Facile Synthesis of Yolk-Shell-Structured Triple-Hybridized Periodic Mesoporous Organosilica Nanoparticles for Biomedicine

Custom-Design of Multi-Stimuli-Responsive Degradable Silica Nanoparticles for Advanced Cancer-Specific Chemotherapy

Chemotherapy is crucial in oncology for combating malignant tumors but often encounters obatacles such as severe adverse effects, drug resistance, and biocompatibility issues. The advantages of degradable silica nanoparticles in tumor diagnosis and treatment lie in their ability to target drug delivery, minimizing toxicity to normal tissues while enhancing therapeutic efficacy. Moreover, their responsiveness to both endogenous and exogenous stimuli opens up new possibilities for integrating multiple treatment modalities. This review scrutinizes the burgeoning utility of degradable silica nanoparticles in combination with chemotherapy and other treatment modalities. Commencing the elucidation of degradable silica synthesis and degradation mechanisms, emphasis is placed on the responsiveness of these materials to endogenous (e.g., pH, redox reactions, hypoxia, and enzymes) and exogenous stimuli (e.g., light and high-intensity focused ultrasound). Moreover, this exploration delves into strategies harnessing degradable silica nanoparticles in chemotherapy alone, coupled with radiotherapy, photothermal therapy, photodynamic therapy, gas therapy, immunotherapy, starvation therapy, and chemodynamic therapy, elucidating multimodal synergies. Concluding with an assessment of advances, challenges, and constraints in oncology, despite hurdles, future investigations are anticipated to augment the role of degradable silica in cancer therapy. These insights can serve as a compass for devising more efficacious combined tumor treatment strategies.

Silicon-containing nanomedicine and biomaterials: materials chemistry, multi-dimensional design, and biomedical application

The invention of silica-based bioactive glass in the late 1960s has sparked significant interest in exploring a wide range of silicon-containing biomaterials from the macroscale to the nanoscale. Over the past few decades, these biomaterials have been extensively explored for their potential in diverse biomedical applications, considering their remarkable bioactivity, excellent biocompatibility, facile surface functionalization, controllable synthesis, etc. However, to expedite the clinical translation and the unexpected utilization of silicon-composed nanomedicine and biomaterials, it is highly desirable to achieve a thorough comprehension of their characteristics and biological effects from an overall perspective. In this review, we provide a comprehensive discussion on the state-of-the-art progress of silicon-composed biomaterials, including their classification, characteristics, fabrication methods, and versatile biomedical applications. Additionally, we highlight the multi-dimensional design of both pure and hybrid silicon-composed nanomedicine and biomaterials and their intrinsic biological effects and interactions with biological systems. Their extensive biomedical applications span from drug delivery and bioimaging to therapeutic interventions and regenerative medicine, showcasing the significance of their rational design and fabrication to meet specific requirements and optimize their theranostic performance. Additionally, we offer insights into the future prospects and potential challenges regarding silicon-composed nanomedicine and biomaterials. By shedding light on these exciting research advances, we aspire to foster further progress in the biomedical field and drive the development of innovative silicon-composed nanomedicine and biomaterials with transformative applications in biomedicine.

Mitochondria-Targeting and Oxygen Self-Supplying Eccentric Hollow Nanoplatform for Enhanced Breast Cancer Photodynamic Therapy

Photodynamic therapy (PDT) has received increasing attention for tumor therapy due to its minimal invasiveness and spatiotemporal selectivity. However, the poor targeting of photosensitizer and hypoxia of the tumor microenvironment limit the PDT efficacy. Herein, eccentric hollow mesoporous organic silica nanoparticles (EHMONs) are prepared by anisotropic encapsulation and hydrothermal etching for constructing PDT nanoplatforms with targeting and hypoxia-alleviating properties. The prepared EHMONs possess a unique eccentric hollow structure, a uniform size (300 nm), a large cavity, and ordered mesoporous channels (2.3 nm). The EHMONs are modified with the mitochondria-targeting molecule triphenylphosphine (CTPP) and photosensitizers chlorin e6 (Ce6). Oxygen-carrying compound perfluorocarbons (PFCs) are further loaded in the internal cavity of EHMONs. Hemolytic assays and in vitro toxicity experiments show that the EHMONs-Ce6-CTPP possesses very good biocompatibility and can target mitochondria of triple-negative breast cancer, thus increasing the accumulation of photosensitizers Ce6 at mitochondria after entering cancer cells. The EHMONs-Ce6-CTPP@PFCs with oxygen-carrying ability can alleviate hypoxia after entering in the cancer cell. Phantom and cellular experiments show that the EHMONs-Ce6-CTPP@PFCs produce more singlet oxygen reactive oxygen species (ROSs). Thus, in vitro and in vivo experiments demonstrated that the EHMONs-Ce6-CTPP@PFCs showed excellent treatment effects for triple-negative breast cancer. This research provides a new method for a targeting and oxygen-carrying nanoplatform for enhancing PDF effectiveness.

Asymmetric Monolayer Mesoporous Nanosheets of Regularly Arranged Semi-Opened Pores via a Dual-Emulsion-Directed Micelle Assembly

Constructing asymmetric two-dimensional (2D) mesoporous nanomaterials with new pore structure, tunable monolayer architectures, and especially anisotropic surfaces remains a great challenge in materials science. Here, we report a dual-emulsion directed micelle assembly approach to fabricate a novel type of asymmetric monolayer mesoporous organosilica nanosheet for the first time. In this asymmetric 2D structure, numerous quasi-spherical semiopened mesopores (∼20 nm in diameter, 24 nm in opening size) were regularly arranged on a plane, endowing the porous nanosheets (several micrometers in size) with a typical surface anisotropy on two sides. Meanwhile, lots of triangular intervoids (4.0-5.0 nm in size) can also be found among each three semiopened mesopores, enabling the nanosheet to be interconnected. Vitally, such interconnected, anisotropic porous nanosheets exhibit ultrahigh accessible surface area (∼714 m2 g-1) and good lipophilicity properties owing to the abundant semiopened mesopores. Additionally, besides the nanosheet, the configuration of the asymmetric porous structure can also be transformed into a microcapsule when controlling the emulsification size via a facile ultrasonic treatment. As a demonstration, we show that the asymmetric microcapsule shows a high demulsification efficiency (>98%) and cyclic stability (>6 recycle times). Our protocol opens up a new avenue for developing next-generation asymmetric mesoporous materials for various applications.

Biosynthesized Ag nanoparticles on urea-based periodic mesoporous organosilica enhance galegine content in Galega

The biological approach for synthesizing nanoparticles (NPs) using plant extracts is an efficient alternative to conventional physicochemical methods. Galegine, isolated from Galega (Galega officinalis L.), has anti-diabetic properties. In the present study, silver nanoparticles (AgNPs) loaded onto urea-based periodic mesoporous organosilica (AgNPs/Ur-PMO) were bio-synthesized using G. officinalis leaf extract. The synthesized NPs were characterized and confirmed via analysis methods. Different concentrations of biosynthesized AgNPs/Ur-PMO nanoparticles (0, 1, 5, 10, and 20 mg L^-1) were used as elicitors in cell suspension culture (CSC) of G. officinalis. The callus cells from hypocotyl explants were treated at their logarithmic growth phase (8^th d) and were collected at time intervals of 24, 72, 120, and 168 h. The viability and growth of cells were reduced (by 17% and 35%, respectively) at higher concentrations and longer treatments of AgNPs/Ur-PMO; however, the contents of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) were increased (1.23 and 3.01 fold, respectively in comparison with the control average). The highest total phenolic (2.43 mg g^-1 dry weight) and flavonoid (2.22 mg g^-1 dry weight) contents were obtained 168 h after treatment with 10 mg L^-1 AgNPs/Ur-PMO. An increasing tendency in the antioxidant enzyme activities was also observed in all the elicitor concentrations. Treatment with AgNPs/Ur-PMO (in particular 5 mg L^-1 for 120 h) significantly enhanced the galegine content (up to 17.42 mg g^-1) about 1.80 fold compared with the control. The results suggest that AgNPs/Ur-PMO can be used as an effective elicitor for enhancing galegine production in the CSC of G. officinalis. KEY POINTS: • The green biosynthesis of AgNPs/Ur-PMO was done using G. officinalis leaf extract • Its toxicity as an elicitor increased with increasing concentration and treatment time • AgNPs/Ur-PMO significantly increased the antioxidant capacity and galegine content.

Gadolinium-hybridized mesoporous organosilica nanoparticles with high magnetic resonance imaging performance for targeted drug delivery

Magnetic resonance (MR) imaging techniques, which can provide images with excellent anatomical detail, are widely used in clinical diagnosis. However, the current clinical small molecule gadolinium (Gd) contrast agents have the defects of relatively low sensitivity and poor tumor-target specificity, preventing their adoption in biology and medicine. Herein, a facile synthetic strategy to fabricate gadolinium-hybridized mesoporous organosilica nanoparticles (MOSG) through a nanoprecipitation reaction, with the surface of nanoparticles grafted with the fluorescent dye isothiocyanate (FITC) and arginine-glycine-aspartic acid (RGD) for delivery of the antitumour drug doxorubicin hydrochloride (DOX), resulting in a high-performance nanotheranostic (RGD-MOSG-FITC/DOX) for targeted magnetic resonance imaging and chemotherapy of tumors. The prepared MOSG had a particle size of 60-80 nm and gadolinium elements were distributed in clusters that exhibited boosted longitudinal relaxivity. Routine blood tests and histopathology indicated good biocompatibility of MOSG. Furthermore, after being decorated with Arg-Gly-Asp peptide (RGD), RGD-MOSG-FITC demonstrated more preferable cellular uptake by HeLa cells (high expression of α_Ⅴβ₃) than MOSG without RGD grafting. Additionally, the tumor growth inhibition effect of RGD-MOSG-FITC/DOX was substantially more effective than that of the other groups. Therefore, this new delivery platform has good application potential in the field of tumor diagnosis and treatment.

Design and characterization of an urea-bridged PMO supporting Cu(II) nanoparticles as highly efficient heterogeneous catalyst for synthesis of tetrazole derivatives

In this work, a new periodic mesoporous organosilica with urea-bridges produced by the reaction of (3-aminopropyl)triethoxysilane and toluene-2,4-diisocyanate (APS-TDU-PMO) is introduced. The obtained APS-TDU-PMO was found to be an appropriate support for loading of Cu(II) nanoparticles to afford supramolecular Cu@APS-TDU-PMO nanocomposite. Uniformity and mesoporosity of both synthesized nanomaterials including APS-TDU-PMO and Cu@APS-TDU-PMO were proved by different spectroscopic, microscopic or analytical techniques including FTIR, EDX, XRD, FESEM, TEM, BET, TGA and DTA. Furthermore, the prepared Cu@APS-TDU-PMO nanomaterial was also used, as a heterogeneous and recyclable catalyst, for the synthesis of tetrazole derivatives through cascade condensation, concerted cycloaddition and tautomerization reactions. Indeed, the main advantages of this Cu@APS-TDU-PMO is its simple preparation and high catalytic activity as well as proper surface area which enable it to work under solvent-free conditions. Also, the introduced Cu@APS-TDU-PMO heterogeneous catalyst showed good stability and reusability for six consecutive runs to address more green chemistry principles.

Perturbation of autophagy: An intrinsic toxicity mechanism of nanoparticles

Nanoparticles (NPs) have been widely used for various purposes due to their unique physicochemical properties. Such widespread applications greatly increase the possibility of human exposure to NPs in various ways. Once entering the human body, NPs may interfere with cellular homeostasis and thus affect the physiological system. As a result, it is necessary to evaluate the potential disturbance of NPs to multiple cell functions, including autophagy. Autophagy is an important cell function to maintain cellular homeostasis, and minimizing the disturbance caused by NP exposures to autophagy is critical to nanosafety. Herein, we summarized the recent research progress in nanotoxicity with particular focuses on the perturbation of NPs to cell autophagy. The basic processes of autophagy and complex relationships between autophagy and major human diseases were further discussed to emphasize the importance of keeping autophagy under control. Moreover, the most recent advances on perturbation of different types of NPs to autophagy were also reviewed. Last but not least, we also discussed major research challenges and potential coping strategies and proposed a safe-by-design strategy towards safer applications of NPs.

Dual nanoenzymes loaded hollow mesoporous organotantalum nanospheres for chemo-radio sensitization

Chemo-radiotherapy has been extensively used in clinics, displaying substantial advantages in treatment and prognosis. Stimuli-responsive biodegradable nanoagents that can achieve not only delivery and controlled release of chemotherapeutics, but also hypoxia alleviation to enhance chemoradiotherapy therefore has tremendous potential. Herein, glutathione (GSH)-responsive, biodegradable, doxorubicin-carrying hollow mesoporous organotantalum nanospheres modified with Au and Pt dual nanoenzymes (HMOTP@Pt@Au@Dox) were constructed for chemo-radio sensitization. Degradation of HMOTP@Pt@Au@Dox can be self-activated through GSH stimulation and on-demand release packaged Dox owing to the disulfide bond in the hybrid framework of organotantalum nanospheres. Au and Pt nanoenzymes triggered cascade catalytic reactions that could alleviate hypoxia by utilizing β-d-glucose and H₂O₂, thereby sensitizing ROS-based chemoradiotherapy with synergistic starving therapy. Given the radiosensitization of high-Z elements (Ta, Pt, Au), nanoenzymes induced cascade catalytic reaction for hypoxia relief, and the depletion of the predominant antioxidant GSH, desirable tumor suppression could be achieved both in vitro and in vivo, indicating that HMOTP@Pt@Au@Dox is a promising nanoagent to boost chemo-radiotherapy.

TRAIL-modified, doxorubicin-embedded periodic mesoporous organosilica nanoparticles for targeted drug delivery and efficient antitumor immunotherapy

Traditional anticancer treatments directly target tumor cells. In contrast, cancer immunotherapy fortifies host immunity. Nanoparticles that incorporate both immunomodulatory and chemotherapeutic agents regulate the tumor microenvironment by activating immune cells and enhancing antitumor immunity. Nanoparticle-based cancer immunotherapy has received considerable attention and has been extensively studied in recent years. In this study, we developed a targeted drug delivery system to enhance immunotherapeutic efficacy and overcome drug resistance by inducing tumor apoptosis and immunogenic cell death (ICD), and activating immune cells. Periodic mesoporous organosilica nanoparticles (PMOs) bore tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) on their surfaces, and their inner cores were loaded with doxorubicin (DOX). TRAIL enhanced the nanoparticle-targeting capacity and worked synergistically with DOX against breast cancer cells in vitro and in vivo. Furthermore, we revealed for the first time the ability of PMOs to activate dendritic cells (DCs) and elevate ICD levels of DOX in vitro, and TRAIL further enhances the immunomodulatory function of PMOs. Systemic exposure to DOX@PMO-hT induced an immune response, activated DCs and CD4⁺ and CD8⁺ T cells, and significantly suppressed tumor growth in a 4T1-bearing immunocompetent mouse model. Overall, our study demonstrates that TRAIL-modified, DOX-embedded PMO nanoparticles represent a good candidate for tumor-targeted immunotherapy, which has relatively superior therapeutic efficacy and highly promising future application prospects. STATEMENT OF SIGNIFICANCE: This study revealed for the first time the ability of PMOs to elevate ICD levels and activate DCs in vitro. The results explained the immunomodulatory function of PMOs and demonstrated the synergistic effects of TRAIL and DOX in triple-negative breast cancer. In addition, immunomodulatory effects of the drug delivery vectors constructed in this study were verified in vivo.

Periodic mesoporous organosilica coupled with chlorin e6 and catalase for enhanced photodynamic therapy to treat triple-negative breast cancer

Photodynamic therapy (PDT) has become a promising treatment option for highly aggressive triple-negative breast cancer (TNBC); however, hypoxia limits the efficacy of PDT and promotes tumour aggression. In this work, we first constructed a multifunctional yolk-shell structured nanoplatform consisting of periodic mesoporous organosilica (PMO) coupled with chlorin e6 (Ce6) and catalase (Catalase) (Yolk-Shell PMO-Ce6@Catalase) for enhanced PDT against TNBC. This nanoplatform has an organic-inorganic hybrid skeleton structure, a uniform size and good stability and biocompatibility. In vitro experiments showed that the nanoplatform has a good ability to generate singlet oxygen. Catalase can convert H₂O₂ into O₂, increasing the concentration of oxygen around the cells and overcoming the problem of hypoxia in the tumour, which enhances the effects of PDT. The in vivo experimental results showed that PDT with the Yolk-Shell PMO-Ce6@Catalase nanoplatform, compared with free Ce6 and Yolk-Shell PMO-Ce6 PDT, can significantly inhibit tumour growth, revealing the most extensive cellular apoptosis and necrosis in the tumour area in this treatment group. Additionally, the histopathological results showed that PDT did not cause significant side effects to the major organs. Therefore, we believe that this Yolk-Shell PMO-Ce6@Catalase nanoplatform has excellent clinical potential for PDT against TNBC.

Self-transformation synthesis of hierarchically porous benzene-bridged organosilica nanoparticles for efficient drug delivery

Herein, a feasible outside-in hydrothermal self-transformation strategy is presented to fabricate hierarchically porous benzene-bridged organosilica nanoparticles (HPBONs), and detailed mechanistic investigations were performed to study the formation of hierarchically porous nanostructures. The obtained HPBONs consisted of a mesoporous core (2.3 nm) and a large mesoporous flocculent shell (12.6 nm), which corresponded to an overall diameter of ∼ 200 nm and good water dispersibility, respectively. Owing to the unique hierarchically porous structure and high surface area (877 m²/g), HPBONs showed a high coloading capacity for the hydrophilic drug doxorubicin (DOX) and the hydrophobic photosensitizer chlorin e6 (Ce6) (355 µg/mg, 38 µg/mg, respectively) and acid-responsive DOX drug release (42.62%), leading to precise chemo-photodynamic therapy in vitro, as the cytotoxicity assay revealed 70% killing of breast cancer (MCF-7) cells. This research provides a new method to construct hierarchically porous organosilica-based nanodelivery systems.

Two-Dimensional Silicene/Silicon Nanosheets: An Emerging Silicon-Composed Nanostructure in Biomedicine

Silicon-composed nanomedicines are one of the most representative inorganic nanosystems in theranostic biomedicine. The emerging of new family members of silicon-composed nanosystems substantially contributes to their further clinical translation. 2D silicene/silicon nanosheets have recently been developed as an emerging topology of silicon-composed nanoparticles, which features unique planar nanostructure with large surface area, abundant surface chemistry, specific physiochemical property, and desirable biological effects. This progress report highlights and discusses the state-of-art developments of the elaborate construction of 2D silicene/silicon nanosheets for versatile biomedical applications, including top-down fabrication, multifunctionalization, surface engineering, and their available biomedical applications in tumor theranostics (e.g., bioimaging, photothermal ablation, chemotherapy, chemoreactive nanotherapy, radiotherapy, and synergistic nanotherapy) and antibacteria. Their large surface area originating from 2D nanostructure not only enables efficient loading and delivery of chemotherapeutic drugs, but also guarantees the multifunctionalization. Especially, 2D silicene/silicon nanosheets harness desirable photothermal-conversion performance for photonic hyperthermia and photoacoustic imaging in the near infrared biowindow, accompanied with the desirable biodegradability and biocompatibility, which is typically not possessed in other silicon-composed counterparts. The multivariate analysis on the facing challenges and future developments of these 2D silicene/silicon nanosheets have also been conducted and outlooked for further underpinning their clinical translations.

Organic Hollow Mesoporous Silica as a Promising Sandalwood Essential Oil Carrier

As film-forming agents, fillers and adsorbents, microplastics are often added to daily personal care products. Because of their chemical stability, they remain in the environment for thousands of years, endangering the safety of the environment and human health. Therefore, it is urgent to find an environmentally friendly substitute for microplastics. Using n-octyltrimethoxysilane (OTMS) and tetraethoxysilane (TEOS) as silicon sources, a novel, environmentally friendly, organic hollow mesoporous silica system is designed with a high loading capacity and excellent adsorption characteristics in this work. In our methodology, sandalwood essential oil (SEO) was successfully loaded into the nanoparticle cavities, and was involved in the formation of Pickering emulsion as well, with a content of up to 40% (w/w). The developed system was a stable carrier for the dispersion of SEO in water. This system can not only overcome the shortcomings of poor water solubility and volatility of sandalwood essential oil, but also act as a microplastic substitute with broad prospects in the cosmetics and personal care industry, laying a foundation for the preparation and applications of high loading capacity microcapsules in aqueous media.

Intricately structured mesoporous organosilica nanoparticles: synthesis strategies and biomedical applications

Intricately structured mesoporous organosilica nanoparticles (IMONs) are being increasingly studied from their synthesis strategies to their use in biomedical applications, because of their distinctive hierarchical structures, excellent physicochemical features and satisfactory biological properties. This minireview is the first to summarize recently developed IMONs, including yolk-shell-structured nanoparticles, multi-shelled hollow spheres, deformable nanocapsules, Janus nanostructures and virus-like bionic-structured nanocarriers, and describe the corresponding formation mechanisms and recent evolution of the strategies used to synthesize these kinds of IMONs. Structure-dependent biomedical applications, such as multidrug delivery, bioimaging, synergistic therapy and biocatalysis, are also discussed. Finally, we provide an outlook for IMONs ranging from their structural control to synthesis strategies and ending with their use in biomedical applications.

Polymer-Scaffolded Synthesis of Periodic Mesoporous Organosilica Nanomaterials for Delivery Systems in Cancer Cells

We developed four types of para-phenylene-bridged periodic mesoporous organosilica NPs (p-P PMO NPs) with tailored physical parameters including size, morphology, porosity, and surface area using a new polymer-scaffolding approach. The particles have been formulated to facilitate the codelivery of small-molecule hydrophobic/hydrophilic cargos such as model anticancer drugs (i.e., doxorubicin hydrochloride (DOX) and O⁶-benzylguanine) and model fluorescent dyes (i.e., rhodamine 6G and Nile red). p-P PMO NPs were synthesized via a cetyltrimethylammonium bromide (CTAB)-directed sol-gel process using two different organic solvents and in the presence of polymeric scaffolding constituents that led to morphologically distinct PMO NPs despite using the same organosilane precursors. After the formulation process, the polymeric scaffolding agent was conveniently washed away from the PMO NPs. Extensive analyses were used to characterize the physicochemical attributes of the PMO NPs such as their chemical composition, morphologies, etc. Spherical and rod-shaped PMOs of diameters ranging between 79 and 342 nm, surface areas between 770 and 1060 m²/g, and pore volumes between 0.79 and 1.37 cm³/g were prepared using the polymer-scaffolding approach. The performance of these materials toward drug-loading capacity, cytotoxicity, and cancer cell internalization was evaluated. Interestingly, the designed particles exhibited significantly high payloads of drugs and dyes (up to 78 and 94%, respectively). Cellular studies also demonstrated exceptional biocompatibility and marked internalization into both human breast cancer MCF-7 and glioblastoma U-87 MG cells. Further, DOX also possessed a noticeable release from particles and accumulation in cell nuclei with increased incubation time in vitro. Ultimately, this work validates the controlled design and synthesis of PMO NPs using a polymer-scaffolding approach and highlights the potential of these materials as excellent delivery systems for combination therapy with high loading capability to improve the therapeutic index for cancers.

Recent Trends in Morphology-Controlled Synthesis and Application of Mesoporous Silica Nanoparticles

The outstanding journey towards the investigation of mesoporous materials commences with the discovery of high surface area porous silica materials, named MCM-41 (Mobil Composition of Matter-41) according to the inventors' name Mobile scientists in the United States. Based on a self-assembled supramolecular templating mechanism, the synthesis of mesoporous silica has extended to wide varieties of silica categories along with versatile applications of all these types in many fields. These silica families have some extraordinary structural features, like highly tunable nanoscale sized pore diameter, good Brunauer-Emmett-Teller (BET) surface areas, good flexibility to accommodate different organic and inorganic functional groups, metals etc., onto their surface. As a consequence, thousands of scientists and researchers throughout the world have reported numerous silica materials in the form of published articles, communication, reviews, etc. Beside this, attention is also given to the morphology-oriented synthesis of silica nanoparticles and their significant effects on the emerging fields of study like catalysis, energy applications, sensing, environmental, and biomedical research. This review highlights a consolidated overview of those morphology-based mesoporous silica particles, emphasizing their syntheses and potential role in many promising fields of research.

Mesoporous silica nanoparticles: facile surface functionalization and versatile biomedical applications in oncology

Mesoporous silica nanoparticles (MSNs) have received increasing interest due to their tunable particle size, large surface area, stable framework, and easy surface modification. They are increasingly being used in varying applications as delivery vehicles including bio-imaging, drug delivery, biosensors and tissue engineering etc. Precise structure control and the ability to modify surface properties of MSNs are important for their applications. This review summarises the different synthetic methods for the preparation of well-ordered MSNs with tunable pore volume as well as the approaches of drugs loading, especially highlighting the facile surface functionalization for various purposes and versatile biomedical applications in oncology. Finally, the challenges of clinical transformation of MSNs-based nanomedicines are further discussed.

Controllable synthesis of versatile mesoporous organosilica nanoparticles as precision cancer theranostics

Despite the advantages of mesoporous silica nanoparticles (MSNs) in drug delivery, the inherent non-biodegradability seriously impedes the clinical translation of inorganic MSNs, so the current research focus has been turned to mesoporous organosilica nanoparticles (MONs) with higher biocompatibility and easier biodegradability. Recent remarkable advances in silica fabrication chemistry have catalyzed the emergence of a library of MONs with various structures and functions. This review will summarize the latest state-of-the-art studies on the precise control of morphology, structure, framework, particle size and pore size of MONs, which enables the precise synthesis of MONs with suitable engineering for precision stimuli-responsive drug delivery/release, bioimaging and synergistic therapy. Besides, the potential challenges about the future development of MONs are also outlooked with the intention of attracting more researchers to promote the clinical translation of MONs.

Hydrophobicity-Tuned Periodic Mesoporous Organo-Silica Nanoparticles for Photodynamic Therapy

Since their invention, periodic mesoporous organosilicas (PMOs), an innovative class of materials based on organic as well as inorganic hybrid nanocomposites, have gathered enormous interest owing to their advantageous physicochemical attributes over the pristine mesoporous silica nanoparticles (MSNs). To further increase the interactions with the therapeutic guest species and subsequent compatibility as well as the physicochemical properties of PMOs, we demonstrate the post-hydroxylation of benzene-bridged PMO-based nanoparticles for photodynamic therapy (PDT). Initially, the hydrophobic benzene group in the PMO framework is modified through electrophilic substitution-assisted hydroxylation mediated by Fenton as well as Fenton-like reactions utilizing divalent and trivalent metal salts, respectively. These post-grafted PMOs with tuned hydrophobicity resulted in improved biocompatibility as well as drug loading efficiency through governing the interactions in host-guest chemistry by changing the physicochemical properties of the PMO frameworks. Furthermore, the photosensitizer, protoporphyrin IX (PpIX) molecules, encapsulated in the PMO frameworks showed a significant PDT effect in colon carcinoma (HT-29 cell line) and Gram-negative bacterial strain, Escherichia coli (E. coli). Furthermore, the light-induced cytotoxic properties in vitro are confirmed by various tests, including lactate dehydrogenase (LDH) assay for cell membrane damage and caspase assay for apoptosis determination. Indeed, the delivered PpIX molecules from PMOs generated deadly singlet oxygen species intracellularly under visible light irradiation, resulting in cell death through concomitantly triggered apoptotic caspases. Together, our findings demonstrate that this post-modified PMO design is highly advantageous and can be used as an effective PDT platform.

Overview of stimuli-responsive mesoporous organosilica nanocarriers for drug delivery

The application of nanomaterials is regarded nowadays as a highly promising approach for overcoming the limitations of the currently available cancer treatments, contributing for the creation of more effective, precise, and safer therapies. In the last years, organosilica nanoparticles arisen as alternatives to the most common mesoporous silica nanoparticles. The organosilica nanoparticles combine the advantages of the mesoporous silica, such as structural stability and mesoporous structure, with the increased biocompatibility and biodegradability of organic materials. Therefore, the variety of organic bridges that can be incorporated into the silica matrix allowed the development of new and exciting compositions, properties, and functions for improving the therapeutic effectiveness of the anticancer nanomedicines. In this review, the strategies that have been explored to create stimuli-responsive organosilica-based drug delivery systems are highlighted, describing the practical approaches and mechanisms controlling the drug release. Additionally, the organosilica nanoparticles surface modifications aimed for increasing the blood circulation time and the tumor targeting are also described.

Synthesis and Characterization of Novel Pyridine Periodic Mesoporous Organosilicas and Its Catalytic Activity in the Knoevenagel Condensation Reaction

The preparation of novel organic-inorganic hybrid mesoporous organosilica containing pyridinedicarboxamide functional groups uniformly distributed inside the nanostructured pore walls has been addressed. The mesoporosity and uniformity of the synthesized nanomaterials were characterized by different techniques such as nitrogen adsorption/desorption measurements and powder X-ray diffraction (PXRD). Additionally, the presence of the pyridinedicarboxamide in the pore walls of the nanomaterials was assessed by Fourier-transform infrared spectroscopy (FT-IR), as well as ²⁹Si and ¹³C solid-state cross-polarization and magic angle spinning nuclear magnetic resonance (CP/MAS-NMR). The Knoevenagel condensation of aldehydes with active methylene compounds was carried out over the pyridinedicarboxamide functionalized mesoporous organosilica, which has been proven to be an efficient heterogeneous basic catalyst in the presence of ethanol as solvent. The catalytic activity of the investigated materials was investigated in the Knoevenagel condensation between malononitrile and several benzaldehyde derivatives exhibiting a high conversion (>90%) and excellent selectivity toward the final condensation products under very mild reaction conditions. Furthermore, the catalyst stability is noteworthy as it could be recycled and reused at least twelve times without any significant change in the performance.

One-pot synthesis of highly active and hydrothermally stable Pd@mHSiO2 yolk-shell-structured nanoparticles for high-temperature reactions in hydrothermal environments

The facile synthesis of yolk-shell-structured nanoparticles (YSNPs) with mobile active metal cores and mesoporous inorganic-organic hybrid silica shells (mHSiO2) is important for their applications. In this work, Pd@mHSiO2 YSNPs have been synthesized in aqueous solution at 95 °C by a one-pot method without the need for extensive purification and separation steps. The method is simple and facile, and ingeniously combines the controlled synthesis of Pd nanocubes, coating of mesoporous silica, and transition from core-shell-structured nanoparticles (CSNPs) to YSNPs. 29Si NMR spectroscopy, FTIR spectroscopy, and detailed control experiments have demonstrated that the incorporation of 1,2-bis(trimethoxysilyl)ethane (BTME) modifies the degree of condensation between the outer hybrid silica layer and the inner pure silica section, and that high temperature water is really responsible for dissolving the inner pure silica layer leading to a transition from the CSNPs to the YSNPs. The obtained Pd@mHSiO2 YSNPs have a controllable diameter, tunable shell thickness, a high specific surface area, and uniform mesoporosity. Thermal stability tests have indicated that the Pd@mHSiO2 YSNPs are remarkably stable at high temperatures up to 650 °C. Importantly, the Pd@mHSiO2 YSNPs exhibit a much higher catalytic activity and hydrothermal stability than Pd@mSiO2 CSNPs or Pd/mHSiO2 NSs in the conversion of levulinic acid (LA) into γ-valerolactone (GVL), because the hollow voids provide low mass-transfer resistance and improve the accessibility of the catalytic sites, and the incorporation of organic groups enhances the hydrothermal stability of the outer shell.

Polydopamine-doped virus-like structured nanoparticles for photoacoustic imaging guided synergistic chemo-/photothermal therapy

The therapeutic diagnosis effect of cancer commonly depends on the cellular uptake efficiency of nanomaterials. However, the morphology of nanomaterials significantly affects cellular uptake capability. Herein, we designed a polydopamine-doped virus-like structured nanoparticle (GNR@HPMO@PVMSN) composed of a gold nanorod (GNR) core, hollow periodic mesoporous organosilica (HPMO) shell and polydopamine-doped virus-like mesoporous silica nanoparticle (PVMSN) outer shell. Compared with conventional gold nanorod@hollow periodic mesoporous organosilica core–shell nanoparticles (GNR@HPMO), GNR@HPMO@PVMSN with its virus-like structure was proved to enhance the efficiency of cellular uptake. GNR@HPMO@PVMSN with the virtues of high photothermal conversion efficiency and good photoacoustic imaging (PAI) ability was expected to be a promising nanotheranostic agent for imaging guided cancer treatment. The experiments in vitro and in vivo proved that GNR@HPMO@PVMSN had good biocompatibility as well as photothermal conversion ability. In addition, DOX loading and pH-/NIR-response DOX release abilities of GNR@HPMO@PVMSN were also verified in vitro. Therefore, the GNR@HPMO@PVMSN offers a promising strategy for PAI directed synergistic chemo-/photothermal therapy, which improves the therapeutic effect of the nanomaterial on tumors. This work explores the effects of rough surfaces on cellular uptake and provides a versatile theranostic platform for biomedical applications.

The therapeutic diagnosis effect of cancer commonly depends on the cellular uptake efficiency of nanomaterials.

Mesoporous Organosilica Hollow Nanoparticles: Synthesis and Applications

Hollow periodic mesoporous organosilicas (PMOs) with molecularly homogeneous organic functional groups in the inorganic pore walls are attracting more and more attention due to the high surface areas, tunable pore sizes, low densities, large cavities in the center, permeable thin shells, and versatile organic-inorganic hybrid frameworks, which make them promising in a variety of applications including adsorption, catalysis, drug delivery, and nanotheranostics. Herein, recent advances in the synthesis of hollow PMO nanoparticles with various organic moieties are summarized, and the mechanism and new insights of synthesis approaches, including hard-core templating methods, liquid-interface assembly methods, and the interfacial reassembly and transformation strategy are discussed in-depth. Meanwhile, the design principles, properties, and synthetic strategies for some smart hollow architectures such as multishelled hollow PMOs, yolk-shell structured PMOs, and nonspherical hollow PMOs are discussed. Moreover, the typical applications of hollow PMO nanomaterials as nanoreactors for chemical transformations and nanoplatforms for biomedicine are summarized. Finally, the challenges and prospects for the future development of hollow PMOs are described.

Dual Bond Enhanced Multidimensional Constructed Composite Silicon Anode for High-Performance Lithium Ion Batteries

The development of silicon-based anode materials is important for improving the energy density of current lithium ion batteries. However, there are still strong demands for these materials with better cycle stability and higher reversible capacity. Here, a kind of dual bond restricted MXene-Si-CNT composite anode materials with enhanced electrochemical performance is reported. These dual bonds have been clearly revealed by an X-ray photoelectron spectroscopy technique and also proven by theoretical calculations with spontaneous reaction energy values (-0.190 and -0.429 eV/atom for Ti-Si and C-Si bonds, respectively). The cycle stability of the composites, prepared by a facile ball-milling synthetic method, can obviously be improved because of the existence of these dual bonds and the multidimensional constructed architecture. The MXene-Si-CNT composite with 60 wt % silicon possesses the best overall performance, with ∼80% capacity retention after 200 cycles, and achieves 841 mAh g^-1 at 2 A g^-1. This approach demonstrates a promising strategy to exploit high-performance anode materials and lessens the immanent negative effect of silicon-based materials. Furthermore, it is significant to extend this method to other anode materials with serious volumetric change problems during the cycling process.

Simultaneous T Cell Activation and Macrophage Polarization to Promote Potent Tumor Suppression by Iron Oxide-Embedded Large-Pore Mesoporous Organosilica Core-Shell Nanospheres

Nanomaterial-based immunotherapy stimulating T cell activation or tumor-associated macrophage (TAM) conversion holds great promise for promoting tumor suppression. Herein, a novel nanoplatform, iron oxide-embedded large-pore mesoporous organosilica nanospheres (IO-LPMONs), is prepared for the first time to simultaneously activate cytotoxic T cells and polarize macrophages for potent tumor immunotherapy. The IO-LPMONs have large mesopores (6.3 nm) and inorganic-organic hybrid shells, which contribute to a high payload (500 µg mg^-1 ) of the antigen ovalbumin (OVA). The IO-LPMONs effectively deliver OVA to dendritic cells (DCs) and activate DCs. Subsequently, high activation of both CD4⁺ and CD8⁺ effector antigen-specific T cells is achieved for powerful antitumor effects. Moreover, the IO-LPMONs also act as an immune modulator to polarize TAMs from an immunosuppressive M2 to a tumor-killing M1 phenotype, which induces efficient apoptosis of tumor cells. The combined T cell activation and macrophage polarization strategy based on the IO-LPMONs elicits remarkable combined antitumor effects in vivo, showing great promise for tumor treatment.

Ultrasound/Acidity-Triggered and Nanoparticle-Enabled Analgesia

Local anesthetics have been extensively employed to treat postoperative pain, but they generally suffer from short acting duration and potential neurotoxicity under high local concentrations, which require the controlled and sustained releasing patterns of treatment drugs. In this work, it is reported, for the first time, the construction of hollow mesoporous organosilica nanoparticles (HMONs)-based nanoplatforms for localized delivery and controlled/sustained release of loaded ropivacaine for local anesthetics, which can be repeatedly triggered by either external ultrasound irradiation or acidity triggering to release the payload, causing on-demand and long-lasting analgesia. Based on the in vivo mouse model of incision pain, the controlled and sustained release of ropivacaine achieves more than six hours of continuous analgesia, which is almost three times longer as compared to single free ropivacaine injection. The low neurotoxicity and high biocompatibility of HMONs for nanoparticle-enabled analgesia are also demonstrated both in vitro and in vivo. This designed/constructed HMONs-based nanoplatform provides a potential methodology for clinical pain management via on-demand and long-lasting pain relief.

Facile Synthesis of Monodisperse Hollow Mesoporous Organosilica/Silica Nanospheres by an in Situ Dissolution and Reassembly Approach

Hollow structured mesoporous organosilicas are a research hotspot because of their molecularly organic-inorganic hybrid frameworks, large void spaces, permeable shells, high surface areas, uniform pores, and various applications. However, the previous reported hard-core templating method and liquid-interface assembly approach suffered from complex preparation procedures and poor uniformity for the products. In this work, we demonstrate an in situ dissolution and reassembly method to synthesize monodisperse benzene-bridged hollow mesoporous organosilica/silica nanoparticles (HMOSNs) by sequential addition of tetraethoxysilane (TEOS) and 1,4-bis(triethoxysilyl)benzene in a solution containing a cetyltrimethylammonium bromide (CTAB) surfactant. The formation of HMOSNs is completed in one pot, which is very effective and convenient. The formation mechanism of HMOSNs is ascribed to the fact that TEOS first assembles with CTAB to form mesostructured silica cores, which further dissolve and migrate to the outer layers during the deposition of mesostructured organosilica shells. The prepared benzene-bridged HMOSNs possess uniform diameter (140 nm), large pore volume (2.79 m³/g), high specific surface area (2926 m²/g), and a high doxorubicin-loading content of 16.7%. HMOSNs can deliver doxorubicin (Dox) into human breast cancer cells and reduce their excretion. Thus, the Dox-loaded HMOSNs show a high killing effect against the cancer cells.

Biodegradable Hollow Mesoporous Organosilica Nanotheranostics for Mild Hyperthermia-Induced Bubble-Enhanced Oxygen-Sensitized Radiotherapy

Alleviation of tumor hypoxia has been the premise for improving the effectiveness of radiotherapy, which hinges upon the advanced delivery and rapid release of oxygen within the tumor region. Herein, we propose a "bubble-enhanced oxygen diffusion" strategy to achieve whole tumor oxygenation for significant radiation enhancement based on the "bystander effect". Toward this end, sub-50 nm CuS-modified and ⁶⁴Cu-labeled hollow mesoporous organosilica nanoparticles were constructed for tumor-specific delivery of O₂-saturated perfluoropentane (PFP). Through the aid of PFP gasification arising from NIR laser-triggered mild hyperthermia, simultaneous PET/PA/US multimodality imaging and rapid oxygen diffusion across the tumor can be achieved for remarkable hypoxic radiosensitization. Furthermore, the multifunctional oxygen-carrying nanotheranostics also allow for other oxygen-dependent treatments, thus greatly advancing the development of bubble-enhanced synergistic therapy platforms.

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.

Timely coordinated phototherapy mediated by mesoporous organosilica coated triangular gold nanoprisms

Mesoporous organosilica coated triangular gold nanoprisms for timely coordinated phototherapy.

Biodegradable AIEgen-functionalised mesoporous bioactive glass nanoparticles for drug delivery and cell imaging

AIEgen-functionalised mesoporous bioactive glass nanospheres with excellent degradability in an acid environment show potential application in drug delivery and cell imaging.

Synthesis of pH-Responsive Biodegradable Mesoporous Silica-Calcium Phosphate Hybrid Nanoparticles as a High Potential Drug Carrier

Biodegradability is one of the most critical issues for silica-based nanodrug delivery systems because they are crucial prerequisites for the successful translation in clinics. In this work, a novel mesoporous silica-calcium phosphate (MS-CAP) hybrid nanocarrier with a fast pH-responsive biodegradation rate was developed by a one-step method, where CAP precursors (Ca²⁺ and PO₄^3-) were incorporated into silica matrix during the growth process. The morphology and structure of MS-CAP were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), N₂ adsorption-desorption isotherms, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Furthermore, the drug loading and the release behavior of MS-CAP have been tested. TEM and inductively coupled plasma-optical emission spectrometry results indicated that the pH-responsive biodegradation of MS-CAP was so fast that could be almost finished within 24 h owing to the easy dissolution of CAP embedded in the particle and the escape of Ca²⁺ from the structure of Si-O-Ca in acid environment. The MS-CAP exhibited a high doxorubicin (DOX) entrapment efficiency (EE) of 97.79%, which was about fourfold higher compared with that of pure mesoporous silica nanoparticles, and our density functional theory calculational results suggested that the higher drug EE of MS-CAP would originate from the strong interaction between calcium in the particle and carboxylate group of DOX. The loaded DOX was effectively released, with a cumulative release as high as 98.06% within 48 h at pH 4.5 in buffer solution, owing to the rapid degradation of MS-CAP. The obtained results indicated that the as-synthesized MS-CAP could act as a promising drug delivery system and would have a hopeful prospect in the clinical translation.