" mechanism: at low temperature (ca. 20 °C) the polymer shell is hydrophilic and expanded, opposing cargo diffusion out of the shell and retaining the molecules released from the mesopores; above room temperature (ca. 40-50 °C) the polymer network becomes more hydrophobic and collapses onto the silica surface, releasing the cargo by a sponge-like squeezing effect. The release kinetics depends on the polymer shell type, with better results obtained for the gel-coated nanoparticles. Our proof-of-concept system shows that by modulating the temperature, it is possible to achieve a pumping regime that increases the release rate in a controlled way.

NIR Light-, Temperature-, pH-, and Redox-Responsive Polymer-Modified Reduced Graphene Oxide/Mesoporous Silica Sandwich-Like Nanocomposites for Controlled Release

Here a novel quadruple-responsive nanocarrier based on reduced graphene oxide/mesoporous silica sandwich-like nanocomposites (rGO@MS) modified by pH- and temperature-responsive poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) with a linker of disulfide was constructed via surface-initiated atom transfer radical polymerization. The polymer chains would be used as gatekeepers to control the release of the loaded cargo molecules under pH, temperature, NIR light and redox stimuli. The cargo molecules (rhodamine B) were demonstrated to release from the polymer-modified nanocomposites triggered by the quadruple-stimuli. It is noted that the release of the loaded rhodamine B from the nanocarriers could be enhanced greatly under the synergistic effect of multiple stimuli. The prepared quadruple-responsive polymer-modified nanocomposites show a bright prospect in the field of smart nanocarriers for controlled release.

NO2-controlled cargo delivery from gated silica mesoporous nanoparticles

Cargo delivery from mesoporous silica nanoparticles loaded with sulforhodamine B and capped with a difluoroboron-dipyrromethene (BODIPY) derivative was triggered by a NO₂-induced oxidative process.

A light-regulated host-guest-based nanochannel system inspired by channelrhodopsins protein

The light-controlled gating of ion transport across membranes is central to nature (e.g., in protein channels). Herein, inspired by channelrhodopsins, we introduce a facile non-covalent approach towards light-responsive biomimetic channelrhodopsin nanochannels using host-guest interactions between a negative pillararene host and a positive azobenzene guest. By switching between threading and dethreading states with alternating visible and UV light irradiation, the functional channels can be flexible to regulate the inner surface charge of the channels, which in turn was exploited to achieve different forms of ion transport, for instance, cation-selective transport and anion-selective transport. Additionally, the pillararene-azobenzene-based nanochannel system could be used to construct a light-activated valve for molecular transport. Given these promising results, we suggest that this system could not only provide a better understanding of some biological processes, but also be applied for drug delivery and various biotechnological applications.Light-controlled gating of ion transport across membranes occurs in nature via channelrhodopsin nanochannels. Here, the authors show facile non-covalent approach towards light-responsive biomimetic nanochannels using host-guest interactions between a negative pillararene host and a positive azobenzene guest.

Fabrication of Mesoporous-Silica-Coated Upconverting Nanoparticles with Ultrafast Photosensitizer Loading and 808 nm NIR-Light-Triggering Capability for Photodynamic Therapy

A novel photodynamic therapy nanoplatform based on mesoporous-silica-coated upconverting nanoparticles (UCNP) with electrostatic-driven ultrafast photosensitizer (PS) loading and 808 nm near infrared (NIR)-light-triggering capabilities has been fabricated. By positively charging inner channels of the mesoporous silica shell with amino groups, a quantitative dosage of negatively charged PS, exemplified with Rose Bengal (RB) molecules, can be loaded in 2 min. In addition, the electrostatic-driven technique simultaneously provides the platform with both excellent PS dispersity and leak-proof properties due to the repulsion between the same-charged molecules and the electrostatic attraction between different-charged PS and silica channel walls, respectively. The as-coated silica shell with an ultrathin thickness of 12±2 nm is delicately fabricated to facilitate ultrafast PS loading and efficient energy transfer from UCNP to PS. The outside surface of the silica shell is capped with hydrophilic β-cyclodextrin, which not only enhances the dispersion of resulting nanoparticles in water but also plays a role of "gatekeeper", blocking the pore opening and preventing PS leaking. The in vitro cellular lethality experiment demonstrates that RB molecules can be activated to effectively generate singlet oxygen and kill cancer cells upon 808 nm NIR light irradiation.

Aptavalve-gated Mesoporous Carbon Nanospheres image Cellular Mucin and provide On-demand Targeted Drug Delivery

In this report, we present a mesoporous carbon nanosphere that can target drugs to tumors and image tumor biomarkers. A single-strand DNA (P₀ aptamer) aptavalve was capped on the surface of doxorubicin-loaded oxide mesoporous carbon nanospheres (Dox-OMCN-P₀) through π-π stacking for real-time imaging-guided on-demand targeting drug delivery. The Dox-OMCN-P₀ could not only realize the detection of MUC1 tumor marker with a wide linear range (0.1 - 10.6 μmol/L) and a low detection limit (17.5 nmol) based on different apparatuses, but also achieve in-situ targeting imaging of cellular MUC1 concentration in vitro and in vivo via "off-on" fluorescence biosensing. Much attractively, as a real-time feedback of the diagnostic/imaging outcomes, Dox-OMCN-P₀ accomplished the on-demand targeting drug delivery in quantitative response to MUC1. Controllable chemotherapy with sustained release and pH-sensitiveness, together with the potential photothermal therapy, were also clearly demonstrated. This is a simple but advanced platform, which could well achieve the real-time switchable imaging of cellular mucin for targeting cancer therapy.

Simultaneous Imaging of Endogenous Survivin mRNA and On-Demand Drug Release in Live Cells by Using a Mesoporous Silica Nanoquencher

The design of multifunctional drug delivery systems capable of simultaneous target detection, imaging, and therapeutics in live mammalian cells is critical for biomedical research. In this study, by using mesoporous silica nanoparticles (MSNs) chemically modified with a small-molecule dark quencher, followed by sequential drug encapsulation, MSN capping with a dye-labeled antisense oligonucleotide, and bioorthogonal surface modification with cell-penetrating poly(disulfide)s, the authors have successfully developed the first mesoporous silica nanoquencher (qMSN), characterized by high drug-loading and endocytosis-independent cell uptake, which is able to quantitatively image endogenous survivin mRNA and release the loaded drug in a manner that depends on the survivin expression level in tumor cells. The authors further show that this novel drug delivery system may be used to minimize potential cytotoxicity encountered by many existing small-molecule drugs in cancer therapy.

Mesoporous polydopamine nanoparticles with co-delivery function for overcoming multidrug resistance via synergistic chemo-photothermal therapy

Theranostic agents for combined chemo-photothermal therapy have attracted intensive interest in the treatment of multi-drug resistance (MDR) in cancer therapy. However, the development of simple theranostic agents as dual hosts for both heat and a high payload of chemotherapeutic agents remains a big challenge. Herein, mesoporous polydopamine nanoparticles (MPDA) were successfully developed with properties of a high payload of DOX (up to 2000 μg mg^-1) and the drug efflux inhibitor TPGS (d-α-tocopheryl polyethylene glycol 1000 succinate), as well as strong near-infrared absorption. Particularly, DOX and TPGS were sequentially loaded in the pore space and on the external particle surface of MPDA via π-π stacking and hydrophobic interactions, resulting in a MPDA-DOX@TPGS complex. The DOX release observably relies on the pH value and glutathione (GSH). Furthermore, it is possible to accelerate the rate of drug release by NIR irradiation. Importantly, the MPDA-DOX@TPGS complex was found to escape from endosomes after cellular uptake and release the loaded drugs into the cytosol. By TPGS mediated MDR reversal, the delivered DOX induced significant cytotoxicity to MCF-7/ADR cells. Besides, MPDA can absorb the NIR light and convert it into fatal heat to kill the cancer cells. As a consequence, the combined therapy in our system yields a synergistic effect with high therapeutic efficacy.

Phosphonated Pillar[5]arene-Valved Mesoporous Silica Drug Delivery Systems

To explore the diversity and promising applications of pillararene-based molecular machines, phosphonated pillar[5]arenes (PPA[5]) were synthesized to construct novel supramolecular nanovalves for the first time, based on mesoporous silica nanoparticles (MSNs) functionalized with choline and pyridinium moieties, respectively. PPA[5] encircled the choline or pyridinium stalks to construct supramolecular nanovalves for encapsulation of drugs within the MSN pores. PPA[5] showed a high binding affinity for the quaternary ammonium stalks through the host-guest interactions primarily via ion pairing between the phosphonate and quaternary ammonium moieties, in comparison with carboxylated pillar[5]arene (CPA[5]), to minimize premature drug release. The specific ion pairing between the phosphonate and quaternary ammonium moieties was elaborated for the first time to construct supramolecular nanovalves. The supramolecular nanovalves were activated by low pH, Zn²⁺ coordination, and competitive agents for controlled drug release, and release efficiency and antitumor efficacy were further enhanced when gold nanorod (GNR)-embedded MSNs (GNR@MSNs) were used instead under illumination of near-infrared (NIR) light, attributed to the synergistic effect of photothermo-chemotherapy. The constructed PPA[5]-valved GNR@MSN delivery system has promising applications in tumor photothermo-chemotherapy.