Synthesis and surface functionalization of silica nanoparticles for nanomedicine

Injectable Mechanophore Nanoparticles for Deep-Tissue Mechanochemical Dynamic Therapy

Photodynamic therapy (PDT) and sonodynamic therapy (SDT), using nonionizing light and ultrasound to generate reactive oxygen species, offer promising localized treatments for cancers. However, the effectiveness of PDT is hampered by inadequate tissue penetration, and SDT largely relies on pyrolysis and sonoluminescence, which may cause tissue injury and imprecise targeting. To address these issues, we have proposed a mechanochemical dynamic therapy (MDT) that uses free radicals generated from mechanophore-embedded polymers under mechanical stress to produce reactive oxygen species for cancer treatment. Yet, their application in vivo is constrained by the bulk form of the polymer and the need for high ultrasound intensities for activation. In this study, we developed injectable, nanoscale mechanophore particles with enhanced ultrasound sensitivity by leveraging a core-shell structure comprising silica nanoparticles (NPs) whose interfaces are linked to polymer brushes by an azo mechanophore moiety. Upon focused ultrasound (FUS) treatment, this injectable NP generates reactive oxygen species (ROS), demonstrating promising results in both an in vitro 4T1 cell model and an in vivo mouse model of orthotopic breast cancers. This research offers an alternative therapy technique, integrating force-responsive azo mechanophores and FUS under biocompatible conditions.

Pickering Emulsions Biocatalysis: Recent Developments and Emerging Trends

Biocatalysis within biphasic systems is gaining significant attention in the field of synthetic chemistry, primarily for its ability to solve the problem of incompatible solubilities between biocatalysts and organic compounds. By forming an emulsion from these two-phase systems, a larger surface area is created, which greatly improves the mass transfer of substrates to the biocatalysts. Among the various types of emulsions, Pickering emulsions stand out due to their excellent stability, compatibility with biological substances, and the ease with which they can be formed and separated. This makes them ideal for reusing both the emulsifiers and the biocatalysts. This review explores the latest developments in biocatalysis using Pickering emulsions. It covers the structural features, methods of creation, innovations in flow biocatalysis, and the role of interfaces in these processes. Additionally, the challenges and future directions are discussed in combining chemical and biological catalysts within Pickering emulsion frameworks to advance synthetic methodologies.

Artificial intelligence in nanotechnology for treatment of diseases

Nano-based drug delivery systems (DDSs) have demonstrated the ability to address challenges posed by therapeutic agents, enhancing drug efficiency and reducing side effects. Various nanoparticles (NPs) are utilised as DDSs with unique characteristics, leading to diverse applications across different diseases. However, the complexity, cost and time-consuming nature of laboratory processes, the large volume of data, and the challenges in data analysis have prompted the integration of artificial intelligence (AI) tools. AI has been employed in designing, characterising and manufacturing drug delivery nanosystems, as well as in predicting treatment efficiency. AI's potential to personalise drug delivery based on individual patient factors, optimise formulation design and predict drug properties has been highlighted. By leveraging AI and large datasets, developing safe and effective DDSs can be accelerated, ultimately improving patient outcomes and advancing pharmaceutical sciences. This review article investigates the role of AI in the development of nano-DDSs, with a focus on their therapeutic applications. The use of AI in DDSs has the potential to revolutionise treatment optimisation and improve patient care.

Exploring the influence of silicon oxide microchips shape on cellular uptake using imaging flow cytometry

Nano- and micro-carriers of therapeutic molecules offer numerous advantages for drug delivery, and the shape of these particles plays a vital role in their biodistribution and their interaction with cells. However, analysing how microparticles are taken up by cells presents methodological challenges. Qualitative methods like microscopy provide detailed imaging but are time-consuming, whereas quantitative methods such as flow cytometry enable high-throughput analysis but struggle to differentiate between internalised and surface-bound particles. Instead, imaging flow cytometry combines the best of both worlds, offering high-resolution imaging with the efficiency of flow cytometry, allowing for quantitative analysis at the single-cell level. This study focuses on fluorescently labelled silicon oxide microchips of various morphologies but related surface areas and volumes: rectangular cuboids and apex-truncated square pyramid microchips fabricated using photolithography techniques, offering a reliable basis for comparison with the more commonly studied spherical particles. Imaging flow cytometry was utilised to evaluate the effect of particle shape on cellular uptake using RAW 264.7 cells and revealed phagocytosis of particles with all shapes. Increasing the particle dose enhanced the uptake, while macrophage stimulation had minimal effect. Using a ratio particle:cell of 10:1 cuboids and spheres showed an uptake rate of approximately 50%, in terms of the percentage of cells with internalised particles, and the average number of particles taken up per cell ranging from about 1-1.5 particle/cell for all the different shapes. This study indicates how differently shaped micro-carriers offer insights into particle uptake variations, demonstrating the potential of non-spherical micro-carriers for precise drug delivery applications.

Bionano Interactions of Organosilica Nanoparticles with Myeloid Derived Immune Cells

Investigating the interactions between nanomaterials and the cells they are likely to encounter in vivo is a critical aspect of designing nanomedicines for imaging and therapeutic applications. Immune cells such as dendritic cells, macrophages, and myeloid derived suppressor cells have a frontline role in the identification and removal of foreign materials from the body, with interactions shown to be heavily dependent on variables such as nanoparticle size, charge, and surface chemistry. Interactions such as cellular association or uptake of nanoparticles can lead to diminished functionality or rapid clearance from the body, making it critical to consider these interactions when designing and synthesizing nanomaterials for biomedical applications ranging from drug delivery to imaging and biosensing. We investigated the interactions between PEGylated organosilica nanoparticles and naturally endocytic immune cells grown from stem cells in murine bone marrow. Specifically, we varied the particle size from 60 nm up to 1000 nm and investigated the effects of size on immune cell association, activation, and maturation with these critical gatekeeper cells. These results will help inform future design parameters for in vitro and in vivo biomedical applications utilizing organosilica nanoparticles.

Upconverting Nanoparticles Coated with Light-Breakable Mesoporous Silica for NIR-Triggered Release of Hydrophobic Molecules

Upconverting nanoparticles (UCNPs) doped with Yb3+ and Tm3+ are near-infrared (NIR) to ultraviolet (UV) transducers that can be used for NIR-controlled drug delivery. However, due to the low quantum yield of upconversion, high laser powers and long irradiation times are required to trigger this drug release. In this work, we report the one-step synthesis of a nanocomposite consisting of a LiYbF4:Tm3+@LiYF4 UCNP coated with mesoporous UV-breakable organosilica shells of various thicknesses. We demonstrate that a thin shell accelerates the breakage of the shell at 1 W/cm2 NIR light exposure, a laser power up to 9 times lower than that of conventional systems. When the mesopores are loaded with hydrophobic vitamin D3 precursor 7-dehydrocholesterol (7-DH), shell breakage results in subsequent cargo release. Its minimal toxicity in HeLa cells and successful internalization into the cell cytoplasm demonstrate its biocompatibility and potential application in biological systems. The tunability of this system due to its simple, one-step synthesis process and its ability to operate at low laser powers opens up avenues in UCNP-powered NIR-triggered drug delivery toward a more scalable, flexible, and ultimately translational option.

Effects of Different Surface Functionalizations of Silica Nanoparticles on Mesenchymal Stem Cells

Physicochemical properties of nanoparticles, such as particle size, surface charge, and particle shape, have a significant impact on cell activities. However, the effects of surface functionalization of nanoparticles with small chemical groups on stem cell behavior and function remain understudied. Herein, we incorporated different chemical functional groups (amino, DETA, hydroxyl, phosphate, and sulfonate with charges of +9.5, + 21.7, -14.1, -25.6, and -37.7, respectively) to the surface of inorganic silica nanoparticles. To trace their effects on mesenchymal stem cells (MSCs) of rat bone marrow, these functionalized silica nanoparticles were used to encapsulate Rhodamine B fluorophore dye. We found that surface functionalization with positively charged and short-chain chemical groups facilitates cell internalization and retention of nanoparticles in MSCs. The endocytic pathway differed among functionalized nanoparticles when tested with ion-channel inhibitors. Negatively charged nanoparticles mainly use lysosomal exocytosis to exit cells, while positively charged nanoparticles can undergo endosomal escape to avoid scavenging. The cytotoxic profiles of these functionalized silica nanoparticles are still within acceptable limits and tolerable. They exerted subtle effects on the actin cytoskeleton and migration ability. Last, phosphate-functionalized nanoparticles upregulate osteogenesis-related genes and induce osteoblast-like morphology, implying that it can direct MSCs lineage specification for bone tissue engineering. Our study provides insights into the rational design of biomaterials for effective drug delivery and regenerative medicine.

Navigating the future: Microfluidics charting new routes in drug delivery

Microfluidics has emerged as a transformative force in the field of drug delivery, offering innovative avenues to produce a diverse range of nano drug delivery systems. Thanks to its precise manipulation of small fluid volumes and its exceptional command over the physicochemical characteristics of nanoparticles, this technology is notably able to enhance the pharmacokinetics of drugs. It has initiated a revolutionary phase in the domain of drug delivery, presenting a multitude of compelling advantages when it comes to developing nanocarriers tailored for the delivery of poorly soluble medications. These advantages represent a substantial departure from conventional drug delivery methodologies, marking a paradigm shift in pharmaceutical research and development. Furthermore, microfluidic platformsmay be strategically devised to facilitate targeted drug delivery with the objective of enhancing the localized bioavailability of pharmaceutical substances. In this paper, we have comprehensively investigated a range of significant microfluidic techniques used in the production of nanoscale drug delivery systems. This comprehensive review can serve as a valuable reference and offer insightful guidance for the development and optimization of numerous microfluidics-fabricated nanocarriers.

[18F]-Radiolabelled Nanoplatforms: A Critical Review of Their Intrinsic Characteristics, Radiolabelling Methods, and Purification Techniques

A wide range of nano-objects is found in many applications of our everyday life. Recognition of their peculiar properties and ease of functionalization has prompted their engineering into multifunctional platforms that are supposed to afford efficient tools for the development of biomedical applications. However, bridging the gap between bench to bedside cannot be expected without a good knowledge of their behaviour in vivo, which can be obtained through non-invasive imaging techniques, such as positron emission tomography (PET). Their radiolabelling with [18F]-fluorine, a technique already well established and widely used routinely for PET imaging, with [18F]-FDG for example, and in preclinical investigation using [18F]-radiolabelled biological macromolecules, has, therefore, been developed. In this context, this review highlights the various nano-objects studied so far, the reasons behind their radiolabelling, and main in vitro and/or in vivo results obtained thereof. Then, the methods developed to introduce the radioelement are presented. Detailed indications on the chemical steps involved are provided, and the stability of the radiolabelling is discussed. Emphasis is then made on the techniques used to purify and analyse the radiolabelled nano-objects, a point that is rarely discussed despite its technical relevance and importance for accurate imaging. The pros and cons of the different methods developed are finally discussed from which future work can develop.

A non-residue surface modification strategy for active-targeting fluorescent silica nanoparticles to cellular organelles

Silica nanoparticles (SiNPs) with a chemically modified surface typically have a complicated chemical composition, which can significantly differ from their intended design. In this study, we systematically studied the effects of two surface modification methods on active-targeting of intracellular organelles of SiNPs: (1) the widely used step-by-step approach, which involves modifying SiNPs in two steps, i.e., the outer surface of SiNPs was firstly modified with amino groups and then these amino groups were linked with targeting groups, and (2) a newly developed one-step approach in which the ligand-silane complex is initially synthesized, followed by chemically immobilizing the complex on the surface of SiNPs. In the one-step approach, the molar ratio of reactants was precisely tuned so that there are no reactive groups left on the outer surface of SiNPs. Two essential organelles, mitochondria and the nucleus, were selected to compare the targeting performances of SiNPs synthesized via these two approaches. By characterizing physicochemical properties, including structural properties, the number of amino groups, surface charge, polydispersity, and cell colocalization, we demonstrated that SiNPs synthesized via the one-step approach with no residual linkage groups on their surface showed significantly improved mitochondria- and nucleus-targeting performances. This precise control of surface properties allows for optimized biological behavior and active-targeting efficiency of SiNPs. We anticipate that such simple and efficient synthetic strategies will enable the synthesis of effective SiNPs for active-targeting organelles in various biological applications.

Influence of Phthalein dyes on structural, optical, and sensing properties of zinc oxide supported Silica-titania nanocomposite

Owed to rapid responsive pH sensing attributes, the zinc-supported Silica-titania (Z/ST) nanocomposite is synthesized by the sol-gel method. Three distinct pH dyes such as phenolphthalein, creosol red, and phenol red are immobilized in Z/ST to examine their influence on the structural and optical properties of Z/ST nanocomposite. Microscopic analyses possessed that Z/ST and dyes immobilized Z/ST have crack-free porous morphology. The phenol red immobilized Z/ST (P-Z/ST) has a low surface roughness ∼0.5 nm, ultra-thin coating ∼2.1 nm, and more hydrophilic features than C-Z/ST (creosol red immobilized Z/ST), and HPh-Z/ST (phenolphthalein immobilized Z/ST). The P-Z/ST possessed 0.3 s against pH 12 and pka 10, C-Z/ST shows a time response 0.5 s and pka (negative log of the acid dissociation constant) value around 8, while Hph-Z/ST revealed a time response 0.68 s and high pka around 11. All three nanocomposites attributed stable and fast responses in basic media.

Engineered Silica Nanoparticles for Nucleic Acid Delivery

The development of nucleic acid-based drugs holds great promise for therapeutic applications, but their effective delivery into cells is hindered by poor cellular membrane permeability and inherent instability. To overcome these challenges, delivery vehicles are required to protect and deliver nucleic acids efficiently. Silica nanoparticles (SiNPs) have emerged as promising nanovectors and recently bioregulators for gene delivery due to their unique advantages. In this review, a summary of recent advancements in the design of SiNPs for nucleic acid delivery and their applications is provided, mainly according to the specific type of nucleic acids. First, the structural characteristics and working mechanisms of various types of nucleic acids are introduced and classified according to their functions. Subsequently, for each nucleic acid type, the use of SiNPs for enhancing delivery performance and their biomedical applications are summarized. The tailored design of SiNPs for selected type of nucleic acid delivery will be highlighted considering the characteristics of nucleic acids. Lastly, the limitations in current research and personal perspectives on future directions in this field are presented. It is expected this opportune review will provide insights into a burgeoning research area for the development of next-generation SiNP-based nucleic acid delivery systems.

Stimuli-responsive biodegradable silica nanoparticles: From native structure designs to biological applications

Due to their inherent advantages, silica nanoparticles (SiNPs) have greatly potential applications as bioactive materials in biosensors/biomedicine. However, the long-term and nonspecific accumulation in healthy tissues may give rise to toxicity, thereby impeding their widespread clinical application. Hence, it is imperative and noteworthy to develop biodegradable and clearable SiNPs for biomedical purposes. Recently, the design of multi-stimuli responsive SiNPs to improve degradation efficiency under specific pathological conditions has increased their clinical trial potential as theranostic nanoplatform. This review comprehensively summaries the rational design and recent progress of biodegradable SiNPs under various internal and external stimuli for rapid in vivo degradation and clearance. In addition, the factors that affect the biodegradation of SiNPs are also discussed. We believe that this systematic review will offer profound stimulus and timely guide for further research in the field of SiNP-based nanosensors/nanomedicine.

Role of Functionalized Peptides in Nanomedicine for Effective Cancer Therapy

Peptide-functionalized nanomedicine, which addresses the challenges of specificity and efficacy in drug delivery, is emerging as a pivotal approach for cancer therapy. Globally, cancer remains a leading cause of mortality, and conventional treatments, such as chemotherapy, often lack precision and cause adverse effects. The integration of peptides into nanomedicine offers a promising solution for enhancing the targeting and delivery of therapeutic agents. This review focuses on the three primary applications of peptides: cancer cell-targeting ligands, building blocks for self-assembling nanostructures, and elements of stimuli-responsive systems. Nanoparticles modified with peptides improved targeting of cancer cells, minimized damage to healthy tissues, and optimized drug delivery. The versatility of self-assembled peptide structures makes them an innovative vehicle for drug delivery by leveraging their biocompatibility and diverse nanoarchitectures. In particular, the mechanism of cell death induced by self-assembled structures offers a novel approach to cancer therapy. In addition, peptides in stimuli-responsive systems enable precise drug release in response to specific conditions in the tumor microenvironment. The use of peptides in nanomedicine not only augments the efficacy and safety of cancer treatments but also suggests new research directions. In this review, we introduce systems and functionalization methods using peptides or peptide-modified nanoparticles to overcome challenges in the treatment of specific cancers, including breast cancer, lung cancer, colon cancer, prostate cancer, pancreatic cancer, liver cancer, skin cancer, glioma, osteosarcoma, and cervical cancer.

Multifaceted roles of silicon nano particles in heavy metals-stressed plants

Heavy metal (HM) contamination has emerged as one of the most damaging abiotic stress factors due to their prominent release into the environment through industrialization and urbanization worldwide. The increase in HMs concentration in soil and the environment has invited attention of researchers/environmentalists to minimize its' impact by practicing different techniques such as application of phytohormones, gaseous molecules, metalloids, and essential nutrients etc. Silicon (Si) although not considered as the essential nutrient, has received more attention in the last few decades due to its involvement in the amelioration of wide range of abiotic stress factors. Silicon is the second most abundant element after oxygen on earth, but is relatively lesser available for plants as it is taken up in the form of mono-silicic acid, Si(OH)4. The scattered information on the influence of Si on plant development and abiotic stress adaptation has been published. Moreover, the use of nanoparticles for maintenance of plant functions under limited environmental conditions has gained momentum. The current review, therefore, summarizes the updated information on Si nanoparticles (SiNPs) synthesis, characterization, uptake and transport mechanism, and their effect on plant growth and development, physiological and biochemical processes and molecular mechanisms. The regulatory connect between SiNPs and phytohormones signaling in counteracting the negative impacts of HMs stress has also been discussed.

Biohybrid Nanoparticle-Based In Situ Monitoring of In Vivo Drug Delivery

Nanomaterials have gained huge attention worldwide owing to their unique physicochemical characteristics which enable their applications in the field of biomedicine and drug delivery systems. Although nanodrug delivery systems (NDDSs) have better target specificity and bioavailability than traditional drug delivery systems, their behavior and clearance mechanisms in living subjects remain unclear. In this regard, the importance of bioimaging methods has come to the forefront for investigating the biodistribution of nanocarriers and discovering drug release mechanisms in vivo. In this review, we introduce several examples of biohybrid nanoparticles and their clinical applications, focusing on their advantages and limitations. The various bioimaging methods for monitoring the fate of nanodrugs in biological systems and the future perspectives of NDDSs have also been discussed.

Improving Cancer Targeting: A Study on the Effect of Dual-Ligand Density on Targeting of Cells Having Differential Expression of Target Biomarkers

Silica nanoparticles with hyaluronic acid (HA) and folic acid (FA) were developed to study dual-ligand targeting of CD44 and folate receptors, respectively, in colon cancer. Characterization of particles with dynamic light scattering showed them to have hydrodynamic diameters of 147-271 nm with moderate polydispersity index (PDI) values. Surface modification of the particles was achieved by simultaneous reaction with HA and FA and results showed that ligand density on the surface increased with increasing concentrations in the reaction mixture. The nanoparticles showed minimal to no cytotoxicity with all formulations showing ≥ 90% cell viability at concentrations up to 100 µg/mL. Based on flow cytometry results, SW480 cell lines were positive for both receptors, the WI38 cell line was positive for CD44 receptor, and Caco2 was positive for the folate receptor. Cellular targeting studies demonstrated the potential of the targeted nanoparticles as promising candidates for delivery of therapeutic agents. The highest cellular targeting was achieved with particles synthesized using folate:surface amine (F:A) ratio of 9 for SW480 and Caco2 cells and at F:A = 0 for WI38 cells. The highest selectivity was achieved at F:A = 9 for both SW480:WI38 and SW480:Caco2 cells. Based on HA conjugation, the highest cellular targeting was achieved at H:A = 0.5-0.75 for SW480 cell, at H:A = 0.75 for WI38 cell and at H:A = 0.5 for Caco2 cells. The highest selectivity was achieved at H:A = 0 for both SW480:WI38 and SW480:Caco2 cells. These results demonstrated that the optimum ligand density on the nanoparticle for targeting is dependent on the levels of biomarker expression on the target cells. Ongoing studies will evaluate the therapeutic efficacy of these targeted nanoparticles using in vitro and in vivo cancer models.

Tuning ultrasmall theranostic nanoparticles for MRI contrast and radiation dose amplification

Background: The introduction of magnetic resonance (MR)-guided radiation treatment planning has opened a new space for theranostic nanoparticles to reduce acute toxicity while improving local control. In this work, second-generation AGuIX® nanoparticles (AGuIX-Bi) are synthesized and validated. AGuIX-Bi are shown to maintain MR positive contrast while further amplifying the radiation dose by the replacement of some Gd3+ cations with higher Z Bi3+. These next-generation nanoparticles are based on the AGuIX® platform, which is currently being evaluated in multiple Phase II clinical trials in combination with radiotherapy. Methods: In this clinically scalable methodology, AGuIX® is used as an initial chelation platform to exchange Gd3+ for Bi3+. AGuIX-Bi nanoparticles are synthesized with three ratios of Gd/Bi, each maintaining MR contrast while further amplifying radiation dose relative to Bi3+. Safety, efficacy, and theranostic potential of the nanoparticles were evaluated in vitro and in vivo in a human non-small cell lung cancer model. Results: We demonstrated that increasing Bi3+ in the nanoparticles is associated with more DNA damage and improves in vivo efficacy with a statistically significant delay in tumor growth and 33% complete regression for the largest Bi/Gd ratio tested. The addition of Bi3+ by our synthetic method leads to nanoparticles that present slightly altered pharmacokinetics and lengthening of the period of high tumor accumulation with no observed evidence of toxicity. Conclusions: We confirmed the safety and enhanced efficacy of AGuIX-Bi with radiation therapy at the selected ratio of 30Gd/70Bi. These results provide crucial evidence towards patient translation.

Silica nanoparticles mediated insect pest management

Silicon is known for mitigating the biotic and abiotic stresses of crop plants. Many studies have proved beneficial effects of bulk silicon against biotic stresses in general and insect pests in particular. However, the beneficial effects of silica nanoparticles in crop plants against insect pests were barely studied and reported. By virtue of its physical and chemical nature, silica nanoparticles offer various advantages over bulk silicon sources for its applications in the field of insect pest management. Silica nanoparticles can act as insecticide for killing target insect pest or it can act as a carrier of insecticide molecule for its sustained release. Silica nanoparticles can improve plant resistance to insect pests and also aid in attracting natural enemies via enhanced volatile compounds emission. Silica nanoparticles are safe to use and eco-friendly in nature in comparison to synthetic pesticides. This review provides insights into the applications of silica nanoparticles in insect pest management along with discussion on its synthesis, side effects and future course of action.

Microfluidics for nano-drug delivery systems: From fundamentals to industrialization

In recent years, owing to the miniaturization of the fluidic environment, microfluidic technology offers unique opportunities for the implementation of nano drug delivery systems (NDDSs) production processes. Compared with traditional methods, microfluidics improves the controllability and uniformity of NDDSs. The fast mixing and laminar flow properties achieved in the microchannels can tune the physicochemical properties of NDDSs, including particle size, distribution and morphology, resulting in narrow particle size distribution and high drug-loading capacity. The success of lipid nanoparticles encapsulated mRNA vaccines against coronavirus disease 2019 by microfluidics also confirmed its feasibility for scaling up the preparation of NDDSs via parallelization or numbering-up. In this review, we provide a comprehensive summary of microfluidics-based NDDSs, including the fundamentals of microfluidics, microfluidic synthesis of NDDSs, and their industrialization. The challenges of microfluidics-based NDDSs in the current status and the prospects for future development are also discussed. We believe that this review will provide good guidance for microfluidics-based NDDSs.

Structural Analysis of Si(OEt)4 Deposits on Au(111)/SiO2 Substrates at the Nanometer Scale Using Focused Electron Beam-Induced Deposition

The focused electron beam-induced deposition (FEBID) process was used by employing a GeminiSEM with a beam characteristic of 1 keV and 24 pA to deposit pillars and line-shaped nanostructures with heights between 9 nm and 1 μm and widths from 5 nm to 0.5 μm. All structures have been analyzed to their composition looking at a desired Si/O/C content measuring a 1:2:0 ratio. The C content of the structure was found to be ∼over 60% for older deposits kept in air (∼at room temperature) and less than 50% for later deposits, only 12 h old. Upon depositing Si(OEt)4 at high rates and at a deposition temperature of under 0 °C, the obtained Si content of our structures was between 10 and 15 atom % (compositional percentage). The FEBID structures have been deposited on Au(111)/SiO2. The Au(111) was chosen as a substrate for the deposition of Si(OEt)4 due to its structural and morphological properties. With its surface granulation following a Chevron pattern and surface defects having an increased contribution to the changes in the composition of the final structure content, the Au(111) surface characteristic behavior at the deposition of Si(OEt)4 is an increase in the O ratio and a reduction in the nanodeposit heights.

Synthetic strategies for nonporous organosilica nanoparticles from organosilanes

Organosilica nanoparticles refer to silica nanoparticles containing carbon along with organic or functional groups and can be divided into mesoporous organosilica nanoparticles and nonporous organosilica nanoparticles. During the past few decades, considerable efforts have been devoted to the development of organosilica nanoparticles directly from organosilanes. However, most of the reports have focused on mesoporous organosilica nanoparticles, while relatively few are concerned with nonporous organosilica nanoparticles. The synthesis of nonporous organosilica nanoparticles typically involves (i) self-condensation of an organosilane as the single source, (ii) co-condensation of two or more types of organosilanes, (iii) co-condensation of tetraalkoxysilane and an organosilane, and (iv) spontaneous emulsification and the subsequent radical polymerization of 3-(trimethoxysilyl)propyl methacrylate (TPM). This article aims to provide a review on the synthetic strategies of this important type of colloidal particle, followed by a brief discussion on their applications and future perspectives.

pH-Sensitive Hybrid System Based on Eu3+/Gd3+ Co-Doped Hydroxyapatite and Mesoporous Silica Designed for Theranostic Applications

Nanomaterials such as pH-responsive polymers are promising for targeted drug delivery systems, due to the difference in pH between tumor and healthy regions. However, there is a significant concern about the application of these materials in this field due to their low mechanical resistance, which can be attenuated by combining these polymers with mechanically resistant inorganic materials such as mesoporous silica nanoparticles (MSN) and hydroxyapatite (HA). Mesoporous silica has interesting properties such as high surface area and hydroxyapatite has been widely studied to aid in bone regeneration, providing special properties adding multifunctionality to the system. Furthermore, fields of medicine involving luminescent elements such as rare earth elements are an interesting option in cancer treatment. The present work aims to obtain a pH-sensitive hybrid system based on silica and hydroxyapatite with photoluminescent and magnetic properties. The nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption methods, CHN elemental analysis, Zeta Potential, scanning electron microscopy (SEM), and transmission electron microscopy (TEM), vibrational sample magnetometry (VSM), and photoluminescence analysis. Incorporation and release studies of the antitumor drug doxorubicin were performed to evaluate the potential use of these systems in targeted drug delivery. The results showed the luminescent and magnetic properties of the materials and showed suitable characteristics for application in the release of pH-sensitive drugs.

Nanoparticles labeled with gamma-emitting radioisotopes: an attractive approach for in vivo tracking using SPECT imaging

Providing accurate molecular imaging of the body and biological process is critical for diagnosing disease and personalizing treatment with the minimum side effects. Recently, diagnostic radiopharmaceuticals have gained more attention in precise molecular imaging due to their high sensitivity and appropriate tissue penetration depth. The fate of these radiopharmaceuticals throughout the body can be traced using nuclear imaging systems, including single-photon emission computed tomography (SPECT) and positron emission tomography (PET) modalities. In this regard, nanoparticles are attractive platforms for delivering radionuclides into targets because they can directly interfere with the cell membranes and subcellular organelles. Moreover, applying radiolabeled nanomaterials can decrease their toxicity concerns because radiopharmaceuticals are usually administrated at low doses. Therefore, incorporating gamma-emitting radionuclides into nanomaterials can provide imaging probes with valuable additional properties compared to the other carriers. Herein, we aim to review (1) the gamma-emitting radionuclides used for labeling different nanomaterials, (2) the approaches and conditions adopted for their radiolabeling, and (3) their application. This study can help researchers to compare different radiolabeling methods in terms of stability and efficiency and choose the best way for each nanosystem.

Iron Oxide@Mesoporous Silica Core-Shell Nanoparticles as Multimodal Platforms for Magnetic Resonance Imaging, Magnetic Hyperthermia, Near-Infrared Light Photothermia, and Drug Delivery

The design of core-shell nanocomposites composed of an iron oxide core and a silica shell offers promising applications in the nanomedicine field, especially for developing efficient theranostic systems which may be useful for cancer treatments. This review article addresses the different ways to build iron oxide@silica core-shell nanoparticles and it reviews their properties and developments for hyperthermia therapies (magnetically or light-induced), combined with drug delivery and MRI imaging. It also highlights the various challenges encountered, such as the issues associated with in vivo injection in terms of NP-cell interactions or the control of the heat dissipation from the core of the NP to the external environment at the macro or nanoscale.

Hybrid organic-inorganic nanoparticles with associated functionality for catalytic transformation of biomass substrates

We present the one-pot synthesis of functionalized organosilica nanoparticles to generate multi-functional hybrid catalysts. Octadecyl, alkyl-thiol and alkyl-amino moieties were used separately and in different combinations, to generate different hybrid spherical nanoparticles with tunable acidic, basic and amphiphilic properties, covalently incorporating up to three organic functional elements onto the surface of the nanoparticles. Several parameters were optimised such as the concentration of the base employed during the hydrolysis and condensation synthesis process that showed a strong influence on the particle size. The physico-chemical properties of the hybrid materials were fully characterized by XRD, elemental and thermogravimetric analysis, electron microscopy, nitrogen adsorption isotherms and ¹³C and ²⁹Si NMR spectroscopy. Finally, the potential uses of the prepared materials as amphiphilic catalysts, with acidic or basic properties for the conversion of biomass molecules into platform chemicals were evaluated.

Revisiting Alkoxysilane Assembly on Silica Surfaces: Grafting versus Homo-Condensation in Solution

Silica surface functionalization is often done through the condensation of functional silanes on silanols, silica surfaces' terminal groups. APTES, aminopropyltriethoxysilane, is widely used due to its assumed high reactivity with silanols, kinetically promoted by the catalytic action of the terminal amine function. Here, we revisit, based on a quantitative analysis by solid-state ²⁹Si NMR, the assembly of this silane on silica surfaces to investigate whether its presence results from grafting, i.e., hetero-condensation with silanol groups or from homo-condensation of silane molecules in solution leading to polycondensates physisorbed on silica. We investigate the interaction of APTES with a crystalline layered silicate, ilerite, and with amorphous nonporous silica. We also studied a second silane, cyanopropyltrichlorosilane (CPTCS), terminated with a nitrile group. Our results undoubtedly prove that while CPTCS is grafted on the silica surface, the presence of APTES on silica and silicate materials is only marginally associated with silanol consumption. The analysis of the signal related to silicon atoms from silanes (Tⁿ species) and those from silica (Qⁿ species) allowed for the accurate estimation of the extent of homo-condensation vs grafting based on the ratio of T-O-T/Q-O-T siloxane bridges. These findings deeply question the well-established certainties on APTES assembly on silica that should no longer be seen as grafting of alkoxysilane by hetero-condensation with silanol groups but more accurately as a homo-condensed network of silanes, predominantly physisorbed on the surface but including some sparse anchoring points to the surface involving less than 6% of the overall silanol groups.

Nanoengineering Triplet-Triplet Annihilation Upconversion: From Materials to Real-World Applications

Using light to control matter has captured the imagination of scientists for generations, as there is an abundance of photons at our disposal. Yet delivering photons beyond the surface to many photoresponsive systems has proven challenging, particularly at scale, due to light attenuation via absorption and scattering losses. Triplet-triplet annihilation upconversion (TTA-UC), a process which allows for low energy photons to be converted to high energy photons, is poised to overcome these challenges by allowing for precise spatial generation of high energy photons due to its nonlinear nature. With a wide range of sensitizer and annihilator motifs available for TTA-UC, many researchers seek to integrate these materials in solution or solid-state applications. In this Review, we discuss nanoengineering deployment strategies and highlight their uses in recent state-of-the-art examples of TTA-UC integrated in both solution and solid-state applications. Considering both implementation tactics and application-specific requirements, we identify critical needs to push TTA-UC-based applications from an academic curiosity to a scalable technology.

Novel Approach for the Isolation and Immobilization of a Recombinant Transaminase: Applying an Advanced Nanocomposite System

The increasing application of recombinant enzymes demands not only effective and sustainable fermentation, but also highly efficient downstream processing and further stabilization of the enzymes by immobilization. In this study, a novel approach for the isolation and immobilization of His-tagged transaminase from Chromobacterium violaceum (CvTA) has been developed. A recombinant of CvTA was simultaneously isolated and immobilized by binding on silica nanoparticles (SNPs) with metal affinity linkers and additionally within poly(lactic acid) (PLA) nanofibers. The linker length and the nature of the metal ion significantly affected the enzyme binding efficiency and biocatalytic activity of CvTA-SNPs. The formation of PLA nanofibers by electrospinning enabled rapid embedding of CvTA-SNPs biocatalysts and ensured enhanced stability and activity. The developed advanced immobilization method reduces the time required for enzyme isolation, purification and immobilization by more than fourfold compared to a classical stepwise technique.

Ultrasmall silica nanoparticles in translational biomedical research: Overview and outlook

The exemplary progress of silica nanotechnology has attracted extensive attention across a range of biomedical applications such as diagnostics and imaging, drug delivery, and therapy of cancer and other diseases. Ultrasmall silica nanoparticles (USNs) have emerged as a particularly promising class demonstrating unique properties that are especially suitable for and have shown great promise in translational and clinical biomedical research. In this review, we discuss synthetic strategies that allow precise engineering of USNs with excellent control over size and surface chemistry, functionalization, and pharmacokinetic and toxicological profiles. We summarize the current state-of-the-art in the biomedical applications of USNs with a particular focus on select clinical studies. Finally, we illustrate long-standing challenges in the translation of inorganic nanotechnology, particularly in the context of ultrasmall nanomedicines, and provide our perspectives on potential solutions and future opportunities in accelerating the translation and widespread adoption of USN technology in biomedical research.

Cellular Uptake of Silica Particles Influences EGFR Signaling Pathway and is Affected in Response to EGF

Background

The human epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is involved in several key cellular processes, such as cell proliferation and differentiation, and it has been linked to the development and progression of various cancers (e.g., breast and lung). Researchers have attempted to improve current cancer-targeted therapies by conjugating molecules on the surface of (nano)particles to efficiently target and inhibit EGFR. However, very few in vitro studies have investigated the effect of particles per se on EGFR signaling and dynamics. Furthermore, the impact of concomitant exposure of particles and EGFR ligands, such as epidermal growth factor (EGF) on cellular uptake efficiency has received little attention.

Purpose

The purpose of this research was to determine the effects of silica (SiO₂) particles on EGFR expression and intracellular signaling pathways in A549 lung epithelial cells, in the presence or absence of epidermal growth factor (EGF).

Results

We showed that A549 cells are able to internalize SiO₂ particles with core diameters of 130 nm and 1 µm without affecting cell proliferation or migration. However, both SiO₂ particles interfere with the EGFR signaling pathway by raising the endogenous levels of extracellular signal-regulated kinase (ERK) 1/2. Furthermore, both in the presence and absence of SiO₂ particles, the addition of EGF increased cell migration. EGF also stimulated cellular uptake of 130 nm SiO₂ particles but not 1 µm particles. The increased uptake is primarily associated with EGF-stimulated macropinocytosis.

Conclusion

This study shows that SiO₂ particle uptake interferes with cellular signaling pathways and can be boosted by concurrent exposure to the bioactive molecule EGF. SiO₂ particles, both alone and in combination with the ligand EGF, interfere with EGFR signaling pathway in a size-dependent manner.

Hollow Silica Nano and Micro Spheres with Polystyrene Templating: A Mini-Review

Synthesis of monodisperse hollow silica nanospheres, especially using a hard template route, has been shown to be successful, but a high yield is needed for this strategy to be used on an industrial scale. On the other hand, there is a research gap in the synthesis of hollow silica microspheres due to the popularity and easiness of the synthesis of silica nanospheres despite the larger spheres being beneficial in some fields. In this review, current trends in producing hollow silica nanospheres using hard templates, especially polystyrene, are briefly presented. Soft templates have also been used to make highly polydisperse hollow silica spheres, and complex designs have improved polydispersity. The effect of the main parameters on the coating is presented here to provide a basic understanding of the interactions between the silica and template surface in the absence or presence of surfactants. Surface charge, surface modification, parameters in the sol-gel method and interaction between the silica and templates need to be further improved to have a uniform coating and better control over the size, dispersity, wall thickness and porosity. As larger organic templates will have lower surface energy, the efficiency of the micro sphere synthesis needs to be improved. Control over the physical structure of hollow silica spheres will open up many opportunities for them to be extensively used in fields ranging from waste removal to energy storage.

Mesoporous silica nanoparticles incorporated with Ir(III) complexes: From photophysics to photodynamic therapy

Organically modified mesoporous silica nanoparticles (MSNs) containing Ir complexes (Ir1, Ir2 and Ir3) were successfully synthesized. These Ir-entrapped MCM41-COOH nanoparticles have shown relevant photophysical characteristics including high efficiency in the photoproduction and delivery of singlet oxygen (¹O₂), which is particularly promising for photodynamic therapy (PDT) applications. In vitro tests have evidenced that complex@MCM41-COOH are able to reduce cell proliferation after 10 min of blue-light irradiation in Hep-G2 liver cancer cells.

Development of Biodegradable GQDs-hMSNs for Fluorescence Imaging and Dual Cancer Treatment via Photodynamic Therapy and Drug Delivery

Recently, nano-based cancer therapeutics have been researched and developed, with some nanomaterials showing anticancer properties. When it comes to cancer treatment, graphene quantum dots (GQDs) contain the ability to generate ¹O₂, a reactive oxidative species (ROS), allowing for the synergistic imaging and photodynamic therapy (PDT) of cancer. However, due to their small particle size, GQDs struggle to remain in the target area for long periods of time in addition to being poor drug carriers. To address this limitation of GQDs, hollow mesoporous silica nanoparticles (hMSNs) have been extensively researched for drug delivery applications. This project investigates the utilization and combination of biomass-derived GQDs and Stöber silica hMSNs to make graphene quantum dots-hollow mesoporous silica nanoparticles (GQDs-hMSNs) for fluorescent imaging and dual treatment of cancer via drug delivery and photodynamic therapy (PDT). Although the addition of hMSNs made the newly synthesized nanoparticles slightly more toxic at higher concentrations, the GQDs-hMSNs displayed excellent drug delivery using fluorescein (FITC) as a mock drug, and PDT treatment by using the GQDs as a photosensitizer (PS). Additionally, the GQDs retained their fluorescence through the surface binding to hMSNs, allowing them to still be used for cell-labeling applications.

Smart and Multi-Functional Magnetic Nanoparticles for Cancer Treatment Applications: Clinical Challenges and Future Prospects

Iron oxide nanoparticle (IONPs) have become a subject of interest in various biomedical fields due to their magnetism and biocompatibility. They can be utilized as heat mediators in magnetic hyperthermia (MHT) or as contrast media in magnetic resonance imaging (MRI), and ultrasound (US). In addition, their high drug-loading capacity enabled them to be therapeutic agent transporters for malignancy treatment. Hence, smartening them allows for an intelligent controlled drug release (CDR) and targeted drug delivery (TDD). Smart magnetic nanoparticles (SMNPs) can overcome the impediments faced by classical chemo-treatment strategies, since they can be navigated and release drug via external or internal stimuli. Recently, they have been synchronized with other modalities, e.g., MRI, MHT, US, and for dual/multimodal theranostic applications in a single platform. Herein, we provide an overview of the attributes of MNPs for cancer theranostic application, fabrication procedures, surface coatings, targeting approaches, and recent advancement of SMNPs. Even though MNPs feature numerous privileges over chemotherapy agents, obstacles remain in clinical usage. This review in particular covers the clinical predicaments faced by SMNPs and future research scopes in the field of SMNPs for cancer theranostics.

An insight into the green synthesis of SiO2 nanostructures as a novel adsorbent for removal of toxic water pollutants

Green synthesis of nanomaterials is a sustainable, biologically safe, reliable, and eco-friendly approach. Green synthesis is beneficial to reduce the devastating effects of the traditional chemical synthesis methods and particularly aims at decreasing the usage of toxic chemicals. This review deals with the green synthesis of silica nanoparticles (SiO₂ NPs) with emphasis on the engineering surface properties for enhanced adsorption capability and their applications as novel nano-adsorbents for water pollutants removal. Green synthesized SiO₂ NPs have shown excellent adsorption properties with higher adsorption capacity of 150-200 mg/g and more than 95% removal for various toxic water pollutants along with reusability for more than 5 cycles. These SiO₂ NPs show fascinating physical and chemical properties i.e. tunable size (5 nm to more than 100 nm), low toxicity, biocompatibility, high porosity, higher specific surface area (500--700 m²/g) making them attractive/suitable for several applications in biomedical, agriculture, catalysis, construction, water treatment, etc. Commonly, highly pure SiO₂ NPs are synthesized from organic chemicals (very expensive and highly toxic in nature) as a precursor that led to high production costs, high energy consumption, and environmental hazards. On the other hand, green synthesis of SiO₂ NPs from natural resources like biomass that includes rice husk, bamboo leaves/stem, sugarcane bagasse, corn cobs, wheat straw, etc. is cost-effective, less toxic, and eco-friendly which has been discussed in detail. Furthermore, the effect of key synthesis parameters (i.e., temperature, time, concentration, pH, etc.) on the morphology, size, purity, and specific surface area of SiO₂ NPs have been summarized. Finally, the applications of SiO₂ NPs as nano-adsorbents for the removal of toxic water pollutants (i.e., heavy metal cations, anions, dyes, etc.) including the adsorption mechanisms along with the future scope, challenges, and suggestions have been discussed.

Design Principles of Hybrid Nanomaterials for Radiotherapy Enhanced by Photodynamic Therapy

Radiation (RT) remains the most frequently used treatment against cancer. The main limitation of RT is its lack of specificity for cancer tissues and the limited maximum radiation dose that can be safely delivered without damaging the surrounding healthy tissues. A step forward in the development of better RT is achieved by coupling it with other treatments, such as photodynamic therapy (PDT). PDT is an anti-cancer therapy that relies on the light activation of non-toxic molecules-called photosensitizers-to generate ROS such as singlet oxygen. By conjugating photosensitizers to dense nanoscintillators in hybrid architectures, the PDT could be activated during RT, leading to cell death through an additional pathway with respect to the one activated by RT alone. Therefore, combining RT and PDT can lead to a synergistic enhancement of the overall efficacy of RT. However, the involvement of hybrids in combination with ionizing radiation is not trivial: the comprehension of the relationship among RT, scintillation emission of the nanoscintillator, and therapeutic effects of the locally excited photosensitizers is desirable to optimize the design of the hybrid nanoparticles for improved effects in radio-oncology. Here, we discuss the working principles of the PDT-activated RT methods, pointing out the guidelines for the development of effective coadjutants to be tested in clinics.

Detection of ochratoxin A by fluorescence sensing based on mesoporous materials

We developed a new ochratoxin A (OTA) aptamer biosensor to promptly detect OTA in food. Mesoporous silica nanoparticles (MSN) were used as carriers, and aptamers were used as recognition probes and gating molecules. The fluorescent dye Rhodamine 6G (Rh6G) was loaded into mesoporous silica, and through electrostatic contact, the OTA aptamer was adsorbed on amino-modified mesoporous silica. The fluorescent dye released from the mesopore in the presence of OTA because of the conformational change induced in the aptamer by the target. The amount of ochratoxin was determined by measuring the fluorescence intensity. Our findings revealed a positive relationship between the fluorescence intensity and OTA concentration, with a limit of detection of 0.28 ng mL-1, and the detection range was 0.05-200 ng mL-1. The recovery rate was 80.7%-110.8% in real samples. The proposed approach is suitable for the quantification of other toxins.

Silica nanoparticles as novel sustainable approach for plant growth and crop protection

Agriculture crops encounter several biotic and abiotic stresses, including pests, diseases, nutritional deficits, and climate change, which necessitate the development of new agricultural technologies. By developing nano-based fertilizers, insecticides and herbicides, and early disease diagnostics, nanotechnology may help to increase agricultural crop quality and production. The application of silica nanoparticles (SiNPs) may be the solution for increasing the yield to combat the agriculture crisis in the near future. SiNPs have unique physiological properties, such as large surface area, aggregation, reactivity, penetrating ability, size, and structure, which enable them to penetrate plants and regulate their metabolic processes. Pesticide delivery, enhanced nutrition supply, disease management, and higher photosynthetic efficiency and germination rate are all attributed to SiNPs deposition on plant tissue surfaces. SiNPs have been demonstrated to be non-toxic in nature, making them suitable for usage in agriculture. In this regard, the current work provides the most important and contemporary applications of SiNPs in agriculture as well as biogenic and non-biogenic synthetic techniques. As a result, this review summarizes the literature on SiNPs and explores the use of SiNPs in a variety of agricultural disciplines.

In vivo toxicity assessment of eugenol and vanillin-functionalised silica particles using Caenorhabditis elegans

The toxicological properties of different silica particles functionalised with essential oil components (EOCs) were herein assessed using the in vivo model C. elegans. In particular, the effects of the acute and long-term exposure to three silica particle types (SAS, MCM-41 micro, MCM-41 nano), either bare or functionalised with eugenol or vanillin, were evaluated on different biological parameters of nematodes. Acute exposure to the different particles did not reduce nematodes survival, brood growth or locomotion, but reproduction was impaired by all the materials, except for vanillin-functionalised MCM-41 nano. Moreover, long-term exposure to particles led to strongly inhibited nematodes growth and reproduction. The eugenol-functionalised particles exhibited higher functionalisation yields and had the strongest effects during acute and long-term exposures. Overall, the vanillin-functionalised particles displayed milder acute toxic effects on reproduction than pristine materials, but severer toxicological responses for the 96-hour exposure assays. Our findings suggest that the EOC type anchored to silica surfaces and functionalisation yield are crucial for determining the toxicological effects of particles on C. elegans. The results obtained with this alternative in vivo model can help to anticipate potential toxic responses to these new materials for human health and the environment.

A Brief Review of Carbon Dots-Silica Nanoparticles Synthesis and their Potential Use as Biosensing and Theragnostic Applications

Carbon dots (CDs) are carbon nanoparticles with sizes below 10 nm and have attracted attention due to their relatively low toxicity, great biocompatibility, water solubility, facile synthesis, and exceptional photoluminescence properties. Accordingly, CDs have been widely exploited in different sensing and biomedical applications, for example, metal sensing, catalysis, biosensing, bioimaging, drug and gene delivery, and theragnostic applications. Similarly, the well-known properties of silica, such as facile surface functionalization, good biocompatibility, high surface area, and tunable pore volume, have allowed the loading of diverse inorganic and organic moieties and nanoparticles, creating complex hybrid nanostructures that exploit distinct properties (optical, magnetic, metallic, mesoporous, etc.) for sensing, biosensing, bioimaging, diagnosis, and gene and drug delivery. In this context, CDs have been successfully grafted into diverse silica nanostructures through various synthesis methods (e.g., solgel chemistry, inverse microemulsion, surfactant templating, and molecular imprinting technology (MIT)), imparting hybrid nanostructures with multimodal properties for distinct objectives. This review discusses the recently employed synthesis methods for CDs and silica nanoparticles and their typical applications. Then, we focus on combined synthesis techniques of CD-silica nanostructures and their promising biosensing operations. Finally, we overview the most recent potential applications of these materials as innovative smart hybrid nanocarriers and theragnostic agents for the nanomedical field.

Nano-Silica Carriers Coated by Chloramphenicol: Synthesis, Characterization, and Grinding Trial as a Way to Improve the Release Profile

Silica nanoparticles were applied as the carrier of chloramphenicol (2,2-dichloro-N-[(1R,2R)-1,3-dihydroxy-1-(4-nitrophenyl)propan-2-yl]acetamide), and were loaded in a 1% carbopol-based gel (poly(acrylic acid)), which allowed obtainment of an upgraded drug form. The samples of silica materials were obtained by means of modified Stöber synthesis, and their morphological properties were analyzed using Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) method, elemental analysis (EA), thermogravimetric analysis (TGA), analysis of the specific surface properties, X-ray diffraction study (XRD), scanning electron microscope (SEM), and dynamic light scattering (DLS) methods, which permitted the selection of the drug carrier. The two obtained silica carriers were coated with chloramphenicol and loaded into 1% carbopol gel. The release studies were then performed. The release results were evaluated using mathematical models as well as model-independent analysis. It was found that the modification of the synthesis of the silica by the sol-gel method to form a product coated with chloramphenicol and further grinding of the silica material influenced the release of the active substance, thus allowing the modification of its pharmaceutical availability. The change in the parameters of silica synthesis influenced the structure and morphological properties of the obtained silica carrier. The grinding process determined the way of adsorption of the active substance on its surface. The studies showed that the proper choice of silica carrier has a considerable effect on the release profile of the prepared hydrogel formulations.

Nano-Silica Carriers Coated by Chloramphenicol: Synthesis, Characterization, and Grinding Trial as a Way to Improve the Release Profile

Silica nanoparticles were applied as the carrier of chloramphenicol (2,2-dichloro-N-[(1R,2R)-1,3-dihydroxy-1-(4-nitrophenyl)propan-2-yl]acetamide), and were loaded in a 1% carbopol-based gel (poly(acrylic acid)), which allowed obtainment of an upgraded drug form. The samples of silica materials were obtained by means of modified Stöber synthesis, and their morphological properties were analyzed using Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) method, elemental analysis (EA), thermogravimetric analysis (TGA), analysis of the specific surface properties, X-ray diffraction study (XRD), scanning electron microscope (SEM), and dynamic light scattering (DLS) methods, which permitted the selection of the drug carrier. The two obtained silica carriers were coated with chloramphenicol and loaded into 1% carbopol gel. The release studies were then performed. The release results were evaluated using mathematical models as well as model-independent analysis. It was found that the modification of the synthesis of the silica by the sol-gel method to form a product coated with chloramphenicol and further grinding of the silica material influenced the release of the active substance, thus allowing the modification of its pharmaceutical availability. The change in the parameters of silica synthesis influenced the structure and morphological properties of the obtained silica carrier. The grinding process determined the way of adsorption of the active substance on its surface. The studies showed that the proper choice of silica carrier has a considerable effect on the release profile of the prepared hydrogel formulations.

Shape Memory Polymer Foams with Phenolic Acid-Based Antioxidant Properties

Phenolic acids (PAs) are natural antioxidant agents in the plant kingdom that are part of the human diet. The introduction of naturally occurring PAs into the network of synthetic shape memory polymer (SMP) polyurethane (PU) foams during foam fabrication can impart antioxidant properties to the resulting scaffolds. In previous work, PA-containing SMP foams were synthesized to provide materials that retained the desirable shape memory properties of SMP PU foams with additional antimicrobial properties that were derived from PAs. Here, we explore the impact of PA incorporation on SMP foam antioxidant properties. We investigated the antioxidant effects of PA-containing SMP foams in terms of in vitro oxidative degradation resistance and cellular antioxidant activity. The PA foams showed surprising variability; p-coumaric acid (PCA)-based SMP foams exhibited the most potent antioxidant properties in terms of slowing oxidative degradation in H₂O₂. However, PCA foams did not effectively reduce reactive oxygen species (ROS) in short-term cellular assays. Vanillic acid (VA)- and ferulic acid (FA)-based SMP foams slowed oxidative degradation in H₂O₂ to lesser extents than the PCA foams, but they demonstrated higher capabilities for scavenging ROS to alter cellular activity. All PA foams exhibited a continuous release of PAs over two weeks. Based on these results, we hypothesize that PAs must be released from SMP foams to provide adequate antioxidant properties; slower release may enable higher resistance to long-term oxidative degradation, and faster release may result in higher cellular antioxidant effects. Overall, PCA, VA, and FA foams provide a new tool for tuning oxidative degradation rates and extending potential foam lifetime in the wound. VA and FA foams induced cellular antioxidant activity that could help promote wound healing by scavenging ROS and protecting cells. This work could contribute a wound dressing material that safely releases antimicrobial and antioxidant PAs into the wound at a continuous rate to ideally improve healing outcomes. Furthermore, this methodology could be applied to other oxidatively degradable biomaterial systems to enhance control over degradation rates and to provide multifunctional scaffolds for healing.

Surface Functionalization of Silica Nanoparticles: Strategies to Optimize the Immune-Activating Profile of Carrier Platforms

Silica nanoparticles (SiNPs) are generally regarded as safe and may represent an attractive carrier platform for nanomedical applications when loaded with biopharmaceuticals. Surface functionalization by different chemistries may help to optimize protein loading and may further impact uptake into the targeted tissues or cells, however, it may also alter the immunologic profile of the carrier system. In order to circumvent side effects, novel carrier candidates need to be tested thoroughly, early in their development stage within the pharmaceutical innovation pipeline, for their potential to activate or modify the immune response. Previous studies have identified surface functionalization by different chemistries as providing a plethora of modifications for optimizing efficacy of biopharmaceutical (nano)carrier platforms while maintaining an acceptable safety profile. In this study, we synthesized SiNPs and chemically functionalized them to obtain different surface characteristics to allow their application as a carrier system for allergen-specific immunotherapy. In the present study, crude natural allergen extracts are used in combination with alum instead of well-defined active pharmaceutical ingredients (APIs), such as recombinant allergen, loaded onto (nano)carrier systems with immunologically inert and stable properties in suspension. This study was motivated by the hypothesis that comparing different charge states could allow tailoring of the binding capacity of the particulate carrier system, and hence the optimization of biopharmaceutical uptake while maintaining an acceptable safety profile, which was investigated by determining the maturation of human antigen-presenting cells (APCs). The functionalized nanoparticles were characterized for primary and hydrodynamic size, polydispersity index, zeta potential, endotoxin contamination. As potential candidates for allergen-specific immunotherapy, the differently functionalized SiNPs were non-covalently coupled with a highly purified, endotoxin-free recombinant preparation of the major birch pollen allergen Bet v 1 that functioned for further immunological testing. Binding efficiencies of allergen to SiNPs was controlled to determine uptake of API. For efficacy and safety assessment, we employed human monocyte-derived dendritic cells as model for APCs to detect possible differences in the particles’ APC maturation potential. Functionalization of SiNP did not affect the viability of APCs, however, the amount of API physisorbed onto the nanocarrier system, which induced enhanced uptake, mainly by macropinocytosis. We found slight differences in the maturation state of APCs for the differently functionalized SiNP–API conjugates qualifying surface functionalization as an effective instrument for optimizing the immune response towards SiNPs. This study further suggests that surface-functionalized SiNPs could be a suitable, immunologically inert vehicle for the efficient delivery of biopharmaceutical products, as evidenced here for allergen-specific immunotherapy.

Recent progress in the applications of silica-based nanoparticles

Functionalized silica nanoparticles (SiO2 NPs) have attracted great attention due to their promising distinctive, versatile, and privileged physiochemical characteristics. These enhanced properties make this type of functionalized nanoparticles particularly appropriate for different applications. A lack of reviews that summarizes the fabrications of such nanomaterials and their different applications in the same work has been observed in the literature. Therefore, in this work, we will discuss the recent signs of progress in the fabrication of functionalized silica nanoparticles and their attractive applications that have been extensively highlighted (advanced catalysis, drug-delivery, biomedical applications, environmental remediation applications, and wastewater treatment). These applications have been selected for demonstrating the role of the surface modification step on the various properties of the silica surface. In addition, the current challenges in the applications of functionalized silica nanoparticles and corresponding strategies to discuss these issues and future perspectives for additional improvement have been addressed.