Escaping the endosome: assessing cellular trafficking mechanisms of non-viral vehicles

Size and Surface Properties of Functionalized Organosilica Particles Impact Cell-Particle Interactions Including Mitochondrial Activity

Understanding of the interactions between macrophages and multifunctional nanoparticles is important for development of novel macrophage-based immunotherapies. Here, we investigated the effects of fluorescent thiol-organosilica particle size and surface properties on cell-particle interactions, including mitochondrial activity, using the mouse macrophage cell line J774A.1. Three different sizes of thiol-organosilica particles (150, 400, and 680 nm in diameter) containing fluorescein (OS/F150, OS/F400, and OS/F680) and particles surface functionalized with polyethylenimine (PEI) (OS/F150PEI, OS/F400PEI, and OS/F680PEI) were prepared. Flow cytometric analysis, time-lapse imaging, and single-cell analysis of particle uptake and mitochondrial activity of J774A.1 cells demonstrated variations in uptake and kinetics depending on the particle size and surface as well as on each individual cell. Cells treated with OS/F150 and OS/F150PEI showed higher uptake and mitochondrial activity than those treated with other particles. The interaction between endosomes and mitochondria was observed using 3D fluorescent imaging and was characterized by the involvement of iron transport into mitochondria by iron-containing proteins adsorbed on the particle surface. Scanning electron microscopy of the cells treated with the particles revealed alterations in cell membrane morphology, depending on particle size and surface. We performed correlative light and electron microscopy combined with time-lapse and 3D imaging to develop an integrated correlation analysis of particle uptake, mitochondrial activity, and cell membrane morphology in single macrophages. These cell-specific characteristics of macrophages against functional particles and their evaluation methods are crucial for understanding the immunological functions of individual macrophages and developing novel immunotherapies.

A potent bioreducible ionizable lipid nanoparticle enables siRNA delivery for retinal neovascularization inhibition

Small interfering RNA (siRNA) is emerging as a promising treatment for retinal neovascularization due to its specific inhibition of the expression of target genes. However, the clinical translation of siRNA drugs is hindered by the efficiency and safety of delivery vectors. Here, we describe the properties of a new bioreducible ionizable lipid nanoparticle (LNP) 2N12H, which is based on a rationally designed novel ionizable lipid called 2N12B. 2N12H exhibited degradation in response to the mimic cytoplasmic glutathione condition and ionization with a pKa value of 6.5, which remaining neutral at pH 7.4. At a nitrogen to phosphorus ratio of 5, 2N12H efficiently encapsulated and protected siRNA from degradation. Compared to the commercial vehicle Lipofectamine 2000, 2N12H demonstrated similar silencing efficiency and improved safety in the in vitro cell experiments. 2N12H/siVEGFA reduced the expression of VEGFA in retinal pigment epithelium cells and mouse retina, consequently suppressing cell migration and retinal neovascularization. In the mouse model, the therapeutic effect of 2N12H/siVEGFA was comparable to that of the clinical drug ranibizumab. Together, these results suggest the potential of this novel ionizable LNP to facilitate the development of nonviral ocular gene delivery systems.

Escape sites from the endo-lysosomal trafficking route manipulate exocytosis of nanoparticles in polar epithelium

The endo-lysosomal pathway is a major barrier for the trans-epithelial transport of nanoparticles (NPs), but escape strategies could facilitate trans-epithelial delivery. Based on the polarization properties of the epithelium, different escape compartments may result in different exocytosis fates of NPs and further affect the delivery efficiency. Therefore, optimizing the escape sites is critical for trans-epithelial delivery. Here, commonly used PEG-coated-poly(lactic-co-glycolic acid) (PLGA)-based nanoparticles were fabricated as model nanoparticles (MNPs) and the intestinal epithelium was chosen as the polarized epithelium. The MNPs were incubated with different endosomolytic agents for early endosomal escape, late endosomal escape and lysosomal escape, respectively. According to in vitro and in vivo studies, MNPs escaping from early endosomes and late endosomes exhibited stronger capacity for trans-epithelial transport than those escaping from lysosomes. By further probing into the mechanism, we surprisingly found that although MNPs escaping from early endosomes quickly egressed from the apical side of epithelia, they were subsequently followed by "reuptake" via caveolae and trafficked through the endoplasmic reticulum-Golgi apparatus (ER/GA) secretory pathway, achieving efficient trans-epithelial transport; MNPs escaping from late endosomes, which were located near the nucleus, were prone to enter the ER/GA for efficient basolateral exocytosis. However, MNPs escaping from lysosomes were detained within cells by autophagosomes. Collectively, our research suggested that early endosomes and late endosomes were ideal escape sites for trans-epithelial delivery.

Poly(β-aminoester) Physicochemical Properties Govern the Delivery of siRNA from Electrostatically Assembled Coatings

Localized short interfering RNA (siRNA) therapy has the potential to drive high-specificity molecular-level treatment of a variety of disease states. Unfortunately, effective siRNA therapy suffers from several barriers to its intracellular delivery. Thus, drug delivery systems that package and control the release of therapeutic siRNAs are necessary to overcome these obstacles to clinical translation. Layer-by-layer (LbL) electrostatic assembly of thin film coatings containing siRNA and protonatable, hydrolyzable poly(β-aminoester) (PBAE) polymers is one such drug delivery strategy. However, the impact of PBAE physicochemical properties on the transfection efficacy of siRNA released from LbL thin film coatings has not been systematically characterized. In this study, we investigate the siRNA transfection efficacy of four structurally similar PBAEs in vitro. We demonstrate that small changes in structure yield large changes in physicochemical properties, such as hydrophobicity, pKa, and amine chemical structure, driving differences in the interactions between PBAEs and siRNA in polyplexes and in LbL thin film coatings for wound dressings. In our polymer set, Poly3 forms the most stable interactions with siRNA (Keff,w/w = 0.298) to slow release kinetics and enhance transfection of reporter cells in both colloidal and thin film coating approaches. This is due to its unique physiochemical properties: high hydrophobicity (clog P = 7.86), effective pKa closest to endosomal pH (pKa = 6.21), and high cooperativity in buffering (nhill = 7.2). These properties bestow Poly3 with enhanced endosomal buffering and escape properties. Taken together, this work elucidates the connections between small changes in polymer structure, emergent properties, and polyelectrolyte theory to better understand PBAE transfection efficacy.

Comparing chemical transfection, electroporation, and lentiviral vector transduction to achieve optimal transfection conditions in the Vero cell line

BACKGROUND

Transfection is an important analytical method for studying gene expression in the cellular environment. There are some barriers to efficient DNA transfection in host cells, including circumventing the plasma membrane, escaping endosomal compartmentalization, autophagy, immune sensing pathways, and translocating the nuclear envelope. Therefore, it would be very useful to introduce an optimum transfection approach to achieve a high transfection efficiency in the Vero cell line. The aim of this study was to compare various transfection techniques and introduce a highly efficient method for gene delivery in Vero cells.

METHODS

In the current study, three transfection methods were used, including chemical transfection, electroporation, and lentiviral vector transduction, to obtain the optimum transfection conditions in the Vero cell line. Vero cells were cultured and transfected with chemical transfection reagents, electroporation, or HIV-1-based lentivectors under different experimental conditions. Transfection efficiency was assessed using flow cytometry and fluorescence microscopy to detect GFP-positive cells.

RESULTS

Among the tested methods, TurboFect™ chemical transfection exhibited the highest efficiency. Optimal transfection conditions were achieved using 1 µg DNA and 4 µL TurboFect™ in 6 × 104 Vero cells.

CONCLUSION

TurboFect™, a cationic polymer transfection reagent, demonstrated superior transfection efficiency in Vero cells compared with electroporation and lentivirus particles, and is the optimal choice for chemical transfection in the Vero cell line.

Tailoring lipid nanoparticles for T-cell targeting in allergic asthma: Insights into efficacy and specificity

Asthma impacts over 300 million patients globally, with significant health implications, especially in cases of its allergic subtype. The disease is characterized by a complex interplay of airway inflammation and immune responses, often mediated by Th2 cell-related cytokines. In this study, we engineered lipid nanoparticles (LNPs) to specifically deliver therapeutic siRNA via the transferrin receptor to T cells. Strain-promoted azide-alkyne cycloaddition (SPAAC) was employed for the conjugation of transferrin ligands to PEGylated lipids in the LNPs, with the goal of enhancing cellular uptake and gene knockdown. The obtained LNPs exhibited characteristics that make them suitable for pulmonary delivery. Using methods such as nanoparticle tracking analysis (NTA) and enzyme-linked immunosorbent assay (ELISA), we determined the average number of transferrin molecules bound to individual LNPs. Additionally, we found that cellular uptake was ligand-dependent, achieving a GATA3 knockdown of more than 50% in relevant in vitro and ex vivo models. Notably, our findings highlight the limitations inherent to modifying the surface of LNPs, particularly with regard to their targeting capabilities. This work paves the way for future research aimed at optimizing targeted LNPs for the treatment of immunologic diseases such as allergic asthma.

Peptide-based non-viral gene delivery: A comprehensive review of the advances and challenges

Gene therapy is the most effective treatment option for diseases, but its effectiveness is affected by the choice and design of gene carriers. The genes themselves have to pass through multiple barriers in order to enter the cell and therefore require additional vectors to carry them inside the cell. In gene therapy, peptides have unique properties and potential as gene carriers, which can effectively deliver genes into specific cells or tissues, protect genes from degradation, improve gene transfection efficiency, and enhance gene targeting and biological responsiveness. This paper reviews the research progress of peptides and their derivatives in the field of gene delivery recently, describes the obstacles encountered by foreign materials to enter the interior of the cell, and introduces the following classes of functional peptides that can carry materials into the interior of the cell, and assist in transmembrane translocation of carriers, thus breaking through endosomal traps to enable successful entry of genetic materials into the nucleus of the cell. The paper also discusses the combined application of peptide vectors with other vectors to enhance its transfection ability, explores current challenges encountered by peptide vectors, and looks forward to future developments in the field.

Organismal Function Enhancement through Biomaterial Intervention

Living organisms in nature, such as magnetotactic bacteria and eggs, generate various organic-inorganic hybrid materials, providing unique functionalities. Inspired by such natural hybrid materials, researchers can reasonably integrate biomaterials with living organisms either internally or externally to enhance their inherent capabilities and generate new functionalities. Currently, the approaches to enhancing organismal function through biomaterial intervention have undergone rapid development, progressing from the cellular level to the subcellular or multicellular level. In this review, we will concentrate on three key strategies related to biomaterial-guided bioenhancement, including biointerface engineering, artificial organelles, and 3D multicellular immune niches. For biointerface engineering, excess of amino acid residues on the surfaces of cells or viruses enables the assembly of materials to form versatile artificial shells, facilitating vaccine engineering and biological camouflage. Artificial organelles refer to artificial subcellular reactors made of biomaterials that persist in the cytoplasm, which imparts cells with on-demand regulatory ability. Moreover, macroscale biomaterials with spatiotemporal regulation characters enable the local recruitment and aggregation of cells, denoting multicellular niche to enhance crosstalk between cells and antigens. Collectively, harnessing the programmable chemical and biological attributes of biomaterials for organismal function enhancement shows significant potential in forthcoming biomedical applications.

Nuclear localization signal-tagged systems: relevant nuclear import principles in the context of current therapeutic design

Nuclear targeting of therapeutics provides a strategy for enhancing efficacy of molecules active in the nucleus and minimizing off-target effects. 'Active' nuclear-directed transport and efficient translocations across nuclear pore complexes provide the most effective means of maximizing nuclear localization. Nuclear-targeting systems based on nuclear localization signal (NLS) motifs have progressed significantly since the beginning of the current millennium. Here, we offer a roadmap for understanding the basic mechanisms of nuclear import in the context of actionable therapeutic design for developing NLS-therapeutics with improved treatment efficacy.

Lipid Nanoparticles Optimized for Targeting and Release of Nucleic Acid

Lipid nanoparticles (LNPs) are currently the most promising clinical nucleic acids drug delivery vehicles. LNPs prevent the degradation of cargo nucleic acids during blood circulation. Upon entry into the cell, specific components of the lipid nanoparticles can promote the endosomal escape of nucleic acids. These are the basic properties of lipid nanoparticles as nucleic acid carriers. As LNPs exhibit hepatic aggregation characteristics, enhancing targeting out of the liver is a crucial way to improve LNPs administrated in vivo. Meanwhile, endosomal escape of nucleic acids loaded in LNPs is often considered inadequate, and therefore, much effort is devoted to enhancing the intracellular release efficiency of nucleic acids. Here, different strategies to efficiently deliver nucleic acid delivery from LNPs are concluded and their mechanisms are investigated. In addition, based on the information on LNPs that are in clinical trials or have completed clinical trials, the issues that are necessary to be approached in the clinical translation of LNPs are discussed, which it is hoped will shed light on the development of LNP nucleic acid drugs.

Nanobiomaterials: exploring mechanistic roles in combating microbial infections and cancer

The initiation of the "nanotechnology era" within the past decade has been prominently marked by advancements in biomaterials. This intersection has opened up numerous possibilities for enhancing the detection, diagnosis, and treatment of various illnesses by leveraging the synergy between biomaterials and nanotechnology. The term "nano biomaterials" referring to biomaterials featuring constituent or surface feature sizes below 100 nm, presents a realm of extraordinary materials endowed with unique structures and properties. Beyond addressing common biomedical challenges, these nano biomaterials contribute unprecedented insights and principles that enrich our understanding of biology, medicine, and materials science. A critical evaluation of recent technological progress in employing biomaterials in medicine is essential, along with an exploration of potential future trends. Nanotechnology breakthroughs have yielded novel surfaces, materials, and configurations with notable applications in the biomedical domain. The integration of nanotechnology has already begun to enhance traditional biomedical practices across diverse fields such as tissue engineering, intelligent systems, the utilization of nanocomposites in implant design, controlled release systems, biosensors, and more. This mini review encapsulates insights into biomaterials, encompassing their types, synthesis methods, and the roles of organic and inorganic nanoparticles, elucidating their mechanisms of action. Furthermore, the focus is squarely placed on nano biomaterials and their versatile applications, with a particular emphasis on their roles in anticancer and antimicrobial interventions. This review underscores the dynamic landscape of nanotechnology, envisioning a future where nano biomaterials play a pivotal role in advancing medical applications, particularly in combating cancer and microbial infections.

Inkjet-Based Intracellular Delivery System that Effectively Utilizes Cell-Penetrating Peptides for Cytosolic Introduction of Biomacromolecules through the Cell Membrane

In the drug delivery system, the cytosolic delivery of biofunctional molecules such as enzymes and genes must achieve sophisticated activities in cells, and microinjection and electroporation systems are typically used as experimental techniques. These methods are highly reliable, and they have high intracellular transduction efficacy. However, a high degree of proficiency is necessary, and induced cytotoxicity is considered as a technical problem. In this research, a new intracellular introduction technology was developed through the cell membrane using an inkjet device and cell-penetrating peptides (CPPs). Using the inkjet system, the droplet volume, droplet velocity, and dropping position can be accurately controlled, and minute samples (up to 30 pL/shot) can be carried out by direct administration. In addition, CPPs, which have excellent cell membrane penetration functions, can deliver high-molecular-weight drugs and nanoparticles that are difficult to penetrate through the cell membrane. By using the inkjet system, the CPPs with biofunctional cargo, including peptides, proteins such as antibodies, and exosomes, could be accurately delivered to cells, and efficient cytosolic transduction was confirmed.

Lipid-based nanocarriers challenging the ocular biological barriers: Current paradigm and future perspectives

Eye is the most specialized and sensory body organ and treating eye diseases efficiently is necessary. Despite various attempts, the design of a consummate ophthalmic drug delivery system remains unsolved because of anatomical and physiological barriers that hinder drug transport into the desired ocular tissues. It is important to advance new platforms to manage ocular disorders, whether they exist in the anterior or posterior cavities. Nanotechnology has piqued the interest of formulation scientists because of its capability to augment ocular bioavailability, control drug release, and minimize inefficacious drug absorption, with special attention to lipid-based nanocarriers (LBNs) because of their cellular safety profiles. LBNs have greatly improved medication availability at the targeted ocular site in the required concentration while causing minimal adverse effects on the eye tissues. Nevertheless, the exact mechanisms by which lipid-based nanocarriers can bypass different ocular barriers are still unclear and have not been discussed. Thus, to bridge this gap, the current work aims to highlight the applications of LBNs in the ocular drug delivery exploring the different ocular barriers and the mechanisms viz. adhesion, fusion, endocytosis, and lipid exchange, through which these platforms can overcome the barrier characteristics challenges.

Biomedical applications of PLGA nanoparticles in nanomedicine: advances in drug delivery systems and cancer therapy

INTRODUCTION

During the last decades, the ever-increasing proportion of patients with cancer has been led to serious concerns worldwide. Therefore, the development and use of novel pharmaceuticals, like nanoparticles (NPs)-based drug delivery systems (DDSs), can be potentially effective in cancer therapy.

AREA COVERED

Poly lactic-co-glycolic acid (PLGA) NPs, as a kind of bioavailable, biocompatible, and biodegradable polymers, have approved by the Food and Drug Administration (FDA) for some biomedical and pharmaceutical applications. PLGA is comprised of lactic acid (LA) and glycolic acid (GA) and their ratio could be controlled during various syntheses and preparation approaches. LA/GA ratio determines the stability and degradation time of PLGA; lower content of GA results in fast degradation. There are several approaches for preparing PLGA NPs that can affect their various aspects, such as size, solubility, stability, drug loading, pharmacokinetics, and pharmacodynamics, and so on.

EXPERT OPINION

These NPs have indicated the controlled and sustained drug release in the cancer site and can use in passive and active (via surface modification) DDSs. This review aims to provide an overview of PLGA NPs, their preparation approach and physicochemical aspects, drug release mechanism and the cellular fate, DDSs for efficient cancer therapy, and status in the pharmaceutical industry and nanomedicine.

Nanoparticles as a Therapeutic Delivery System for Skin Cancer Prevention and Treatment

The use of nanoparticles (NPs) as a therapeutic delivery system has expanded markedly over the past decade, particularly regarding applications targeting the skin. The delivery of NP-based therapeutics to the skin requires special consideration owing to its role as both a physical and immunologic barrier, and specific technologies must not only take into consideration the target but also the pathway of delivery. The unique challenge this poses has been met with the development of a wide panel of NP-based technologies meant to precisely address these considerations. In this review article, we describe the application of NP-based technologies for drug delivery targeting the skin, summarize the types of NPs, and discuss the current landscape of NPs for skin cancer prevention and skin cancer treatment as well as future directions within these applications.

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.

Advanced Strategies for Overcoming Endosomal/Lysosomal Barrier in Nanodrug Delivery

Nanocarriers have therapeutic potential to facilitate drug delivery, including biological agents, small-molecule drugs, and nucleic acids. However, their efficiency is limited by several factors; among which, endosomal/lysosomal degradation after endocytosis is the most important. This review summarizes advanced strategies for overcoming endosomal/lysosomal barriers to efficient nanodrug delivery based on the perspective of cellular uptake and intracellular transport mechanisms. These strategies include promoting endosomal/lysosomal escape, using non-endocytic methods of delivery to directly cross the cell membrane to evade endosomes/lysosomes and making a detour pathway to evade endosomes/lysosomes. On the basis of the findings of this review, we proposed several promising strategies for overcoming endosomal/lysosomal barriers through the smarter and more efficient design of nanodrug delivery systems for future clinical applications.

Cargo-selective and adaptive delivery of nucleic acid therapeutics by bola-amphiphilic dendrimers

Nucleic acid therapeutics are becoming an important drug modality, offering the unique opportunity to address "undruggable" targets, respond rapidly to evolving pathogens, and treat diseases at the gene level for precision medicine. However, nucleic acid therapeutics have poor bioavailability and are chemolabile and enzymolabile, imposing the need for delivery vectors. Dendrimers, by virtue of their well-defined structure and cooperative multivalence, represent precision delivery systems. We synthesized and studied bola-amphiphilic dendrimers for cargo-selective and on-demand delivery of DNA and small interfering RNA (siRNA), both important nucleic acid therapeutics. Remarkably, superior performances were achieved for siRNA delivery with the second-generation dendrimer, yet for DNA delivery with the third generation. We systematically studied these dendrimers with regard to cargo binding, cellular uptake, endosomal release, and in vivo delivery. Differences in size both of the dendrimers and their nucleic acid cargos impacted the cooperative multivalent interactions for cargo binding and release, leading to cargo-adaptive and selective delivery. Moreover, both dendrimers harnessed the advantages of lipid and polymer vectors, while offering nanotechnology-based tumor targeting and redox-responsive cargo release. Notably, they allowed tumor- and cancer cell-specific delivery of siRNA and DNA therapeutics for effective treatment in different cancer models, including aggressive and metastatic malignancies, outperforming the currently available vectors. This study provides avenues to engineer tailor-made vectors for nucleic acid delivery and precision medicine.

Synthetic Ionizable Colloidal Drug Aggregates Enable Endosomal Disruption

Colloidal drug aggregates enable the design of drug-rich nanoparticles; however, the efficacy of stabilized colloidal drug aggregates is limited by entrapment in the endo-lysosomal pathway. Although ionizable drugs are used to elicit lysosomal escape, this approach is hindered by toxicity associated with phospholipidosis. It is hypothesized that tuning the pK_a of the drug would enable endosomal disruption while avoiding phospholipidosis and minimizing toxicity. To test this idea, 12 analogs of the nonionizable colloidal drug fulvestrant are synthesized with ionizable groups to enable pH-dependent endosomal disruption while maintaining bioactivity. Lipid-stabilized fulvestrant analog colloids are endocytosed by cancer cells, and the pK_a of these ionizable colloids influenced the mechanism of endosomal and lysosomal disruption. Four fulvestrant analogs-those with pK_a values between 5.1 and 5.7-disrupted endo-lysosomes without measurable phospholipidosis. Thus, by manipulating the pK_a of colloid-forming drugs, a tunable and generalizable strategy for endosomal disruption is established.

Boron Dopants in Red-Emitting B and N Co-Doped Carbon Quantum Dots Enable Targeted Imaging of Lysosomes

Lysosomes are of great significance to cell growth, metabolism, and survival, as they independently maintain acidity and regulate various balances in cells. Therefore, it is essential to develop advanced probes for lysosome visualization and live tracking. Herein, a type of lysosome-targeting probe based on boron (B) and nitrogen (N) co-doped carbon quantum dots (B/N-CQDs) is presented, which exhibits red emission at 618 nm, high quantum yield (28%), and excellent fluorescence stability (97% at 1 h). These B/N-CQDs are prepared by a novel and green solid-state reaction and purified using a simple extraction process without additional chemical modifications. It is found that the boron dopants in the structure play a crucial role in the resultant lysosome-specific targeting property through borate esterification between boronic acid groups in the sample and diol structures in glycoproteins. This can be applied as a powerful tool for cell apoptosis, necrosis, and endosomal escape tracking. This work not only offers a new concept for targeted subcellular probe designs via chemical doping but also demonstrates the feasibility of these tools for analyzing complex cellular physiological activities.

Non-Viral Carriers for Nucleic Acids Delivery: Fundamentals and Current Applications

Over the past decades, non-viral DNA and RNA delivery systems have been intensively studied as an alternative to viral vectors. Despite the most significant advantage over viruses, such as the lack of immunogenicity and cytotoxicity, the widespread use of non-viral carriers in clinical practice is still limited due to the insufficient efficacy associated with the difficulties of overcoming extracellular and intracellular barriers. Overcoming barriers by non-viral carriers is facilitated by their chemical structure, surface charge, as well as developed modifications. Currently, there are many different forms of non-viral carriers for various applications. This review aimed to summarize recent developments based on the essential requirements for non-viral carriers for gene therapy.

Prospects of Using Protein Engineering for Selective Drug Delivery into a Specific Compartment of Target Cells

A large number of proteins are successfully used to treat various diseases. These include natural polypeptide hormones, their synthetic analogues, antibodies, antibody mimetics, enzymes, and other drugs based on them. Many of them are demanded in clinical settings and commercially successful, mainly for cancer treatment. The targets for most of the aforementioned drugs are located at the cell surface. Meanwhile, the vast majority of therapeutic targets, which are usually regulatory macromolecules, are located inside the cell. Traditional low molecular weight drugs freely penetrate all cells, causing side effects in non-target cells. In addition, it is often difficult to elaborate a small molecule that can specifically affect protein interactions. Modern technologies make it possible to obtain proteins capable of interacting with almost any target. However, proteins, like other macromolecules, cannot, as a rule, freely penetrate into the desired cellular compartment. Recent studies allow us to design multifunctional proteins that solve these problems. This review considers the scope of application of such artificial constructs for the targeted delivery of both protein-based and traditional low molecular weight drugs, the obstacles met on the way of their transport to the specified intracellular compartment of the target cells after their systemic bloodstream administration, and the means to overcome those difficulties.

Dual factor coactivatable fluorescent nanosensor with boosted cytoplasmic biomarker accessibility toward selective tumor imaging

Fluorescent nanosensor-based tumor imaging holds great promise in cancer diagnosis and treatment assistance, yet the signal contrast is heavily hampered by the unspecific/unwanted activation at microscopic regions with a highly restricted local abundance of biomarkers. Herein, we developed an activation boosting strategy by the integration and manipulation of dual-factor coactivation of sensing and lysosome escape facilitated the rise of cytosolic biomarker accessibility. By employing hybrid DNA probes on gold nanoquenchers, ATP sensing initiated conformation switch of the corresponding aptamer units triggered the exposure of a hidden toehold in a loop structure. Sequentially, miRNA-21 sensing was triggered by toehold-mediated strand displacement and detachment of the binding complexes. The application of lysosomotropic agent chloroquine at optimized time interval facilitated the release of nanosensors into the cytosol and a ∼10.5-fold increment of intracellular fluorescence in vitro, while coactivation improved the cancer-to-normal cell signal ratio by ∼5.9 times. The synergy effects led to a high tumor-to-normal tissue ratio value of ∼7.9 in the in vivo imaging results. This strategy establishes a new paradigm of fluorescent nanosensors for selective and specific tumor imaging.

Ionizable drug delivery systems for efficient and selective gene therapy

Gene therapy has shown great potential to treat various diseases by repairing the abnormal gene function. However, a great challenge in bringing the nucleic acid formulations to the market is the safe and effective delivery to the specific tissues and cells. To be excited, the development of ionizable drug delivery systems (IDDSs) has promoted a great breakthrough as evidenced by the approval of the BNT162b2 vaccine for prevention of coronavirus disease 2019 (COVID-19) in 2021. Compared with conventional cationic gene vectors, IDDSs can decrease the toxicity of carriers to cell membranes, and increase cellular uptake and endosomal escape of nucleic acids by their unique pH-responsive structures. Despite the progress, there remain necessary requirements for designing more efficient IDDSs for precise gene therapy. Herein, we systematically classify the IDDSs and summarize the characteristics and advantages of IDDSs in order to explore the underlying design mechanisms. The delivery mechanisms and therapeutic applications of IDDSs are comprehensively reviewed for the delivery of pDNA and four kinds of RNA. In particular, organ selecting considerations and high-throughput screening are highlighted to explore efficiently multifunctional ionizable nanomaterials with superior gene delivery capacity. We anticipate providing references for researchers to rationally design more efficient and accurate targeted gene delivery systems in the future, and indicate ideas for developing next generation gene vectors.

Ready-to-Use-Type Lyophilized Lipid Nanoparticle Formulation for the Postencapsulation of Messenger RNA

Based on the clinical success of an in vitro transcribed mRNA (IVT-mRNA) that is encapsulated in lipid nanoparticles (mRNA-LNPs), there is a growing demand by researchers to test whether their own biological findings might be applicable for use in mRNA-based therapeutics. However, the equipment and/or know-how required for manufacturing such nanoparticles is often inaccessible. To encourage more innovation in mRNA therapeutics, a simple method for preparing mRNA-LNPs is prerequisite. In this study, we report on a method for encapsulating IVT-mRNA into LNPs by rehydrating a Ready-to-Use empty freeze-dried LNP (LNPs(RtoU)) formulation with IVT-mRNA solution followed by heating. The resulting mRNA-LNPs(RtoU) had a similar intraparticle structure compared to the mRNA-LNPs prepared by conventional microfluidic mixing. In vivo genome editing, a promising application of these types of mRNA-LNPs, was accomplished using the LNPs(RtoU) containing co-encapsulated Cas9-mRNA and a small guide RNA.

Anionic liposomes prepared without organic solvents for effective siRNA delivery

Currently, organic solvents are necessary for the preparation of anionic liposomes for siRNA delivery. The removal of organic solvent is time-consuming and the residual organic solvent is not only a hidden danger, but also affects the stability of anionic liposomes. Glycerol, which is physiologically compatible and does not need to be removed, is used to promote the dispersion of lipids and the formation of anionic liposomes. Additionally, the preparation process is simple and not time-consuming. The results showed that anionic liposomes, which were typically spherical with a particle size of 188.9 nm were successfully prepared with glycerol. And with the help of Ca²⁺ , siRNA was encapsulated in anionic liposomes. The highest encapsulation efficiency at 2.4 mM Ca²⁺ reached 91%. And the formation of calcium phosphate could promote the endosomal escape of siRNA effectively. The results from cell viability showed that the anionic liposomes had no obvious cytotoxicity. It was also verified that anionic liposomes could improve the resistance of siRNA against degradation. Additionally, siRNA delivered by anionic liposomes could play an effective role in knockout. Therefore, anionic liposomes prepared with glycerol will be a safe and effective delivery platform for siRNA and even other nucleic acid drugs.

Utilizing endosomal capture for tumor therapy via membrane-lytic mechanism-based Pickering emulsion

Nanocarriers are easily captured by endosomes, where the abundant hydrolases inevitably destroy the nanocarriers and the drugs they carry, ultimately resulting in a compromised or lost therapeutic efficacy. Herein, we report a membrane-lytic mechanism-based Pickering emulsion that can in turn utilize this seemingly unfavorable endosomal capture behavior for tumor therapy. This Pickering emulsion is constructed as an oil-in-water (O/W) emulsion stabilized by the hybrid nanoparticles (HNPs) composed of two molecules with opposite charges, cetyl trimethylamine bromide (CTAB) and linoleic acid (LA), through electrostatic interaction (defined as HNPs@PE). After HNPs@PE enters the lysosomes through macropinocytosis-mediated endocytosis, LA can be protonated in response to the acidic stimulus, and causing the swelling or disintegration of HNPs due to the disrupted electrostatic interaction. The released CTAB holds strong membrane-lytic activity and can directly damage the lysosomal membranes. Under the acidic condition and the participation of excessive iron ions (II) in lysosomes, LA induces lipid peroxidation and the resulting lipid peroxides (LPO) will oxidize the lysosomal membranes, collectively causing the leakage of lysosome membranes and the release of contents into cytoplasm. Subsequently, the diffused CTAB and LPO will continue to attack the mitochondrial membranes and cell membranes, resulting in the death of different types of tumor cells both in vitro and in vivo due to membrane damage. This Pickering emulsion with membrane-lytic ability represents a potential self-anticancer nanocarrier.

Layer-by-Layer siRNA Particle Assemblies for Localized Delivery of siRNA to Epithelial Cells through Surface-Mediated Particle Uptake

Localized delivery of small interfering RNA (siRNA) is a promising approach for spatial control of cell responses at biomaterial interfaces. Layer-by-layer (LbL) assembly of siRNA with cationic polyelectrolytes has been used in film and nanoparticle vectors for transfection. Herein, we combine the ability of particles to efficiently deliver siRNA with the ability of film polyelectrolyte multilayers to act locally. LbL particles were prepared with alternating layers of poly(l-arginine) and siRNA and capped with hyaluronic acid. Negatively charged LbL particles were subsequently assembled on the poly(l-lysine)-functionalized substrate to form a LbL particle-decorated surface. Cells grown in contact with the particle-decorated surface were able to survive, internalize particles, and undergo gene silencing. This work shows that particle-decorated surfaces can be engineered by using electrostatic interactions and used to deliver therapeutic payloads for cell-instructive biointerfaces.

Identification of 5-Carboxyfluorescein as a Probe Substrate of SLC46A3 and Its Application in a Fluorescence-Based In Vitro Assay Evaluating the Interaction with SLC46A3

The therapeutic modalities that involve the endocytosis pathway, including antibody-drug conjugates (ADCs), have recently been developed. Since the drug escape from endosomes/lysosomes is a determinant of their efficacy, it is important to optimize the escape, and the cellular evaluation system is needed. SLC46A3, a lysosomal membrane protein, has been implicated in the pharmacological efficacy of trastuzumab emtansine (T-DM1), a noncleavable ADC used for the treatment of breast cancer, and the cellular uptake efficacy of lipid-based nanoparticles. Recently, we identified the SLC46A3 function as a proton-coupled steroid conjugate and bile acid transporter, which can directly transport active catabolites of T-DM1. Thus, the rapid and convenient assay systems for evaluating the SLC46A3 function may help to facilitate ADC development and to clarify the physiological roles in endocytosis. Here, we show that SLC46A3 dC, which localizes to the plasma membrane owing to lacking a lysosomal-sorting motif, has a great ability to transport 5-carboxyfluorescein (5-CF), a fluorescent probe, in a pH-dependent manner. 5-CF uptake mediated by SLC46A3 was significantly inhibited by compounds reported to be SLC46A3 substrates/inhibitors and competitively inhibited by estrone 3-sulfate, a typical SLC46A3 substrate. The inhibition assays followed by uptake studies revealed that SG3199, a pyrrolobenzodiazepine dimer, which has been used as an ADC payload, is a substrate of SLC46A3. Accordingly, the fluorescence-based assay system for the SLC46A3 function using 5-CF can provide a valuable tool to evaluate the interaction of drugs/drug candidates with SLC46A3.

Engineering poly- and micelleplexes for nucleic acid delivery - A reflection on their endosomal escape

For the longest time, the field of nucleic acid delivery has remained skeptical whether or not polycationic drug carrier systems would ever make it into clinical practice. Yet, with the disclosure of patents on polyethyleneimine-based RNA carriers through leading companies in the field of nucleic acid therapeutics such as BioNTech SE and the progress in clinical studies beyond phase I trials, this aloofness seems to regress. As one of the most striking characteristics of polymer-based vectors, the extraordinary tunability can be both a blessing and a curse. Yet, knowing about the adjustment screws and how they impact the performance of the drug carrier provides the formulation scientist committed to its development with a head start. Here, we equip the reader with a toolbox - a toolbox that should advise and support the developer to conceptualize a cutting-edge poly- or micelleplex system for the delivery of therapeutic nucleic acids; to be specific, to engineer the vector towards maximum endosomal escape performance at minimum toxicity. Therefore, after briefly sketching the boundary conditions of polymeric vector design, we will dive into the topic of endosomal trafficking. We will not only discuss the most recent knowledge of the endo-lysosomal compartment but further depict different hypotheses and mechanisms that facilitate the endosomal escape of polyplex systems. Finally, we will combine the different facets introduced in the previous chapters with the fundamental building blocks of polymer vector design and evaluate the advantages and drawbacks. Throughout the article, a particular focus will be placed on cellular peculiarities, not only as an additional barrier, but also to give inspiration to how such cell-specific traits might be capitalized on.

Nucleic Acid Delivery to the Vascular Endothelium

This Review examines the state-of-the-art in the delivery of nucleic acid therapies that are directed to the vascular endothelium. First, we review the most important homeostatic functions and properties of the vascular endothelium and summarize the nucleic acid tools that are currently available for gene therapy and nucleic acid delivery. Second, we consider the opportunities available with the endothelium as a therapeutic target and the experimental models that exist to evaluate the potential of those opportunities. Finally, we review the progress to date from investigations that are directly targeting the vascular endothelium: for vascular disease, for peri-transplant therapy, for angiogenic therapies, for pulmonary endothelial disease, and for the blood-brain barrier, ending with a summary of the future outlook in this field.

Non-Modulator Therapies: Developing a Therapy for Every Cystic Fibrosis Patient

Cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy brings hope to most patients with cystic fibrosis (CF), but not all. For approximately 12% of CF patients with premature termination codon mutations, large deletions, insertions, and frameshifts, the CFTR modulator therapy is not effective. Many believe that genetic-based therapies such as RNA therapies, DNA therapies, and gene editing technologies will be needed to treat mutations that are not responsive to modulator therapy. Delivery of these therapeutic agents to affected cells is the major challenge that will need to be overcome if we are to harness the power of these emerging therapies for the treatment of CF.

Transformable nanoparticles to bypass biological barriers in cancer treatment

Nanomedicine based drug delivery platforms provide an interesting avenue to explore for the future of cancer treatment. Here we discuss the barriers for drug delivery in cancer therapeutics and how nanomaterials have been designed to bypass these blockades through stimuli responsive transformation in the most recent update. Nanomaterials that address the challenges of each step provide a promising solution for new cancer therapeutics.

Gelatin Nanoparticles for Complexation and Enhanced Cellular Delivery of mRNA

Messenger RNA (mRNA) is increasingly gaining interest as a modality in vaccination and protein replacement therapy. In regenerative medicine, the mRNA-mediated expression of growth factors has shown promising results. In contrast to protein delivery, successful mRNA delivery requires a vector to induce cellular uptake and subsequent endosomal escape to reach its end destination, the ribosome. Current non-viral vectors such as lipid- or polymer-based nanoparticles have been successfully used to express mRNA-encoded proteins. However, to advance the use of mRNA in regenerative medicine, it is required to assess the compatibility of mRNA with biomaterials that are typically applied in this field. Herein, we investigated the complexation, cellular uptake and maintenance of the integrity of mRNA complexed with gelatin nanoparticles (GNPs). To this end, GNPs with positive, neutral or negative surface charge were synthesized to assess their ability to bind and transport mRNA into cells. Positively charged GNPs exhibited the highest binding affinity and transported substantial amounts of mRNA into pre-osteoblastic cells, as assessed by confocal microscopy using fluorescently labeled mRNA. Furthermore, the GNP-bound mRNA remained stable. However, no expression of mRNA-encoded protein was detected, which is likely related to insufficient endosomal escape and/or mRNA release from the GNPs. Our results indicate that gelatin-based nanomaterials interact with mRNA in a charge-dependent manner and also mediate cellular uptake. These results create the basis for the incorporation of further functionality to yield endosomal release.

Delivery of miRNAs through Metal-Organic Framework Nanoparticles for Assisting Neural Stem Cell Therapy for Ischemic Stroke

Stroke is the most common cause of disability globally. Neural stem cell (NSC) therapy, which can replace lost and damaged neurons, has been proposed as a potential treatment for stroke. The therapeutic efficacy of NSC therapy is hindered by the fact that only a small number of NSCs undergo neuronal differentiation. Neuron-specific miR-124, which promotes the differentiation of NSCs into mature neurons, can be combined with NSC therapy to cure ischemic stroke. However, the instability and poor internalization of miR-124 seriously hamper its broad clinical application. Herein, an innovative strategy involving delivery of miR-124 via a Ca-MOF@miR-124 nanodelivery system, which effectively prevents the degradation of miR-124 by nucleases and promotes the internalization of miR-124 by NSCs, is presented. The effect of accelerated neuronal directed differentiation of NSCs was assessed through in vitro cell experiments, and the clinical application potential of this nanodelivery system for the treatment of ischemic stroke was assessed through in vivo experiments involving the combination of NSC therapy and Ca-MOF@miR-124 nanoparticles. The results indicate that Ca-MOF@miR-124 nanoparticles can promote the differentiation of NSCs into mature neurons with electrophysiological function within 5 days. The differentiation rate of cells treated with Ca-MOF@miR-124 nanoparticles was at least 5 days faster than that of untreated cells. Moreover, Ca-MOF@miR-124 nanoparticles decreased the ischemic area to almost normal levels by day 7. The combination of Ca-MOF@miR-124 nanoparticles and NSC therapy will enhance the treatment of traumatic nerve injury and neurodegenerative diseases.

mRNA nanomedicine: Design and recent applications

The rational design and application of mRNA-based medicine have recently yielded some key successes in the clinical management of human diseases. mRNA technology allows for the facile and direct production of proteins in vivo, thus circumventing the need for lengthy drug development cycles and complex production workflows. As such, mRNA formulations can significantly improve upon the biological therapies that have become commonplace in modern medicine. Despite its many advantages, mRNA is inherently fragile and has specific delivery requirements. Leveraging the engineering flexibility of nanobiotechnology, mRNA payloads can be incorporated into nanoformulations such that they do not invoke unwanted immune responses, are targeted to tissues of interest, and can be delivered to the cytosol, resulting in improved safety while enhancing bioactivity. With the rapidly evolving landscape of nanomedicine, novel technologies that are under development have the potential to further improve the clinical utility of mRNA medicine. This review covers the design principles relevant to engineering mRNA-based nanomedicine platforms. It also details the current research on mRNA nanoformulations for addressing viral infections, cancers, and genetic diseases. Given the trends in the field, future mRNA-based nanomedicines have the potential to change how many types of diseases are managed in the clinic.

Tracking the Endosomal Escape: A Closer Look at Calcein and Related Reporters

Crossing the cellular membrane and delivering active pharmaceuticals or biologicals into the cytosol of cells is an essential step in the development of nanomedicines. One of the most important intracellular processes regarding the cellular uptake of biologicals is the endolysosomal pathway. Sophisticated nanocarriers have been developed overcoming a major hurdle, the endosomal entrapment, and delivering their cargo to the required site of action. In parallel, in vitro assays have been established analyzing the performance of these nanocarriers. Among them, the release of the membrane-impermeable dye calcein has become a popular and straightforward method. It is accessible for most researchers worldwide, allows for rapid conclusions about the release potential, and enables the study of release mechanisms. This review is intended to provide an overview and guidance for scientists applying the calcein release assay. It comprises a survey of several applications in the study of endosomal escape, considerations of potential pitfalls, challenges and limitations of the assay, and a brief summary of complementary methods. Based on this review, we hope to encourage further research groups to take advantage of the calcein release assay for their own purposes and help to create a database for more efficient cross-correlations between nanocarriers. This article is protected by copyright. All rights reserved.

In Cellulo and In Vivo Comparison of Cholesterol, Beta-Sitosterol and Dioleylphosphatidylethanolamine for Lipid Nanoparticle Formulation of mRNA

Lipid Nanoparticles (LNPs) are a leading class of mRNA delivery systems. LNPs are made of an ionizable lipid, a polyethyleneglycol (PEG)-lipid conjugate and helper lipids. The success of LNPs is due to proprietary ionizable lipids and appropriate helper lipids. Using a benchmark lipid (D-Lin-MC3) we compared the ability of three helper lipids to transfect dendritic cells in cellulo and in vivo. Studies revealed that the choice of helper lipid does not influence the transfection efficiency of immortalized cells but, LNPs prepared with DOPE (dioleylphosphatidylethanolamine) and β-sitosterol were more efficient for mRNA transfection in murine dendritic cells than LNPs containing DSPC (distearoylphosphatidylcholine). This higher potency of DOPE and β-sitosterol LNPs for mRNA expression was also evident in vivo but only at low mRNA doses. Overall, these data provide valuable insight for the design of novel mRNA LNP vaccines.

Computational Insights into the Role of Cholesterol in Inverted Hexagonal Phase Stabilization and Endosomal Drug Release

Cholesterol is a major component of many lipid-based drug delivery systems, including cationic lipid nanoparticles. Despite its critical role in the drug release stage, the underlying molecular mechanism by which cholesterol assists in endosomal escape remains unclear. An efficient drug release from the endosome requires endosomal disruption. This disruption is believed to involve a lamellar-to-inverted hexagonal (L_α-H_II) phase transition upon fusion of the lipid nanoparticle with the endosomal membrane. We used molecular dynamics simulations to study the structural properties of H_II systems composed of an anionic lipid distearoyl phosphatidylserine (DSPS), an ionizable cationic lipid (KC2H), and cholesterol for several hydration levels and molar ratios. This system corresponds to the lipid mixtures in the hypothesized H_II structure formed upon fusion and is of interest for the rational design of ionizable cationic lipids, including KC2, for an optimal drug release. Simulations suggest a geometry- and symmetry-driven lipid sorting and cholesterol-DSPS co-location around the water cores. Cholesterol preferentially co-locates with negatively charged saturated DSPS lipids at interstitial angles. The observed cholesterol-DSPS co-location results in an overall increase in the DSPS acyl chains' order parameters, which we propose to assist in stabilizing the H_II phase by stretching the DSPS acyl chains for filling the voids formed by three adjacent lipid tubules. Furthermore, a systematic increase in the cholesterol concentration increased the lattice plane spacing and the water core radius but decreased the undulations along the lipid tubule axis. We propose that cholesterol and the degree of saturation/polyunsaturation of the lipid acyl chains, and not the lipid charge, are the main contributors in facilitating the L_α-H_II phase transition and stabilizing/destabilizing the formed H_II phase, whereas the positive charge of the ionizable cationic lipid promotes the LNP-endosomal membrane adhesion and assists in initiating the fusion process at the local contact area. We also propose that the effect of cholesterol on the H_II structure and curvature is the main underlying reason for the well-documented H_II stabilization and destabilization at low and high molar concentrations of cholesterol, respectively.

Recent advances in versatile inverse lyotropic liquid crystals

Owing to the rapid and significant progress in advanced materials and life sciences, nanotechnology is increasingly gaining in popularity. Among numerous bio-mimicking carriers, inverse lyotropic liquid crystals are known for their unique properties. These carriers make accommodation of molecules with varied characteristics achievable due to their complicated topologies. Besides, versatile symmetries of inverse LCNPs (lyotropic crystalline nanoparticles) and their aggregating bulk phases allow them to be applied in a wide range of fields including drug delivery, food, cosmetics, material sciences etc. In this review, in-depth summary, discussion and outlook for inverse lyotropic liquid crystals are provided.

Leveraging self-assembled nanobiomaterials for improved cancer immunotherapy

Nanomaterials and targeted drug delivery vehicles improve the therapeutic index of drugs and permit greater control over their pharmacokinetics, biodistribution, and bioavailability. Here, nanotechnologies applied to cancer immunotherapy are discussed with a focus on current and next generation self-assembling drug delivery systems composed of lipids and/or polymers. Topics covered include the fundamental design, suitability, and inherent properties of nanomaterials that induce anti-tumor immune responses and support anti-cancer vaccination. Established active and passive targeting strategies as well as newer "indirect" methods are presented together with insights into how nanocarrier structure and surface chemistry can be leveraged for controlled delivery to the tumor microenvironment while minimizing off-target effects.

Overcoming barriers in non-viral gene delivery for neurological applications

Gene therapy for neurological disorders has attracted significant interest as a way to reverse or stop various disease pathologies. Typical gene therapies involving the central and peripheral nervous system make use of adeno-associated viral vectors whose questionable safety and limitations in manufacturing has given rise to extensive research into non-viral vectors. While early research studies have demonstrated limited efficacy with these non-viral vectors, investigation into various vector materials and functionalization methods has provided insight into ways to optimize these non-viral vectors to improve desired characteristics such as improved blood-brain barrier transcytosis, improved perfusion in brain region, enhanced cellular uptake and endosomal escape in neural cells, and nuclear transport of genetic material post- intracellular delivery. Using a combination of various strategies to enhance non-viral vectors, research groups have designed multi-functional vectors that have been successfully used in a variety of pre-clinical applications for the treatment of Parkinson's disease, brain cancers, and cellular reprogramming for neuron replacement. While more work is needed in the design of these multi-functional non-viral vectors for neural applications, much of the groundwork has been done and is reviewed here.

Recent advances in research on biointerfaces: From cell surfaces to artificial interfaces

Biointerfaces are regions where biomolecules, cells, and organic materials are exposed to environmental media or come in contact with other biomaterials, cells, and inorganic/organic materials. In this review article, six research topics on biointerfaces are described to show examples of state-of-art research approaches. First, biointerface design of nanoparticles for molecular detection is described. Functionalized gold nanoparticles can be used for sensitive detection of various target molecules, including chemical compounds and biomolecules, such as DNA, proteins, cells, and viruses. Second, the interaction between bacterial cell surfaces and material surfaces, including the introduction of advances in analytical methods and theoretical calculations, are explained as well as their applications to bioprocesses. Third, bioconjugation technologies for localizing functional proteins at biointerfaces are introduced, in particular, by focusing the potential of enzymes as a catalytic tool for designing different types of bioconjugates that function at biointerfaces. Forth topics is focusing on lipid-protein interaction in cell membranes as natural biointerfaces. Examples of membrane lipid engineering are introduced, and it is mentioned how their compositional profiles affect membrane protein functions. Fifth topic is the physical method for molecular delivery across the biointerface being developed currently, such as highly efficient nanoinjection, electroporation, and nanoneedle devices, in which the key is how to perforate the cell membrane. Final topic is the chemical design of lipid- or polymer-based RNA delivery carriers and their behavior on the cell interface, which are currently attracting attention as RNA vaccine technologies targeting COVID-19. Finally, future directions of biointerface studies are presented.

Evolution of drug delivery systems: From 1950 to 2020 and beyond

Modern drug delivery technology began in 1952 with the advent of the Spansule® sustained-release capsule technology, which can deliver a drug for 12 h after oral administration through an initial immediate dose followed by the remaining released gradually. Until the 1980s, oral and transdermal formulations providing therapeutic durations up to 24 h for small molecules dominated the drug delivery field and the market. The introduction of Lupron Depot® in 1989 opened the door for long-acting injectables and implantables, extending the drug delivery duration from days to months and occasionally years. Notably, the new technologies allowed long-term delivery of peptide and protein drugs, although limited to parenteral administration. The introduction of the first PEGylated protein, Adagen®, in 1990 marked the new era of PEGylation, resulting in Doxil® (doxorubicin in PEGylated liposome) in 1995, Movantik® (PEGylated naloxone - naloxegol) in 2014, and Onpattro® (Patisiran - siRNA in PEGylated lipid nanoparticle) in 2018. Drug-polymer complexes were introduced, e.g., InFed® (iron-dextran complex injection) in 1974 and Abraxane® (paclitaxel-albumin complex) in 2005. In 2000, both Mylotarg™ (antibody-drug conjugate - gemtuzumab ozogamicin) and Rapamune® (sirolimus nanocrystal formulation) were introduced. The year 2000 also marked the launching of the National Nanotechnology Initiative by the U.S. government, which was soon followed by the rest of the world. Extensive work on nanomedicine, particularly formulations designed to escape from endosomes after being taken by tumor cells, along with PEGylation technology, ultimately resulted in the timely development of lipid nanoparticle formulations for COVID-19 vaccine delivery in 2020. While the advances in drug delivery technologies for the last seven decades are breathtaking, they are only the tip of an iceberg of technologies that have yet to be utilized in an approved formulation or even to be discovered. As life expectancy continues to increase, more people require long-term care for various diseases. Filling the current and future unmet needs requires innovative drug delivery technologies to overcome age-old familiar hurdles, e.g., improving water-solubility of poorly soluble drugs, overcoming biological barriers, and developing more efficient long-acting depot formulations. The lessons learned from the past are essential assets for developing future drug delivery technologies implemented into products. As the development of COVID-19 vaccines demonstrated, meeting the unforeseen crisis of the uncertain future requires continuous cumulation of failures (as learning experiences), knowledge, and technologies. Conscious efforts of supporting diversified research topics in the drug delivery field are urgently needed more than ever.

Intranasal Administration of Self-Oriented Nanocarriers Based on Therapeutic Exosomes for Synergistic Treatment of Parkinson's Disease

The treatment of Parkinson's disease (PD) has been hindered by the complex pathologies and multiple membrane barriers during drug delivery. Although exosomes derived from mesenchymal stem cells (MSCs) have great potential for PD, MSC-derived exosomes alone could not fully meet the therapeutic requirements due to their limitation in therapy and delivery. Here, we develop a self-oriented nanocarrier called PR-EXO/PP@Cur that combines therapeutic MSC-derived exosomes with curcumin. PR-EXO/PP@Cur can be self-oriented across the multiple membrane barriers and directly release drugs into the cytoplasm of target cells after intranasal administration. With enhanced accumulation of drugs in the action site, PR-EXO/PP@Cur achieves three-pronged synergistic treatment to deal with the complex pathologies of PD by reducing α-synuclein aggregates, promoting neuron function recovery, and alleviating the neuroinflammation. After treatment with PR-EXO/PP@Cur, the movement and coordination ability of PD model mice are significantly improved. These results show that PR-EXO/PP@Cur has great prospects in treatment of PD or other neurodegenerative diseases.

Submit to Biomaterials Science 10th anniversary collection: Spherical α-helical polypeptide-mediated E2F1 silencing against myocardial ischemia-reperfusion injury (MIRI)

Apoptosis of cardiomyocytes is a critical outcome of myocardial ischemia-reperfusion injury (MIRI), which leads to the permanent impairment of cardiac function. Up-regulated E2F1 is implicated in inducing cardiomyocyte apoptosis, and...

Effect of micro- and nanoparticle shape on biological processes

In the drug delivery field, there is beyond doubt that the shape of micro- and nanoparticles (M&NPs) critically affects their biological fate. Herein, following an introduction describing recent technological advances for designing nonspherical M&NPs, we highlight the role of particle shape in cell capture, subcellular distribution, intracellular drug delivery, and cytotoxicity. Then, we discuss theoretical approaches for understanding the effect of particle shape on internalization by the cell membrane. Subsequently, recent advances on shape-dependent behaviors of M&NPs in the systemic circulation are detailed. In particular, the interaction of M&NPs with blood proteins, biodistribution, and circulation under flow conditions are analyzed. Finally, the hurdles and future directions for developing nonspherical M&NPs are underscored.

Rational preparation and application of a mRNA delivery system with cytidinyl/cationic lipid

The messenger RNA (mRNA)-based therapy, especially mRNA vaccines, has shown its superiorities in versatile design, rapid development and scale production, since the outbreak of coronavirus disease 2019 (COVID-19). Although the Pfizer-BioNTech and Moderna COVID-19 mRNA vaccines had been approved for application, unexpected adverse events were reported to be most likely associated with the mRNA delivery systems. Thus, the development of mRNA delivery system with good efficacy and safety remains a challenge. Here, for the first time, we report that the neutral cytidinyl lipid, 2-(4-amino-2-oxopyrimidin-1-yl)-N-(2,3-dioleoyl-oxypropyl) acetamide (DNCA), and the cationic lipid, dioleoyl-3,3'-disulfanediylbis-[2-(2,6-diaminohexanamido)] propanoate (CLD), could encapsulate and deliver the COVID-19 mRNA-1096 into the cytoplasm to induce robust adaptive immune response. In the formulation, the molar ratio of DNCA/CLD to a single nucleotide of COVID-19 mRNA-1096 was about 0.9: 0.5: 1 (the N/P ratio was about 7: 1). The DNCA/CLD-mRNA-1096 lipoplexes were rationally prepared by the combination of the lipids DNCA/CLD with the aqueous mRNA solution under mild sonication to stimulate multiple interactions, including H-bonding, π-stacking and electrostatic force between the lipids and the mRNA. After intramuscular applications of the DNCA/CLD-mRNA-1096 lipoplexes, robust neutralizing antibodies and long-lived Th1-biased SARS-CoV-2-specific cell immunity were detected in the immunized mice, thus suggesting the DNCA/CLD a promising mRNA delivery system. Moreover, our study might also inspire better ideas for developing mRNA delivery systems.