RNA-Based Immunostimulatory Liposomal Spherical Nucleic Acids as Potent TLR7/8 Modulators

Recent advances in gene delivery nanoplatforms based on spherical nucleic acids

Gene therapy is a therapeutic option for mitigating diseases that do not respond well to pharmacological therapy. This type of therapy allows for correcting altered and defective genes by transferring nucleic acids to target cells. Notably, achieving a desirable outcome is possible by successfully delivering genetic materials into the cell. In-vivo gene transfer strategies use two major classes of vectors, namely viral and nonviral. Both of these systems have distinct pros and cons, and the choice of a delivery system depends on therapeutic objectives and other considerations. Safe and efficient gene transfer is the main feature of any delivery system. Spherical nucleic acids (SNAs) are nanotechnology-based gene delivery systems (i.e., non-viral vectors). They are three-dimensional structures consisting of a hollow or solid spherical core nanoparticle that is functionalized with a dense and highly organized layer of oligonucleotides. The unique structural features of SNAs confer them a high potency in internalization into various types of tissue and cells, a high stability against nucleases, and efficay in penetrating through various biological barriers (such as the skin, blood-brain barrier, and blood-tumor barrier). SNAs also show negligible toxicity and trigger minimal immune response reactions. During the last two decades, all these favorable physicochemical and biological attributes have made them attractive vehicles for drug and nucleic acid delivery. This article discusses the unique structural properties, types of SNAs, and also optimization mechanisms of SNAs. We also focus on recent advances in the synthesis of gene delivery nanoplatforms based on the SNAs.

Spherical nucleic acids: emerging amplifiers for therapeutic nanoplatforms

Gene therapy is a revolutionary treatment approach in the 21st century, offering significant potential for disease prevention and treatment. However, the efficacy of gene delivery is often compromised by the inherent challenges of gene properties and vector-related defects. It is crucial to explore ways to enhance the curative effect of gene drugs and achieve safer, more widespread, and more efficient utilization, which represents a significant challenge in amplification gene therapy advancements. Spherical nucleic acids (SNAs), with their unique physicochemical properties, are considered an innovative solution for scalable gene therapy. This review aims to comprehensively explore the amplifying contributions of SNAs in gene therapy and emphasize the contribution of SNAs to the amplification effect of gene therapy from the aspects of structure, application, and recent clinical translation - an aspect that has been rarely reported or explored thus far. We begin by elucidating the fundamental characteristics and scaling-up properties of SNAs that distinguish them from traditional linear nucleic acids, followed by an analysis of combined therapy treatment strategies, theranostics, and clinical translation amplified by SNAs. We conclude by discussing the challenges of SNAs and provide a prospect on the amplification characteristics. This review seeks to update the current understanding of the use of SNAs in gene therapy amplification and promote further research into their clinical translation and amplification of gene therapy.

Gender Control of Mouse Embryos by Activation of TLR7/8 on X Sperm via Ligands dsRNA-40 and dsRNA-DR

Gender control technologies are promising for enhancing the production efficiency of the farm animal industry, and preventing sex-linked hereditary diseases in humans. It has been shown that the X sperm of mammalian animals specifically expresses X-chromosome-derived toll-like receptor 7/8 (TLR7/8), and the activation of TLR7/8 on the X sperm by their agonist, R848, can separate X and Y sperm via the specific inhibition of X sperm motility. The use of R848-preselected sperm for fertilization resulted in sex-ratio-skewed embryos or offspring. In this study, we aimed to investigate whether two other TLR7/8 ligands, double-stranded RNA-40 (dsRNA-40) and double-stranded RNA-DR (dsRNA-DR), are also effective in the separation of mouse X and Y sperm and the subsequent generation of gender-ratio-skewed in vitro fertilization (IVF) embryos. Our results indicated that cholesterol modification significantly enhances the transfection of dsRNA-40 and dsRNA-DR into sperm cells. dsRNA-40 and dsRNA-DR incubation with mouse sperm could separate X and Y sperm by the specific suppression of X sperm motility by decreasing its ATP level and mitochondrial activity. The use of a dsRNA-40- or dsRNA-DR-preselected upper layer of sperm, which predominantly contains high-motility Y sperm, for IVF caused a male-biased sex ratio shift in resulting embryos (with 65.90-74.93% of embryos being male). This study develops a simple new method for the efficient separation of mammalian X and Y sperm, enabling the selective production of male or female progenies.

Magnetic Bead Spherical Nucleic Acid Microstructure for Reliable DNA Preservation and Repeated DNA Reading

DNA is an attractive medium for long-term data storage because of its density, ease of copying, sustainability, and longevity. Recent advances have focused on the development of new encoding algorithms, automation, and sequencing technologies. Despite progress in these subareas, the most challenging hurdle in the deployment of DNA storage remains the reliability of preservation and the repeatability of reading. Herein, we report the construction of a magnetic bead spherical nucleic acid (MB-SNA) composite microstructure and its use as a cost-effective platform for reliable DNA preservation and repeated reading. MB-SNA has an inner core of silica@γ-Fe2O3@silica microbeads and an outer spherical shell of double-stranded DNA (dsDNA) with a density as high as 34 pmol/cm2. For MB-SNA, each strand of dsDNA stored a piece of data, and the high-density packing of dsDNA achieved high-capacity storage. MB-SNA was advantageous in terms of reliable preservation over free DNA. By accelerated aging tests, the data of MB-SNA is demonstrated to be readable after 0.23 million years of preservation at -18 °C and 50% relative humidity. Moreover, MB-SNA facilitated repeated reading by facile PCR-magnetic separation. After 10 cycles of PCR access, the retention rate of dsDNA for MB-SNA is demonstrated to be as high as 93%, and the accuracy of sequencing is more than 98%. In addition, MB-SNA makes cost-effective DNA storage feasible. By serial dilution, the physical limit for MB-SNA to achieve accurate reading is probed to be as low as two microstructures.

Smart Nanocarriers for the Targeted Delivery of Therapeutic Nucleic Acid for Cancer Immunotherapy

A wide variety of therapeutic approaches and technologies for delivering therapeutic agents have been investigated for treating cancer. Recently, immunotherapy has achieved success in cancer treatment. Successful clinical results of immunotherapeutic approaches for cancer treatment were led by antibodies targeting immune checkpoints, and many have advanced through clinical trials and obtained FDA approval. A major opportunity remains for the development of nucleic acid technology for cancer immunotherapy in the form of cancer vaccines, adoptive T-cell therapies, and gene regulation. However, these therapeutic approaches face many challenges related to their delivery to target cells, including their in vivo decay, the limited uptake by target cells, the requirements for nuclear penetration (in some cases), and the damage caused to healthy cells. These barriers can be avoided and resolved by utilizing advanced smart nanocarriers (e.g., lipids, polymers, spherical nucleic acids, metallic nanoparticles) that enable the efficient and selective delivery of nucleic acids to the target cells and/or tissues. Here, we review studies that have developed nanoparticle-mediated cancer immunotherapy as a technology for cancer patients. Moreover, we also investigate the crosstalk between the function of nucleic acid therapeutics in cancer immunotherapy, and we discuss how nanoparticles can be functionalized and designed to target the delivery and thus improve the efficacy, toxicity, and stability of these therapeutics.

The emerging nanomedicine-based technology for non-small cell lung cancer immunotherapy: how far are we from an effective treatment

Non-small cell lung cancer (NSCLC) is a prominent etiology of cancer-related mortality. The heterogeneous nature of this disease impedes its accurate diagnosis and efficacious treatment. Consequently, constant advancements in research are imperative in order to comprehend its intricate nature. In addition to currently available therapies, the utilization of nanotechnology presents an opportunity to enhance the clinical outcomes of NSCLC patients. Notably, the burgeoning knowledge of the interaction between the immune system and cancer itself paves the way for developing novel, emerging immunotherapies for treating NSCLC in the early stages of the disease. It is believed that with the novel engineering avenues of nanomedicine, there is a possibility to overcome the inherent limitations derived from conventional and emerging treatments, such as off-site drug cytotoxicity, drug resistance, and administration methods. Combining nanotechnology with the convergence points of current therapies could open up new avenues for meeting the unmet needs of NSCLC treatment.

Three-Dimensional Nucleic Acid Nanostructures Based on Self-Assembled Polymer-Oligonucleotide Conjugates of Comblike and Coil-Comb Chain Architectures

Spherical nucleic acids have emerged as a class of nanostructures, exhibiting a wide variety of properties, distinctly different from those of linear nucleic acids, and a plethora of applications in therapeutics and diagnostics. Herein, we report on preparation of 3D nucleic acid nanostructures, prepared by self-assembly of polymer-oligonucleotide conjugates. The latter are obtained by grafting multiple alkyne-functionalized oligonucleotide strands onto azide-modified homo-, block, and random (co)polymers of chloromethylstyrene via initiator-free click coupling chemistry to form conjugates of comblike and coil-comb chain architectures. The resulting conjugates are amphiphilic and form stable nanosized supramolecular structures in aqueous solution. The nanoconstructs are thoroughly investigated and a number of physical characteristics, in particular, molar mass, size, aggregation number, zeta potential, material density, number of oligonucleotide strands per particle, grafting density, and their relation to hallmark properties of spherical nucleic acids - biocompatibility, resistance against DNase I, cellular uptake without the need for transfection agents - are determined.

Immunomodulation with Nucleic Acid Nanodevices

The precise regulation of interactions of specific immunological components is crucial for controllable immunomodulation, yet it remains a great challenge. With the assistance of advanced computer design, programmable nucleic acid nanotechnology enables the customization of synthetic nucleic acid nanodevices with unprecedented geometrical and functional precision, which have shown promising potential for precise immunoengineering. Notably, the inherently immunologic functions of nucleic acids endow these nucleic acid-based assemblies with innate advantages in immunomodulatory engagement. In this review, the roles of nucleic acids in innate immunity are discussed, focusing on the definition, immunologic modularity, and enhanced bioavailability of structural nucleic acid nanodevices. In light of this, molecular programming and precise organization of functional modules with nucleic acid nanodevices for immunomodulation are emphatically reviewed. At last, the present challenges and future perspectives of nucleic acid nanodevices for immunomodulation are discussed.

Nucleotides Entrapped in Liposome Nanovesicles as Tools for Therapeutic and Diagnostic Use in Biomedical Applications

The use of nucleotides for biomedical applications is an old desire in the scientific community. As we will present here, there are references published over the past 40 years with this intended use. The main problem is that, as unstable molecules, nucleotides require some additional protection to extend their shelf life in the biological environment. Among the different nucleotide carriers, the nano-sized liposomes proved to be an effective strategic tool to overcome all these drawbacks related to the nucleotide high instability. Moreover, due to their low immunogenicity and easy preparation, the liposomes were selected as the main strategy for delivery of the mRNA developed for COVID-19 immunization. For sure this is the most important and relevant example of nucleotide application for human biomedical conditions. In addition, the use of mRNA vaccines for COVID-19 has increased interest in the application of this type of technology to other health conditions. For this review article, we will present some of these examples, especially focused on the use of liposomes to protect and deliver nucleotides for cancer therapy, immunostimulatory activities, enzymatic diagnostic applications, some examples for veterinarian use, and the treatment of neglected tropical disease.

Osmani R, Hani U, Yoonus Thajudeen K, Kiran Raj G, Gowda DV. Recent advances in the liposomal nanovesicles based immunotherapy in the treatment of cancer: A review

Immunotherapy, along with chemotherapy, targeted delivery, radiation and surgery has become one of the most common cancer treatments. The aim of cancer immunology is to use the bodys immune system to combat tumors and develop a robust antitumor immune response. In the last few years, immune checkpoint inhibitors and chimeric antigen receptor-modified T cells have made substantial advancements in cancer immunotherapy. By boosting cell type-specific delivery and immunological responses, nanocarriers like liposomes have the ability to enhance greater immune responses. The efficacy of anti-tumor therapeutics is being significantly improved as liposomes can assist in resolving a number of issues that can arise from a variety of cancer immunotherapies. Since, liposomes can be loaded with both hydrophilic and hydrophobic drugs and protect the immunotherapeutic agents loaded inside the core, they offer significant advantages over other nano delivery systems. The use of liposomes for accurate and timely delivery of immunotherapies to particular targeted neoplasms, with little or no injury to healthy cells, maximizes immunotherapy efficacy. Liposomes are also suitable vehicles for delivering medications simultaneously with other therapies such as chemotherapy, radiation, and phototherapy. Liposomal nanoparticles will be introduced and used as an objective immunotherapy delivery system for great precision, making them a viable cancer treatment approach.With an emphasis on dendritic cells, T cells, tumor and natural killer cells, and macrophages; outline of many forms of immune-therapies in oncology and cutting-edge advances in liposomal nanovesicles for cancer immunotherapy are covered in this review.

Nucleic acid-based supramolecular structures: vesicular spherical nucleic acids from a non-phospholipid nucleolipid

Vesicular spherical nucleic acids are dynamic nucleic acid-based supramolecular structures that are held together via non-covalent bonds. They have promising applications as drug and nucleic acid delivery materials, diagnostic and imaging tools and platforms for development of various therapeutic schemes. In this contribution, we report on vesicular spherical nucleic acids, constructed from a non-phospholipid nucleolipid - an original hybrid biomacromolecule, composed of a hydrophobic residue, resembling that of the naturally occurring phospholipids, and a DNA oligonucleotide strand. The nucleolipid was synthesized by coupling of dibenzocyclooctyne-functionalized oligonucleotide and azidated 1,3-dihexadecyloxy-propane-2-ol via an azide-alkyne click reaction. In aqueous solution it spontaneously self-associated into nanosized supramolecular structures, identified as unilamellar vesicles composed of a self-closed interdigitated bilayer. Vesicular structures were also formed upon intercalation of the nucleolipid via its lipid-mimetic residue in the phospholipid bilayer membrane of liposomes prepared from readily available and FDA-approved lipids (1,2-dipalmitoyl-rac-glycero-3-phosphocholine and cholesterol). The vesicular structures are thoroughly investigated by light scattering (dynamic, static, and electrophoretic) and cryogenic TEM and the physical characteristics, in particular, number of strands per particle, grafting density, and conformation of the strands, were compared to those of reference spherical nucleic acids. Finally, the vesicular structures were shown to exhibit cellular internalization with no need of transfection agents and enhanced colloidal and nuclease stability.

Rational Vaccinology: Harnessing Nanoscale Chemical Design for Cancer Immunotherapy

Cancer immunotherapy is a powerful treatment strategy that mobilizes the immune system to fight disease. Cancer vaccination is one form of cancer immunotherapy, where spatiotemporal control of the delivery of tumor-specific antigens, adjuvants, and/or cytokines has been key to successfully activating the immune system. Nanoscale materials that take advantage of chemistry to control the nanoscale structural arrangement, composition, and release of immunostimulatory components have shown significant promise in this regard. In this Outlook, we examine how the nanoscale structure, chemistry, and composition of immunostimulatory compounds can be modulated to maximize immune response and mitigate off-target effects, focusing on spherical nucleic acids as a model system. Furthermore, we emphasize how chemistry and materials science are driving the rational design and development of next-generation cancer vaccines. Finally, we identify gaps in the field that should be addressed moving forward and outline future directions to galvanize researchers from multiple disciplines to help realize the full potential of this form of cancer immunotherapy through chemistry and rational vaccinology.

Spherical nucleic acids: Organized nucleotide aggregates as versatile nanomedicine

Spherical nucleic acids (SNAs) are composed of a nanoparticle core and a layer of densely arranged oligonucleotide shells. After the first report of SNA by Mirkin and coworkers in 1996, it has created a significant interest by offering new possibilities in the field of gene and drug delivery. The controlled aggregation of oligonucleotides on the surface of organic/inorganic nanoparticles improves the delivery of genes and nucleic acid-based drugs and alters and regulates the biological profiles of the nanoparticle core within living organisms. Here in this review, we present an overview of the recent progress of SNAs that has speeded up their biomedical application and their potential transition to clinical use. We start with introducing the concept and characteristics of SNAs as drug/gene delivery systems and highlight recent efforts of bioengineering SNA by imaging and treatmenting various diseases. Finally, we discuss potential challenges and opportunities of SNAs, their ongoing clinical trials, and future translation, and how they may affect the current landscape of clinical practices. We hope that this review will update our current understanding of SNA, organized oligonucleotide aggregates, for disease diagnosis and treatment.

Delivery of therapeutic oligonucleotides in nanoscale

Therapeutic oligonucleotides (TOs) represent one of the most promising drug candidates in the targeted cancer treatment due to their high specificity and capability of modulating cellular pathways that are not readily druggable. However, efficiently delivering of TOs to cancer cellular targets is still the biggest challenge in promoting their clinical translations. Emerging as a significant drug delivery vector, nanoparticles (NPs) can not only protect TOs from nuclease degradation and enhance their tumor accumulation, but also can improve the cell uptake efficiency of TOs as well as the following endosomal escape to increase the therapeutic index. Furthermore, targeted and on-demand drug release of TOs can also be approached to minimize the risk of toxicity towards normal tissues using stimuli-responsive NPs. In the past decades, remarkable progresses have been made on the TOs delivery based on various NPs with specific purposes. In this review, we will first give a brief introduction on the basis of TOs as well as the action mechanisms of several typical TOs, and then describe the obstacles that prevent the clinical translation of TOs, followed by a comprehensive overview of the recent progresses on TOs delivery based on several various types of nanocarriers containing lipid-based nanoparticles, polymeric nanoparticles, gold nanoparticles, porous nanoparticles, DNA/RNA nanoassembly, extracellular vesicles, and imaging-guided drug delivery nanoparticles.

A Comprehensive Review of Recent Advancements in Cancer Immunotherapy and Generation of CAR T Cell by CRISPR-Cas9

The mechanisms involved in immune responses to cancer have been extensively studied for several decades, and considerable attention has been paid to harnessing the immune system’s therapeutic potential. Cancer immunotherapy has established itself as a promising new treatment option for a variety of cancer types. Various strategies including cancer vaccines, monoclonal antibodies (mAbs), adoptive T-cell cancer therapy and CAR T-cell therapy have gained prominence through immunotherapy. However, the full potential of cancer immunotherapy remains to be accomplished. In spite of having startling aspects, cancer immunotherapies have some difficulties including the inability to effectively target cancer antigens and the abnormalities in patients’ responses. With the advancement in technology, this system has changed the genome-based immunotherapy process in the human body including the generation of engineered T cells. Due to its high specificity, CRISPR-Cas9 has become a simple and flexible genome editing tool to target nearly any genomic locus. Recently, the CD19-mediated CAR T-cell (chimeric antigen receptor T cell) therapy has opened a new avenue for the treatment of human cancer, though low efficiency is a major drawback of this process. Thus, increasing the efficiency of the CAR T cell (engineered T cells that induce the chimeric antigen receptor) by using CRISPR-Cas9 technology could be a better weapon to fight against cancer. In this review, we have broadly focused on recent immunotherapeutic techniques against cancer and the use of CRISPR-Cas9 technology for the modification of the T cell, which can specifically recognize cancer cells and be used as immune-therapeutics against cancer.

Activation of Innate Immunity by Therapeutic Nucleic Acids

Nucleic acid-based therapeutics have gained increased attention during recent decades because of their wide range of application prospects. Immunostimulatory nucleic acids represent a promising class of potential drugs for the treatment of tumoral and viral diseases due to their low toxicity and stimulation of the body’s own innate immunity by acting on the natural mechanisms of its activation. The repertoire of nucleic acids that directly interact with the components of the immune system is expanding with the improvement of both analytical methods and methods for the synthesis of nucleic acids and their derivatives. Despite the obvious progress in this area, the problem of delivering therapeutic acids to target cells as well as the unresolved issue of achieving a specific therapeutic effect based on activating the mechanism of interferon and anti-inflammatory cytokine synthesis. Minimizing the undesirable effects of excessive secretion of inflammatory cytokines remains an unsolved task. This review examines recent data on the types of immunostimulatory nucleic acids, the receptors interacting with them, and the mechanisms of immunity activation under the action of these molecules. Finally, data on immunostimulatory nucleic acids in ongoing and completed clinical trials will be summarized.

Chemically Tuning the Antigen Release Kinetics from Spherical Nucleic Acids Maximizes Immune Stimulation

Cancer vaccine structure is emerging as an important design factor that offers tunable parameters to enhance the targeted immune response. We report the impact of altering the antigen release rate from spherical nucleic acid (SNA) vaccines-nanoparticles with a liposomal core and surface-anchored adjuvant DNA-on immune stimulation. Peptide antigens were incorporated into SNAs using either a nonreducible linker or one of a series of reduction-triggered traceless linkers that release the native peptide at rates controlled by their substitution pattern. Compared with a nonreducible linkage, the traceless attachment of antigens resulted in lower EC50 of T cell proliferation in vitro and greater dendritic cell (DC) activation and higher T cell killing ability in vivo. Traceless linker fragmentation rates affected the rates of antigen presentation by DCs and were correlated with the in vitro potencies of SNAs. Antigen release was correlated with the ex vivo -log(EC50), and more rapid antigen release resulted in an order of magnitude improvement in the EC50 and earlier and greater antigen presentation over the same time-period. In vivo, increasing the rate of antigen release resulted in higher T cell activation and target killing. These findings provide fundamental insights into and underscore the importance of vaccine structure.

Harnessing the combined potential of cancer immunotherapy and nanomedicine: A new paradigm in cancer treatment

Cancer immunotherapy has recently emerged as a rising star due to its ability to activate patients' immune systems to fight tumors and prevent relapse. Conversely, the interest in cancer nanomedicine has seemingly waned due to its lackluster clinical translation. Despite being hailed as a game-changer in oncology, cancer immunotherapy still faces numerous challenges. Combining both entities together has thus been one among several solutions proposed to circumvent these challenges. This solution has since gained traction and has also led to a renaissance of cancer nanomedicine. While most combinations are currently experimental at best, some have progressed on to clinical trials. This review thus seeks to examine the advantages and disadvantages of integrating both modalities as a cancer treatment. The opportunities, challenges and future directions of this emerging field will also be explored with the hope that such a combination will lead to a paradigm shift in cancer treatments.

Synergistic Immunostimulation through the Dual Activation of Toll-like Receptor 3/9 with Spherical Nucleic Acids

Toll-like receptors (TLRs) are a family of proteins that modulate the innate immune system and control the initiation of downstream immune responses. Spherical nucleic acids (SNAs) designed to stimulate single members of the TLR family (e.g., TLR7 or TLR9) have shown utility in cancer immunotherapy. We hypothesized that SNAs synthesized with multiple TLR agonists would enable the simultaneous activation of multiple TLR pathways for maximally synergistic immune activation. Here, we describe the synthesis of SNAs that incorporate both a TLR3 agonist (polyinosinic:polycytidylic acid, poly(I:C)) and TLR9 agonist (CpG oligonucleotide) on the same liposomal scaffold. In this design, CpG comprises the SNA oligonucleotide shell, and poly(I:C) is encapsulated in the liposome core. These dual-TLR activating SNAs efficiently codeliver high quantities of both agonists to the same target cell, yielding enhanced immunostimulation in various murine and human antigen-presenting cells (APCs). Moreover, codelivery of TLR agonists using the SNA both synchronizes and prolongs the duration of costimulatory molecule and major histocompatibility complex class II expression in APCs, which has been shown to be important for efficient downstream immune responses. Taken together, this SNA design provides a strategy for potently activating immune cells and increasing the efficiency of their activation, which likely will inform the preparation of nanomaterials for highly potent immunotherapies.

Mimicking Pathogens to Augment the Potency of Liposomal Cancer Vaccines

Liposomes have emerged as interesting vehicles in cancer vaccination strategies as their composition enables the inclusion of both hydrophilic and hydrophobic antigens and adjuvants. In addition, liposomes can be decorated with targeting moieties to further resemble pathogenic particles that allow for better engagement with the immune system. However, so far liposomal cancer vaccines have not yet reached their full potential in the clinic. In this review, we summarize recent preclinical studies on liposomal cancer vaccines. We describe the basic ingredients for liposomal cancer vaccines, tumor antigens, and adjuvants, and how their combined inclusion together with targeting moieties potentially derived from pathogens can enhance vaccine immunogenicity. We discuss newly identified antigen-presenting cells in humans and mice that pose as promising targets for cancer vaccines. The lessons learned from these preclinical studies can be applied to enhance the efficacy of liposomal cancer vaccination in the clinic.

Nucleic acid nanoparticles (NANPs) as molecular tools to direct desirable and avoid undesirable immunological effects

Nucleic acid nanoparticles (NANPs) represent a highly versatile molecular platform for the targeted delivery of various therapeutics. However, despite their promise, further clinical translation of this innovative technology can be hindered by immunological off-target effects. All human cells are equipped with an arsenal of receptors that recognize molecular patterns specific to foreign nucleic acids and understanding the rules that guide this recognition offer the key rationale for the development of therapeutic NANPs with tunable immune stimulation. Numerous recent studies have provided increasing evidence that in addition to NANPs' physicochemical properties and therapeutic effects, their interactions with cells of the immune system can be regulated through multiple independently programmable architectural parameters. The results further suggest that defined immunomodulation by NANPs can either support their immunoquiescent delivery or be used for conditional stimulation of beneficial immunological responses.

Exosomes: Powerful weapon for cancer nano-immunoengineering

Cancer immunotherapy (CIT) that targets the tumor immune microenvironment is regarded as a revolutionary advancement in the fight against cancer. The success and failure of CIT are due to the complexity of the immunosuppressive microenvironment. Cancer nanomedicine is a potential adjuvant therapeutic strategy for immune-based combination therapy. Exosomes are natural nanomaterials that play a pivotal role in mediating intercellular communications and package delivery in the tumor microenvironment. They affect the immune response or the effectiveness of immunotherapy. In particular, exosomal PD-L1 promotes cancer progression and resistance to immunotherapy. Exosomes possess high bioavailability, biological stability, targeting specificity, low toxicity, and immune characteristics, which indicate their potential for cancer therapy. They can be engineered to act as effective cancer therapeutic tools that activate anti-tumor immune response and start immune surveillance. In the current review, we introduce the role of exosomes in a tumor immune microenvironment, highlight the application of engineered exosomes to CIT, and discuss the challenges and prospects for clinical application.

Emerging skin-targeted drug delivery strategies to engineer immunity: A focus on infectious diseases

INTRODUCTION

Infectious pathogens are global disrupters. Progress in biomedical science and technology has expanded the public health arsenal against infectious diseases. Specifically, vaccination has reduced the burden of infectious pathogens. Engineering systemic immunity by harnessing the cutaneous immune network has been particularly attractive since the skin is an easily accessible immune-responsive organ. Recent advances in skin-targeted drug delivery strategies have enabled safe, patient-friendly, and controlled deployment of vaccines to cutaneous microenvironments for inducing long-lived pathogen-specific immunity to mitigate infectious diseases, including COVID-19.

AREAS COVERED

This review briefly discusses the basics of cutaneous immunomodulation and provides a concise overview of emerging skin-targeted drug delivery systems that enable safe, minimally invasive, and effective intracutaneous administration of vaccines for engineering systemic immune responses to combat infectious diseases.

EXPERT OPINION

In-situ engineering of the cutaneous microenvironment using emerging skin-targeted vaccine delivery systems offers remarkable potential to develop diverse immunization strategies against pathogens. Mechanistic studies with standard correlates of vaccine efficacy will be important to compare innovative intracutaneous drug delivery strategies to each other and to existing clinical approaches. Cost-benefit analyses will be necessary for developing effective commercialization strategies. Significant involvement of industry and/or government will be imperative for successfully bringing novel skin-targeted vaccine delivery methods to market for their widespread use.

Design and enhanced gene silencing activity of spherical 2'-fluoroarabinose nucleic acids (FANA-SNAs)

Drug delivery vectors for nucleic acid therapeutics (NATs) face significant barriers for translation into the clinic. Spherical nucleic acids (SNAs) – nanoparticles with an exterior shell made up of DNA strands and a hydrophobic interior – have recently shown great potential as vehicles to improve the biodistribution and efficacy of NATs. To date, SNA design has not taken advantage of the powerful chemical modifications available to NATs. Here, we modify SNAs with 2′-deoxy-2′-fluoro-d-arabinonucleic acid (FANA-SNA), and show increased stability, enhanced gene silencing potency and unaided uptake (gymnosis) as compared to free FANA. By varying the spacer region between the nucleic acid strand and the attached hydrophobic polymer, we show that a cleavable DNA based spacer is essential for maximum activity. This design feature will be important when implementing functionalized nucleic acids into nanostructures for gene silencing. The modularity of the FANA-SNA was demonstrated by silencing two different targets. Transfection-free delivery was superior for the modified SNA compared to the free FANA oligonucleotide.

Optimizing FANA modified spherical nucleic acids (FANA-SNAs) for highly efficient delivery of nucleic acid therapeutics.

Immunostimulating RNA Delivered by P1500 PEGylated Cationic Liposomes Limits Influenza Infection in C57Bl/6 Mice

The emergence of highly pathogenic viruses and a high speed of infection spread put forward the problem of the development of novel antivirals and their delivery vehicles. In this study, we investigated the antiviral effect of the previously identified immunostimulatory 19-bp dsRNA (isRNA) with 3'-nucleotide overhangs, which stimulates interferon α synthesis when delivered using cationic liposomes consisting of 1,26-bis(cholest-5-en-3β-yloxycarbonylamino)-7,11,16,20-tetraazahexacosan tetrahydrochloride and lipid-helper dioleoylphosphatidylethanolamine and its PEGylated formulation P1500 in vitro and in vivo. In vitro data showed that isRNA/2X3-DOPE complexes protected L929 cells from encephalomyocarditis virus infection, while isRNA/P1500 complexes were not active, which correlates with their lower transfection activity in cell culture. Comparison of the interferon-inducing activity of isRNA in BALB/c, CBA and C57Bl/6 mice showed that PEGylated liposomes significantly enhance the interferon-inducing activity of isRNA in vivo. The antiviral efficacy of the isRNA in vivo was considerably affected by the delivery system. The cationic liposomes 2X3-DOPE did not enhance the antiviral properties of isRNA in vivo. Similar liposomes equipped with a PEGylated lipoconjugate provided a pronounced anti-influenza effect of the isRNA in vivo. Administration of isRNA to C57Bl/6 led to a decrease in virus titers in the lungs and a significant decrease in the severity of the infection. Administration of a similar formulation to BALB/c mice caused only a mild antiviral effect at the initial stages of the infection. The data show that isRNA in combination with the PEGylated delivery system can be considered an effective means of suppressing influenza A infection.

Chemical Strategies to Boost Cancer Vaccines

Personalized cancer vaccines (PCVs) are reinvigorating vaccine strategies in cancer immunotherapy. In contrast to adoptive T-cell therapy and checkpoint blockade, the PCV strategy modulates the innate and adaptive immune systems with broader activation to redeploy antitumor immunity with individualized tumor-specific antigens (neoantigens). Following a sequential scheme of tumor biopsy, mutation analysis, and epitope prediction, the administration of neoantigens with synthetic long peptide (SLP) or mRNA formulations dramatically improves the population and activity of antigen-specific CD4+ and CD8+ T cells. Despite the promising prospect of PCVs, there is still great potential for optimizing prevaccination procedures and vaccine potency. In particular, the arduous development of tumor-associated antigen (TAA)-based vaccines provides valuable experience and rational principles for augmenting vaccine potency which is expected to advance PCV through the design of adjuvants, delivery systems, and immunosuppressive tumor microenvironment (TME) reversion since current personalized vaccination simply admixes antigens with adjuvants. Considering the broader application of TAA-based vaccine design, these two strategies complement each other and can lead to both personalized and universal therapeutic methods. Chemical strategies provide vast opportunities for (1) exploring novel adjuvants, including synthetic molecules and materials with optimizable activity, (2) constructing efficient and precise delivery systems to avoid systemic diffusion, improve biosafety, target secondary lymphoid organs, and enhance antigen presentation, and (3) combining bioengineering methods to innovate improvements in conventional vaccination, "smartly" re-educate the TME, and modulate antitumor immunity. As chemical strategies have proven versatility, reliability, and universality in the design of T cell- and B cell-based antitumor vaccines, the union of such numerous chemical methods in vaccine construction is expected to provide new vigor and vitality in cancer treatment.

Tumor cell lysate-loaded immunostimulatory spherical nucleic acids as therapeutics for triple-negative breast cancer

Highly heterogenous cancers, such as triple-negative breast cancer (TNBC), remain challenging immunotherapeutic targets. Herein, we describe the synthesis and evaluation of immunotherapeutic liposomal spherical nucleic acids (SNAs) for TNBC therapy. The SNAs comprise immunostimulatory oligonucleotides (CpG-1826) as adjuvants and encapsulate lysates derived from TNBC cell lines as antigens. The resulting nanostructures (Lys-SNAs) enhance the codelivery of adjuvant and antigen to immune cells when compared to simple mixtures of lysates with linear oligonucleotides both in vitro and in vivo, and reduce tumor growth relative to simple mixtures of lysate and CpG-1826 (Lys-Mix) in both Py230 and Py8119 orthotopic syngeneic mouse models of TNBC. Furthermore, oxidizing TNBC cells prior to lysis and incorporation into SNAs (OxLys-SNAs) significantly increases the activation of dendritic cells relative to their nonoxidized counterparts. When administered peritumorally in vivo in the EMT6 mouse mammary carcinoma model, OxLys-SNAs significantly increase the population of cytotoxic CD8+ T cells and simultaneously decrease the population of myeloid derived suppressor cells (MDSCs) within the tumor microenvironment, when compared with Lys-SNAs and simple mixtures of oxidized lysates with CpG-1826. Importantly, animals administered OxLys-SNAs exhibit significant antitumor activity and prolonged survival relative to all other treatment groups, and resist tumor rechallenge. Together, these results show that the way lysates are processed and packaged has a profound impact on their immunogenicity and therapeutic efficacy. Moreover, this work points toward the potential of oxidized tumor cell lysate-loaded SNAs as a potent class of immunotherapeutics for cancers lacking common therapeutic targets.

Controlling timing and location in vaccines

Vaccines are one of the most powerful technologies supporting public health. The adaptive immune response induced by immunization arises following appropriate activation and differentiation of T and B cells in lymph nodes. Among many parameters impacting the resulting immune response, the presence of antigen and inflammatory cues for an appropriate temporal duration within the lymph nodes, and further within appropriate subcompartments of the lymph nodes- the right timing and location- play a critical role in shaping cellular and humoral immunity. Here we review recent advances in our understanding of how vaccine kinetics and biodistribution impact adaptive immunity, and the underlying immunological mechanisms that govern these responses. We discuss emerging approaches to engineer these properties for future vaccines, with a focus on subunit vaccines.

Enhanced Immunostimulatory Activity of a Cytosine-Phosphate-Guanosine Immunomodulator by the Assembly of Polymer DNA Wires and Spheres

Unmethylated cytosine-phosphate-guanosine (CpG) oligodeoxynucleotides are immunostimulatory nucleic acids wildly utilized as adjuvants or for vaccines to treat diseases. However, there is a lack of simple and efficient vectors for CpG oligodeoxynucleotide delivery with long-lasting immune stimulation. Herein, self-assembled polymer wires consisting of CpG motifs by hybridization chain reaction were constructed with excellent biocompatibility and immunostimulatory activity. The designed polymer DNA wires acted as programmable multivalent immunoadjuvants and triggered immune response, stimulated pro-inflammatory cytokine secretion, and induced the apoptosis of cancer cells. More strikingly, polymer nanospheres assembled from the polymer DNA wires and cationic poly-l-lysine further improved cellular uptake and continuously stimulate the lysosomal Toll-like receptor 9 of immune cells, thereby remarkably enhancing the activation of immune cells. These results demonstrated that self-assembled polymer DNA nanoassemblies with multivalent CpG could trigger strong immune response and further induce cancer cell death.

Antibody Response against Cowpea Mosaic Viral Nanoparticles Improves In Situ Vaccine Efficacy in Ovarian Cancer

Cancer immunotherapies are designed to facilitate recognition and elimination of transformed cells by the immune system. We have established the immunotherapeutic efficacy of the plant virus cowpea mosaic virus (CPMV) as an in situ vaccine in several syngeneic tumor mouse models as well as in companion dogs with metastatic melanoma. Intratumoral injection of CPMV modulates the local tumor microenvironment to relieve immunosuppression and potentiate antitumor immunity. The viral nucleocapsid that drives this antitumor immunity, however, also is a potent immunogen itself, and thus immune response in the form of anti-CPMV antibodies is expected during the treatment based on repeat administrations. Moreover, being part of the food chain, pre-existing antibodies to plant viruses may be prevalent. The presence of such pre-existing anti-CPMV immunity could potentially impact immunotherapeutic efficacy of the in situ vaccine and could have translational implications. To address such concerns, this study evaluated the efficacy of CPMV in situ vaccine in the presence of pre-existing antibodies in a syngeneic mouse model of ovarian cancer. Our results indicate that prior exposure to CPMV had no negative impact on the efficacy of CPMV in situ vaccine. Strikingly, an improved efficacy of CPMV in situ vaccine was observed. This study therefore presents an important milestone in the translational development of plant viral-based in situ vaccines and alleviates concerns about the presence of anti-CPMV antibodies, which are developed during the course of treatment but have no impact on immunotherapeutic efficacy.

Advances in biomolecule inspired polymeric material decorated interfaces for biological applications

With the development of surface modification technology, interface properties have great effects on the interaction between biomedical materials and cells and biomolecules, which significantly affects the biocompatibility and functionality of materials. As an orderly and perfect system, biological organisms in nature effectively integrate all kinds of bio-interfaces with physiological functions, which shed light on the importance of biomolecules in organisms. It gives birth to a bio-inspiration strategy to design and fabricate smart materials with specific functionalities, e.g. osteogenic and chondrocytic induced materials inspired by bone sialoprotein and chondroitin sulfate. Through this mimicking approach, various functional materials were utilized to decorate the interfaces and further optimize the performance of biomedical materials, which would widely expand their applications. In this review, followed by a summary and brief introduction of surface modification methods, we highlight recent advances in the fabrication of functional polymeric materials inspired by a range of biomolecules for decorating interfaces. Then, the other applications of biomolecule inspired materials including tissue engineering, diagnosis and treatment of diseases and physiological function regulation are presented and the future outlook is discussed as well.

Liposomal Spherical Nucleic Acid Scaffolded Site-Selective Hybridization of Nanoparticles for Visual Detection of MicroRNAs

In this study, the advanced liposomal spherical nucleic acid (L-SNA) is exploited for the first time to establish a spherical, three-dimensional biosensing platform by hybridizing with a set of nanoparticles. By hydrophilic and hydrophobic interactions as well as programmable base-pairing, red-emission quantum dots (QDs), green-emission QDs, and gold nanoparticles (AuNPs) are encapsulated into the internal aqueous core, the intermediate lipid bilayer, and the outer SNA shell, respectively, producing an L-SNA-nanoparticle hybrid. As a result of the site-selective encapsulation, the hybrid constitutes a liposomal fluorescent "core-resonance energy transfer" system surrounded by a SNA shell, as is imaged at the single-particle resolution by confocal microscopy. With the outer SNA shell as three-dimensional substrate for duplex-specific nuclease target recycling reaction, the hybrid is capable of amplified detection of microRNAs, featuring one target to many AuNP-manipulated, dual-emission QD-based ratiometric fluorescence. More importantly, the ratiometric fluorescence facilitates the hybrid to visualize microRNAs with remarkably high resolution, which is exemplified by traffic light-type transition in fluorescence color for diagnosing circulating microRNAs in clinical serum samples. Substantially, the controllable hybridization with functional nanoparticles opens an avenue for the exciting biomedical applications of liposomal spherical nucleic acids.

Development of RNA/DNA Hydrogel Targeting Toll-Like Receptor 7/8 for Sustained RNA Release and Potent Immune Activation

Guanosine- and uridine-rich single-stranded RNA (GU-rich RNA) is an agonist of Toll-like receptor (TLR) 7 and TLR8 and induces strong immune responses. A nanostructured GU-rich RNA/DNA assembly prepared using DNA nanotechnology can be used as an adjuvant capable of improving the biological stability of RNA and promoting efficient RNA delivery to target immune cells. To achieve a sustained supply of GU-rich RNA to immune cells, we developed a GU-rich RNA/DNA hydrogel (RDgel) using nanostructured GU-rich RNA/DNA assembly, from which GU-rich RNA can be released in a sustained manner. A hexapod-like GU-rich RNA/DNA nanostructure, or hexapodRD6, was designed using a 20-mer phosphorothioate-stabilized GU-rich RNA and six phosphodiester DNAs. Two sets of hexapodRD6 were mixed to obtain RDgel. Under serum-containing conditions, GU-rich RNA was gradually released from the RDgel. Fluorescently labeled GU-rich RNA was efficiently taken up by DC2.4 murine dendritic cells and induced a high level of tumor necrosis factor-α release from these cells when it was incorporated into RDgel. These results indicate that the RDgel constructed using DNA nanotechnology can be a useful adjuvant in cancer therapy with sustained RNA release and high immunostimulatory activity.

Enhancing cancer immunotherapy with nanomedicine

Therapeutic targeting of the immune system in cancer is now a clinical reality and marked successes have been achieved, most notably through the use of checkpoint blockade antibodies and chimeric antigen receptor T cell therapy. However, efforts to develop new immunotherapy agents or combination treatments to increase the proportion of patients who benefit have met with challenges of limited efficacy and/or significant toxicity. Nanomedicines - therapeutics composed of or formulated in carrier materials typically smaller than 100 nm - were originally developed to increase the uptake of chemotherapy agents by tumours and to reduce their off-target toxicity. Here, we discuss how nanomedicine-based treatment strategies are well suited to immunotherapy on the basis of nanomaterials' ability to direct immunomodulators to tumours and lymphoid organs, to alter the way biologics engage with target immune cells and to accumulate in myeloid cells in tumours and systemic compartments. We also discuss early efforts towards clinical translation of nanomedicine-based immunotherapy.

DNA Nanostructure as an Efficient Drug Delivery Platform for Immunotherapy

Immunotherapy has received increasing attention due to its low potential side effects and high specificity. For instance, cancer immunotherapy has achieved great success. CpG is a well-known and commonly used immunotherapeutic and vaccine adjuvant, but it has the disadvantage of being unstable and low in efficacy and needs to be transported through an effective nanocarrier. With perfect structural programmability, permeability, and biocompatibility, DNA nanostructures are one of the most promising candidates to deliver immune components to realize immunotherapy. However, the instability and low capability of the payload of ordinary DNA assemblies limit the relevant applications. Consequently, DNA nanostructure with a firm structure, high drug payloads is highly desirable. In the paper, the latest progress of biostable, high-payload DNA nanoassemblies of various structures, including cage-like DNA nanostructure, DNA particles, DNA polypods, and DNA hydrogel, are reviewed. Cage-like DNA structures hold drug molecules firmly inside the structure and leave a large space within the cavity. These DNA nanostructures use their unique structure to carry abundant CpG, and their biocompatibility and size advantages to enter immune cells to achieve immunotherapy for various diseases. Part of the DNA nanostructures can also achieve more effective treatment in conjunction with other functional components such as aPD1, RNA, TLR ligands.

Sequence Multiplicity within Spherical Nucleic Acids

The synthesis and evaluation of spherical nucleic acids (SNAs) incorporating two physically and chemically distinct classes of oligonucleotides (ODNs) at programmed ratios are described. These SNAs are single entity agents that enter the same target cell at defined stoichiometries, and as such allow one to control important cell signaling and regulatory processes. To study the effect of sequence multiplicity within such structures, we synthesized SNAs consisting of a mixture of class A CpG and class B CpG, immunostimulatory ODNs that activate two different toll-like receptor 9 signaling pathways, each in a sequence-specific fashion. These dual-CpG SNAs exhibit high cellular uptake and codelivery of the two ODNs, relative to mixtures of the linear ODN counterparts, and remain highly associated inside the cell over time. Furthermore, the dual-CpG SNAs augment dendritic cell maturation, compared to the same amounts of oligonucleotides delivered in linear or SNA form but not conjugated to one another. Consequently, these structures constitute a platform for designing oligonucleotide-based combination therapeutics with highly tailorable activities.

Organic-inorganic nanoflowers: from design strategy to biomedical applications

Organic-inorganic hybrid nanoflowers (NF) with sizes or features on a nanoscale are a class of flower-shaped nanomaterials self-assembled from metal ions and organic components. Here, to be more specific, the organic components mainly refer to biomolecules ranging from proteins, peptides, and amino acids to DNA/RNA. Beyond their pleasing aesthetics, their unique properties and integrated functions have attracted widespread interest and made them promising candidates in the application of biomedical areas. Great efforts have been made to design and synthesize versatile functional hybrid nanoflowers. In this review, we begin with the clarification of versatile recently reported hybrid nanoflowers according to the types of metal ions and biomolecules employed. To highlight the design of organic-inorganic hybrid nanoflowers, their synthetic methods and mechanisms, structural and biological characteristics are discussed. After that, the state-of-the-art applications of hybrid nanoflowers in biomedical fields including biosensing, biocatalysis, and cancer therapy are demonstrated. In the end, we discuss the prospects of organic-inorganic hybrid nanoflowers and highlight the challenges and opportunities for future research.

Impact of Sequence Specificity of Spherical Nucleic Acids on Macrophage Activation in Vitro and in Vivo

The effects of spherical nucleic acid (SNA) gold nanoparticle conjugates on the activation of macrophages in vitro and release of cytokines in vivo were explored. Herein, we show that G-quadruplexes, the formation of which is enhanced on gold nanoparticle surfaces, elicit an increase in cytokine release from mouse and human macrophages and induce the upregulation of activation receptors as well as NO₂ production in vitro. Moreover, these G-rich SNAs can induce cytokine release when injected intravenously, though there were no severe, long-term effects observed. These results further reinforce the notion that nucleic acid sequence and structure play an important role in how SNAs interact in biological milieu and highlight a key design parameter.

Overview of recent advances in liposomal nanoparticle-based cancer immunotherapy

The clinical performance of conventional cancer therapy approaches (surgery, radiotherapy, and chemotherapy) has been challenged by tumor metastasis and recurrence that is mainly responsible for cancer-caused mortalities. The cancer immunotherapy is being emerged nowadays as a promising therapeutic modality in order to achieve a highly efficient therapeutic performance while circumventing tumor metastasis and relapse. Liposomal nanoparticles (NPs) may serve as an ideal platform for systemic delivery of the immune modulators. In this review, we summarize the cutting-edge progresses in liposomal NPs for cancer immunotherapy, with focus on dendritic cells, T cells, tumor cells, natural killer cells, and macrophages. The review highlights the major challenges and provides a perspective regarding the clinical translation of liposomal nanoparticle-based immunotherapy.

Development of a Nanostructured RNA/DNA Assembly as an Adjuvant Targeting Toll-Like Receptor 7/8

Adjuvants are essential for efficiently inducing an antigen-specific immune response in vaccine therapy. Single-stranded RNA (ssRNA) containing guanosine- and uridine-rich sequences is recognized by Toll-like receptor (TLR)7 and/or TLR8 and induces strong immune responses; thus, the application of ssRNA as an adjuvant is desirable. The development of a ssRNA-based adjuvant, however, requires the efficient delivery of ssRNA into the endosomes of antigen-presenting cells, where the TLRs exist. To achieve this, we developed a nanostructured RNA/DNA assembly using DNA nanotechnology, which can be efficiently recognized by antigen-presenting cells. The nanostructured RNA/DNA assembly, named tetrapodRD3, was designed using a 40-mer phosphorothioate-stabilized RNA and three 40-mer phosphodiester DNAs. TetrapodRD3 was more stable than ssRNA under serum conditions. The secreted alkaline phosphatase assay using HEK-Blue hTLR cells showed that tetrapodRD3 triggered human TLR8-specific responses. Fluorescently labeled tetrapodRD3 was efficiently taken up by murine dendritic DC2.4 cells and induced a high level of tumor necrosis factor-α release from the cells. Antigen presentation by the major histocompatibility complex class I on bone marrow-derived dendritic cells was significantly increased by the addition of an antigen along with tetrapodRD3. These results indicate that tetrapodRD3 constructed using DNA nanotechnology can be a useful adjuvant targeting human TLR8.

Dual Toll-Like Receptor Targeting Liposomal Spherical Nucleic Acids

Liposomal spherical nucleic acids (LSNAs) are a class of nanomaterial used broadly for biomedical applications. Their intrinsic capacity to rapidly enter cells and engage cell surface and intracellular ligands stems from their unique three-dimensional architecture, which consists of densely packed and uniformly oriented oligonucleotides on the surface of a liposomal core. Such structures are promising for therapeutics because they can carry chemical cargo within the lipid core in addition to the nucleic acids that define them, in principle enabling delivery of multiple signals to a single cell. On the basis of these traits, we have designed novel dual-targeting LSNAs that deliver a nucleic acid specific for TLR9 inhibition and a small molecule (TAK-242) that inhibits TLR4. Toll-like receptors (TLRs) play a large role in pathogen recognition and disease initiation, and TLR subtypes are differentially located within the lipid membranes of the cell surface and within intracellular endosomes. Oftentimes, in acute or chronic inflammatory conditions, multiple TLRs are activated, leading to stimulation of distinct, and sometimes overlapping, downstream pathways. As such, these inflammatory conditions may respond to attenuation of more than one initiating receptor. We show that dual targeting LSNAs, comprised of unilamellar liposomal cores, the INH-18 oligonucleotide sequence, and TAK-242 robustly inhibit TLR-9 and TLR-4 respectively, in engineered TLR reporter cells and primary mouse peritoneal macrophages. Importantly, the LSNAs exhibit up to a 10- and a 1000-fold increase, respectively, in TLR inhibition compared to the linear sequence and TAK-242 alone. Moreover, the timing of delivery is shown to be a critical factor in effecting TLR-inhibition, with near-complete TLR-4 inhibition occurring when cells were pretreated with SNAs for 4 h prior to stimulation. The most pronounced effect observed from this approach is the benefit of delivering the small molecule within the SNA via the receptor-mediated internalization pathway common to SNAs.