Externally Controlled Nanomachines on Mesoporous Silica Nanoparticles for Biomedical Applications

Bio-Inspired Nanomaterials for Micro/Nanodevices: A New Era in Biomedical Applications

Exploring bio-inspired nanomaterials (BINMs) and incorporating them into micro/nanodevices represent a significant development in biomedical applications. Nanomaterials, engineered to imitate biological structures and processes, exhibit distinctive attributes such as exceptional biocompatibility, multifunctionality, and unparalleled versatility. The utilization of BINMs demonstrates significant potential in diverse domains of biomedical micro/nanodevices, encompassing biosensors, targeted drug delivery systems, and advanced tissue engineering constructs. This article thoroughly examines the development and distinctive attributes of various BINMs, including those originating from proteins, DNA, and biomimetic polymers. Significant attention is directed toward incorporating these entities into micro/nanodevices and the subsequent biomedical ramifications that arise. This review explores biomimicry's structure-function correlations. Synthesis mosaics include bioprocesses, biomolecules, and natural structures. These nanomaterials' interfaces use biomimetic functionalization and geometric adaptations, transforming drug delivery, nanobiosensing, bio-inspired organ-on-chip systems, cancer-on-chip models, wound healing dressing mats, and antimicrobial surfaces. It provides an in-depth analysis of the existing challenges and proposes prospective strategies to improve the efficiency, performance, and reliability of these devices. Furthermore, this study offers a forward-thinking viewpoint highlighting potential avenues for future exploration and advancement. The objective is to effectively utilize and maximize the application of BINMs in the progression of biomedical micro/nanodevices, thereby propelling this rapidly developing field toward its promising future.

Mesoporous Silica Nanoparticles-Based Nanoplatforms: Basic Construction, Current State, and Emerging Applications in Anticancer Therapeutics

In recent years, researchers are developing novel nanoparticles for diagnostic applications using imaging techniques and for therapeutic purposes through drug delivery techniques. The unique physical and chemical properties of mesoporous silica nanoparticles (MSNs) make it possible to integrate a variety of commonly used therapeutic and imaging agents to construct a multimodal synergistic anticancer drug delivery system. Herein, recent advances in MSNs synthesis for drug delivery and smart response applications are reviewed. First, synthetic strategies for the fabrication of ordered MSNs, hollow MSNs, core-shell structured MSNs, dendritic MSNs, and biodegradable MSNs are outlined. Then, the recent research progress in designing functional MSN materials with various controlled release mechanisms in anticancer therapy is discussed, and new properties are introduced to suggest the latest design requirements as drug delivery materials. The review also highlights significant achievements in bioimaging using MSNs and their multifunctional counterparts as delivery vehicles. Finally, personal views on key directions for future work in this area are presented.

Stimuli-Responsive Adaptive Nanotoxin to Directly Penetrate the Cellular Membrane by Molecular Folding and Unfolding

Biological nanomachines, including proteins and nucleic acids whose function is activated by conformational changes, are involved in every biological process, in which their dynamic and responsive behaviors are controlled by supramolecular recognition. The development of artificial nanomachines that mimic the biological functions for potential application as therapeutics is emerging; however, it is still limited to the lower hierarchical level of the molecular components. In this work, we report a synthetic machinery nanostructure in which actuatable molecular components are integrated into a hierarchical nanomaterial in response to external stimuli to regulate biological functions. Two nanometers core-sized gold nanoparticles are covered with ligand layers as actuatable components, whose folding/unfolding motional response to the cellular environment enables the direct penetration of the nanoparticles across the cellular membrane to disrupt intracellular organelles. Furthermore, the pH-responsive conformational movements of the molecular components can induce the apoptosis of cancer cells. This strategy based on the mechanical motion of molecular components on a hierarchical nanocluster would be useful to design biomimetic nanotoxins.

Magnetism, Ultrasound, and Light-Stimulated Mesoporous Silica Nanocarriers for Theranostics and Beyond

Stimuli-responsive multifunctional mesoporous silica nanoparticles (MSNs) have been studied intensively during the past decade. A large variety of mesopore capping systems have been designed, initially to show that it could be done and later for biomedical applications such as drug delivery and imaging. On-command release of cargo molecules such as drugs from the pores can be activated by a variety of stimuli. This paper focuses on three noninvasive, biologically usable external stimuli: magnetism, ultrasound, and light. We survey the variety of MSNs that have been and are being used and assess capping designs and the advantages and drawbacks of the nanoplatforms' responses to the various stimuli. We discuss important recent advances, their basic mechanisms, and their requirements for stimulation. On the basis of our survey, we identify fundamental challenges and suggest future directions for research that will unleash the full potential of these fascinating nanosystems for clinical applications.

Recent advances in the design of inorganic and nano-clay particles for the treatment of brain disorders

Inorganic materials, in particular nanoclays and silica nanoparticles, have attracted enormous attention due to their versatile and tuneable properties, making them ideal candidates for a wide range of biomedical applications, such as drug delivery. This review aims at overviewing recent developments of inorganic nanoparticles (like porous or mesoporous silica particles) and different nano-clay materials (like montmorillonite, laponites or halloysite nanotubes) employed for overcoming the blood brain barrier (BBB) in the treatment and therapy of major brain diseases such as Alzheimer's, Parkinson's, glioma or amyotrophic lateral sclerosis. Recent strategies of crossing the BBB through invasive and not invasive administration routes by using different types of nanoparticles compared to nano-clays and inorganic particles are overviewed.

Artificial Bioaugmentation of Biomacromolecules and Living Organisms for Biomedical Applications

The synergistic union of nanomaterials with biomaterials has revolutionized synthetic chemistry, enabling the creation of nanomaterial-based biohybrids with distinct properties for biomedical applications. This class of materials has drawn significant scientific interest from the perspective of functional extension via controllable coupling of synthetic and biomaterial components, resulting in enhancement of the chemical, physical, and biological properties of the obtained biohybrids. In this review, we highlight the forefront materials for the combination with biomacromolecules and living organisms and their advantageous properties as well as recent advances in the rational design and synthesis of artificial biohybrids. We further illustrate the incredible diversity of biomedical applications stemming from artificially bioaugmented characteristics of the nanomaterial-based biohybrids. Eventually, we aim to inspire scientists with the application horizons of the exciting field of synthetic augmented biohybrids.

Expanding nanoparticle multifunctionality: size-selected cargo release and multiple logic operations

Physically stimulated nanoparticles that deliver size-selected cargo and function as logic gates are reported. To achieve this goal the particle requires multiple components, and we recognized early on that the components, not just the released cargo, could be used to demonstrate logic operations (OR and AND logic). For stimuli, we chose two non-invasive types, red light and alternating magnetic fields (AMF), because they both have potential biological relevance. To realize cargo delivery with size selection and logic operations, we mechanized the surface of core@shell nanoparticles with a superparamagnetic core that generates localized heating when exposed to an AMF, and a mesoporous silica shell into which cargo molecules with different sizes were loaded. We demonstrate the core@shell nanoparticles can load the dual cargos with different sizes and subsequently release the smaller (∼0.5 nm) and bigger (∼2 nm) cargos in succession when stimulated by a red light followed by an AMF. Finally, we demonstrate that the multi-component nanoparticles could function as nanoparticle-based Boolean logic gates where AMF and red light served as the two inputs and the release of small cargo, and free cyclodextrin served as the outputs. The construction of two Boolean logic gates (OR, and AND) was realized.

A multi-functionalized nanocomposite constructed by gold nanorod core with triple-layer coating to combat multidrug resistant colorectal cancer

Multi-drug resistance (MDR) remains the main culprit for the low survival rate of advanced colorectal cancer (CRC). Photothermal-therapy (PPT) is effective to kill MDR tumor cells, but fails to completely eradicate tumors. In this study, we prepared a nanocomposite based on gold nanorod core with triple layer coating (GNRs/mSiO₂/PHIS/TPGS/DOX) to combat multidrug resistant (MDR) colorectal cancer via multi-strategies. We first synthesized the mesoporous silica-coated gold nanorods (GNRs/mSiO₂), and loaded with antitumor drug doxorubicin (DOX) to realize a combination of chemo- and photothermal-therapy. To reverse DOX resistance, pH responsive poly-histidine (PHIS) was conjugated on GNRs/mSiO₂ to increase drug intracellular accumulation via efficient endo/lysosome escape; d-α-tocopherol polyethylene glycol 1000 succinate (TPGS) was then assembled on the surface of the particles to realize drug intracellular retention by inhibition P-glycoprotein. The results showed that the nanocomposite exhibited a highly efficient photothermal conversion in the NIR region, a pH and NIR triggered drug release profile and an increment of DOX intracellular accumulation and cytotoxicity on MDR SW620/Ad300 cells. Most importantly, the nanocomposite showed the most potent antitumor efficacy without obvious systemic toxicity comparing to other control groups with either chemo- or photothermal therapy alone on SW620/Ad300 tumor bearing mice. Altogether, the successful preparation of the nanocomposite and its potent efficacy might provide evidence for the future design and develop of nano-therapeutic system in the treatment of MDR colorectal cancer.

Shortwave Infrared Imaging with J-Aggregates Stabilized in Hollow Mesoporous Silica Nanoparticles

Tissue is translucent to shortwave infrared (SWIR) light, rendering optical imaging superior in this region. However, the widespread use of optical SWIR imaging has been limited, in part, by the lack of bright, biocompatible contrast agents that absorb and emit light above 1000 nm. J-Aggregation offers a means to transform stable, near-infrared (NIR) fluorophores into red-shifted SWIR contrast agents. Here we demonstrate that J-aggregates of NIR fluorophore IR-140 can be prepared inside hollow mesoporous silica nanoparticles (HMSNs) to result in nanomaterials that absorb and emit SWIR light. The J-aggregates inside PEGylated HMSNs are stable for multiple weeks in buffer and enable high resolution imaging in vivo with 980 nm excitation.

Nanoparticle Characterization: What to Measure?

What to measure? is a key question in nanoscience, and it is not straightforward to address as different physicochemical properties define a nanoparticle sample. Most prominent among these properties are size, shape, surface charge, and porosity. Today researchers have an unprecedented variety of measurement techniques at their disposal to assign precise numerical values to those parameters. However, methods based on different physical principles probe different aspects, not only of the particles themselves, but also of their preparation history and their environment at the time of measurement. Understanding these connections can be of great value for interpreting characterization results and ultimately controlling the nanoparticle structure-function relationship. Here, the current techniques that enable the precise measurement of these fundamental nanoparticle properties are presented and their practical advantages and disadvantages are discussed. Some recommendations of how the physicochemical parameters of nanoparticles should be investigated and how to fully characterize these properties in different environments according to the intended nanoparticle use are proposed. The intention is to improve comparability of nanoparticle properties and performance to ensure the successful transfer of scientific knowledge to industrial real-world applications.

Nanomachines and Other Caps on Mesoporous Silica Nanoparticles for Drug Delivery

Mesoporous silica nanoparticles (MSNs) are delivery vehicles that can carry cargo molecules and release them on command. The particles used in the applications reported in this Account are around 100 nm in diameter (about the size of a virus) and contain 2.5 nm tubular pores with a total volume of about 1 cm³/g. For the biomedical applications discussed here, the cargo is trapped in the pores until the particles are stimulated to release it. The challenges are to get the particles to the site of a disease and then to deliver the cargo on command. We describe methods to do both, and we illustrate the applicability of the particles to cure cancer and intracellular infectious disease. Our first steps were to design multifunctional nanoparticles with properties that allow them to carry and deliver hydrophobic drugs. Many important pharmaceuticals are hydrophobic and cannot reach the diseased sites by themselves. We describe how we modified MSNs to make them dispersible, imagable, and targetable and discuss in vitro studies. We then present examples of surface modifications that allow them to deliver large molecules such as siRNA. In vivo studies of siRNA delivery to treat triple-negative breast and ovarian cancers are presented. The next steps are to attach nanomachines and other types of caps that trap drug molecules but release them when stimulated. We describe nanomachines that respond autonomously (without human intervention) to stimuli specific to disease sites. A versatile type of machine is a nanovalve that is closed at neutral (blood) pH but opens upon acidification that occurs in endolysosomes of cancer cells. Another type of machine, a snap-top cap, is stimulated by reducing agents such as glutathione in the cytosol of cells. Both of these platforms were studied in vitro to deliver antibiotics to infected macrophages and in vivo to cure and kill the intracellular bacteria M. tuberculosis and F. tularensis. The latter is a tier 1 select agent of bioterrorism. Finally, we describe nanomachines for drug delivery that are controlled by externally administered light and magnetic fields. A futuristic dream for nanotherapy is the ability to control a nano-object everywhere in the body. Magnetic fields penetrate completely and have spatial selectivity governed by the size of the field-producing coil. We describe how to control nanovalves with alternating magnetic fields (AMFs) and superparamagnetic cores inside the MSNs. The AMF heats the cores, and temperature-sensitive caps release the cargo. In vitro studies demonstrate dose control of the therapeutic to cause apoptosis without overheating the cells. Nanocarriers have great promise for therapeutic applications, and MSNs that can carry drugs to the site of a disease to produce a high local concentration without premature release and off-target damage may have the capability of realizing this goal.

Photocracking Silica: Tuning the Plasmonic Photothermal Degradation of Mesoporous Silica Encapsulating Gold Nanoparticles for Cargo Release

The degradation of bionanomaterials is essential for medical applications of nanoformulations, but most inorganic-based delivery agents do not biodegrade at controllable rates. In this contribution, we describe the controllable plasmonic photocracking of gold@silica nanoparticles by tuning the power and wavelength of the laser irradiation, or by tuning the size of the encapsulated gold cores. Particles were literally broken to pieces or dissolved from the inside out upon laser excitation of the plasmonic cores. The photothermal cracking of silica, probably analogous to thermal fracturing in glass, was then harnessed to release cargo molecules from gold@silica@polycaprolactone nanovectors. This unique and controllable plasmonic photodegradation has implications for nanomedicine, photopatterning, and sensing applications.

Impact of the mesoporous silica SBA-15 functionalization on the mode of action of Ph3Sn(CH2)6OH

Herein appropriateness of nonfunctionalized mesoporous silica nanoparticles SBA-15 and functionalized with (3-chloropropyl)triethoxysilane (→ SBA-15~Cl) and (3-aminopropyl)triethoxysilane (→ SBA-15~NH₂) on delivery of physically adsorbed Ph₃Sn(CH₂)₆OH (Sn6) is evaluated. Fluorescent nanomaterial, bearing isatoic moiety, loaded with Sn6 (→ SBA-15~NF|Sn6) was used for cellular uptake study. The fluorescent nanomaterial is efficiently acquired and distributed into the cytoplasm of the cells even after 2 h of cultivation. According to the attained data, all SBA-15 materials loaded with Sn6 diminished cellular viability in dose dependent manner while carriers alone (SBA-15, SBA-15~Cl, SBA-15~NH₂) did not show cytotoxicity against B16 cells. According to the MC₅₀ values structural modification of SBA-15 did not improve the efficacy of tested drug. While progressive apoptosis was detected upon the treatment with SBA-15|Sn6, exposure of cells to SBA-15~NH₂|Sn6 revealed extinguished apoptosis in time, accompanied with lower caspase activity. This effect is probably due to triggered autophagic process under the treatment with the SBA-15~NH₂|Sn6, thus opposed to apoptosis. Presented results suggested that functionalization of SBA-15 was not beneficial for the efficacy of loaded drug, thus, all of them are almost equally efficient considering loaded Sn6 content. Importantly, functionalization of SBA-15 does have an influence on the mode of action and differentiation inducing properties.

Ultrasound responsive mesoporous silica nanoparticles for biomedical applications

Nanotechnology, which has already revolutionised many technological areas, is expected to transform life sciences. In this sense, nanomedicine could address some of the most important limitations of conventional medicine. In general, nanomedicine includes three major objectives: (1) trap and protect a great amount of therapeutic agents; (2) carry them to the specific site of disease avoiding any leakage; and (3) release on-demand high local concentrations of therapeutic agents. This feature article will make special emphasis on mesoporous silica nanoparticles that release their therapeutic cargo in response to ultrasound.

Large Pore Mesoporous Silica and Organosilica Nanoparticles for Pepstatin A Delivery in Breast Cancer Cells

(1) Background: Nanomedicine has recently emerged as a new area of research, particularly to fight cancer. In this field, we were interested in the vectorization of pepstatin A, a peptide which does not cross cell membranes, but which is a potent inhibitor of cathepsin D, an aspartic protease particularly overexpressed in breast cancer. (2) Methods: We studied two kinds of nanoparticles. For pepstatin A delivery, mesoporous silica nanoparticles with large pores (LPMSNs) and hollow organosilica nanoparticles (HOSNPs) obtained through the sol⁻gel procedure were used. The nanoparticles were loaded with pepstatin A, and then the nanoparticles were incubated with cancer cells. (3) Results: LPMSNs were monodisperse with 100 nm diameter. HOSNPs were more polydisperse with diameters below 100 nm. Good loading capacities were obtained for both types of nanoparticles. The nanoparticles were endocytosed in cancer cells, and HOSNPs led to the best results for cancer cell killing. (4) Conclusions: Mesoporous silica-based nanoparticles with large pores or cavities are promising for nanomedicine applications with peptides.

A l-glutamate-responsive delivery system based on enzyme-controlled self-immolative arylboronate-gated nanoparticles

Janus Au–mesoporous silica nanoparticles functionalized withl-glutamate oxidase and self-immolative arylboronate as al-glutamate-responsive delivery system.

Barriers for Extrusion of a Guest from the Interior Binding Cavity of a Host: Gas Phase Experimental and Computational Results for Ion-Capped Decamethylcucurbit[5]uril Complexes

Factors affecting the extrusion of guests from metal ion-capped decamethylcucurbit[5]uril (mc5) molecular container complexes are investigated using both collision-induced dissociation techniques and molecular mechanics simulations. For guests without polar bonds, the extrusion barrier increases with increasing guest volume. This is likely because escape of larger guests requires more displacement of the metal ion caps and, thus, more disruption of the ion-dipole interactions between the ion caps and the electronegative rim oxygens of mc5. However, guests larger than the optimum size for encapsulation displace the ion caps prior to collision-induced dissociation, resulting in less stable complexes and lower dissociation thresholds. The extrusion barriers obtained for guests with polar bonds are smaller than those obtained for similarly sized guests without polar bonds. This is likely because the partial charges on the guest allow electrostatic interactions with the ion cap and rim oxygens of mc5 during extrusion, thus stabilizing the extrusion transition state and reducing the extrusion barrier. Results from this study demonstrate simple principles to consider for designing host-guest complexes with specific guest-loss behaviors. Similar trends are observed between the experimental and computational results, demonstrating that molecular mechanics simulations can be used to approximate the relative stability of mc5 molecular container complexes and likely those of other similar complexes.

Silica Nanoparticle-Endothelial Interaction: Uptake and Effect on Platelet Adhesion under Flow Conditions

Silica nanoparticles are extensively used in biomedical applications and consumer products. Little is known about the interaction of these NPs with the endothelium and effect on platelet adhesion under flow conditions in circulation. In this study, we investigated the effect of silica nanoparticles on the endothelium and its inflammation, and subsequent adhesion of flowing platelets in vitro. Platelet counts adhered onto the surface of endothelial cells in the presence of nanoparticles increased at both low and high concentrations of nanoparticles. Preincubation of endothelial cells with nanoparticles also increased platelet adhesion. Interestingly, platelet adhesion onto TNF-α-treated endothelial cells decreased in the presence of nanoparticles at different concentrations as compared with the absence of nanoparticles. We monitored the expression of different endothelial proteins, known to initiate platelet adhesion, in the presence and absence of silica nanoparticles. We found that silica nanoparticles caused changes in the endothelium such as overexpression of PECAM that promoted platelet adhesion to the endothelial cell.

Facile Strategy Enabling Both High Loading and High Release Amounts of the Water-Insoluble Drug Clofazimine Using Mesoporous Silica Nanoparticles

The use of nanocarriers to deliver poorly soluble drugs to the sites of diseases is an attractive and general method, and mesoporous silica nanoparticles (MSNs) are increasingly being used as carriers. However, both loading a large amount of drugs into the pores and still being able to release the drug is a challenge. In this paper, we demonstrate a general strategy based on a companion molecule that chaperones the drug into the pores and also aids it in escaping. A common related strategy is to use a miscible co-solvent dimethyl sulfoxide (DMSO), but although loading may be efficient in DMSO, this co-solvent frequently diffuses into an aqueous environment, leaving the drug behind. We demonstrate the method by using acetophenone (AP), an FDA-approved food additive as the chaperone for clofazimine (CFZ), a water-insoluble antibiotic used to treat leprosy and multidrug-resistant tuberculosis. AP enables a high amount of CFZ cargo into the MSNs and also carries CFZ cargo out from the MSNs effectively when they are in an aqueous biorelevant environment. The amount of loading and the CFZ release efficiency from MSNs were optimized; 4.5 times more CFZ was loaded in MSNs with AP than that with DMSO and 2300 times more CFZ was released than that without the assistance of the AP. In vitro treatment of macrophages infected by Mycobacterium tuberculosis with the optimized CFZ-loaded MSNs killed the bacteria in the cells in a dose-dependent manner. These studies demonstrate a highly efficient method for loading nanoparticles with water-insoluble drug molecules and the efficacy of the nanoparticles in delivering drugs into eukaryotic cells in aqueous media.

Stimuli-Responsive Nanomachines and Caps for Drug Delivery

In this review we focus on methods that are used to trap and release on command therapeutic drugs from mesoporous silica nanoparticles (MSNs). The pores in the MSNs are large enough to accommodate a wide range of cargo molecules such as anticancer and antibiotic drugs and yet small enough to be blocked by a variety of bulky molecules that act as caps. The caps are designed to be tightly attached to the pore openings and trap the cargo molecules without leakage, but upon application of a designed stimulus detach from the nanoparticles and release the cargo. Of special emphasis in this review are nanomachines that respond to stimuli administered from external sources such as light or magnetic fields, or from chemical stimuli produced by the biological system such as a general change in pH or redox potential, or a highly specific chemical produced by a cancer cell or infectious bacterium. The goal is to release a high local concentration of the cargo only where and when it is needed, thus minimizing off-target side effects. We discuss sophisticated reversible nanomachines but also discuss some useful caps that simply break off from the nanoparticles in response to the selected stimulus. Many ingenious systems have been and are being designed; we primarily highlight those that have been demonstrated to operate in vitro and/or in vivo. In most cases the closed MSNs are endocytosed by diseased or infected cells and opened inside the cells to release the drugs. We begin with an overview of the nanoparticles and nanomachines and then present examples of drug release triggered by internal chemical stimuli from the organism and finally by external light and magnetic field stimuli.

Biodegradable Silica-Based Nanoparticles: Dissolution Kinetics and Selective Bond Cleavage

Silica-based nanomaterials are extensively used in industrial applications and academic biomedical research, thus properly assessing their toxicity and biodegradability is essential for their safe and effective formulation and use. Unfortunately, there is often a lot of confusion in the literature with respect to the toxicity and biodegradability of silica since various studies have yielded contradictory results. In this contribution, we first endeavor to underscore that the simplistic model of silica should be discarded in favor of a more realistic model recognizing that all silicas are not created equal and should thus be considered in the plural as silicas and silica hybrids, which indeed hold various biocompatibility and biodegradability profiles. We then demonstrated that all silicas are-as displayed in Nature-degradable in water by dissolution, as governed by the laws of kinetics. Lastly, we explore the vast potential of tuning the degradability of silica by materials design using various silica hybrids for redox-, pH-, enzymatic-, and biochelation-mediated lysis mechanisms.

Biocompatible crosslinked β-cyclodextrin nanoparticles as multifunctional carriers for cellular delivery

Nanoparticle-based biomedicine has received enormous attention for theranostic applications, as these systems are expected to overcome several drawbacks of conventional therapy. Herein, effective and controlled drug delivery systems with on-demand release abilities and biocompatible properties are used as a versatile and powerful class of nanocarriers. We report the synthesis of a novel biocompatible and multifunctional material, entirely consisting of covalently crosslinked organic molecules. Specifically, β-cyclodextrin (CD) precursors were crosslinked with rigid organic linker molecules to obtain small (∼150 nm), thermally stable and highly water-dispersible nanoparticles with an accessible pore system containing β-CD rings. The nanoparticles can be covalently labeled with dye molecules to allow effective tracking in in vitro cell experiments. Rapid sugar-mediated cell-uptake kinetics were observed with HeLa cells, revealing exceptional particle uptake within only 30 minutes. Additionally, the particles could be loaded with different cargo molecules showing pH-responsive release behavior. Successful nuclei staining with Hoechst 33342 dye and effective cell killing with doxorubicin cargo molecules were demonstrated in live-cell experiments, respectively. This novel nanocarrier concept provides a promising platform for the development of controllable and highly biocompatible theranostic systems.

Two-Photon-Excited Silica and Organosilica Nanoparticles for Spatiotemporal Cancer Treatment

Coherent two-photon-excited (TPE) therapy in the near-infrared (NIR) provides safer cancer treatments than current therapies lacking spatial and temporal selectivities because it is characterized by a 3D spatial resolution of 1 µm³ and very low scattering. In this review, the principle of TPE and its significance in combination with organosilica nanoparticles (NPs) are introduced and then studies involving the design of pioneering TPE-NIR organosilica nanomaterials are discussed for bioimaging, drug delivery, and photodynamic therapy. Organosilica nanoparticles and their rich and well-established chemistry, tunable composition, porosity, size, and morphology provide ideal platforms for minimal side-effect therapies via TPE-NIR. Mesoporous silica and organosilica nanoparticles endowed with high surface areas can be functionalized to carry hydrophobic and biologically unstable two-photon absorbers for drug delivery and diagnosis. Currently, most light-actuated clinical therapeutic applications with NPs involve photodynamic therapy by singlet oxygen generation, but low photosensitizing efficiencies, tumor resistance, and lack of spatial resolution limit their applicability. On the contrary, higher photosensitizing yields, versatile therapies, and a unique spatial resolution are available with engineered two-photon-sensitive organosilica particles that selectively impact tumors while healthy tissues remain untouched. Patients suffering pathologies such as retinoblastoma, breast, and skin cancers will greatly benefit from TPE-NIR ultrasensitive diagnosis and therapy.

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.

Mesoporous silica nanoparticles in recent photodynamic therapy applications

In this review, the use of mesoporous silica nanoparticles for photodynamic therapy (PDT) applications is described for the year 2017.

Biogenic Nanostructured Porous Silicon as a Carrier for Stabilization and Delivery of Natural Therapeutic Species

Nanostructured mesoporous silicon (pSi) derived from the silicon-accumulator plant Tabasheer (Bambuseae) is demonstrated to serve as a potential carrier matrix for carrying and stabilizing naturally active, but otherwise metastable, therapeutic agents. Particularly, in this study, garlic oil containing phytochemicals (namely, allicin) that are capable of inhibiting Staphylococcus aureus (S. aureus) bacterial growth were incorporated into Tabasheer-derived porous silicon. Thermogravimetric analysis (TGA) indicated that relatively high amounts of the extract (53.1 ± 2.2 wt %) loaded into pSi are possible by simple infiltration. Furthermore, by assessing the antibacterial activity of the samples using a combination technique of agar disk diffusion and turbidity assays against S. aureus, we report that biogenic porous silicon can be utilized to stabilize and enhance the therapeutic effects of garlic oil for up to 4 weeks when the samples were stored under refrigerated conditions (4 °C) and 1 week at room temperature (25 °C). Critically, under ultraviolet (UV) light (365 nm) irradiation for 24 h intervals, plant-derived pSi is shown to have superior performance in protecting garlic extracts over porous silica (pSiO₂) derived from the same plant feedstock or extract-only controls. The mechanism for this effect has also been investigated.

Mixed shell mesoporous silica nanoparticles for controlled drug encapsulation and delivery

Aim: Smart mesoporous silica nanoparticles (MSNs) with mixed polymeric shell (MS-MSNs) were prepared to realize controlled encapsulation and responsive delivery of anticancer drugs. Materials & methods: Two kinds of polymers, including nonthermoresponsive poly(ethylene glycol) and thermoresponsive poly(N-isopropyl acrylamide), were grafted onto the outlets of the MSNs through acidic liable Schiff base bonds. Results: Poly(N-isopropyl acrylamide) chains could control the release rate of drugs through phase transition, while poly(ethylene glycol) chains could maintain the colloid stability of MSNs. Drugs can be released through the gradual hydrolysis of Schiff base bonds in tumor acidic environment. Conclusion: The MS-MSNs gave consideration to both the responsiveness and stability of carriers, and could realize the release of drugs as much as possible in tumor tissues.

Photochemistry and Photophysics in Silica-Based Materials: Ultrafast and Single Molecule Spectroscopy Observation

Silica-based materials (SBMs) are widely used in catalysis, photonics, and drug delivery. Their pores and cavities act as hosts of diverse guests ranging from classical dyes to drugs and quantum dots, allowing changes in the photochemical behavior of the confined guests. The heterogeneity of the guest populations as well as the confinement provided by these hosts affect the behavior of the formed hybrid materials. As a consequence, the observed reaction dynamics becomes significantly different and complex. Studying their photobehavior requires advanced laser-based spectroscopy and microscopy techniques as well as computational methods. Thanks to the development of ultrafast (spectroscopy and imaging) tools, we are witnessing an increasing interest of the scientific community to explore the intimate photobehavior of these composites. Here, we review the recent theoretical and ultrafast experimental studies of their photodynamics and discuss the results in comparison to those in homogeneous media. The discussion of the confined dynamics includes solvation and intra- and intermolecular proton-, electron-, and energy transfer events of the guest within the SBMs. Several examples of applications in photocatalysis, (photo)sensors, photonics, photovoltaics, and drug delivery demonstrate the vast potential of the SBMs in modern science and technology.

Silicon-based nanotheranostics

With the rapid expansion of nanoscience and nanotechnology in interdisciplinary fields, multifunctional nanomaterials have attracted particular attention. Recent advances in nanotherapeutics for cancer applications provided diverse groups of synthetic particles with defined cellular and biological functions. The advance of nanotechnology significantly increased the number of possibilities for the construction of diverse biological tools. Such materials are destined to be of great importance because of the opportunity to combine the biotechnological potential of nanoparticles together with the recognition, sensitivity and modulation of cellular pathways or genes when applied to living organisms. In this mini review three main types of Si-based nanomaterials are highlighted in the area of their application for therapy and imaging: porous silicon nanoparticles (pSiNPs), mesoporous silica nanoparticles (MSNs), focusing on their nanoconstructs containing coordination compounds, and periodic mesoporous silica nanoparticles (PMONPs). Moreover, a critical discussion on the research efforts in the construction of nanotheranostics is presented.

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.

Silica nanoparticles induced intrinsic apoptosis in neuroblastoma SH-SY5Y cells via CytC/Apaf-1 pathway

The present study was to investigate effects of Silica nanoparticles (SiNPs) on nervous system and explore potential mechanisms in human neuroblastoma cells (SH-SY5Y). Cytotoxicity was detected by cell viability and Lactate dehydrogenase (LDH) release. Flow cytometry analysis was applied to assess mitochondrial membrane potential (MMP) loss, intracellular Ca²⁺ and apoptosis. To clarify the mechanism of SiNPs-induced apoptosis, intrinsic apoptosis-related proteins were detected. Our results showed that SiNPs caused cytotoxicity, cell membrane damage and Ca²⁺ increase in a dose-dependent manner in SH-SY5Y cells. Both the mitochondrial membrane potential (MMP) loss and potential mitochondria damage resulted in Cyt C release to the cytoplasm. The elevated Cyt C and Apaf1 further triggered intrinsic apoptosis via executive molecular caspase-9 and caspase-3. The present study confirmed that SiNPs induced intrinsic apoptosis in neuroblastoma SH-SY5Y cells via CytC/Apaf-1 pathway and provided a better understanding of the potential toxicity induced by SiNPs on human neurocyte.

A Pathogen-Specific Cargo Delivery Platform Based on Mesoporous Silica Nanoparticles

We present a synthetic approach to a highly pathogen-selective detection and delivery platform based on the interaction of an antibody nanovalve with a tetrasaccharide from the O-antigen of the lipopolysaccharide (LPS) of Francisella tularensis bacteria, a Tier 1 Select Agent of bioterrorism. Different design considerations are explored, and proof-of-concept for highly pathogen-specific cargo release from mesoporous silica nanoparticles is demonstrated by comparisons of the release of a signal transducer and model drug by LPS from F. tularensis vs Pseudomonas aeruginosa and by F. tularensis live bacteria vs the closely related bacterium Francisella novocida. In addition to the specific response to a biowarfare agent, treatment of infectious diseases in general could benefit tremendously from a delivery platform that releases its antibiotic payload only at the site of infection and only in the presence of the target pathogen, thereby minimizing off-target toxicities.

Degradability and Clearance of Silicon, Organosilica, Silsesquioxane, Silica Mixed Oxide, and Mesoporous Silica Nanoparticles

The biorelated degradability and clearance of siliceous nanomaterials have been questioned worldwide, since they are crucial prerequisites for the successful translation in clinics. Typically, the degradability and biocompatibility of mesoporous silica nanoparticles (MSNs) have been an ongoing discussion in research circles. The reason for such a concern is that approved pharmaceutical products must not accumulate in the human body, to prevent severe and unpredictable side-effects. Here, the biorelated degradability and clearance of silicon and silica nanoparticles (NPs) are comprehensively summarized. The influence of the size, morphology, surface area, pore size, and surface functional groups, to name a few, on the degradability of silicon and silica NPs is described. The noncovalent organic doping of silica and the covalent incorporation of either hydrolytically stable or redox- and enzymatically cleavable silsesquioxanes is then described for organosilica, bridged silsesquioxane (BS), and periodic mesoporous organosilica (PMO) NPs. Inorganically doped silica particles such as calcium-, iron-, manganese-, and zirconium-doped NPs, also have radically different hydrolytic stabilities. To conclude, the degradability and clearance timelines of various siliceous nanomaterials are compared and it is highlighted that researchers can select a specific nanomaterial in this large family according to the targeted applications and the required clearance kinetics.

Colloidal Gold Nanoclusters Spiked Silica Fillers in Mixed Matrix Coatings: Simultaneous Detection and Inhibition of Healthcare-Associated Infections

Healthcare-associated infections (HAIs) are the infections that patients get while receiving medical treatment in a medical facility with bacterial HAIs being the most common. Silver and gold nanoparticles (NPs) have been successfully employed as antibacterial motifs; however, NPs leaching in addition to poor dispersion and overall reproducibility are major hurdles to further product development. In this study, the authors design and fabricate a smart antibacterial mixed-matrix membrane coating comprising colloidal lysozyme-templated gold nanoclusters as nanofillers in poly(ethylene oxide)/poly(butylene terephthalate) amphiphilic polymer matrix. Mesoporous silica nanoparticles-lysozyme functionalized gold nanoclusters disperse homogenously within the polymer matrix with no phase separation and zero NPs leaching. This mixed-matrix coating can successfully sense and inhibit bacterial contamination via a controlled release mechanism that is only triggered by bacteria. The system is coated on a common radiographic dental imaging device (photostimulable phosphor plate) that is prone to oral bacteria contamination. Variation and eventually disappearance of the red fluorescence surface under UV light signals bacterial infection. Kanamycin, an antimicrobial agent, is controllably released to instantly inhibit bacterial growth. Interestingly, the quality of the images obtained with these coated surfaces is the same as uncoated surfaces and thus the safe application of such smart coatings can be expanded to include other medical devices without compromising their utility.

Cellular Internalization and Biocompatibility of Periodic Mesoporous Organosilica Nanoparticles with Tunable Morphologies: From Nanospheres to Nanowires

This work describes the sol-gel syntheses of para-substituted phenylene-bridged periodic mesoporous organosilica (PMO) nanoparticles (NPs) with tunable morphologies ranging from nanowires to nanospheres. The findings show the key role of the addition of organic co-solvents in the aqueous templates on the final morphologies of PMO NPs. Other factors such as the temperature, the stirring speed, and the amount of organic solvents also influence the shape of PMO NPs. The tuning of the shape of the PMO nanomaterials made it possible to study the influence of the particle morphology on the cellular internalization and biocompatibility.

Current Multistage Drug Delivery Systems Based on the Tumor Microenvironment

The development of traditional tumor-targeted drug delivery systems based on EPR effect and receptor-mediated endocytosis is very challenging probably because of the biological complexity of tumors as well as the limitations in the design of the functional nano-sized delivery systems. Recently, multistage drug delivery systems (Ms-DDS) triggered by various specific tumor microenvironment stimuli have emerged for tumor therapy and imaging. In response to the differences in the physiological blood circulation, tumor microenvironment, and intracellular environment, Ms-DDS can change their physicochemical properties (such as size, hydrophobicity, or zeta potential) to achieve deeper tumor penetration, enhanced cellular uptake, timely drug release, as well as effective endosomal escape. Based on these mechanisms, Ms-DDS could deliver maximum quantity of drugs to the therapeutic targets including tumor tissues, cells, and subcellular organelles and eventually exhibit the highest therapeutic efficacy. In this review, we expatiate on various responsive modes triggered by the tumor microenvironment stimuli, introduce recent advances in multistage nanoparticle systems, especially the multi-stimuli responsive delivery systems, and discuss their functions, effects, and prospects.

One-pot synthesis of redox-triggered biodegradable hybrid nanocapsules with a disulfide-bridged silsesquioxane framework for promising drug delivery

Redox-triggered biodegradable hybrid nanocapsules with the disulfide-bridged silsesquioxane framework were developed for promising drug delivery.

Crown ether triad modified core–shell magnetic mesoporous silica nanocarrier for pH-responsive drug delivery and magnetic hyperthermia applications

A “host–guest” complexation-based core–shell FeNP@SiOH@CET NP system was fabricated for chemotherapy and magnetic hyperthermia applications.

Biodegradable Magnetic Silica@Iron Oxide Nanovectors with Ultra-Large Mesopores for High Protein Loading, Magnetothermal Release, and Delivery

The delivery of large cargos of diameter above 15nm for biomedical applications has proved challenging since it requires biocompatible, stably-loaded, and biodegradable nanomaterials. In this study, we describe the design of biodegradable silica-iron oxide hybrid nanovectors with large mesopores for large protein delivery in cancer cells. The mesopores of the nanomaterials spanned from 20 to 60nm in diameter and post-functionalization allowed the electrostatic immobilization of large proteins (e.g. mTFP-Ferritin, ~534kDa). Half of the content of the nanovectors was based with iron oxide nanophases which allowed the rapid biodegradation of the carrier in fetal bovine serum and a magnetic responsiveness. The nanovectors released large protein cargos in aqueous solution under acidic pH or magnetic stimuli. The delivery of large proteins was then autonomously achieved in cancer cells via the silica-iron oxide nanovectors, which is thus a promising for biomedical applications.

Evaluation of functionalized mesoporous silica SBA-15 as a carrier system for Ph3Sn(CH2)3OH against the A2780 ovarian carcinoma cell line

SBA-15|Sn3, a mesoporous silica-based material (derivative of SBA-15) loaded with an organotin compound Ph₃Sn(CH₂)₃OH (Sn3), possesses improved antitumor potential against the A2780 high-grade serous ovarian carcinoma cell line in comparison to Sn3. It is demonstrated that both the compound and the nanostructured material are internalized by the A2780 cells. A similar mode of action of Sn3 and SBA-15|Sn3 against the A2780 cell line was found. Explicitly, induction of apoptosis, caspase 2, 3, 8 and 9 activation, accumulation of cells in the hypodiploid phase as well as accumulation of ROS were observed. Interestingly, Sn3 loaded in the mesoporous silica-based material needed to reach a concentration 3.5 times lower than the IC₅₀ value of the Sn3 compound, pointing out a higher effect of the SBA-15|Sn3 than Sn3 alone. Clonogenic potential, growth in 3D culture as well as mobility of cells were disturbed in the presence of SBA-15|Sn3. Such behavior could be associated with the suppression of p-38 MAPK. Less profound effect of Sn3 compared to SBA-15|Sn3 could be attributed to a different regulation of p-38 and STAT-3, which are mainly responsible for an appropriate cellular response to diverse stimuli or metastatic properties.

Protein-gold clusters-capped mesoporous silica nanoparticles for high drug loading, autonomous gemcitabine/doxorubicin co-delivery, and in-vivo tumor imaging

Functional nanocarriers capable of transporting high drug contents without premature leakage and to controllably deliver several drugs are needed for better cancer treatments. To address this clinical need, gold cluster bovine serum albumin (AuNC@BSA) nanogates were engineered on mesoporous silica nanoparticles (MSN) for high drug loadings and co-delivery of two different anticancer drugs. The first drug, gemcitabine (GEM, 40wt%), was loaded in positively-charged ammonium-functionalized MSN (MSN-NH3(+)). The second drug, doxorubicin (DOX, 32wt%), was bound with negatively-charged AuNC@BSA electrostatically-attached onto MSN-NH3(+), affording highly loaded pH-responsive MSN-AuNC@BSA nanocarriers. The co-delivery of DOX and GEM was achieved for the first time via an inorganic nanocarrier, possessing a zero-premature leakage behavior as well as drug loading capacities seven times higher than polymersome NPs. Besides, unlike the majority of strategies used to cap the pores of MSN, AuNC@BSA nanogates are biotools and were applied for targeted red nuclear staining and in-vivo tumor imaging. The straightforward non-covalent combination of MSN and gold-protein cluster bioconjugates thus leads to a simple, yet multifunctional nanotheranostic for the next generation of cancer treatments.