Microfluidic self-assembly of folate-targeted monomolecular siRNA-lipid nanoparticles

Advances in Microfluidic-Based Core@Shell Nanoparticles Fabrication for Cancer Applications

Current research in cancer therapy focuses on personalized therapies, through nanotechnology-based targeted drug delivery systems. Particularly, controlled drug release with nanoparticles (NPs) can be designed to safely transport various active agents, optimizing delivery to specific organs and tumors, minimizing side effects. The use of microfluidics (MFs) in this field has stood out against conventional methods by allowing precise control over parameters like size, structure, composition, and mechanical/biological properties of nanoscale carriers. This review compiles applications of microfluidics in the production of core-shell NPs (CSNPs) for cancer therapy, discussing the versatility inherent in various microchannel and/or micromixer setups and showcasing how these setups can be utilized individually or in combination, as well as how this technology allows the development of new advances in more efficient and controlled fabrication of core-shell nanoformulations. Recent biological studies have achieved an effective, safe, and controlled delivery of otherwise unreliable encapsulants such as small interfering RNA (siRNA), plasmid DNA (pDNA), and cisplatin as a result of precisely tuned fabrication of nanocarriers, showing that this technology is paving the way for innovative strategies in cancer therapy nanofabrication, characterized by continuous production and high reproducibility. Finally, this review analyzes the technical, biological, and technological limitations that currently prevent this technology from becoming the standard.

Unlocking the potential of nanocarrier-mediated mRNA delivery across diverse biomedical frontiers: A comprehensive review

Messenger RNA (mRNA) has gained marvelous attention for managing and preventing various conditions like cancer, Alzheimer's, infectious diseases, etc. Due to the quick development and success of the COVID-19 mRNA-based vaccines, mRNA has recently grown in prominence. A lot of products are in clinical trials and some are already FDA-approved. However, still improvements in line of optimizing stability and delivery, reducing immunogenicity, increasing efficiency, expanding therapeutic applications, scalability and manufacturing, and long-term safety monitoring are needed. The delivery of mRNA via a nanocarrier system gives a synergistic outcome for managing chronic and complicated conditions. The modified nanocarrier-loaded mRNA has excellent potential as a therapeutic strategy. This emerging platform covers a wide range of diseases, recently, several clinical studies are ongoing and numerous publications are coming out every year. Still, many unexplained physical, biological, and technical problems of mRNA for safer human consumption. These complications were addressed with various nanocarrier formulations. This review systematically summarizes the solved problems and applications of nanocarrier-based mRNA delivery. The modified nanocarrier mRNA meaningfully improved mRNA stability and abridged its immunogenicity issues. Furthermore, several strategies were discussed that can be an effective solution in the future for managing complicated diseases.

Microfluidics for Development of Lipid Nanoparticles: Paving the Way for Nucleic Acids to the Clinic

Nucleic acid therapeutics hold an unprecedented promise toward treating many challenging diseases; however, their use is hampered by delivery issues. Microfluidics, dealing with fluids in the microscale dimensions, have provided a robust means to screening raw materials for development of nano delivery vectors, in addition to controlling their size and minimizing their polydispersity. In this mini-review, we are briefly highlighting the different types of nucleic acid therapies with emphasis on the delivery requirement for each type. We provide a thorough review of available methods for the development of nanoparticles, especially lipid nanoparticles (LNPs) that resulted in FDA approval of the first ever nucleic acid nanomedicine. We then focus on recent research attempts for how microfluidic synthesis of lipid nanoparticles and discuss the various parameters required for successful formulation of LPNs including chip design, flow regimes, and lipid composition. We then identify key areas of research in microfluidics and related fields that require attention for future success in clinical translation of nucleic acid nanomedicines.

Lipid nanoparticles for siRNA delivery in cancer treatment

RNA-based therapies, and siRNAs in particular, have attractive therapeutic potential for cancer treatment due to their ability to silence genes that are imperative for tumor progression. To be effective and solve issues related to their poor half-life and poor pharmacokinetic properties, siRNAs require adequate drug delivery systems that protect them from degradation and allow intracellular delivery. Among the various delivery vehicles available, lipid nanoparticles have emerged as the leading choice. These nanoparticles consist of cholesterol, phospholipids, PEG-lipids and most importantly ionizable cationic lipids. These ionizable lipids enable the binding of negatively charged siRNA, resulting in the formation of stable and neutral lipid nanoparticles with exceptionally high encapsulation efficiency. Lipid nanoparticles have demonstrated their effectiveness and versatility in delivering not only siRNAs but also multiple RNA molecules, contributing to their remarkable success. Furthermore, the advancement of efficient manufacturing techniques such as microfluidics, enables the rapid mixing of two miscible solvents without the need for shear forces. This facilitates the reproducible production of lipid nanoparticles and holds enormous potential for scalability. This is shown by the increasing number of preclinical and clinical trials evaluating the potential use of siRNA-LNPs for the treatment of solid and hematological tumors as well as in cancer immunotherapy. In this review, we provide an overview of the progress made on siRNA-LNP development for cancer treatment and outline the current preclinical and clinical landscape in this area. Finally, the translational challenges required to bring siRNA-LNPs further into the clinic are also discussed.

Strategies for targeted gene delivery using lipid nanoparticles and cell-derived nanovesicles

Gene therapy is a promising approach for the treatment of many diseases. However, the effective delivery of the cargo without degradation in vivo is one of the major hurdles. With the advent of lipid nanoparticles (LNPs) and cell-derived nanovesicles (CDNs), gene delivery holds a very promising future. The targeting of these nanosystems is a prerequisite for effective transfection with minimal side-effects. In this review, we highlight the emerging strategies utilized for the effective targeting of LNPs and CDNs, and we summarize the preparation methodologies for LNPs and CDNs. We have also highlighted the non-ligand targeting of LNPs toward certain organs based on their composition. It is highly expected that continuing the developments in the targeting approaches of LNPs and CDNs for the delivery system will further promote them in clinical translation.

Immune-Modulating Lipid Nanomaterials for the Delivery of Biopharmaceuticals

In recent years, with the approval of preventative vaccines for pandemics, lipid nanoparticles have become a prominent RNA delivery vehicle. The lack of long-lasting effects of non-viral vectors is an advantage for infectious disease vaccines. With the introduction of microfluidic processes that facilitate the encapsulation of nucleic acid cargo, lipid nanoparticles are being studied as delivery vehicles for various RNA-based biopharmaceuticals. In particular, using microfluidic chip-based fabrication processes, nucleic acids such as RNA and proteins can be effectively incorporated into lipid nanoparticles and utilized as delivery vehicles for various biopharmaceuticals. Due to the successful development of mRNA therapies, lipid nanoparticles have emerged as a promising approach for the delivery of biopharmaceuticals. Biopharmaceuticals of various types (DNA, mRNA, short RNA, proteins) possess expression mechanisms that are suitable for manufacturing personalized cancer vaccines, while also requiring formulation with lipid nanoparticles. In this review, we describe the basic design of lipid nanoparticles, the types of biopharmaceuticals used as carriers, and the microfluidic processes involved. We then present research cases focusing on lipid-nanoparticle-based immune modulation and discuss the current status of commercially available lipid nanoparticles, as well as future prospects for the development of lipid nanoparticles for immune regulation purposes.

Design of Folate-Containing Liposomal Nucleic Acid Delivery Systems for Antitumor Therapy

The delivery of therapeutic nucleic acids is a prospective method for the treatment of both inherited and acquired diseases including cancer. To achieve maximal delivery efficiency and selectivity, nucleic acids should be targeted to the cells of interest. In the case of cancer, such targeting may be provided through folate receptors overexpressed in many tumor cells. For this purpose, folic acid and its lipoconjugates are used. Compared to other targeting ligands, folic acid provides low immunogenicity, rapid tumor penetration, high affinity to a wide range of tumors, chemical stability, and easy production. Different delivery systems can utilize targeting by folate ligand including liposomal forms of anticancer drugs, viruses, and lipid and polymer nanoparticles. This review focuses on the liposomal gene delivery systems that provide targeted nucleic acid transport into tumor cells due to folate lipoconjugates. Moreover, important development step, such as rational design of lipoconjugates, folic acid content, size, and ζ-potential of lipoplexes are discussed.

mRNA therapy for myocardial infarction: A review of targets and delivery vehicles

Cardiovascular diseases are the leading cause of death in the world. This is partly due to the low regenerative capacity of adult hearts. mRNA therapy is a promising approach under development for cardiac diseases. In mRNA therapy, expression of the target protein is modulated by delivering synthetic mRNA. mRNA therapy benefits cardiac regeneration by increasing cardiomyocyte proliferation, reducing fibrosis, and promoting angiogenesis. Because mRNA is translated in the cytoplasm, the delivery efficiency of mRNA into the cytoplasm and nucleus significantly affects its therapeutic efficacy. To improve delivery efficiency, non-viral vehicles such as lipid nanoparticles have been developed. Non-viral vehicles can protect mRNA from enzymatic degradation and facilitate the cellular internalization of mRNA. In addition to non-viral vehicles, viral vectors have been designed to deliver mRNA templates into cardiac cells. This article reviews lipid nanoparticles, polymer nanoparticles, and viral vectors that have been utilized to deliver mRNA into the heart. Because of the growing interest in lipid nanoparticles, recent advances in lipid nanoparticles designed for cardiac mRNA delivery are discussed. Besides, potential targets of mRNA therapy for myocardial infarction are discussed. Gene therapies that have been investigated in patients with cardiac diseases are analyzed. Reviewing mRNA therapy from a clinically relevant perspective can reveal needs for future investigations.

Microfluidic production of mRNA-loaded lipid nanoparticles for vaccine applications

INTRODUCTION

During past years, lipid nanoparticles (LNPs) have emerged as promising carriers for RNA delivery, with several clinical trials focusing on both infectious diseases and cancer. More recently, the success of messenger RNA (mRNA) vaccines for the treatment of severe diseases such as acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is partially justified by the development of LNPs encapsulating mRNA for efficient cytosolic delivery.

AREAS COVERED

This review examines the production and formulation of LNPs by using microfluidic devices, the status of mRNA-loaded LNPs therapeutics and explores spray drying process, as a promising dehydration process to enhance LNP stability and provide alternative administration routes.

EXPERT OPINION

Microfluidic techniques for preparation of LNPs based on organic solvent injection method promotes the generation of stable, uniform, and monodispersed nanoparticles enabling higher encapsulation efficiency. In particular, the application of microfluidics for the fabrication of mRNA-loaded LNPs is based on rapid mixing of small volumes of ethanol solution containing lipids and aqueous solution containing mRNA. Control of operating parameters and formulation has enabled the optimization of nanoparticle physicochemical characteristics and encapsulation efficiency.

Microfluidic Manufacture of Lipid-Based Nanomedicines

Nanoparticulate technologies have revolutionized drug delivery allowing for passive and active targeting, altered biodistribution, controlled drug release (temporospatial or triggered), enhanced stability, improved solubilization capacity, and a reduction in dose and adverse effects. However, their manufacture remains immature, and challenges exist on an industrial scale due to high batch-to-batch variability hindering their clinical translation. Lipid-based nanomedicines remain the most widely approved nanomedicines, and their current manufacturing methods remain discontinuous and face several problems such as high batch-to-batch variability affecting the critical quality attributes (CQAs) of the product, laborious multistep processes, need for an expert workforce, and not being easily amenable to industrial scale-up involving typically a complex process control. Several techniques have emerged in recent years for nanomedicine manufacture, but a paradigm shift occurred when microfluidic strategies able to mix fluids in channels with dimensions of tens of micrometers and small volumes of liquid reagents in a highly controlled manner to form nanoparticles with tunable and reproducible structure were employed. In this review, we summarize the recent advancements in the manufacturing of lipid-based nanomedicines using microfluidics with particular emphasis on the parameters that govern the control of CQAs of final nanomedicines. The impact of microfluidic environments on formation dynamics of nanomaterials, and the application of microdevices as platforms for nanomaterial screening are also discussed.

Microfluidic Nanoparticles for Drug Delivery

Nanoparticles (NPs) have attracted tremendous interest in drug delivery in the past decades. Microfluidics offers a promising strategy for making NPs for drug delivery due to its capability in precisely controlling NP properties. The recent success of mRNA vaccines using microfluidics represents a big milestone for microfluidic NPs for pharmaceutical applications, and its rapid scaling up demonstrates the feasibility of using microfluidics for industrial-scale manufacturing. This article provides a critical review of recent progress in microfluidic NPs for drug delivery. First, the synthesis of organic NPs using microfluidics focusing on typical microfluidic methods and their applications in making popular and clinically relevant NPs, such as liposomes, lipid NPs, and polymer NPs, as well as their synthesis mechanisms are summarized. Then, the microfluidic synthesis of several representative inorganic NPs (e.g., silica, metal, metal oxide, and quantum dots), and hybrid NPs is discussed. Lastly, the applications of microfluidic NPs for various drug delivery applications are presented.

In Vitro CRISPR/Cas9 Transfection and Gene-Editing Mediated by Multivalent Cationic Liposome-DNA Complexes

Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated nuclease 9 (Cas9) gene-editing offers exciting new therapeutic possibilities for disease treatment with a genetic etiology such as cancer, cardiovascular, neuronal, and immune disorders. However, its clinical translation is being hampered by the lack of safe, versatile, and effective nonviral delivery systems. Herein we report on the preparation and application of two cationic liposome−DNA systems (i.e., lipoplexes) for CRISPR/Cas9 gene delivery. For that purpose, two types of cationic lipids are used (DOTAP, monovalent, and MVL5, multivalent with +5e nominal charge), along with three types of helper lipids (DOPC, DOPE, and monoolein (GMO)). We demonstrated that plasmids encoding Cas9 and single-guide RNA (sgRNA), which are typically hard to transfect due to their large size (>9 kb), can be successfully transfected into HEK 293T cells via MVL5-based lipoplexes. In contrast, DOTAP-based lipoplexes resulted in very low transfection rates. MVL5-based lipoplexes presented the ability to escape from lysosomes, which may explain the superior transfection efficiency. Regarding gene editing, MVL5-based lipoplexes achieved promising GFP knockout levels, reaching rates of knockout superior to 35% for charge ratios (+/−) of 10. Despite the knockout efficiency being comparable to that of Lipofectamine 3000® commercial reagent, the non-specific gene knockout is more pronounced in MVL5-based formulations, probably resulting from the considerable cytotoxicity of these formulations. Altogether, these results show that multivalent lipid-based lipoplexes are promising CRISPR/Cas9 plasmid delivery vehicles, which by further optimization and functionalization may become suitable in vivo delivery systems.

Shining Light on Polymeric Drug Nanocarriers with Fluorescence Correlation Spectroscopy

The use of nanoparticles as carriers is an extremely promising way for administration of therapeutic agents, such as drug molecules, proteins and nucleic acids. Such nanocarriers (NCs) can increase the solubility of hydrophobic compounds, protect their cargo from the environment, and if properly functionalized, deliver it to specific target cells and tissues. Polymer-based NCs are especially promising, because they offer high degree of versatility and tunability. However, in order to get a full advantage of this therapeutic approach and develop efficient delivery systems, a careful characterization of the NCs is needed. This Feature Article highlights the fluorescence correlation spectroscopy (FCS) technique as a powerful and versatile tool for NCs characterization at all stages of the drug delivery process. In particular, FCS can monitor and quantify the size of the NCs and the drug loading efficiency after preparation, the NCs stability and possible interactions with, e.g., plasma proteins in the blood stream and the kinetic of drug release in the cytoplasm of the target cells. This article is protected by copyright. All rights reserved.

Microfluidic Applications in Drug Development: Fabrication of Drug Carriers and Drug Toxicity Screening

Microfluidic technology has been highly useful in nanovolume sample preparation, separation, synthesis, purification, detection and assay, which are advantageous in drug development. This review highlights the recent developments and trends in microfluidic applications in two areas of drug development. First, we focus on how microfluidics has been developed as a facile tool for the fabrication of drug carriers including microparticles and nanoparticles. Second, we discuss how microfluidic chips could be used as an independent platform or integrated with other technologies in drug toxicity screening. Challenges and future perspectives of microfluidic applications in drug development have also been provided considering the present technological limitations.

Microfluidic nanomaterials: From synthesis to biomedical applications

Microfluidic platforms gain popularity in biomedical research due to their attractive inherent features, especially in nanomaterials synthesis. This review critically evaluates the current state of the controlled synthesis of nanomaterials using microfluidic devices. We describe nanomaterials' screening in microfluidics, which is very relevant for automating the synthesis process for biomedical applications. We discuss the latest microfluidics trends to achieve noble metal, silica, biopolymer, quantum dots, iron oxide, carbon-based, rare-earth-based, and other nanomaterials with a specific size, composition, surface modification, and morphology required for particular biomedical application. Screening nanomaterials has become an essential tool to synthesize desired nanomaterials using more automated processes with high speed and repeatability, which can't be neglected in today's microfluidic technology. Moreover, we emphasize biomedical applications of nanomaterials, including imaging, targeting, therapy, and sensing. Before clinical use, nanomaterials have to be evaluated under physiological conditions, which is possible in the microfluidic system as it stimulates chemical gradients, fluid flows, and the ability to control microenvironment and partitioning multi-organs. In this review, we emphasize the clinical evaluation of nanomaterials using microfluidics which was not covered by any other reviews. In the future, the growth of new materials or modification in existing materials using microfluidics platforms and applications in a diversity of biomedical fields by utilizing all the features of microfluidic technology is expected.

Lipids and Lipid Derivatives for RNA Delivery

RNA-based therapeutics have shown great promise in treating a broad spectrum of diseases through various mechanisms including knockdown of pathological genes, expression of therapeutic proteins, and programmed gene editing. Due to the inherent instability and negative-charges of RNA molecules, RNA-based therapeutics can make the most use of delivery systems to overcome biological barriers and to release the RNA payload into the cytosol. Among different types of delivery systems, lipid-based RNA delivery systems, particularly lipid nanoparticles (LNPs), have been extensively studied due to their unique properties, such as simple chemical synthesis of lipid components, scalable manufacturing processes of LNPs, and wide packaging capability. LNPs represent the most widely used delivery systems for RNA-based therapeutics, as evidenced by the clinical approvals of three LNP-RNA formulations, patisiran, BNT162b2, and mRNA-1273. This review covers recent advances of lipids, lipid derivatives, and lipid-derived macromolecules used in RNA delivery over the past several decades. We focus mainly on their chemical structures, synthetic routes, characterization, formulation methods, and structure-activity relationships. We also briefly describe the current status of representative preclinical studies and clinical trials and highlight future opportunities and challenges.

Scalable mRNA and siRNA Lipid Nanoparticle Production Using a Parallelized Microfluidic Device

A major challenge to advance lipid nanoparticles (LNPs) for RNA therapeutics is the development of formulations that can be produced reliably across the various scales of drug development. Microfluidics can generate LNPs with precisely defined properties, but have been limited by challenges in scaling throughput. To address this challenge, we present a scalable, parallelized microfluidic device (PMD) that incorporates an array of 128 mixing channels that operate simultaneously. The PMD achieves a >100× production rate compared to single microfluidic channels, without sacrificing desirable LNP physical properties and potency typical of microfluidic-generated LNPs. In mice, we show superior delivery of LNPs encapsulating either Factor VII siRNA or luciferase-encoding mRNA generated using a PMD compared to conventional mixing, with a 4-fold increase in hepatic gene silencing and 5-fold increase in luciferase expression, respectively. These results suggest that this PMD can generate scalable and reproducible LNP formulations needed for emerging clinical applications, including RNA therapeutics and vaccines.

Microfluidic formulation of nanoparticles for biomedical applications

Nanomedicine has made significant advances in clinical applications since the late-20th century, in part due to its distinct advantages in biocompatibility, potency, and novel therapeutic applications. Many nanoparticle (NP) therapies have been approved for clinical use, including as imaging agents or as platforms for drug delivery and gene therapy. However, there are remaining challenges that hinder translation, such as non-scalable production methods and the inefficiency of current NP formulations in delivering their cargo to their target. To address challenges with existing formulation methods that have batch-to-batch variability and produce particles with high dispersity, microfluidics-devices that manipulate fluids on a micrometer scale-have demonstrated enormous potential to generate reproducible NP formulations for therapeutic, diagnostic, and preventative applications. Microfluidic-generated NP formulations have been shown to have enhanced properties for biomedical applications by formulating NPs with more controlled physical properties than is possible with bulk techniques-such as size, size distribution, and loading efficiency. In this review, we highlight advances in microfluidic technologies for the formulation of NPs, with an emphasis on lipid-based NPs, polymeric NPs, and inorganic NPs. We provide a summary of microfluidic devices used for NP formulation with their advantages and respective challenges. Additionally, we provide our analysis for future outlooks in the field of NP formulation and microfluidics, with emerging topics of production scale-independent formulations through device parallelization and multi-step reactions within droplets.

Cell membrane cloaked nanomedicines for bio-imaging and immunotherapy of cancer: Improved pharmacokinetics, cell internalization and anticancer efficacy

Despite enormous advancements in the field of oncology, the innocuous and effectual treatment of various types of malignancies remained a colossal challenge. The conventional modalities such as chemotherapy, radiotherapy, and surgery have been remained the most viable options for cancer treatment, but lacking of target-specificity, optimum safety and efficacy, and pharmacokinetic disparities are their impliable shortcomings. Though, in recent decades, numerous encroachments in the field of onco-targeted drug delivery have been adapted but several limitations (i.e., short plasma half-life, early clearance by reticuloendothelial system, immunogenicity, inadequate internalization and localization into the onco-tissues, chemoresistance, and deficient therapeutic efficacy) associated with these onco-targeted delivery systems limits their clinical viability. To abolish the aforementioned inadequacies, a promising approach has been emerged in which stealthing of synthetic nanocarriers has been attained by cloaking them into the natural cell membranes. These biomimetic nanomedicines not only retain characteristics features of the synthetic nanocarriers but also inherit the cell-membrane intrinsic functionalities. In this review, we have summarized preparation methods, mechanism of cloaking, and pharmaceutical and therapeutic superiority of cell-membrane camouflaged nanomedicines in improving the bio-imaging and immunotherapy against various types of malignancies. These pliable adaptations have revolutionized the current drug delivery strategies by optimizing the plasma circulation time, improving the permeation into the cancerous microenvironment, escaping the immune evasion and rapid clearance from the systemic circulation, minimizing the immunogenicity, and enabling the cell-cell communication via cell membrane markers of biomimetic nanomedicines. Moreover, the preeminence of cell-membrane cloaked nanomedicines in improving the bio-imaging and theranostic applications, alone or in combination with phototherapy or radiotherapy, have also been pondered.

Microfluidic enhancement of self-assembly systems

Dynamic, kinetically-controlled, self-assembly processes are commonly observed in nature and are capable of creating intricate, functional architectures from simple precursors. However, notably, much of the research into molecular self-assembly has been performed using conventional bulk techniques where the resultant species are dictated by thermodynamic stability to yield relatively simple assemblies. Whereas, the environmental control offered by microfluidic systems offers methods to achieve non-equilibrium reaction conditions capable of increasingly sophisticated self-assembled structures. Alterations to the immediate microenvironment during the assembly of the molecules is possible, providing the basis for kinetically-controlled assembly. This review examines the key mechanism offered by microfluidic systems and the architectures required to access them. The mechanisms include diffusion-led mixing, shear gradient alignment, spatial and temporal confinement, and structural templates in multiphase systems. The works are selected and categorised in terms of the microfluidic approaches taken rather than the chemical constructs which are formed.

Folate Receptor-Mediated siRNA Delivery: Recent Developments and Future Directions for RNAi Therapeutics

RNA interference (RNAi), a gene regulatory process mediated by small interfering RNAs (siRNAs), has made remarkable progress as a potential therapeutic agent against various diseases. However, RNAi is associated with fundamental challenges such as poor systemic delivery and susceptibility to the nucleases. Targeting ligand-bound delivery vehicles has improved the accumulation of drug at the target site, which has resulted in high transfection efficiency and enhanced gene silencing. Recently, folate receptor (FR)-mediated targeted delivery of siRNAs has garnered attention due to their enhanced cellular uptake and high transfection efficiency toward tumor cells. Folic acid (FA), due to its small size, low immunogenicity, high in vivo stability, and high binding affinity toward FRs, has attracted much attention for targeted siRNA delivery. FRs are overexpressed in a large number of tumors, including ovarian, breast, kidney, and lung cancer cells. In this review, we discuss recent advances in FA-mediated siRNA delivery to treat cancers and inflammatory diseases. This review summarizes various FA-conjugated nanoparticle systems reported so far in the literature, including liposome, silica, metal, graphene, dendrimers, chitosan, organic copolymers, and RNA nanoparticles. This review will help in the design and development of potential delivery vehicles for siRNA drug targeting to tumor cells using an FR-mediated approach.

Controlling Nanoparticle Formulation: A Low-Budget Prototype for the Automation of a Microfluidic Platform

Active pharmaceutical ingredients (API) with suboptimal pharmacokinetic properties may require formulation into nanoparticles. In addition to the quality of the excipients, production parameters are crucial for producing nanoparticles which reliably deliver APIs to their target. Microfluidic platforms promise increased control over the formulation process due to the decreased degrees of freedom at the micro- and nanoscale. Publications about these platforms usually provide only limited information about the soft- and hardware required to integrate the microfluidic chip seamlessly into an experimental set-up. We describe a modular, low-budget prototype for microfluidic mixing in detail. The prototype consists of four modules. The control module is a raspberry pi executing customizable python scripts to control the syringe pumps and the fraction collector. The feeding module consists of up to three commercially available, programable syringe pumps. The formulation module can be any macro- or microfluidic chip connectable to syringe pumps. The collection module is a custom-built fraction collector. We describe each feature of the working prototype and demonstrate its power with polyplexes formulated from siRNA and two different oligomers that are fed to the chip at two different stages during the assembly of the nanoparticles.

The Possible Uses and Challenges of Nanomaterials in Mast Cell Research

Mast cells are tissue-resident immune cells that are involved in inflammation and fibrosis but also serve beneficial roles, including tissue maintenance, angiogenesis, pathogen clearance, and immunoregulation. Their multifaceted response and the ability of their mediators to target multiple organs and tissues means that mast cells play important roles in numerous conditions, including asthma, atopic dermatitis, drug sensitivities, ischemic heart disease, Alzheimer disease, arthritis, irritable bowel syndrome, infections (parasites, bacteria and viruses), and cancer. As a result, mast cells have become an important target for drug discovery and diagnostic research. Recent work has focused on applying novel nanotechnologies to explore cell biology. In this brief review, we will highlight the use of nanomaterials to modify mast cell functions and will discuss the potential of these technologies as research tools for understanding mast cell biology.

Lipid-Nucleic Acid Complexes: Physicochemical Aspects and Prospects for Cancer Treatment

Cancer is an extremely complex disease, typically caused by mutations in cancer-critical genes. By delivering therapeutic nucleic acids (NAs) to patients, gene therapy offers the possibility to supplement, repair or silence such faulty genes or to stimulate their immune system to fight the disease. While the challenges of gene therapy for cancer are significant, the latter approach (a type of immunotherapy) starts showing promising results in early-stage clinical trials. One important advantage of NA-based cancer therapies over synthetic drugs and protein treatments is the prospect of a more universal approach to designing therapies. Designing NAs with different sequences, for different targets, can be achieved by using the same technologies. This versatility and scalability of NA drug design and production on demand open the way for more efficient, affordable and personalized cancer treatments in the future. However, the delivery of exogenous therapeutic NAs into the patients’ targeted cells is also challenging. Membrane-type lipids exhibiting permanent or transient cationic character have been shown to associate with NAs (anionic), forming nanosized lipid-NA complexes. These complexes form a wide variety of nanostructures, depending on the global formulation composition and properties of the lipids and NAs. Importantly, these different lipid-NA nanostructures interact with cells via different mechanisms and their therapeutic potential can be optimized to promising levels in vitro. The complexes are also highly customizable in terms of surface charge and functionalization to allow a wide range of targeting and smart-release properties. Most importantly, these synthetic particles offer possibilities for scaling-up and affordability for the population at large. Hence, the versatility and scalability of these particles seem ideal to accommodate the versatility that NA therapies offer. While in vivo efficiency of lipid-NA complexes is still poor in most cases, the advances achieved in the last three decades are significant and very recently a lipid-based gene therapy medicine was approved for the first time (for treatment of hereditary transthyretin amyloidosis). Although the path to achieve efficient NA-delivery in cancer therapy is still long and tenuous, these advances set a new hope for more treatments in the future. In this review, we attempt to cover the most important biophysical and physicochemical aspects of non-viral lipid-based gene therapy formulations, with a perspective on future cancer treatments in mind.

Innovative Therapeutic and Delivery Approaches Using Nanotechnology to Correct Splicing Defects Underlying Disease

Alternative splicing of pre-mRNA contributes strongly to the diversity of cell- and tissue-specific protein expression patterns. Global transcriptome analyses have suggested that >90% of human multiexon genes are alternatively spliced. Alterations in the splicing process cause missplicing events that lead to genetic diseases and pathologies, including various neurological disorders, cancers, and muscular dystrophies. In recent decades, research has helped to elucidate the mechanisms regulating alternative splicing and, in some cases, to reveal how dysregulation of these mechanisms leads to disease. The resulting knowledge has enabled the design of novel therapeutic strategies for correction of splicing-derived pathologies. In this review, we focus primarily on therapeutic approaches targeting splicing, and we highlight nanotechnology-based gene delivery applications that address the challenges and barriers facing nucleic acid-based therapeutics.

Folate decorated polymeric micelles for targeted delivery of the kinase inhibitor dactolisib to cancer cells

One of the main challenges in clinical translation of polymeric micelles is retention of the drug in the nanocarrier system upon its systemic administration. Core crosslinking and coupling of the drug to the micellar backbone are common strategies to overcome these issues. In the present study, polymeric micelles were prepared for tumor cell targeting of the kinase inhibitor dactolisib which inhibits both the mammalian Target of Rapamycin (mTOR) kinase and phosphatidylinositol-3-kinase (PI3K). We employed platinum(II)-based linker chemistry to couple dactolisib to the core of poly(ethylene glycol)-b-poly(acrylic acid) (PEG-b-PAA) polymeric micelles. The formed dactolisib-PEG-PAA unimers are amphiphilic and self-assemble in an aqueous milieu into core-shell polymeric micelles. Folate was conjugated onto the surface of the micelles to yield folate-decorated polymeric micelles which can target folate receptor over-expressing tumor cells. Fluorescently labeled polymeric micelles were prepared using a lissamine-platinum complex linked in a similar manner as dactolisib. Dactolisib polymeric micelles showed good colloidal stability in water and released the coupled drug in buffers containing chloride or glutathione. Folate decorated micelles were avidly internalized by folate-receptor-positive KB cells and displayed targeted cellular cytotoxicity at 50-75 nM IC₅₀. In conclusion, we have prepared a novel type of folate-receptor targeted polymeric micelles in which platinum(II) linker chemistry modulates drug retention and sustained release of the coupled inhibitor dactolisib.

The challenge and prospect of mRNA therapeutics landscape

Messenger RNA (mRNA)-based therapeutics hold the potential to cause a major revolution in the pharmaceutical industry because they can be used for precise and individualized therapy, and enable patients to produce therapeutic proteins in their own bodies without struggling with the comprehensive manufacturing issues associated with recombinant proteins. Compared with the current therapeutics, the production of mRNA is much cost-effective, faster and more flexible because it can be easily produced by in vitro transcription, and the process is independent of mRNA sequence. Moreover, mRNA vaccines allow people to develop personalized medications based on sequencing results and/or personalized conditions rapidly. Along with the great potential from bench to bedside, technical obstacles facing mRNA pharmaceuticals are also obvious. The stability, immunogenicity, translation efficiency, and delivery are all pivotal issues need to be addressed. In the recently published research results, these issues are gradually being overcome by state-of-the-art development technologies. In this review, we describe the structural properties and modification technologies of mRNA, summarize the latest advances in developing mRNA delivery systems, review the preclinical and clinical applications, and put forward our views on the prospect and challenges of developing mRNA into a new class of drug.

Recent advances in siRNA delivery mediated by lipid-based nanoparticles

Small interfering RNA (siRNA) has been expected to be a unique pharmaceutic for the treatment of broad-spectrum intractable diseases. However, its unfavorable properties such as easy degradation in the blood and negative-charge density are still a formidable barrier for clinical use. For disruption of this barrier, siRNA delivery technology has been significantly advanced in the past two decades. The approval of Patisiran (ONPATTRO™) for the treatment of transthyretin-mediated amyloidosis, the first approved siRNA drug, is a most important milestone. Since lipid-based nanoparticles (LNPs) are used in Patisiran, LNP-based siRNA delivery is now of significant interest for the development of the next siRNA formulation. In this review, we describe the design of LNPs for the improvement of siRNA properties, bioavailability, and pharmacokinetics. Recently, a number of siRNA-encapsulated LNPs were reported for the treatment of intractable diseases such as cancer, viral infection, inflammatory neurological disorder, and genetic diseases. We believe that these contributions address and will promote the development of an effective LNP-based siRNA delivery system and siRNA formulation.

Surface engineering of nanomaterials with phospholipid-polyethylene glycol-derived functional conjugates for molecular imaging and targeted therapy

In recent years, phospholipid-polyethylene glycol-derived functional conjugates have been widely employed to decorate different nanomaterials, due to their excellent biocompatibility, long blood circulation characteristics, and specific targeting capability. Numerous in vivo studies have demonstrated that nanomedicines peripherally engineered with phospholipid-polyethylene glycol-derived functional conjugates show significantly increased selective and efficient internalization by target cells/tissues. Targeting moieties including small-molecule ligands, peptides, proteins, and antibodies are generally conjugated onto PEGylated phospholipids to decorate liposomes, micelles, hybrid nanoparticles, nanocomplexes, and nanoemulsions for targeted delivery of diagnostic and therapeutic agents to diseased sites. In this review, the synthesis methods of phospholipid-polyethylene glycol-derived functional conjugates, biophysicochemical properties of nanomedicines decorated with these conjugates, factors dominating their targeting efficiency, as well as their applications for in vivo molecular imaging and targeted therapy were summarized and discussed.

pH-responsive polydopamine nanoparticles for photothermally promoted gene delivery

Recently, stimuli-responsive gene carriers have been widely studied to overcome the extra- and intracellular barriers in cancer treatment. In this study, we modified polydopamine nanoparticles with low-molecular weight polyethylenimine (PEI_1.8k) and polyethylene glycol-phenylboronic acid (PEG-PBA) to prepare pH-responsive gene carrier PDANP-PEI-rPEG. PBA and polydopamine could form pH-responsive boronate ester bonds. Non-responsive PDANP-PEI-nPEG and non-PEGylated PDANP-PEI were also studied as control. Both PDANP-PEI-rPEG/DNA and PDANP-PEI-nPEG/DNA complexes remained stable in the pH environment of blood circulation or extracellular delivery (pH 7.4) owing to the PEG modification. And after being internalized into endosomes, the boronate ester bonds could be cleaved. The pH responsive ability of PDANP-PEI-rPEG might facilitate complexes dissociation and gene release inside cells. The transfection level of PDANP-PEI-rPEG/DNA complexes was about 100 times higher than that of PDANP-PEI-nPEG/DNA complexes with the same mass ratios. Moreover, after NIR light irradiation at the power density of 2.6 W/cm² for 20 min, the good photothermal conversion ability of PDANP resulted in quick endosomal escape. The transfection level of PDANP-PEI-rPEG/DNA complexes doubled, even higher than that of lipofectamine 2000/DNA complexes. This was also confirmed by Bafilomycin A1 inhibition test and CLSM observation. In response to the acidic pH within cancer cells and the NIR light irradiation, the PDANP-PEI-rPEG carrier could overcome multiple obstacles in gene delivery, which was promising for further application in gene therapy.

Self-assembly of colloids based on microfluidics

Self-assembly of colloids provides a powerful way for the construction of complex multi-scale materials. Microfluidic techniques possess great potential to precisely control the assembly of micro- and nano-scale building blocks via the rational design of various microfluidic environments. In this review, we first discuss the self-assembly of colloids without templates by using the laminar microfluidic technique. The self-assembly of colloids based on a droplet as a template was subsequently summarized and discussed via droplet microfluidic technique. Moreover, the evaporation-driven self-assembly of colloids in microfluidic channels has been discussed and analysed. Finally, the representative applications in this field have been pointed out. The aim of this review is to summarize the state-of-art on the self-assembly of colloids based on various microfluidic techniques, exhibit their representative applications, and point out the current challenges in this field, hoping to inspire and guide future work.

Development of pH-responsive organic-inorganic hybrid nanocomposites as an effective oral delivery system of protein drugs

This research aimed to develop a pH-responsive organic-inorganic hybrid nanocomposite as an effective oral delivery system for protein drugs. Three different nanocomposites were prepared by using bovine serum albumin (BSA) as a model protein. A nanocomplex of BSA with 3-aminopropyl functionalized magnesium phyllosilicate (AC-BSA) was obtained via the spontaneous co-assembly and then sequentially coated with glycol-chitosan (GAC-BSA) and the pH sensitive polymer, Eudragit®L100-55 (EGAC-BSA). These organic-inorganic hybrid nanocomposites exhibited high entrapment efficiency (86-99%) and their structural characteristics were confirmed by using energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and circular dichroism analysis, indicating that the secondary structure of BSA was well retained in the nanocomposites. At pH 1.2, AC-BSA achieved rapid drug release of about 80% within 2 h, while GAC-BSA and EGAC-BSA exhibited slow drug release of 30% and 15%, respectively, indicating that the surface-coated nanocomposites were more stable in the gastric condition. Furthermore, the conformational stability of BSA entrapped in EGAC-BSA was well retained in the presence of proteolytic enzymes, suggesting that EGAC-BSA should be effective in protecting the protein against gastrointestinal harsh environment. Compared to free BSA, all of tested nanocomposites demonstrated 2.1-3.8-fold higher cellular uptake in Caco-2 cells. Furthermore, energy-dependent endocytosis and paracellular pathway contributed to the cellular transport of nanoparticles. After oral administration in rats, EGAC-BSA significantly enhanced the intestinal permeation of BSA compared to free BSA. In conclusion, EGAC-BSA appears to be promising as an effective oral delivery system for proteins with enhanced intestinal absorption.

Combinatorial siRNA Polyplexes for Receptor Targeting

As synthetic small interfering RNA (siRNA) against antitumoral gene targets show promise for cancer treatment, different siRNA delivery systems have sparkled intense investigations. To develop tumor-specific carriers for cytosolic and systemic siRNA delivery, our laboratory has recently generated folate-conjugated targeted combinatorial siRNA polyplexes based on sequence-defined oligomer platform compatible with solid-phase-supported synthesis. These polyplexes presented efficient siRNA-mediated gene silencing in folate receptor-expressing tumors in vitro and in vivo. In this chapter, we provide a brief background on the formulation design and detailed protocols to evaluate polyplex formation, gene silencing efficiency, and receptor-directed cell killing in cancer cells using targeted combinatorial siRNA polyplexes.

Microfluidics for the Production of Nanomedicines: Considerations for Polymer and Lipid-based Systems

BACKGROUND

Microfluidics is becoming increasingly of interest as a superior technique for the synthesis of nanoparticles, particularly for their use in nanomedicine. In microfluidics, small volumes of liquid reagents are rapidly mixed in a microchannel in a highly controlled manner to form nanoparticles with tunable and reproducible structure that can be tailored for drug delivery. Both polymer and lipid-based nanoparticles are utilized in nanomedicine and both are amenable to preparation by microfluidic approaches.

AIM

Therefore, the purpose of this review is to collect the current state of knowledge on the microfluidic preparation of polymeric and lipid nanoparticles for pharmaceutical applications, including descriptions of the main synthesis modalities. Of special interest are the mechanisms involved in nanoparticle formation and the options for surface functionalisation to enhance cellular interactions.

CONCLUSION

The review will conclude with the identification of key considerations for the production of polymeric and lipid nanoparticles using microfluidic approaches.

Click-Shielded and Targeted Lipopolyplexes

Lipopolyplexes present well-established nucleic acid carriers assembled from sequence-defined cationic lipo-oligomers and DNA or RNA. They can be equipped with additional surface functionality, like shielding and targeting, in a stepwise assembly method using click chemistry. Here, we describe the synthesis of the required compounds, an azide-bearing lipo-oligomer structure and dibenzocyclooctyne (DBCO) click agents as well as the assembly of the compounds with siRNA into a surface-functionalized formulation. Both the lipo-oligomer and the DBCO-equipped shielding and targeting agents are produced by solid-phase synthesis (SPS). This enables for precise variation of all functional units, like variation in the amount of DBCO attachment sites or polyethylene glycol (PEG) length. Special cleavage conditions with only 5% trifluoroacetic acid (TFA) must be applied for the synthesis of the shielding and targeting agents due to acid lability of the DBCO unit. The two-step lipopolyplex assembly technique allows for separate optimization of the core and the shell of the formulation.

A highly antibacterial polymeric hybrid micelle with efficiently targeted anticancer siRNA delivery and anti-infection in vitro/in vivo

Most of the diseases such as tumors are usually accompanied by microbial infection, especially after surgical operation, which prevents successful cancer therapy. It is necessary to develop a safe and efficient siRNA delivery vector with high anti-bacterial capability. Here, three multifunctional polymeric hybrid micelles (PHM1, PHM2 and PHM3) with high antimicrobial activity were prepared by mixing polymers PEG-b-P3/4HB-b-PEI-b-FA (EHP-FA) and PEG-b-P3/4HB-b-EPL (EHE) copolymer at different mixing ratios and evaluated for targeted siRNA delivery and anti-infection applications. The PHM micelles, taking advantage of the binding ability of EHE and the protection ability of EHP-FA, could effectively combine, protect siRNA, release complexed siRNA and target cancer cells. Additionally, PHM micelles displayed good hemocompatibility, lower cytotoxicity and higher gene silencing efficiency than commercial PEI (25 kDa) in A549, HeLa, HepG2 and C2C12 cells. Through optimizing the ratio of EHP-FA and EHE, PHM/sip65 showed a high p65 gene silencing efficiency above 90% in various cancer cells, which were significantly higher than EHP-FA/sip65 alone and EHE/sip65 complexes. Furthermore, PHM2 micelles showed excellent antimicrobial activity towards positive bacteria (S. aureus) in vitro and in vivo. Our study may provide a facile strategy to develop multifunctional polymer gene vectors for highly promising siRNA delivery and anti-infection.

Biocompatible protamine sulfate@silicon nanoparticle-based gene nanocarriers featuring strong and stable fluorescence

The development of biocompatible and fluorescent gene carriers is of particular importance in the gene-delivery field. Taking advantage of the unique optical properties (e.g., strong and robust fluorescence) of silicon nanoparticles (SiNPs), as well as the excellent biocompatibility of silicon and protamine sulfate (PS, approved by the U.S. Food and Drug Administration (FDA) for clinical use), we herein present a type of PS-modified SiNP (PS@SiNP)-based gene carrier. Plasmid DNA (pDNA) with negative charges can be effectively bound onto the surface of the as-prepared fluorescent PS@SiNP-based gene carriers via electrostatic interactions. In particular, such resultant gene carriers possess stable and high fluorescence (photoluminescent quantum yield (PLQY): ∼25%). In addition, the PS@SiNP-based gene carriers show minimal toxic effects on normal mitochondrial metabolic activity (e.g., human retinal pigment epithelial (ARPE-19) cells preserve ∼90% of their cell viability after a 48 h incubation with the resultant carriers). Based on tracking the strong and stable fluorescence signals of SiNPs, the dynamic behavior of the PS@SiNP-based gene carriers in live cells (e.g., clathrin-mediated endocytosis, lysosomal escape, pDNA release, etc.) is investigated in a long-term manner, providing valuable information for understanding the intracellular behavior of gene vectors and designing high-efficacy gene carriers.

Microfluidics for Cancer Nanomedicine: From Fabrication to Evaluation

Self-assembled drug delivery systems (sDDSs), made from nanocarriers and drugs, are one of the major types of nanomedicines, many of which are in clinical use, under preclinical investigation, or in clinical trials. One of the hurdles of this type of nanomedicine in real applications is the inherent complexity of their fabrication processes, which generally lack precise control over the sDDS structures and the batch-to-batch reproducibility. Furthermore, the classic 2D in vitro cell model, monolayer cell culture, has been used to evaluate sDDSs. However, 2D cell culture cannot adequately replicate in vivo tissue-level structures and their highly complex dynamic 3D environments, nor can it simulate their functions. Thus, evaluations using 2D cell culture often cannot correctly correlate with sDDS behaviors and effects in humans. Microfluidic technology offers novel solutions to overcome these problems and facilitates studying the structure-performance relationships for sDDS developments. In this Review, recent advances in microfluidics for 1) fabrication of sDDSs with well-defined physicochemical properties, such as size, shape, rigidity, and drug-loading efficiency, and 2) fabrication of 3D-cell cultures as "tissue/organ-on-a-chip" platforms for evaluations of sDDS biological performance are in focus.

Efficient Shielding of Polyplexes Using Heterotelechelic Polysarcosines

Shielding agents are commonly used to shield polyelectrolyte complexes, e.g., polyplexes, from agglomeration and precipitation in complex media like blood, and thus enhance their in vivo circulation times. Since up to now primarily poly(ethylene glycol) (PEG) has been investigated to shield non-viral carriers for systemic delivery, we report on the use of polysarcosine (pSar) as a potential alternative for steric stabilization. A redox-sensitive, cationizable lipo-oligomer structure (containing two cholanic acids attached via a bioreducible disulfide linker to an oligoaminoamide backbone in T-shape configuration) was equipped with azide-functionality by solid phase supported synthesis. After mixing with small interfering RNA (siRNA), lipopolyplexes formed spontaneously and were further surface-functionalized with polysarcosines. Polysarcosine was synthesized by living controlled ring-opening polymerization using an azide-reactive dibenzo-aza-cyclooctyne-amine as an initiator. The shielding ability of the resulting formulations was investigated with biophysical assays and by near-infrared fluorescence bioimaging in mice. The modification of ~100 nm lipopolyplexes was only slightly increased upon functionalization. Cellular uptake into cells was strongly reduced by the pSar shielding. Moreover, polysarcosine-shielded polyplexes showed enhanced blood circulation times in bioimaging studies compared to unshielded polyplexes and similar to PEG-shielded polyplexes. Therefore, polysarcosine is a promising alternative for the shielding of non-viral, lipo-cationic polyplexes.