Mesoporous silica materials for controlled delivery based on enzymes

Stimuli-responsive mesoporous silica nanoplatforms for smart antibacterial therapies: From single to combination strategies

The demand for new antibacterial therapies is urgent and crucial in the clinical setting because of the growing degree of antibiotic resistance and the limits of conventional antibacterial therapies. Stimuli- responsive nanoplatforms, are sensitive to endogenous or exogenous stimulus (pH, temperature, light, and magnetic fields, etc.) which activate cargo release locally and on-demand, hold great potential in developing next generation personalized precision medicine. For instance, pH-sensitive nanoplatforms can selectively release antibacterial agents in the acidic environment of infection sites. To achieve the stimuli-responsive delivery, mesoporous silica nanoplatforms (MSNs) have demonstrated as prospective candidates for efficient cargo loading and controlled release through strategies such as tunable pore engineering, versatile surface modification/coating, and tailored framework composition. Furthermore, aiming for more precise delivery of MSNs, current research interests are increasingly shifting from single-stimuli antibacterial strategy to integrated strategy that combine multiple-stimulus. In this review, we briefly discuss the microenvironment of bacterial infections and provide a comprehensive summary of current stimuli-responsive strategies, and associated materials design principles of stimuli-responsive mesoporous silica-based smart nanoplatforms (SRMSNs). Additionally, integrative antibacterial strategies with synergistic effects, combining chemodynamic, photodynamic, photothermal, sonodynamic and gas therapies, have also been elaborated. Present research advances and limitations of SRMSNs-based antibacterial therapies, such as limited biodegradability and potential cytotoxicity, have been overviewed with future outlooks presented. This review aims to inspire and guide future research in developing novel antibacterial strategies with integrative solutions.

Sol-Gel Synthesis of Silica-Poly (Vinylpyrrolidone) Hybrids with Prooxidant Activity and Antibacterial Properties

The present work deals with the sol-gel synthesis of silica-poly (vinylpyrrolidone) hybrid materials. The nanohybrids (Si-PVP) have been prepared using an acidic catalyst at ambient temperature. Tetramethyl ortosilane (TMOS) was used as a silica precursor. Poly (vinylpyrrolidone) (PVP) was introduced into the reaction mixture as a solution in ethanol with a concentration of 20%. The XRD established that the as-prepared material is amorphous. The IR and 29Si MAS NMR spectra proved the formation of a polymerized silica network as well as the hydrogen bonding interactions between the silica matrix and OH hydrogens of the silanol groups. The TEM showed spherical particle formation along with increased agglomeration tendency. The efficacy of SiO2/PVP nanoparticles as a potential antimicrobial agent against a wide range of bacteria was evaluated as bacteriostatic, using agar diffusion and spot tests. Combined effects of hybrid nanomaterial and antibiotics could significantly reduce the bactericidal concentrations of both the antibiotic and the particles, and they could also eliminate the antibiotic resistance of the pathogen. The registered prooxidant activity of the newly synthesized material was confirmative and explicatory for the antibacterial properties of the tested substance and its synergetic combination with antibiotics. The effect of new hybrid material on Crustacea Daphnia magna was also estimated as harmless under concentration of 0.1 mg/mL.

A navitoclax-loaded nanodevice targeting matrix metalloproteinase-3 for the selective elimination of senescent cells

Cellular senescence is implicated in the occurrence and progression of multiple age-related disorders. In this context, the selective elimination of senescent cells, senolysis, has emerged as an effective therapeutic strategy. However, the heterogeneous senescent phenotype hinders the discovery of a universal and robust senescence biomarker that limits the effective of senolytic with off-target toxic effects. Therefore, the development of more selective strategies represents a promising approach to increase the specificity of senolytic therapy. In this study, we have developed an innovative nanodevice for the selective elimination of senescent cells (SCs) based on the specific enzymatic activity of the senescent secretome. The results revealed that when senescence is induced in proliferating WI-38 by ionizing radiation (IR), the cells secrete high levels of matrix metalloproteinase-3 (MMP-3). Based on this result, mesoporous silica nanoparticles (MSNs) were loaded with the senolytic navitoclax (Nav) and coated with a specific peptide which is substrate of MMP-3 (NPs(Nav)@MMP-3). Studies in cells confirmed the preferential release of cargo in IR-induced senescent cells compared to proliferating cells, depending on MMP-3 levels. Moreover, treatment with NPs(Nav)@MMP-3 induced a selective decrease in the viability of SCs as well as a protective effect on non-proliferating cells. These results demonstrate the potential use of NPs to develop enhanced senolytic therapies based on specific enzymatic activity in the senescent microenvironment, with potential clinical relevance. STATEMENT OF SIGNIFICANCE: The common β-galactosidase activity has been exploited to develop nanoparticles for the selective elimination of senescent cells. However, the identification of new senescent biomarkers is a key factor for the development of improved strategies. In this scenario, we report for the first time the development of NPs targeting senescent cells based on specific enzymatic activity of the senescent secretome. We report a navitoclax-loaded nanodevice responsive to the matrix metalloproteinase-3 (MMP-3) associated with the senescent phenotype. Our nanosystem achieves the selective release of navitoclax in an MMP-3-dependent manner while limiting off-target effects on non-senescent cells. This opens the possibility of using nanoparticles able to detect an altered senescent environment and selectively release its content, thus enhancing the efficacy of senolytic therapies.

Targeted Delivery of the Pan-Inflammasome Inhibitor MM01 as an Alternative Approach to Acute Lung Injury Therapy

Acute lung injury (ALI) is a severe pulmonary disorder responsible for high percentage of mortality and morbidity in intensive care unit patients. Current treatments are ineffective, so the development of efficient and specific therapies is an unmet medical need. The activation of NLPR3 inflammasome during ALI produces the release of proinflammatory factors and pyroptosis, a proinflammatory form of cell death that contributes to lung damage spreading. Herein, it is demonstrated that modulating inflammasome activation through inhibition of ASC oligomerization by the recently described MM01 compound can be an alternative pharmacotherapy against ALI. Besides, the added efficacy of using a drug delivery nanosystem designed to target the inflamed lungs is determined. The MM01 drug is incorporated into mesoporous silica nanoparticles capped with a peptide (TNFR-MM01-MSNs) to target tumor necrosis factor receptor-1 (TNFR-1) to proinflammatory macrophages. The prepared nanoparticles can deliver the cargo in a controlled manner after the preferential uptake by proinflammatory macrophages and exhibit anti-inflammatory activity. Finally, the therapeutic effect of MM01 free or nanoparticulated to inhibit inflammatory response and lung injury is successfully demonstrated in lipopolysaccharide-mouse model of ALI. The results suggest the potential of pan-inflammasome inhibitors as candidates for ALI therapy and the use of nanoparticles for targeted lung delivery.

Biosafety of mesoporous silica nanoparticles; towards clinical translation

Mesoporous silica nanoparticles (MSNs) have attracted the attention of chemists, who have developed numerous systems for the encapsulation of a plethora of molecules, allowing the use of mesoporous silica nanoparticles for biomedical applications. MSNs have been extensively studied for their use in nanomedicine, in applications such as drug delivery, diagnosis, and bioimaging, demonstrating significant in vivo efficacy in different preclinical models. Nevertheless, for the transition of MSNs into clinical trials, it is imperative to understand the characteristics that make MSNs effective and safe. The biosafety properties of MSNs in vivo are greatly influenced by their physicochemical characteristics such as particle shape, size, surface modification, and silica framework. In this review, we compile the most relevant and recent progress in the literature up to the present by analyzing the contributions on biodistribution, biodegradability, and clearance of MSNs. Furthermore, the ongoing clinical trials and the potential challenges related to the administration of silica materials for advanced therapeutics are discussed. This approach aims to provide a solid overview of the state-of-the-art in this field and to encourage the translation of MSNs to the clinic.

Human Papilloma Virus DNA Detection in Clinical Samples Using Fluorogenic Probes Based on Oligonucleotide Gated Nanoporous Anodic Alumina Films

In this work, fluorogenic probes based on oligonucleotide capped nanoporous anodic alumina films are developed for specific and sensitive detection of human papilloma virus (HPV) DNA. The probe consists of anodic alumina nanoporous films loaded with the fluorophore rhodamine B (RhB) and capped with oligonucleotides bearing specific base sequences complementary to genetic material of different high-risk (hr) HPV types. Synthesis protocol is optimized for scale up production of sensors with high reproducibility. The sensors' surfaces are characterized by scanning electron microscopy (HR-FESEM) and atomic force microscopy (AFM) and their atomic composition is determined by energy dispersive X-ray spectroscopy (EDXS). Oligonucleotide molecules onto nanoporous films block the pores and avoid diffusion of RhB to the liquid phase. Pore opening is produced when specific DNA of HPV is present in the medium, resulting in RhB delivery, that is detected by fluorescence measurements. The sensing assay is optimized for reliable fluorescence signal reading. Nine different sensors are synthesized for specific detection of 14 different hr-HPV types in clinical samples with very high sensitivity (100%) and high selectivity (93-100%), allowing rapid screening of virus infections with very high negative predictive values (100%).

Delivery of miR-200c-3p Using Tumor-Targeted Mesoporous Silica Nanoparticles for Breast Cancer Therapy

Despite advances in breast cancer treatment, it remains the leading cause of cancer-related death in women worldwide. In this context, microRNAs have emerged as potential therapeutic targets but still present some limitations for in vivo applications. Particularly, miR-200c-3p is a well-known tumor suppressor microRNA that inhibits tumor progression and metastasis in breast cancer through downregulating ZEB1 and ZEB2. Based on the above, we describe the design and validation of a nanodevice using mesoporous silica nanoparticles for miR-200c-3p delivery for breast cancer treatment. We demonstrate the biocompatibility of the synthesized nanodevices as well as their ability to escape from endosomes/lysosomes and inhibit tumorigenesis, invasion, migration, and proliferation of tumor cells in vitro. Moreover, tumor targeting and effective delivery of miR-200c-3p from the nanoparticles in vivo are confirmed in an orthotopic breast cancer mouse model, and the therapeutic efficacy is also evidenced by a decrease in tumor size and lung metastasis, while showing no signs of toxicity. Overall, our results provide evidence that miR-200c-3p-loaded nanoparticles are a potential strategy for breast cancer therapy and a safe and effective system for tumor-targeted delivery of microRNAs.

High-Capacity Mesoporous Silica Nanocarriers of siRNA for Applications in Retinal Delivery

The main cause of subretinal neovascularisation in wet age-related macular degeneration (AMD) is an abnormal expression in the retinal pigment epithelium (RPE) of the vascular endothelial growth factor (VEGF). Current approaches for the treatment of AMD present considerable issues that could be overcome by encapsulating anti-VEGF drugs in suitable nanocarriers, thus providing better penetration, higher retention times, and sustained release. In this work, the ability of large pore mesoporous silica nanoparticles (LP-MSNs) to transport and protect nucleic acid molecules is exploited to develop an innovative LP-MSN-based nanosystem for the topical administration of anti-VEGF siRNA molecules to RPE cells. siRNA is loaded into LP-MSN mesopores, while the external surface of the nanodevices is functionalised with polyethylenimine (PEI) chains that allow the controlled release of siRNA and promote endosomal escape to facilitate cytosolic delivery of the cargo. The successful results obtained for VEGF silencing in ARPE-19 RPE cells demonstrate that the designed nanodevice is suitable as an siRNA transporter.

Mesoporous Silica Materials as an Emerging Tool for Cancer Immunotherapy

Cancer immunotherapy has emerged in the past decade as a promising strategy for treating many forms of cancer by stimulating the patient's immune system. Although immunotherapy has achieved some promising results in clinics, more efforts are required to improve the limitations of current treatments related to lack of effective and targeted cancer antigens delivery to immune cells, dose-limiting toxicity, and immune-mediated adverse effects, among others. In recent years, the use of nanomaterials has proven promising to enhance cancer immunotherapy efficacy and reduce side effects. Among nanomaterials, attention has been recently paid to mesoporous silica nanoparticles (MSNs) as a potential multiplatform for enhancing cancer immunotherapy by considering their unique properties, such as high porosity, and good biocompatibility, facile surface modification, and self-adjuvanticity. This review explores the role of MSN and other nano/micro-materials as an emerging tool to enhance cancer immunotherapy, and it comprehensively summarizes the different immunotherapeutic strategies addressed to date by using MSN.

Enhancement of photoactivity and cellular uptake of (Bu4N)2[Mo6I8(CH3COO)6] complex by loading on porous MCM-41 support. Photodynamic studies as an anticancer agent

The incorporation by ionic assembly of the hexanuclear molybdenum cluster (Bu₄N)₂[Mo₆I₈(CH₃CO₂)₆] (1) in amino-decorated mesoporous silica nanoparticles MCM-41, has yielded the new molybdenum-based hybrid photosensitizer 1@MCM-41. The new photoactive material presents a high porosity, due to the intrinsic high specific surface area of MCM-41 nanoparticles (989 m² g^-1) which is responsible for the good dispersion of the hexamolybdenum clusters on the nanoparticles surface, as observed by STEM analysis. The hybrid photosensitizer can generate efficiently singlet oxygen, which was demonstrated by using the benchmark photooxygenation reaction of 9,10-anthracenediyl-bis(methylene)dimalonic acid (ABDA) in water. The photodynamic therapy activity has been tested using LED light as an irradiation source (λ_irr ~ 400-700 nm; 15.6 mW/cm²). The results show a good activity of the hybrid photosensitizer against human cervical cancer (HeLa) cells, reducing up to 70 % their viability after 20 min of irradiation, whereas low cytotoxicity is detected in the darkness. The main finding of this research is that the incorporation of molybdenum complexes at porous MCM-41 supports enhances their photoactivity and improves cellular uptake, compared to free clusters.

Hollow mesoporous silica nanoparticles: Effective silica etching using tri-di- and mono-valent cations

Among different hollow nanostructures, the preparation of hollow mesoporous silica nanoparticles (HMSNs) is still a hotspot research field due to their unique properties e.g., large pore sizes and volumes, high drug loading capacity, ease of surface modification, large surface area, and biodegradability. Herein, novel uniform HMSNs are prepared for the first time by a combination of heterogeneous oil-water biphase stratification and simple mono-, di-, and tri-valent etching reactions. The biphase stratification reaction allows self-assembly of reactants at the oil-water interface, while the subsequent step is designed for the efficient selective silica etching under mild conditions. We have studied the effect of cation's valence (NH₄⁺, Ca²⁺, and Al³⁺) on the silica etching reaction coupled with the biphase stratification reaction both in the absence and presence of the auxiliary pore expanded agent 1, 3, 5 trimethylbenzene (TMB). In the absence of TMB, the Brunauer-Emmett-Teller (BET) analysis confirms that Al³⁺ creates materials with the largest pore size (18.0 nm), whereas the use of NH₄⁺ results in the largest pore volume (2.30 cm³/g). The pores generated using Ca²⁺ and Al³⁺ as silica etching agents have a volume 2.01 cm³/g and 2.05 cm³/g, respectively. Similar experiments in the presence of TMB leads to the formation of HMSN with larger pore sizes (24 nm and 21.5 nm) and volumes (2.70 cm³/g and 2.12 cm³/g) when using Al³⁺ and Ca²⁺, respectively, as etching agents. Drug loading capacity using Langmuir adsorption model indicate our hollow MSN material exhibit the high adsorbing DOX up to 558.23 mg per gram of nanoparticles in pH of 7.2. Furthermore, synthetized NPs exhibited high loading capacity for large protein and biomolecules such as BSA. Our findings confirmed that the charge density of cation has a critical role on selective silica etching in the preparation of HMSNs.

Aerogels as promising materials for antibacterial applications: a mini-review

The increasing cases of bacterial infections originating from resistant bacteria are a serious problem globally and many approaches have been developed for different purposes to treat bacterial infections. Aerogels are a novel class of smart porous materials composed of three-dimensional networks. Recently, aerogels with the advantages of ultra-low density, high porosity, tunable particle and pore sizes, and biocompatibility have been regarded as promising carriers for the design of delivery systems. Recently, aerogels have also been provided with antibacterial activity through loading of antibacterial agents, incorporation of metal/metal oxides and via surface functionalization and coating with various functional groups. In this mini-review, the synthesis of aerogels from both conventional and low-cost precursors is reported and examples of aerogels displaying antibacterial properties are summarized. As a result, it is clear that the encouraging antibacterial performance of aerogels promotes their use in many antibacterial applications, especially in the food industry, pharmaceutics and medicine.

Mesoporous silica nanoparticles for pulmonary drug delivery

Over the last years, respiratory diseases represent a clinical concern, being included among the leading causes of death in the world due to the lack of effective lung therapies, mainly ascribed to the pulmonary barriers affecting the delivery of drugs to the lungs. In this way, nanomedicine has arisen as a promising approach to overcome the limitations of current therapies for pulmonary diseases. The use of nanoparticles allows enhancing drug bioavailability at the target site while minimizing undesired side effects. Despite different approaches have been developed for pulmonary delivery of drugs, including the use of polymers, lipid-based nanoparticles, and inorganic nanoparticles, more efforts are required to achieve effective pulmonary drug delivery. This review provides an overview of the clinical challenges in main lung diseases, as well as highlighted the role of nanomedicine in achieving efficient pulmonary drug delivery. Drug delivery into the lungs is a complex process limited by the anatomical, physiological and immunological barriers of the respiratory system. We discuss how nanomedicine can be useful to overcome these pulmonary barriers and give insights for the rational design of future nanoparticles for enhancing lung treatments. We also attempt herein to display more in detail the potential of mesoporous silica nanoparticles (MSNs) as promising nanocarrier for pulmonary drug delivery by providing a comprehensive overview of their application in lung delivery to date while discussing the use of these particles for the treatment of respiratory diseases.

Sucrose-Responsive Intercommunicated Janus Nanoparticles Network

Inspired by biological systems, the development of artificial nanoscale materials that communicate over a short distance is still at its early stages. This work shows a new example of a cooperating system with intercommunicated devices at the nanoscale. The system is based on the new sucrose-responsive Janus gold-mesoporous silica (Janus Au-MS) nanoparticles network with two enzyme-powered nanodevices. These nanodevices involve two enzymatic processes based on invertase and glucose oxidase, which are anchored on the Au surfaces of different Janus Au-MS nanoparticles, and N-acetyl-L-cysteine and [Ru(bpy)₃]²⁺ loaded as chemical messengers, respectively. Sucrose acts as the INPUT, triggering the sequential delivery of two different cargoes through the enzymatic control. Nanoscale communication using abiotic nanodevices is a developing potential research field and may prompt several applications in different disciplines, such as nanomedicine.

Advanced mesoporous silica nanocarriers in cancer theranostics and gene editing applications

Targeted nanomaterials for cancer theranostics have been the subject of an expanding volume of research studies in recent years. Mesoporous silica nanoparticles (MSNs) are particularly attractive for such applications due to possibilities to synthesize nanoparticles (NPs) of different morphologies, pore diameters and pore arrangements, large surface areas and various options for surface functionalization. Functionalization of MSNs with different organic and inorganic molecules, polymers, surface-attachment of other NPs, loading and entrapping cargo molecules with on-desire release capabilities, lead to seemingly endless prospects for designing advanced nanoconstructs exerting multiple functions, such as simultaneous cancer-targeting, imaging and therapy. Describing composition and multifunctional capabilities of these advanced nanoassemblies for targeted therapy (passive, ligand-functionalized MSNs, stimuli-responsive therapy), including one or more modalities for imaging of tumors, is the subject of this review article, along with an overview of developments within a novel and attractive research trend, comprising the use of MSNs for CRISPR/Cas9 systems delivery and gene editing in cancer. Such advanced nanconstructs exhibit high potential for applications in image-guided therapies and the development of personalized cancer treatment.

Optimized mesoporous silica nanoparticle-based drug delivery system with removable manganese oxide gatekeeper for controlled delivery of doxorubicin

Rapid progress has been made for mesoporous silica nanoparticle (MSN) in recent years; however, efforts to fabricate MSN with adjustable size have been met with limited advancement in drug delivery, especially for the synthesis of MSN with adjustable size in the range of 150-300 nm. Herein we report the construction of a series of MSNs with adjustable specific surface area, size, and pore structure, depending on the different silicon monomers selected. The optimized MSN showed large specific surface area and appropriate size distribution for efficiently anchoring doxorubicin (DOX) through the imine linkage formed. Based on the remarkable features of the unique MSN, a novel MSN-based drug delivery system was prepared through the introduction of polydopamine/manganese oxide (PDA/MnO₂) coating, which reduced the premature leakage of drugs in physiological environments, and yet facilitated drug release when destroyed by responding to endogenous glutathione (GSH) at the tumor sites. Notably, the transformation of MnO₂ to Mn²⁺ resulted in the collapse of the PDA/MnO₂ coating, which facilitated drug release and therefore indicated the controlled release feature. It was demonstrated that the drug-loaded MSN-based drug delivery system delivered drugs into cancer cells and showed effective inhibition against cancer cell growth. These results suggested that the emergence of MSN with adjustable size can expand the application of MSN in drug delivery.

A new 8-oxo-7,8-2'deoxyguanosine nanoporous anodic alumina aptasensor for colorectal cancer diagnosis in blood and urine

Many important human diseases, and especially cancer, have been related to the overproduction of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG). This molecule is a product of oxidative stress processes over nucleophilic bases in DNA. In this work, an aptasensor for the rapid, selective and accurate detection of this oncomarker is presented. The aptasensor consists of a nanoporous anodic alumina material loaded with a dye and is functionalized with an aptamer-based "molecular gate". In the presence of target 8-oxo-dG, the capping aptamer displaces from the surface due to the high affinity of the analyte with the capping aptamer, thus inducing delivery of the preloaded fluorescent dye. In contrast, in the absence of 8-oxo-dG, a poor payload delivery is accomplished. This aptamer-based nanodevice has great sensitivity for 8-oxo-dG, resulting in a LOD of 1 nM and a detection time of ca. 60 min. Moreover, the aptasensor is able to accurately detect 8-oxo-dG in unmodified urine and serum without pre-concentration treatments. This diagnostic tool is validated in a set of 38 urine and serum samples from patients diagnosed of colorectal cancer and control patients. These samples are also analyzed using a standardized and specific ELISA kit. The aptasensor displays excellent sensitivity (95.83/100%) and specificity (80/100%) for 8-oxo-dG detection in serum and urine samples, respectively. Our results may serve as a basis for the development of generalized fluorogenic diagnostic platforms for the easy diagnosis of cancer in biofluids as well as for monitoring therapeutic treatments and detection of relapses without the use of expensive equipment or trained personnel.

Secreted Enzyme-Responsive System for Controlled Antifungal Agent Release

Essential oil components (EOCs) such as eugenol play a significant role in plant antimicrobial defense. Due to the volatility and general reactivity of these molecules, plants have evolved smart systems for their storage and release, which are key prerequisites for their efficient use. In this study, biomimetic systems for the controlled release of eugenol, inspired by natural plant defense mechanisms, were prepared and their antifungal activity is described. Delivery and antifungal studies of mesoporous silica nanoparticles (MSN) loaded with eugenol and capped with different saccharide gates—starch, maltodextrin, maltose and glucose—against fungus Aspergillus niger—were performed. The maltodextrin- and maltose-capped systems show very low eugenol release in the absence of the fungus Aspergillus niger but high cargo delivery in its presence. The anchored saccharides are degraded by exogenous enzymes, resulting in eugenol release and efficient inhibition of fungal growth.

Towards the Enhancement of Essential Oil Components' Antimicrobial Activity Using New Zein Protein-Gated Mesoporous Silica Microdevices

The development of new food preservatives is essential to prevent foodborne outbreaks or food spoilage due to microbial growth, enzymatic activity or oxidation. Furthermore, new compounds that substitute the commonly used synthetic food preservatives are needed to stifle the rising problem of microbial resistance. In this scenario, we report herein, as far as we know, for the first time the use of the zein protein as a gating moiety and its application for the controlled release of essential oil components (EOCs). The design of microdevices consist of mesoporous silica particles loaded with essential oils components (thymol, carvacrol and cinnamaldehyde) and functionalized with the zein (prolamin) protein found in corn as a molecular gate. The zein protein grafted on the synthesized microdevices is degraded by the proteolytic action of bacterial enzymatic secretions with the consequent release of the loaded essential oil components efficiently inhibiting bacterial growth. The results allow us to conclude that the new microdevice presented here loaded with the essential oil component cinnamaldehyde improved the antimicrobial properties of the free compound by decreasing volatility and increasing local concentration.

Nanoporous Anodic Alumina-Based Sensor for miR-99a-5p Detection as an Effective Early Breast Cancer Diagnostic Tool

Circulating microRNAs have emerged as potential diagnostic biomarkers. The deregulation of the microRNA miR-99a-5p has been previously described as an effective biomarker of early breast cancer. Herein, we present a new nanoporous anodic alumina (NAA)-based biosensor that can detect plasma miR-99a-5p with high sensitivity and selectivity. NAA pores are loaded with rhodamine B and capped with a specific oligonucleotide that is able to block cargo release until the target is present. In the presence of miR-99a-5p, the capping oligonucleotide recognizes the miR-99a-5p sequence and displaces it allowing the release of the encapsulated dye. This method is able to successfully distinguish healthy controls from breast cancer patients, even at early stages with high efficiency, showing the presented system as a promising tool for breast cancer detection.

Nanoparticle-cell-nanoparticle communication by stigmergy to enhance poly(I:C) induced apoptosis in cancer cells

Nanoparticle-cell-nanoparticle communication by stigmergy was demonstrated using two capped nanodevices. The first community of nanoparticles (i.e.S(RA)IFN) is loaded with 9-cis-retinoic acid and capped with interferon-γ, whereas the second community of nanoparticles (i.e.S(sulf)PIC) is loaded with sulforhodamine B and capped with poly(I:C). The uptake of S(RA)IFN by SK-BR-3 breast cancer cells enhanced the expression of TLR3 receptor facilitating the subsequent uptake of S(sulf)PIC and cell killing.

A chemical circular communication network at the nanoscale

In nature, coordinated communication between different entities enables a group to accomplish sophisticated functionalities that go beyond those carried out by individual agents. The possibility of programming and developing coordinated communication networks at the nanoscale-based on the exchange of chemical messengers-may open new approaches in biomedical and communication areas. Here, a stimulus-responsive circular model of communication between three nanodevices based on enzyme-functionalized Janus Au-mesoporous silica capped nanoparticles is presented. The output in the community of nanoparticles is only observed after a hierarchically programmed flow of chemical information between the members.

Triplex Hybridization-Based Nanosystem for the Rapid Screening of Pneumocystis Pneumonia in Clinical Samples

Pneumocystis pneumonia (PcP) is a disease produced by the opportunistic infection of the fungus Pneumocystis jirovecii. As delayed or unsuitable treatments increase the risk of mortality, the development of rapid and accurate diagnostic tools for PcP are of great importance. Unfortunately, current standard methods present severe limitations and are far from adequate. In this work, a time-competitive, sensitive and selective biosensor based on DNA-gated nanomaterials for the identification of P. jirovecii is presented. The biosensor consists of a nanoporous anodic alumina (NAA) scaffold which pores are filled with a dye reporter and capped with specific DNA oligonucleotides. In the presence of P. jirovecii genomic DNA, the gated biosensor is open, and the cargo is delivered to the solution where it is monitored through fluorescence spectroscopy. The use of capping oligonucleotides able to form duplex or triplex with P. jirovecii DNA is studied. The final diagnostic tool shows a limit of detection (LOD) of 1 nM of target complementary DNA and does not require previous amplification steps. The method was applied to identify DNA from P. jirovecii in unmodified bronchoalveolar lavage, nasopharyngeal aspirates, and sputum samples in 60 min. This is a promising alternative method for the routinely diagnosis of Pneumocystis pneumonia.

MUC1 Aptamer-Capped Mesoporous Silica Nanoparticles for Navitoclax Resistance Overcoming in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype. In the last years, navitoclax has emerged as a possible treatment for TNBC. Nevertheless, rapid navitoclax resistance onset has been observed thorough Mcl-1 overexpression. As a strategy to overcome Mcl-1-mediated resistance, herein we present a controlled drug co-delivery system based on mesoporous silica nanoparticles (MSNs) targeted to TNBC cells. The nanocarrier is loaded with navitoclax and the Mcl-1 inhibitor S63845 and capped with a MUC1-targeting aptamer (apMUC1-MSNs(Nav/S63845)). The apMUC1-capped nanoparticles effectively target TNBC cell lines and successfully induce apoptosis, overcoming navitoclax resistance. Moreover, navitoclax encapsulation protects platelets against apoptosis. These results point apMUC1-gated MSNs as suitable BH3 mimetics nanocarriers in the targeted treatment of MUC1-expressing TNBC.

A Sensitive Nanosensor for the In Situ Detection of the Cannibal Drug

A bio-inspired nanodevice for the selective and sensitive fluorogenic detection of 3,4-methylenedioxypyrovalerone (MDPV), usually known as Cannibal drug, is reported. The sensing nanodevice is based on mesoporous silica nanoparticles (MSNs), loaded with a fluorescent reporter (rhodamine B), and functionalized on their external surface with a dopamine derivative (3), which specifically interacts with the recombinant human dopamine transporter (DAT), capping the pores. In the presence of MDPV, DAT detaches from the MSNs consequently, causing rhodamine B release and allowing drug detection. The nanosensor shows a detection limit of 5.2 μM, and it is able to detect the MDPV drug both in saliva and blood plasma samples.

Surfactant-Triggered Molecular Gate Tested on Different Mesoporous Silica Supports for Gastrointestinal Controlled Delivery

In recent decades, the versatility of mesoporous silica particles and their relevance to develop controlled release systems have been demonstrated. Within them, gated materials able to modulate payload delivery represent great advantages. However, the role played by the porous matrix in this kind of systems is scarce. In this work, different mesoporous silica materials (MCM-41, MCM-48, SBA-15 and UVM-7) are functionalized with oleic acid as a molecular gate. All systems are fully characterized and their ability to confine the entrapped cargo and release it in the presence of bile salts is validated with release assays and in vitro digestion experiments. The cargo release profile of each synthesized support is studied, paying attention to the inorganic scaffold. Obtained release profiles fit to Korsmeyer–Peppas model, which explains the differences among the studied supports. Based on the results, UVM-7 material was the most appropriate system for duodenal delivery and was tested in an in vivo model of the Wistar rat. Payload confinement and its complete release after gastric emptying is achieved, establishing the possible use of mesoporous silica particles as protection and direct release agents into the duodenum and, hence, demonstrating that these systems could serve as an alternative to the administration methods employed until now.

Chitosan-Gated Fluorescent Mesoporous Silica Nanocarriers for the Real-Time Monitoring of Drug Release

We have constructed a novel gated nanocarrier for the real-time monitoring of drug release, consisting of three parts: (i) mesoporous silica nanoparticles (MSNs) as the drug carrier, (ii) chitosan as the nanovalve to block and unlock the pores, and (iii) 1,8-naphthalimide fluorophore as a connecting arm and fluorescent signal source. In the absence of glutathione (GSH), the integrity of the system results in the formation of pores in a closed state and the sulfone would block the intramolecular charge transfer (ICT) process, leading to no fluorescence emission. However, the nucleophilic attack of GSH can cause the removal of the chitosan and recovery of ICT property, thus triggering drug release and green fluorescence emission. The results demonstrate that the change of GSH concentration in vivo or vitro would lead to a change in drug release as well as a concurrent change in fluorescence signal, which can expand the application of our gated nanocarrier for monitoring different drug release in real time.

Real-Time In Vivo Detection of Cellular Senescence through the Controlled Release of the NIR Fluorescent Dye Nile Blue

In vivo detection of cellular senescence is accomplished by using mesoporous silica nanoparticles loaded with the NIR-FDA approved Nile blue (NB) dye and capped with a galactohexasaccharide (S3). NB emission at 672 nm is highly quenched inside S3, yet a remarkable emission enhancement is observed upon cap hydrolysis in the presence of β-galactosidase and dye release. The efficacy of the probe to detect cellular senescence is tested in vitro in melanoma SK-Mel-103 and breast cancer 4T1 cells and in vivo in palbociclib-treated BALB/cByJ mice bearing breast cancer tumor.

Preclinical antitumor efficacy of senescence-inducing chemotherapy combined with a nanoSenolytic

The induction of senescence produces a stable cell cycle arrest in cancer cells, thereby inhibiting tumor growth; however, the incomplete immune cell-mediated clearance of senescent cells may favor tumor relapse, limiting the long-term anti-tumorigenic effect of such drugs. A combination of senescence induction and the elimination of senescent cells may, therefore, represent an efficient means to inhibit tumor relapse. In this study, we explored the antitumor efficacy of a combinatory senogenic and targeted senolytic therapy in an immunocompetent orthotopic mouse model of the aggressive triple negative breast cancer subtype. Following palbociclib-induced senogenesis and senolysis by treatment with nano-encapsulated senolytic agent navitoclax, we observed inhibited tumor growth, reduced metastases, and a reduction in the systemic toxicity of navitoclax. We believe that this combination treatment approach may have relevance to other senescence-inducing chemotherapeutic drugs and additional tumor types. SIGNIFICANCE: While the application of senescence inducers represents a successful treatment strategy in breast cancer patients, some patients still relapse, perhaps due to the subsequent accumulation of senescent cells in the body that can promote tumor recurrence. We now demonstrate that a combination treatment of a senescence inducer and a senolytic nanoparticle selectively eliminates senescent cells, delays tumor growth, and reduces metastases in a mouse model of aggressive breast cancer. Collectively, our results support targeted senolysis as a new therapeutic opportunity to improve outcomes in breast cancer patients.

Electro-responsive films containing voltage responsive gated mesoporous silica nanoparticles grafted onto PEDOT-based conducting polymer

The characteristics and electromechanical properties of conductive polymers together to their biocompatibility have boosted their application as a suitable tool in regenerative medicine and tissue engineering. However, conducting polymers as drug release materials are far from being ideal. A possibility to overcome this drawback is to combine conducting polymers with on-command delivery particles with inherent high-loading capacity. In this scenario, we report here the preparation of conduction polymers containing gated mesoporous silica nanoparticles (MSN) loaded with a cargo that is delivered on command by electro-chemical stimuli increasing the potential use of conducting polymers as controlled delivery systems. MSNs are loaded with Rhodamine B (Rh B), anchored to the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly[(4-styrenesulfonic acid)-co-(maleic acid)], functionalized with a bipyridinium derivative and pores are capped with heparin (P3) by electrostatic interactions. P3 releases the entrapped cargo after the application of -640 mV voltage versus the saturated calomel electrode (SCE). Pore opening in the nanoparticles and dye delivery is ascribed to both (i) the reduction of the grafted bipyridinium derivative and (ii) the polarization of the conducting polymer electrode to negative potentials that induce detachment of positively charged heparin from the surface of the nanoparticles. Biocompatibility and cargo release studies were carried out in HeLa cells cultures.

New Advances in In Vivo Applications of Gated Mesoporous Silica as Drug Delivery Nanocarriers

One appealing concept in the field of hybrid materials is related to the design of gated materials. These materials are prepared in such a way that the release of chemical or biochemical species from voids of porous supports to a solution is triggered upon the application of external stimuli. Such gated materials are mainly composed of two subunits: i) a porous inorganic scaffold in which a cargo is stored, and ii) certain molecular or supramolecular entities, grafted onto the external surface, that can control mass transport from the interior of the pores. On the basis of this concept, a large number of examples are developed in the past ten years. A comprehensive overview of gated materials used in drug delivery applications in in vivo models from 2016 to date is thus given here.

Overview of the Evolution of Silica-Based Chromo-Fluorogenic Nanosensors

This review includes examples of silica-based, chromo-fluorogenic nanosensors with the aim of illustrating the evolution of the discipline in recent decades through relevant research developed in our group. Examples have been grouped according to the sensing strategies. A clear evolution from simply functionalized materials to new protocols involving molecular gates and the use of highly selective biomolecules such as antibodies and oligonucleotides is reported. Some final examples related to the evolution of chromogenic arrays and the possible use of nanoparticles to communicate with other nanoparticles or cells are also included. A total of 64 articles have been summarized, highlighting different sensing mechanisms.

Recent advances in metallopolymer-based drug delivery systems

Metallopolymers (MPs) or metal-containing polymers have shown great potential as new drug delivery systems (DDSs) due to their unique properties, including universal architectures, composition, properties and surface chemistry. Over the past few decades, the exponential growth of many new classes of MPs that deal with these issues has been demonstrated. This review presents and assesses the recent advances and challenges associated with using MPs as DDSs. Among the most widely used MPs for these purposes, metal complexes based on synthetic and natural polymers, coordination polymers, metal-organic frameworks, and metallodendrimers are distinguished. Particular attention is paid to the stimulus- and multistimuli-responsive metallopolymer-based DDSs. Of considerable interest is the use of MPs for combination therapy and multimodal systems. Finally, the problems and future prospects of using metallopolymer-based DDSs are outlined. The bibliography includes articles published over the past five years.

Not always what closes best opens better: mesoporous nanoparticles capped with organic gates

Four types of calcined MCM-41 silica nanoparticles, loaded with dyes and capped with different gating ensembles are prepared and characterized. N1 and N2 nanoparticles are loaded with rhodamine 6G and capped with bulky poly(ethylene glycol) derivatives bearing ester groups (1 and 2). N3-N4 nanoparticles are loaded with sulforhodamine B and capped with self-immolative derivatives bearing ester moieties. In the absence of esterase enzyme negligible cargo release from N1, N3 and N4 nanoparticles is observed whereas a remarkable release for N2 is obtained most likely due to the formation of an irregular coating on the outer surface of the nanoparticles. In contrast, a marked delivery is found in N1, N3, and N4 in the presence of esterase enzyme. The delivery rate is related to the hydrophilic/hydrophobic character of the coating shell. The use of hydrophilic poly(ethylene glycol) derivatives as gating ensembles on N1 and N2 enables an easy access of esterase to the ester moieties with subsequent fast cargo release. On the other hand, the presence of a hydrophobic monolayer on N3 and N4 partially hinders esterase enzyme access to the ester groups and the rate of cargo release was decreased.

Mesoporous Silica-Based Materials with Bactericidal Properties

Bacterial infections are the main cause of chronic infections and even mortality. In fact, due to extensive use of antibiotics and, then, emergence of antibiotic resistance, treatment of such infections by conventional antibiotics has become a major concern worldwide. One of the promising strategies to treat infection diseases is the use of nanomaterials. Among them, mesoporous silica materials (MSMs) have attracted burgeoning attention due to high surface area, tunable pore/particle size, and easy surface functionalization. This review discusses how one can exploit capacities of MSMs to design and fabricate multifunctional/controllable drug delivery systems (DDSs) to combat bacterial infections. At first, the emergency of bacterial and biofilm resistance toward conventional antimicrobials is described and then how nanoparticles exert their toxic effects upon pathogenic cells is discussed. Next, the main aspects of MSMs (e.g., physicochemical properties, multifunctionality, and biosafety) which one should consider in the design of MSM-based DDSs against bacterial infections are introduced. Finally, a comprehensive analysis of all the papers published dealing with the use of MSMs for delivery of antibacterial chemicals (antimicrobial agents functionalized/adsorbed on mesoporous silica (MS), MS-loaded with antimicrobial agents, gated MS-loaded with antimicrobial agents, MS with metal-based nanoparticles, and MS-loaded with metal ions) is provided.

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

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

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

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

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

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

Mesoporous silica microparticles gated with a bulky azo derivative for the controlled release of dyes/drugs in colon

Mesoporous silica microparticles were prepared, loaded with the dye safranin O (M-Saf) or with the drug budesonide (M-Bud) and capped by the grafting of a bulky azo derivative. Cargo release from M-Saf at different pH values (mimicking those found in the gastrointestinal tract) in the absence or presence of sodium dithionite (a reducing agent mimicking azoreductase enzyme present in the colon) was tested. Negligible safranin O release was observed at pH 6.8 and 4.5, whereas a moderate delivery at pH 1.2 was noted and attributed to the hydrolysis of the urea bond that linked the azo derivative onto the external surface of the inorganic scaffold. Moreover, a marked release was observed when sodium dithionite was present and was ascribed to the rupture of the azo bond in the molecular gate. Budesonide release from M-Bud in the presence of sodium dithionite was also assessed by ultraviolet-visible spectroscopy and high performance liquid chromatography measurements. In addition, preliminary in vivo experiments with M-Saf carried out in mice indicated that the chemical integrity of the microparticles remained unaltered in the stomach and the small intestine, and safranin O seemed to be released in the colon.

Functional Magnetic Mesoporous Silica Microparticles Capped with an Azo-Derivative: A Promising Colon Drug Delivery Device

Magnetic micro-sized mesoporous silica particles were used for the preparation of a gated material able to release an entrapped cargo in the presence of an azo-reducing agent and, to some extent, at acidic pH. The magnetic mesoporous microparticles were loaded with safranin O and the external surface was functionalized with an azo derivative 1 (bearing a carbamate linkage) yielding solid S1. Aqueous suspensions of S1 at pH 7.4 showed negligible safranin O release due to the presence of the bulky azo derivative attached onto the external surface of the inorganic scaffold. However, in the presence of sodium dithionite (azoreductive agent), a remarkable safranin O delivery was observed. At acidic pH, a certain safranin O release from S1 was also found. The pH-triggered safranin O delivery was ascribed to the acid-induced hydrolysis of the carbamate moiety that linked the bulky azo derivatives onto the mesoporous inorganic magnetic support. The controlled release behavior of S1 was also tested using a model that simulated the gastro intestinal tract.