Mesoporous Silica Nanoparticles as an Ideal Platform for Cancer Immunotherapy: Recent Advances and Future Directions.

Cancer immunotherapy has recently transformed the traditional approaches against various cancer malignancies. Immunotherapy includes systemic and local treatments to enhance immune responses against cancer; and involves strategies such as immune checkpoints, cancer vaccines, immune modulatory agents, mimetic antigen-presenting cells, and adoptive cell therapy. Despite promising results, these approaches still suffer from several limitations including a lack of precise delivery of immune-modulatory agents to the target cells, off-target toxicity, among others that can be overcome using nanotechnology. Mesoporous silica nanoparticles (MSNs) have been investigated to improve various aspects of cancer immunotherapy attributed to the advantageous structural features of this nanomaterial. MSNs can be engineered to alter their properties such as size, shape, porosity, surface functionality, and adjuvanticity. This review explores the immunological properties of MSNs; and the use of MSNs as delivery vehicles for immune-adjuvants, vaccines, and mimetic antigen-presenting cells (APCs). The review also details the current strategies to remodel the tumor microenvironment to positively reciprocate towards the anti-tumor immune cells and the use of MSNs for immunotherapy in combination with other anti-tumor therapies including photodynamic/thermal therapies to enhance the therapeutic effect against cancer. Lastly, the present demands and future scenarios for the use of MSNs for cancer immunotherapy are discussed. This article is protected by copyright. All rights reserved.

Improving DNA nanostructure stability: A review of the biomedical applications and approaches.

DNA's programmable, predictable, and precise self-assembly properties enable structural DNA nanotechnology. DNA nanostructures have a wide range of applications in drug delivery, bioimaging, biosensing, and theranostics. However, physiological conditions, including low cationic ions and the presence of nucleases in biological systems, can limit the efficacy of DNA nanostructures. Several strategies for stabilizing DNA nanostructures have been developed, including i) coating them with biomolecules or polymers, ii) chemical cross-linking of the DNA strands, and iii) modifications of the nucleotides and nucleic acids backbone. These methods significantly enhance the structural stability of DNA nanostructures and thus enable in vivo and in vitro applications. This study reviews the present perspective on the distinctive properties of the DNA molecule and explains various DNA nanostructures, their advantages, and their disadvantages. We provide a brief overview of the biomedical applications of DNA nanostructures and comprehensively discuss possible approaches to improve their biostability. Finally, the shortcomings and challenges of the current biostability approaches are examined.

Demonstrating the Synthesis and Antibacterial Properties of Nanostructured Silver.

Investigating and understanding novel antibacterial agents is a necessary task as there is a constant increase in the number of multidrug-resistant bacterial species. The use of nanotechnology to combat drug-resistant bacteria is an important research area. The laboratory experiment described herein demonstrates that changes in the nanostructure of a material lead to significantly different antibacterial efficacies. Silver has been known to be an effective antibacterial agent throughout history, but its therapeutic uses are limited when present as either the bulk material or cations in solution. Silver nanoparticles (AgNPs) and DNA-templated silver nanoclusters (DNA-AgNCs) are both nanostructured silver materials that show vastly different antibacterial activities when incubated with E. coli in liquid culture. This work aims to provide students with hands-on experience in the synthesis and characterization of nanomaterials and basic microbiology skills; moreover, it is applicable to undergraduate and graduate curricula.

Synthesis of Mesoporous Silica Nanoparticles for the Delivery of Nucleic Acid Nanostructures.

Nanomaterials have been extensively used for the delivery of nucleic acids. This is attributed to the unique features of nanoparticles to carry genetic material with different physiochemical properties. Mesoporous silica nanoparticles (MSNPs) are a versatile platform for the efficient delivery of nuclei acid-based materials. In this chapter, we describe the synthesis of MSNPs to efficiently transport nucleic acid nanoparticles.

Autophagy Regulation Using Multimodal Chlorin e6-Loaded Polysilsesquioxane Nanoparticles to Improve Photodynamic Therapy.

Photodynamic therapy (PDT) is a promising anticancer noninvasive technique that relies on the generation of reactive oxygen species (ROS). Unfortunately, PDT still has many limitations, including the resistance developed by cancer cells to the cytotoxic effect of ROS. Autophagy, which is a stress response mechanism, has been reported as a cellular pathway that reduces cell death following PDT. Recent studies have demonstrated that PDT in combination with other therapies can eliminate anticancer resistance. However, combination therapy is usually challenged by the differences in the pharmacokinetics of the drugs. Nanomaterials are excellent delivery systems for the efficient codelivery of two or more therapeutic agents. In this work, we report on the use of polysilsesquioxane (PSilQ) nanoparticles for the codelivery of chlorin-e6 (Ce6) and an autophagy inhibitor for early- or late-stage autophagy. Our results, obtained from a reactive oxygen species (ROS) generation assay and apoptosis and autophagy flux analyses, demonstrate that the reduced autophagy flux mediated by the combination approach afforded an increase in the phototherapeutic efficacy of Ce6-PSilQ nanoparticles. We envision that the promising results in the use of multimodal Ce6-PSilQ material as a codelivery system against cancer pave the way for its future application with other clinically relevant combinations.

Antiviral activity of nano-monocaprin against Phi6 as a surrogate for SARS-CoV-2 / Actividad antiviral de nano-monocaprina contra Phi6 como sustituto del SARS-CoV-2

The COVID-19 pandemic involving SARS-CoV-2 has raised interest in using antimicrobial lipid formulations to inhibit viral entry into their host cells or to inactivate them. Lipids are a part of the innate defense mechanism against pathogens. Here, we evaluated the use of nano-monocaprin (NMC) in inhibiting enveloped (phi6) and unenveloped (MS2) bacteriophages. NMC was prepared using the sonochemistry technique. Size and morphology analysis revealed the formation of ~ 8.4 ± 0.2-nm NMC as measured by dynamic light scattering. We compared the antiviral activity of NMC with molecular monocaprin (MMC) at 0.5 mM and 2 mM concentrations against phi6, which we used as a surrogate for SARS-CoV-2. The synthesized NMC exhibited 50% higher antiviral activity against phi6 than MMC at pH 7 using plaque assay. NMC inactivated phi6 stronger at pH 4 than at pH 7. To determine if NMC is toxic to mammalian cells, we used MTS assay to assess its IC50 for HPDE and HeLa cell lines, which were ~ 203 and 221 µM, respectively. NMC may be used for prophylactic application either as a drop or spray since many viruses enter the human body through the mucosal lining of the nose, eyes, and lungs.(AU)

Antiviral activity of nano-monocaprin against Phi6 as a surrogate for SARS-CoV-2.

The COVID-19 pandemic involving SARS-CoV-2 has raised interest in using antimicrobial lipid formulations to inhibit viral entry into their host cells or to inactivate them. Lipids are a part of the innate defense mechanism against pathogens. Here, we evaluated the use of nano-monocaprin (NMC) in inhibiting enveloped (phi6) and unenveloped (MS2) bacteriophages. NMC was prepared using the sonochemistry technique. Size and morphology analysis revealed the formation of ~ 8.4 ± 0.2-nm NMC as measured by dynamic light scattering. We compared the antiviral activity of NMC with molecular monocaprin (MMC) at 0.5 mM and 2 mM concentrations against phi6, which we used as a surrogate for SARS-CoV-2. The synthesized NMC exhibited 50% higher antiviral activity against phi6 than MMC at pH 7 using plaque assay. NMC inactivated phi6 stronger at pH 4 than at pH 7. To determine if NMC is toxic to mammalian cells, we used MTS assay to assess its IC50 for HPDE and HeLa cell lines, which were ~ 203 and 221 µM, respectively. NMC may be used for prophylactic application either as a drop or spray since many viruses enter the human body through the mucosal lining of the nose, eyes, and lungs.

Influence of silver ion release on the inactivation of antibiotic resistant bacteria using light-activated silver nanoparticles.

The widespread increase in antibiotic resistance (AR), in an extensive range of microorganisms, demands the development of alternative antimicrobials with novel non-specific low-mutation bacterial targets. Silver nanoparticles (AgNPs) and photosensitizers (PSs) are promising antimicrobial agents with broad-spectrum activity and low tendency for antimicrobial resistance development. Herein, we investigated the light-mediated oxidation of AgNPs for accelerated release of Ag+ in the antibacterial synergy of PS-AgNP conjugates using protoporphyrin IX (PpIX) as a PS. Also, the influence of polyethyleneimine (PEI) coated AgNPs in promoting antibacterial activity was examined. We synthesized, characterized and tested the antimicrobial effect of three nanoparticles: AgNPs, PpIX-AgNPs, and PEI-PpIX-AgNPs against a methicillin-resistant Staphylococcus aureus strain (MRSA) and a wild-type multidrug resistant (MDR) E. coli. PpIX-AgNPs were the most effective material achieving >7 log inactivation of MRSA and MDR E. coli. The order of bacterial log inactivation was PpIX-AgNPs > PEI-PpIX-AgNPs > AgNPs. This order correlates with the trend of Ag+ concentration released by the NPs (PpIX-AgNPs > PEI-PpIX-AgNPs > AgNPs). Our study confirms a synergistic effect between PpIX and AgNPs in the inactivation of AR pathogens with about 10-fold increase in inactivation of ARB relative to AgNPs only. The concentration of Ag+ released from NPs determined the log inactivation of MRSA and MDR E. coli more than either the phototoxic effect or the electrostatic interaction promoted by surface charge of nanoparticles with bacteria cells. All NPs showed negligible cytotoxicity to mammalian cells at the bacterial inhibitory concentration after 24 h exposure. These observations confirm the crucial role of optimized Ag+ release for enhanced performance of AgNP-based antimicrobials against AR pathogens.

Nanoparticle combination for precise stroma modulation and improved delivery for pancreatic cancer.

Therapeutic success in the treatment of pancreatic ductal adenocarcinoma (PDAC) is hindered by the extensive stroma associated to this disease. Stroma is composed of cellular and non-cellular components supporting and evolving with the tumor. One of the most studied mediators of cancer cell-stroma crosstalk is sonic hedgehog (SHh) pathway leading to the intense desmoplasia observed in PDAC tumors. Herein, we demonstrate that the use of mesoporous silica nanoparticles (MSNs) containing an SHh inhibitor, cyclopamine (CyP), and the combination of chemotherapeutic drugs (Gemcitabine (Gem)/cisplatin (cisPt)) as the main delivery system for the sequential treatment led to the reduction in tumor stroma along with an improvement in the treatment of PDAC. We synthesized two versions of the MSN-based platform containing the SHh inhibitor (CyP-MSNs) and the drug combination (PEG-Gem-cisPt-MSNs). In vitro and in vivo protein analysis show that CyP-MSNs effectively inhibited the SHh pathway. In addition, the sequential combination of CyP-MSNs followed by PEG-Gem-cisPt-MSNs led to effective stromal modulation, increased access of secondary PEG-Gem-cisPt-MSNs at the tumor site, and improved therapeutic performance in HPAF II xenograft mice. Taken together, our findings support the potential of drug delivery using MSNs for stroma modulation and to prevent pancreatic cancer progression.

Nanoparticle-based therapeutic strategies targeting major clinical challenges in pancreatic cancer treatment.

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers due to its aggressiveness and the challenges for early diagnosis and treatment. Recently, nanotechnology has demonstrated relevant strategies to overcome some of the major clinical issues in the treatment of PDAC. This review is focused on the pathological hallmarks of PDAC and the impact of nanotechnology to find solutions. It describes the use of nanoparticle-based systems designed for the delivery of chemotherapeutic agents and combinatorial alternatives that address the chemoresistance associated with PDAC, the development of combination therapies targeting the molecular heterogeneity in PDAC, the investigation of novel therapies dealing with the improvement of immunotherapy and handling the desmoplastic stroma in PDAC by remodeling the tumor microenvironment. A special section is dedicated to the design of nanoparticles for unique non-traditional modalities that could be promising in the future for the improvement in the dismal prognosis of PDAC.

Advanced Nanoengineering Approach for Target-Specific, Spatiotemporal, and Ratiometric Delivery of Gemcitabine-Cisplatin Combination for Improved Therapeutic Outcome in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is an intractable malignancy with a dismal survival rate. Recent combination therapies have had a major impact on the improvement of PDAC prognosis. Nevertheless, clinically used combination regimens such as FOLFIRINOX and gemcitabine (Gem)/nab-paclitaxel still face major challenges due to lack of the safe and ratiometric delivery of multiple drugs. Here, a rationally designed mesoporous silica nanoparticle (MSN)-based platform is reported for the target-specific, spatiotemporal, ratiometric, and safe co-delivery of Gem and cisplatin (cisPt). It is shown that systemic administration of the nanoparticles results in synergistic therapeutic outcome in a syngeneic and clinically relevant genetically engineered PDAC mouse model that has rarely been used for the therapeutic evaluation of nanomedicine. This synergism is associated with a strategic engineering approach, in which nanoparticles provide redox-responsive controlled delivery and in situ differential release of Gem/cisPt drugs with the goal of overcoming resistance to Pt-based drugs. The platform is also rendered with additional tumor-specificity via a novel tumor-associated mucin1 (tMUC1)-specific antibody, TAB004. Overall, the platform suppresses tumor growth and eliminates the off-target toxicities of a highly toxic chemotherapy combination.

Use of Polyhedral Oligomeric Silsesquioxane (POSS) in Drug Delivery, Photodynamic Therapy and Bioimaging.

Polyhedral oligomeric silsesquioxanes (POSS) have attracted considerable attention in the design of novel organic-inorganic hybrid materials with high performance capabilities. Features such as their well-defined nanoscale structure, chemical tunability, and biocompatibility make POSS an ideal building block to fabricate hybrid materials for biomedical applications. This review highlights recent advances in the application of POSS-based hybrid materials, with particular emphasis on drug delivery, photodynamic therapy and bioimaging. The design and synthesis of POSS-based materials is described, along with the current methods for controlling their chemical functionalization for biomedical applications. We summarize the advantages of using POSS for several drug delivery applications. We also describe the current progress on using POSS-based materials to improve photodynamic therapies. The use of POSS for delivery of contrast agents or as a passivating agent for nanoprobes is also summarized. We envision that POSS-based hybrid materials have great potential for a variety of biomedical applications including drug delivery, photodynamic therapy and bioimaging.

Light-Activated Protoporphyrin IX-Based Polysilsesquioxane Nanoparticles Induce Ferroptosis in Melanoma Cells.

The use of nanoparticle-based materials to improve the efficacy of photodynamic therapy (PDT) to treat cancer has been a burgeoning field of research in recent years. Polysilsesquioxane (PSilQ) nanoparticles with remarkable features, such as high loading of photosensitizers, biodegradability, surface tunability, and biocompatibility, have been used for the treatment of cancer in vitro and in vivo using PDT. The PSilQ platform typically shows an enhanced PDT performance following a cell death mechanism similar to the parent photosensitizer. Ferroptosis is a new cell death mechanism recently associated with PDT that has not been investigated using PSilQ nanoparticles. Herein, we synthesized a protoporphyrin IX (PpIX)-based PSilQ platform (PpIX-PSilQ NPs) to study the cell death pathways, with special focus on ferroptosis, during PDT in vitro. Our data obtained from different assays that analyzed Annexin V binding, glutathione peroxidase activity, and lipid peroxidation demonstrate that the cell death in PDT using PpIX-PSilQ NPs is regulated by apoptosis and ferroptosis. These results can provide alternative approaches in designing PDT strategies to enhance therapeutic response in conditions stymied by apoptosis resistance.

Evaluation of Polyhedral Oligomeric Silsesquioxane Porphyrin Derivatives on Photodynamic Therapy.

Polyhedral oligomeric silsesquioxane (POSS) is a promising scaffold to be used as delivery system. POSS can modify the properties of photosensitizers to enhance their efficacy toward photodynamic therapy (PDT). In this work, we designed, synthesized and characterized five different POSS porphyrin (POSSPs 1-5) derivatives containing hydrophobic (1-3) and hydrophilic (4 and 5) functional groups. In general, all the POSSPs showed a better singlet oxygen quantum yield than the parent porphyrins due to the steric hindrance from the POSS unique structure. POSSPs 1 and 3 containing isobutyl groups showed better PDT performance in cancer cells at lower concentrations than POSSPs 4 and 5. However; at higher concentrations, the POSSP4 containing hydrophilic groups has an enhanced PDT efficiency as compared with the parent porphyrin. We envision that the chemical tunability of POSSs can be used as a promising option to improve the delivery and performance of photosensitizers.

Combination of Nucleic Acid and Mesoporous Silica Nanoparticles: Optimization and Therapeutic Performance In Vitro.

Programmable nucleic acid nanoparticles (NANPs) with precisely controlled functional compositions can regulate the conditional activation of various biological pathways and responses in human cells. However, the intracellular delivery of NANPs alone is hindered by their susceptibility to nuclease activity and inefficient crossing of biological membranes. In this work, we optimized the internalization and therapeutic performance of several representative NANPs delivered with mesoporous silica nanoparticles (MSNPs) tailored for efficient electrostatic association with NANPs. We compared the immunostimulatory properties of different NA-MS-NP complexes formed with globular, planar, and fibrous NANPs and demonstrated the maximum immunostimulation for globular NANPs. As a proof of concept, we assessed the specific gene silencing by NA-MS-NP complexes functionalized with siRNA targeting green fluorescent protein expressed in triple-negative human breast cancer cells. We showed that the fibrous NANPs have the highest silencing efficiency when compared to globular or planar counterparts. Finally, we confirmed the multimodal ability of MSNPs to co-deliver a chemotherapy drug, doxorubicin, and NANPs targeting apoptosis regulator gene BCL2 in triple-negative breast cancer and melanoma cell lines. Overall, the combination of NANPs and MSNPs may become a new promising approach to efficiently treat cancer and other diseases via the simultaneous targeting of various pathways.

Nanoparticle mediated silencing of tenascin C in hepatic stellate cells: effect on inflammatory gene expression and cell migration.

Chronic liver dysfunction often begins with hepatic fibrosis. A pivotal event in the progression of liver fibrosis and cirrhosis is hepatic stellate cell (HSC) activation and secretion of extracellular matrix proteins, including tenascin-C (TnC). TnC is often chosen as a therapeutic target for treatment of liver disease. TnC is minimally detected in healthy tissue, but is transiently expressed during tissue injury, and plays a critical role in fibrogenesis and tumorigenesis. siRNA therapy is a promising alternative to knock-down proteins relevant for fibrosis therapy. This study describes the application of a functionalized mesoporous silica nanoparticles (MSNs) for the efficient transport and delivery of siTnC in HSCs. Silencing experiments in HSCs demonstrate the effective reduction of TnC mRNA and protein levels. In addition, attenuation of TnC expression due to the cellular uptake and release of siTnC from MSNs resulted in decreases of inflammatory cytokine levels and hepatocyte migration. We envision this siTnC-MSN platform as a promising alternative to evaluate siRNA therapy of chronic liver disease in preclinical trials.

Multimodal Polysilsesquioxane Nanoparticles for Combinatorial Therapy and Gene Delivery in Triple-Negative Breast Cancer.

Multifunctional hybrid nanoparticles are being developed to carry a wide variety of therapeutic and imaging agents for multiple biomedical applications. Polysilsesquioxane (PSilQ) nanoparticles are a promising hybrid platform with numerous advantages to be used as a delivery system. In this report, we demonstrate the ability of a stimuli-responsive PSilQ-based platform to transport and deliver simultaneously protoporphyrin IX, curcumin, and RNA interference inducers inside human cells. This multimodal delivery system shows a synergistic performance for the combined phototherapy and chemotherapy of triple-negative breast cancer and can be used for efficient transfection of therapeutic nucleic acids. The current work represents the first report of using the PSilQ platform for the combined phototherapy and chemotherapy and gene delivery.

Influence of Cationic meso-Substituted Porphyrins on the Antimicrobial Photodynamic Efficacy and Cell Membrane Interaction in Escherichia coli.

Photodynamic inactivation (PDI) is a non-antibiotic option for the treatment of infectious diseases. Although Gram-positive bacteria have been shown to be highly susceptible to PDI, the inactivation of Gram-negative bacteria has been more challenging due to the impermeability properties of the outer membrane. In the present study, a series of photosensitizers which contain one to four positive charges (1⁻4) were used to evaluate the charge influence on the PDI of a Gram-negative bacteria, Escherichia coli (E. coli), and their interaction with the cell membrane. The dose-response PDI results confirm the relevance of the number of positive charges on the porphyrin molecule in the PDI of E. coli. The difference between the Hill coefficients of cationic porphyrins with 1⁻3 positive charges and the tetra-cationic porphyrin (4) revealed potential variations in their mechanism of inactivation. Fluorescent live-cell microscopy studies showed that cationic porphyrins with 1⁻3 positive charges bind to the cell membrane of E. coli, but are not internalized. On the contrary, the tetra-cationic porphyrin (4) permeates through the membrane of the cells. The contrast in the interaction of cationic porphyrins with E. coli confirmed that they followed different mechanisms of inactivation. This work helps to have a better understanding of the structure-activity relationship in the efficiency of the PDI process of cationic porphyrins against Gram-negative bacteria.

In vitro evaluation of folic acid-conjugated redox-responsive mesoporous silica nanoparticles for the delivery of cisplatin.

The use of cisplatin(IV) prodrugs for the delivery of cisplatin have gained significant attention, because of their low toxicity and reactivity. Recent studies have shown that targeted cisplatin(IV)-prodrug nanoparticle-based delivery systems can improve the internalization of the cisplatin(IV) prodrug. We hypothesized that folic acid-conjugated mesoporous silica nanoparticles (MSNs) containing cisplatin(IV) prodrug could target cancer cells that overexpress the folate receptor and deliver the active cisplatin drug upon intracellular reduction. To prove this hypothesis, internalization and localization studies in HeLa cancer cells were performed using flow cytometry and confocal microscopy. The ability of MSNs to escape from the endolysosomal compartments, the formation of DNA adducts, and the cytotoxic effects of the MSNs were also evaluated. Our results confirmed that this MSN-based delivery platform was capable of delivering cisplatin into the cytosol of HeLa cells, inducing DNA adducts and subsequent cell death.