The crossflow injection technique: an improvement of the ethanol injection method

SPA14 liposomes combining saponin with fully synthetic TLR4 agonist provide adjuvanticity to hCMV vaccine candidate

In the aim of designing and developing a novel saponin-based adjuvant system, we combined the QS21 saponin with low microgram amounts of the fully synthetic TLR4 agonist, E6020, in cholesterol-containing liposomes. The resulting adjuvant system, termed SPA14, appeared as a long-term stable and homogeneous suspension of mostly unilamellar and a few multilamellar vesicles, with an average hydrodynamic diameter of 93 nm, when formulated in citrate buffer at pH 6.0-6.5. When compared in an in vitro human innate immunity construct to AS01B, the QS21/MPL® liposomal adjuvant system of GSK, and with QS21-Liposomes used as benchmarks, SPA14 displayed the strongest immunostimulatory potential based on antigen-presenting cell (APC) activation and cytokine secretion, which was essentially driven by the highly active E6020 agonist in this assay. When tested as an adjuvant in vivo with human cytomegalovirus glycoprotein B (gB) and pentamer complex (PC) as test antigens, SPA14 was generally well tolerated and as active as AS01B for the induction of long-lasting CMV-neutralizing antibodies in mice and non-human primates (NHPs). Both adjuvants promoted the induction of Th-1 responses based on IgG2c production in mice and IFN-γ production in mice and NHPs, but in mice, a higher level of Th-2 cytokines (IL-5) and higher IgG1 over IgG2c secreting cells ratios were obtained with SPA14 indicating that the adjuvant profile of SPA14 could be less Th-1 biased than that of AS01B. From a developability standpoint, SPA14 could be manufactured by a simple and scalable ethanol injection method, owing to the high solubility in ethanol of all its lipidic components, including E6020. Furthermore, E6020 is a single molecule, well-characterized fully synthetic TLR4 agonist constructed in eight synthetic steps from entirely crystalline starting materials and intermediates via an optimized high-yield synthetic route. Overall, our data suggest that SPA14 is a viable, easy-to-manufacture, potent novel adjuvant system that could be broadly applicable as a ready-to-mix adjuvant in the form of a long-term stable liquid formulation.

Comprehensive analysis of lipid nanoparticle formulation and preparation for RNA delivery

Nucleic acid-based therapeutics are a common approach that is increasingly popular for a wide spectrum of diseases. Lipid nanoparticles (LNPs) are promising delivery carriers that provide RNA stability, with strong transfection efficiency, favorable and tailorable pharmacokinetics, limited toxicity, and established translatability. In this review article, we describe the lipid-based delivery systems, focusing on lipid nanoparticles, the need of their use, provide a comprehensive analysis of each component, and highlight the advantages and disadvantages of the existing manufacturing processes. We further summarize the ongoing and completed clinical trials utilizing LNPs, indicating important aspects/questions worth of investigation, and analyze the future perspectives of this significant and promising therapeutic approach.

Photoacoustic Imaging Using Polysaccharide-Porphyrin Complexes by Photoirradiation at Long Wavelengths

Photoacoustic (PA) imaging is a novel biological imaging technique with superior depth resolution compared to fluorescence imaging. The efficacy of PA imaging depends on contrast agents that possess considerable absorbance at longer wavelengths, coupled with high permeability in biological tissue and minimal fluorescence, achieved through mitigating aggregation-caused quenching (ACQ) that attenuates PA intensity. Despite the successful transfer of porphyrin 2 featuring amino moieties from polysaccharides to liposomes, most of 2 incorporated within λ-carrageenan (CGN-2 complex) remained in CGN under acidic lysosomal conditions (pH 5.0). Consequently, the CGN-2 complex exhibited a strong PA signal under 680 nm photoirradiation in Colon26 cells owing to the ACQ of 2. Moreover, the PA intensity of the CGN-2 complex was further enhanced under 780 nm photoirradiation owing to the increased absorbance at 780 nm facilitated by the redshift of the Q-band at pH 5.0.

Scalable microfluidic method for tunable liposomal production by a design of experiment approach

Liposomes constitute a widespread drug delivery platform, gaining more and more attention from the pharmaceutical industry and process development scientists. Their large-scale production as medicinal products for human use is all but trivial, especially when parenteral administration is required. In this study an off-the-shelf microfluidic system and a methodological approach are presented for the optimization, validation and scale-up of highly monodisperse liposomes manufacturing. Starting from a Doxil®-like formulation (HSPC, MPEG-DSPE and cholesterol), a rational approach (Design of Experiments, DoE) was applied for the screening of the process parameters affecting the quality attributes of the product (mainly size and polydispersity). Additional DoEs were conducted to determine the effect of critical process parameters "CPPs" (cholesterol concentration, total flow rate "TFR" and flow rate ratio "FRR"), thus assessing the formulation and process robustness. A scale-up was then successfully accomplished. The procedure was applied to a Marqibo®-like formulation as well (sphingomyelin and cholesterol) to show the generality of the proposed formulation, process development and scale-up approach. The application of the system and method herein presented enables the large-scale manufacturing of liposomes, in compliance with the internationally recognized regulatory standards for pharmaceutical development (Quality by Design).

Microfluidic synthesis of lipid-based nanoparticles for drug delivery: recent advances and opportunities

Microfluidic technologies are revolutionizing the synthesis of nanoscale lipid particles and enabling new opportunities for the production of lipid-based nanomedicines. By harnessing the benefits of microfluidics for controlling diffusive and advective transport within microfabricated flow cells, microfluidic platforms enable unique capabilities for lipid nanoparticle synthesis with precise and tunable control over nanoparticle properties. Here we present an assessment of the current state of microfluidic technologies for lipid-based nanoparticle and nanomedicine production. Microfluidic techniques are discussed in the context of conventional production methods, with an emphasis on the capabilities of microfluidic systems for controlling nanoparticle size and size distribution. Challenges and opportunities associated with the scaling of manufacturing throughput are discussed, together with an overview of emerging microfluidic methods for lipid nanomedicine post-processing. The impact of additive manufacturing on current and future microfluidic platforms is also considered.

Delivery of gene editing therapeutics

For the past decades, gene editing demonstrated the potential to attenuate each of the root causes of genetic, infectious, immune, cancerous, and degenerative disorders. More recently, Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR-associated protein 9 (CRISPR-Cas9) editing proved effective for editing genomic, cancerous, or microbial DNA to limit disease onset or spread. However, the strategies to deliver CRISPR-Cas9 cargos and elicit protective immune responses requires safe delivery to disease targeted cells and tissues. While viral vector-based systems and viral particles demonstrate high efficiency and stable transgene expression, each are limited in their packaging capacities and secondary untoward immune responses. In contrast, the nonviral vector lipid nanoparticles were successfully used for as vaccine and therapeutic deliverables. Herein, we highlight each available gene delivery systems for treating and preventing a broad range of infectious, inflammatory, genetic, and degenerative diseases. STATEMENT OF SIGNIFICANCE: CRISPR-Cas9 gene editing for disease treatment and prevention is an emerging field that can change the outcome of many chronic debilitating disorders.

Impact of ethanol on continuous inline diafiltration of liposomal drug products

Liposomal drug products are playing an increasing role in the field of drug delivery. With this increased demand comes the need to increase the capabilities and capacity of manufacturing options. Continuous manufacturing techniques present a significant opportunity to address these needs for liposomal manufacturing processes. Liposomal formulations have unique considerations that impact translation from batch to continuous process designs. This article examines aspects of converting to a continuous design that were previously viewed as inconsequential in a batch process. The batch process involves the removal of ethanol (EtOH) through tangential flow filtration (TFF). EtOH was found to reduce the permeability of the hollow fibers used for TFF. This effect was determined to have minimal impact on the overall batch process design but considerable influence on the design of continuous TFF such as inline diafiltration (ILDF). Using a pilot scale setup, EtOH was found to decrease permeability in an inverse manner to EtOH concentration. Further assessment found that dilution of the EtOH levels prior to diafiltration can significantly reduce the amount of ILDF stages needed and that a continuous design requires less buffer to the commensurate batch design.

Multifunctional targetable liposomal drug delivery system in the management of leukemia: Potential, opportunities, and emerging strategies

The concern impeding the success of chemotherapy in leukemia treatment is descending efficacy of drugs because of multiple drug resistance (MDR). The previous failure of traditional treatment methods is primarily responsible for the present era of innovative agents to treat leukemia effectively. The treatment option is a chemotherapeutic agent in most available treatment strategies, which unfortunately leads to high unavoidable toxicities. As a result of the recent surge in marketed products, theranostic nanoparticles, i.e., multifunctional targetable liposomes (MFTL), have been approved for improved and more successful leukemia treatment that blends therapeutic and diagnostic characteristics. Since they broadly offer the required characteristics to get past the traditional/previous limitations, such as the absence of site-specific anti-cancer therapeutic delivery and ongoing real-time surveillance of the leukemia target sites while administering therapeutic activities. To prepare MFTL, suitable targeting ligands or tumor-specific antibodies are required to attach to the surface of the liposomes. This review exhaustively covered and summarized the liposomal-based formulation in leukemia treatment, emphasizing leukemia types; regulatory considerations, patents, and clinical portfolios to overcome clinical translation hurdles have all been explored.

Ether lipids from archaeas in nano-drug delivery and vaccination

Archaea are microorganisms more closely related to eukaryotes than bacteria. Almost 50 years after being defined as a new domain of life on earth, new species continue to be discovered and their phylogeny organized. The study of the relationship between their genetics and metabolism and some of their extreme habitats has even positioned them as a model of extraterrestrial life forms. Archaea, however, are deeply connected to the life of our planet: they can be found in arid, acidic, warm areas; on most of the earth's surface, which is cold (below 5 °C), playing a prominent role in the cycles of organic materials on a global scale and they are even part of our microbiota. The constituent materials of these microorganisms differ radically from those produced by eukaryotes and bacteria, and the nanoparticles that can be manufactured using their ether lipids as building blocks exhibit unique properties that are of interest in nanomedicine. Here, we present for the first time a complete overview of the pre-clinical applications of nanomedicines based on ether archaea lipids, focused on drug delivery and adjuvancy over the last 25 years, along with a discussion on their pros, cons and their future industrial implementation.

Lipid-based nucleic acid therapeutics with in vivo efficacy

Synthetic vectors for therapeutic nucleic acid delivery are currently competing significantly with their viral counter parts due to their reduced immunogenicity, large payload capacity, and ease of manufacture under GMP-compliant norms. The approval of Onpattro, a lipid-based siRNA therapeutic, and the proven clinical success of two lipid-based COVID-19 vaccines from Pfizer-BioNTech, and Moderna heralded the specific advantages of lipid-based systems among all other synthetic nucleic acid carriers. Lipid-based systems with diverse payloads-plasmid DNA (pDNA), antisense oligonucleotide (ASO), small interfering RNA (siRNA), microRNA (miRNA), small activating RNA (saRNA), and messenger RNA (mRNA)-are now becoming a mature technology, with growing impact in the clinic. Research over four decades identified the key factors determining the therapeutic success of these multi-component systems. Here, we discuss the main nucleic acid-based technologies, presenting their mechanism of action, delivery barriers facing them, the structural properties of the payload as well as the component lipids that regulate physicochemical properties, pharmacokinetics and biodistribution, efficacy, and toxicity of the resultant nanoparticles. We further detail on the formulation parameters, evolution of the manufacturing techniques that generate reproducible and scalable outputs, and key manufacturing aspects that enable control over physicochemical properties of the resultant particles. Preclinical applications of some of these formulations that were successfully translated from in vitro studies to animal models are subsequently discussed. Finally, clinical success and failure of these systems starting from 1993 to present are highlighted, in a holistic literature review focused on lipid-based nucleic acid delivery systems. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials.

Nonclinical safety assessments of a novel synthetic toll-like receptor 4 agonist and saponin based adjuvant

A full nonclinical safety package was performed to support the clinical use of SPA14, a novel liposome-based vaccine adjuvant containing the synthetic toll-like receptor 4 agonist E6020 and saponin QS21. E6020 and QS21 were tested negative for their potential genotoxic effects in Ames, micronucleus, or mouse-lymphoma TK (thymidine kinase) assay. To evaluate the potential local and systemic effects of SPA14, two toxicity studies were performed in rabbits. In the first dose range finding toxicity study, rabbits received two intramuscular injections of SPA14 at increasing doses of E6020 combined with two antigens, a control (saline), the two antigens alone, or the antigens adjuvanted with a liposome-based adjuvant AS01B. No systemic toxicity was detected, supporting the dose of 5 μg of E6020 for the subsequent pivotal study. In the second repeated dose toxicity study, rabbits received four intramuscular injections of SPA14 alone, a control (saline), SPA14 combined with two antigens, the two antigens alone, or the antigens combined with AF03 adjuvant, which is a squalene-based emulsion. SPA14 alone or in combination with the antigens was well tolerated and did not cause any systemic toxicity. Finally, two safety pharmacology studies were conducted to assess potential cardiovascular and respiratory effects of E6020 and SPA14 in conscious telemetered cynomolgus monkeys and beagle dogs, respectively. One subcutaneous injection of E6020 in monkeys and one intramuscular injection of SPA14 in dogs had no consequences on respiratory and cardiovascular functions. Altogether these results support the clinical development of SPA14.

Anti-Allergic Effects of Quercetin and Quercetin Liposomes in RBL-2H3 Cells

BACKGROUND

Quercetin is a kind of flavonoid with important bioactivities, such as hypoglycemic, antioxidant, anti-inflammatory, and anti-allergic properties. Although it is unstable, it is worth exploring how to better exert its anti-allergic effect.

OBJECTIVE

The current study aimed to elucidate the anti-allergic effect of quercetin liposomes on RBL-2H3 cells in vitro.

METHODS

Quercetin liposomes were prepared to improve the anti-allergic activity of quercetin through a green thin-film dispersion method. We compared the anti-allergic effects of quercetin and quercetin liposomes in RBL-2H3 cells. The anti-allergic activity of the quercetin liposomes was evaluated by the level of β-hexosaminidase, histamine, Ca2+, IL-4, IL-8, and MCP-1.

RESULTS

The results showed that quercetin liposomes could significantly restrain the release of β-hexosaminidase and histamine, calcium influx, and the expression of inflammatory factors, whose effect is stronger than quercetin.

CONCLUSION

Collectively, our research suggests that the quercetin liposome can be used as a potential allergy antagonist.

A tale of nucleic acid-ionizable lipid nanoparticles: Design and manufacturing technology and advancement

INTRODUCTION

Ionizable lipid nanoparticles (LNPs) have been proven to have high encapsulation, cellular uptake, and effective endosomal escape and are therefore promising for nucleic acid delivery. The combination of ionizable lipids, helper lipids, cholesterol, and PEG lipids advances nucleic acid-ionizable LNPs and distinguishes them from liposomes, SLNs, NLCs, and other lipid particles. Solvent injection and microfluidics technology are the primary manufacturing techniques for commercialized ionizable LNPs. Microfluidics technology limitations restrict the rapid industrial scale-up and therapeutic effectiveness of ionized LNPs. Alternative manufacturing technologies and target-specific lipids are urgently needed.

AREA COVERED

This article provides an in-depth update on the lipid compositions, clinical trials, and manufacturing technologies for nucleic acid-ionizable LNPs. For the first time, we updated the distinction between ionizable LNPs and other lipid particles. We also proposed an alternate thermocycling technology for high industrial scale-up and the stability of nucleic acid-ionizing LNPs.

EXPERT OPINION

Nucleic acid-ionizable LNPs have a promising future for delivering nucleic acids in a target-specific manner. Though ionizing LNPs are in their early stages, they face several challenges, including only hepatic delivery, a short shelf life, and ultra-cold storage. In our opinion, ligand-based, target-specific synthesized novel lipids and advanced manufacturing technologies can easily overcome the restrictions and open up a new approach for improved therapeutic efficacy for chronic disorders.

Effect of meso Positioned Substituents on the Stability and Photodynamic Activity of Lipid-Membrane-Incorporated Porphyrin Derivatives

Here, we prepared aqueous solutions of lipid-membrane incorporated tetraarylporphyrins and tetrapyridylporphyrin (LMIPors) by the injection method using dimethyl sulfoxide. The porphyrins with proton-donor groups at the meso position afforded stable aqueous solutions of LMIPors. However, although tetrakis(carboxyphenyl)porphyrin was scarcely incorporated in lipid membranes, it was soluble in water. Among these LMIPors, the photodynamic activity of tetrakis(hydroxyphenyl)porphyrin was higher than that of tetrakis(aminophenyl)porphyrin. This was attributed to the self-aggregation of a part of tetrakis(aminophenyl)porphyrin in the liposomes, which induced self-quenching and the consequent decrease of its photodynamic activity.

A Review of Liposomes as a Drug Delivery System: Current Status of Approved Products, Regulatory Environments, and Future Perspectives

Liposomes have been considered promising and versatile drug vesicles. Compared with traditional drug delivery systems, liposomes exhibit better properties, including site-targeting, sustained or controlled release, protection of drugs from degradation and clearance, superior therapeutic effects, and lower toxic side effects. Given these merits, several liposomal drug products have been successfully approved and used in clinics over the last couple of decades. In this review, the liposomal drug products approved by the U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA) are discussed. Based on the published approval package in the FDA and European public assessment report (EPAR) in EMA, the critical chemistry information and mature pharmaceutical technologies applied in the marketed liposomal products, including the lipid excipient, manufacturing methods, nanosizing technique, drug loading methods, as well as critical quality attributions (CQAs) of products, are introduced. Additionally, the current regulatory guidance and future perspectives related to liposomal products are summarized. This knowledge can be used for research and development of the liposomal drug candidates under various pipelines, including the laboratory bench, pilot plant, and commercial manufacturing.

Liposomal-Based Formulations: A Path from Basic Research to Temozolomide Delivery Inside Glioblastoma Tissue

Glioblastoma (GBM) is a lethal brain cancer with a very difficult therapeutic approach and ultimately frustrating results. Currently, therapeutic success is mainly limited by the high degree of genetic and phenotypic heterogeneity, the blood brain barrier (BBB), as well as increased drug resistance. Temozolomide (TMZ), a monofunctional alkylating agent, is the first line chemotherapeutic drug for GBM treatment. Yet, the therapeutic efficacy of TMZ suffers from its inability to cross the BBB and very short half-life (~2 h), which requires high doses of this drug for a proper therapeutic effect. Encapsulation in a (nano)carrier is a promising strategy to effectively improve the therapeutic effect of TMZ against GBM. Although research on liposomes as carriers for therapeutic agents is still at an early stage, their integration in GBM treatment has a great potential to advance understanding and treating this disease. In this review, we provide a critical discussion on the preparation methods and physico-chemical properties of liposomes, with a particular emphasis on TMZ-liposomal formulations targeting GBM developed within the last decade. Furthermore, an overview on liposome-based formulations applied to translational oncology and clinical trials formulations in GBM treatment is provided. We emphasize that despite many years of intense research, more careful investigations are still needed to solve the main issues related to the manufacture of reproducible liposomal TMZ formulations for guaranteed translation to the market.

mRNA Therapeutic Modalities Design, Formulation and Manufacturing under Pharma 4.0 Principles

In the quest for a formidable weapon against the SARS-CoV-2 pandemic, mRNA therapeutics have stolen the spotlight. mRNA vaccines are a prime example of the benefits of mRNA approaches towards a broad array of clinical entities and druggable targets. Amongst these benefits is the rapid cycle "from design to production" of an mRNA product compared to their peptide counterparts, the mutability of the production line should another target be chosen, the side-stepping of safety issues posed by DNA therapeutics being permanently integrated into the transfected cell's genome and the controlled precision over the translated peptides. Furthermore, mRNA applications are versatile: apart from vaccines it can be used as a replacement therapy, even to create chimeric antigen receptor T-cells or reprogram somatic cells. Still, the sudden global demand for mRNA has highlighted the shortcomings in its industrial production as well as its formulation, efficacy and applicability. Continuous, smart mRNA manufacturing 4.0 technologies have been recently proposed to address such challenges. In this work, we examine the lab and upscaled production of mRNA therapeutics, the mRNA modifications proposed that increase its efficacy and lower its immunogenicity, the vectors available for delivery and the stability considerations concerning long-term storage.

3D Printed Integrated Multi-Layer Microfluidic Chips for Ultra-High Volumetric Throughput Nanoliposome Preparation

Although microfluidic approaches for liposomes preparation have been developed, fabricating microfluidic devices remains expensive and time-consuming. Also, owing to the traditional layout of microchannels, the volumetric throughput of microfluidics has been greatly limited. Herein an ultra-high volumetric throughput nanoliposome preparation method using 3D printed microfluidic chips is presented. A high-resolution projection micro stereolithography (PμSL) 3D printer is applied to produce microfluidic chips with critical dimensions of 400 µm. The microchannels of the microfluidic chip adopt a three-layer layout, achieving the total flow rate (TFR) up to 474 ml min⁻¹, which is remarkably higher than those in the reported literature. The liposome size can be as small as 80 nm. The state of flows in microchannels and the effect of turbulence on liposome formation are explored. The experimental results demonstrate that the 3D printed integrated microfluidic chip enables ultra-high volumetric throughput nanoliposome preparation and can control size efficiently, which has great potential in targeting drug delivery systems.

Orthogonal characterization and pharmacokinetic studies of polylactide-polyethyleneglycol polymeric nanoparticles with different physicochemical properties

To optimize prolonged and sustained delivery of polylactide-block-polyethyleneglycol polymeric nanoparticles (PLA-PEG NPs), in terms of the PLA isomer and molecular weight, we performed orthogonal physicochemical characterization and evaluated the pharmacokinetics of tamoxifen (TAM)-loaded PLA-PEG NPs. DL-lactide- (DL-PEG NP), L-lactide- (L-PEG NPs), and stereocomplex-based (SC-PEG NPs) PLA-PEGs, with two different PLA to PEG ratios (12k-5k and 5k-5k Da) were synthesized, and NPs were prepared by anti-solvent precipitation. Size exclusion chromatography, multi-angle light scattering, dynamic light scattering, and ¹H nuclear magnetic resonance studies revealed that SC-PEG NPs (12k-5k) had a compact structure and the highest PEG density, followed by L-PEG NPs (12k-5k), DL-PEG NPs (12k-5k), and all PLA-PEG NPs (5k-5k). Additionally, solid-phase extraction indicated that SC-PEG NPs (12k-5k) had the highest drug loading content and the lowest surface TAM adsorption, of the PLA-PEGs evaluated. These results were explained by the crystallinity of the PLA core, which was analyzed by X-ray diffraction. In the pharmacokinetic studies, ¹⁴C-TAM-loaded ¹¹¹In-SC-PEG NPs (12k-5k) exhibited the highest area under the plasma concentration-time curve, followed by L-PEG NPs (12k-5k) and DL-PEG NPs (12k-5k), after intravenous injection in mice. These results indicate that SC-PEG NPs (12k-5k) are promising drug carriers for the sustained and prolonged delivery of TAM.

Microfluidic Formulation of DNA-Loaded Multicomponent Lipid Nanoparticles for Gene Delivery

In recent years, lipid nanoparticles (LNPs) have gained considerable attention in numerous research fields ranging from gene therapy to cancer immunotherapy and DNA vaccination. While some RNA-encapsulating LNP formulations passed clinical trials, DNA-loaded LNPs have been only marginally explored so far. To fulfil this gap, herein we investigated the effect of several factors influencing the microfluidic formulation and transfection behavior of DNA-loaded LNPs such as PEGylation, total flow rate (TFR), concentration and particle density at the cell surface. We show that PEGylation and post-synthesis sample concentration facilitated formulation of homogeneous and small size LNPs with high transfection efficiency and minor, if any, cytotoxicity on human Embryonic Kidney293 (HEK-293), spontaneously immortalized human keratinocytes (HaCaT), immortalized keratinocytes (N/TERT) generated from the transduction of human primary keratinocytes, and epidermoid cervical cancer (CaSki) cell lines. On the other side, increasing TFR had a detrimental effect both on the physicochemical properties and transfection properties of LNPs. Lastly, the effect of particle concentration at the cell surface on the transfection efficiency (TE) and cell viability was largely dependent on the cell line, suggesting that its case-by-case optimization would be necessary. Overall, we demonstrate that fine tuning formulation and microfluidic parameters is a vital step for the generation of highly efficient DNA-loaded LNPs.

Parametric Study of the Factors Influencing Liposome Physicochemical Characteristics in a Periodic Disturbance Mixer

Liposomes encapsulate different substances ranging from drugs to genes. Control over the average size and size distribution of these nanoparticles is vital for biomedical applications since these characteristics determine to a high degree where liposomes will accumulate in the human body. Micromixers enable the continuous flow synthesis of liposomes, improving size control and reproducibility. Recently, Dean flow dynamics-based micromixers, such as the periodic disturbance mixer (PDM), have been shown to produce controlled-size liposomes in a scalable and reproducible way. However, contrary to micromixers based on molecular diffusion or chaotic advection, their production factors and their influence over liposome properties have not yet been addressed thoroughly. In this work, we present a comprehensive parametric study of the effects of flow conditions and molecular changing factors such as concentration, lipid type, and temperature on the physicochemical characteristics of liposomes. Numerical models and confocal images are used to quantitatively and qualitatively evaluate mixing performance under different liposome production conditions and their relationship with vesicle properties. The total flow rate (TFR) and, to a lesser extent, the flow rate ratio (FRR) control the liposome size and size distribution. Effects on liposome size are also observed by changing the molecular factors. Moreover, the liposome ζ potential is independent of the factors studied here. The micromixer presented in this work enables the production of liposomes as small as 24 nm, with monodispersed to low or close to low polydispersed liposome populations as well as a production rate as high as 41 mg/h.

Insight into theranostic nanovesicles prepared by thin lipid hydration and microfluidic method

Liposomes are phospholipid-based self-assembled nanoparticles. Various components can be solubilized in the lipid bilayer, encapsulated in the aqueous core or attached to the surface, making liposomes attractive platforms for multimodality functionalization. Here we describe theranostic liposomes delivering a magnetic resonance contrast agent (lipid derivative of gadopentetic acid) and a hydrophobic photosensitizer (zinc phthalocyanine, ZnPc) for photodynamic therapy of cancer. For the first time, this theranostic system was prepared by the microfluidic method. Analogous formulations were produced by thin lipid film hydration (TLH) with down-sizing performed by extrusion for comparison purposes. We demonstrated double the loading capacity of ZnPc into liposomes made by microfluidics compared to TLH/extrusion. Microfluidics resulted in the theranostic nanoliposomes characterized by sizes =2.5x smaller than vesicles prepared by TLH/extrusion. Increased relaxivity was observed for liposomes manufactured by microfluidics compared to TLH, despite a slightly lower Gd chelate recovery. We attributed the improved relaxation to the increased surface area/volume ratio of vesicles and decreased phosphatidylcholine/ZnPc molar ratio, which affected water molecules' diffusion through the liposomal membrane. Finally, we showed photodynamic efficacy of ZnPc loaded into theranostic liposomes in head and neck cancer model, resulting in IC₅₀ of 0.22 - 0.61 μM, depending on the formulation and cell line used. We demonstrate microfluidics' feasibility to be used for theranostic liposome manufacturing and co-entrapment of therapeutic and imaging components in a single-step process with a high yield.

Process Intensification Approach Using Microreactors for Synthesizing Nanomaterials-A Critical Review

Nanomaterials have found many applications due to their unique properties such as high surface-to-volume ratio, density, strength, and many more. This review focuses on the recent developments on the synthesis of nanomaterials using process intensification. The review covers the designing of microreactors, design principles, and fundamental mechanisms involved in process intensification using microreactors for synthesizing nanomaterials. The microfluidics technology operates in continuous mode as well as the segmented flow of gas–liquid combinations. Various examples from the literature are discussed in detail highlighting the advantages and disadvantages of microfluidics technology for nanomaterial synthesis.

Manufacturing Considerations for the Development of Lipid Nanoparticles Using Microfluidics

In the recent of years, the use of lipid nanoparticles (LNPs) for RNA delivery has gained considerable attention, with a large number in the clinical pipeline as vaccine candidates or to treat a wide range of diseases. Microfluidics offers considerable advantages for their manufacture due to its scalability, reproducibility and fast preparation. Thus, in this study, we have evaluated operating and formulation parameters to be considered when developing LNPs. Among them, the flow rate ratio (FRR) and the total flow rate (TFR) have been shown to significantly influence the physicochemical characteristics of the produced particles. In particular, increasing the TFR or increasing the FRR decreased the particle size. The amino lipid choice (cationic-DOTAP and DDAB; ionisable-MC3), buffer choice (citrate buffer pH 6 or TRIS pH 7.4) and type of nucleic acid payload (PolyA, ssDNA or mRNA) have also been shown to have an impact on the characteristics of these LNPs. LNPs were shown to have a high (>90%) loading in all cases and were below 100 nm with a low polydispersity index (≤0.25). The results within this paper could be used as a guide for the development and scalable manufacture of LNP systems using microfluidics.

Conjugation of Native-Like HIV-1 Envelope Trimers onto Liposomes Using EDC/Sulfo-NHS Chemistry: Requirements and Limitations

The display of native-like human immunodeficiency virus type 1 envelope (HIV-1 Env) trimers on liposomes has gained wide attention over the last few years. Currently, available methods have enabled the preparation of Env-liposome conjugates of unprecedented quality. However, these protocols require the Env trimer to be tagged and/or to carry a specific functional group. For this reason, we have investigated N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide/N-Hydroxysulfosuccinimide (EDC/Sulfo-NHS) chemistry for its potential to covalently conjugate tag-free, non-functionalized native-like Env trimers onto the surface of carboxyl-functionalized liposomes. The preservation of the liposome's physical integrity and the immunogen's conformation required a fine-tuned two-step approach based on the controlled use of β-mercaptoethanol. The display of Env trimers was strictly limited to activated liposomes of positive charge, i.e., liposomes with a positive zeta potential that carry amine-reactive Sulfo-NHS esters on their surface. In agreement with that, conjugation was found to be highly ionic strength- and pH-dependent. Overall, we have identified electrostatic pre-concentration (i.e., close proximity between negatively charged Env trimers and positively charged liposomes established through electrostatic attraction) to be crucial for conjugation reactions to proceed. The present study highlights the requirements and limitations of potentially scalable EDC/Sulfo-NHS-based approaches and represents a solid basis for further research into the controlled conjugation of tag-free, non-functionalized native-like Env trimers on the surface of liposomes, and other nanoparticles.

Rapid scale-up and production of active-loaded PEGylated liposomes

Manufacturing of liposomal nanomedicines (e.g. Doxil®/Caelyx®) is a challenging and slow process based on multiple-vessel and batch processing techniques. As a result, the translation of these nanomedicines from bench to bedside has been limited. Microfluidic-based manufacturing offers the opportunity to address this issue, and de-risk the wider adoption of nanomedicines. Here we demonstrate the applicability of microfluidics for continuous manufacturing of PEGylated liposomes encapsulating ammonium sulfate (250 mM). Doxorubicin was subsequently active-loaded into these pre-formed liposomes. Critical process parameters and material considerations demonstrated to influence the liposomal product attributes included solvent selection and lipid concentration, flow rate ratio, and temperature and duration used for drug loading. However, the total flow rate did not affect the liposome product characteristics, allowing high production speeds to be adopted. The final liposomal product comprised of 80-100 nm vesicles (PDI < 0.2) encapsulating ≥ 90% doxorubicin, with matching release profiles to the innovator product and is stable for at least 6 months. Additionally, vincristine and acridine orange were active-loaded into these PEGylated liposomes (≥ 90% and ~100 nm in size) using the same process. These results demonstrate the ability to produce active-loaded PEGylated liposomes with high encapsulation efficiencies and particle sizes which support tumour targeting.

Lipid-based nanoparticle formulations for small molecules and RNA drugs

Introduction: Liposomes and lipid-based nanoparticles (LNPs) effectively deliver cargo molecules to specific tissues, cells, and cellular compartments. Patients benefit from these nanoparticle formulations by altered pharmacokinetic properties, higher efficacy, or reduced side effects. While liposomes are an established delivery option for small molecules, Onpattro® (Sanofi Genzyme, Cambridge, MA) is the first commercially available LNP formulation of a small interfering ribonucleic acid (siRNA). Areas covered: This review article summarizes key features of liposomal formulations for small molecule drugs and LNP formulations for RNA therapeutics. We describe liposomal formulations that are commercially available or in late-stage clinical development and the most promising LNP formulations for ASOs, siRNAs, saRNA, and mRNA therapeutics. Expert opinion: Similar to liposomes, LNPs for RNA therapeutics have matured but still possess a niche application status. RNA therapeutics, however, bear an immense hope for difficult to treat diseases and fuel the imagination for further applications of RNA drugs. LNPs face similar challenges as liposomes including limitations in biodistribution, the risk to provoke immune responses, and other toxicities. However, since properties of RNA molecules within the same group are very similar, the entire class of therapeutic molecules would benefit from improvements in a few key parameters of the delivery technology.

Co-encapsulation of imidacloprid and lambda-cyhalothrin using biocompatible nanocarriers: Characterization and application

A well-known strategy for managing pest resistance is application of mixture of pesticides. Conventionally formulated pesticides have several environmental incompatibilities. The use of biocompatible and biodegradable nanocarriers in formulating pesticides could improve environmental protection. In this study, a mixture of imidacloprid and lambda-cyhalothrin was co-encapsulated for the first time using liposomes as nanocarrier to simultaneously deliver these insecticides. Ethanol injection was used to produce self-assembled liposomes. The formed nanoliposomes were coated with different concentrations of chitosan. Nanoparticles were characterized by dynamic light scattering (DLS), scanning electron microscope (SEM) and FT-IR spectroscopy. The encapsulation efficiencies of lambda-cyhalothrin and imidacloprid were about 93% and 51%, respectively. The insecticide carrying liposomes had a size and surface charge of 57 nm and +0.6 mV, respectively. The size and surface charge of the particles produced were increased to 69 nm and +31 mV after being coated with chitosan (0.1%, W/V). In this study, residual activity of technical grade imidacloprid, lambda-cyhalothrin and their mixture and the effect of adjuvants used in commercial and nano formulations of these insecticides on Myzus persicae Sulzer was investigated. The insecticidal effects and duration of residual activity of nano-formulations was correlated with concentration of chitosan in final formulation. In accordance with the life cycle of M. persicae, using the mixture of imidacloprid and lambda-cyhalothrin improves the residual effect over their use alone. The use of lipid nanocarriers makes the improvement even further and can be a better alternative to conventional combination of these insecticides due to their more environmental friendliness.

Conception of nanosized hybrid liposome/poloxamer particles to thicken the interior core of liposomes and delay hydrophilic drug delivery

Liposomes are nanocarriers composed of phospholipids, especially designed to potentially carry drugs. However, liposomes suffer in terms of leakage of small hydrophilic drugs. To control the release, a system with lipid shell and polymeric viscous core, namely Hybrid liposome/polymer inside (HLP_in), has been designed. For this purpose, we setup a syringe pump apparatus equipped with homemade tubing system. HLPin formulation consisting of poloxamer (5% w/v) was found to be optimal when produced at injection rates of 5 mL.min^-1. Then, we tend to characterize the HLP_in with DLS, TEM, TRPS, thermal analysis and densitometry in comparison with a polymer added after formation of the liposomes. The optimal formulation was evaluated for its stability and cytotoxicity. The selected conditions and composition resulted in nanocarriers which are highly reproducible with mono-disperse size distribution with an average size of 206 ± 4.8 nm and a polydispersity index of 0.15 ± 0.015. Densitometry and thermal analysis results confirmed the formation of HLP_in. Interestingly, HLP_in were stable over 2 months, produced no cytotoxicity and exhibited slow release of rhodamine and Doxorubicin in comparison to liposome formulation. Our homemade tubing system coupled with syringe pump apparatus achieved reproducible, precisely controlled production for the HLPin formulation which can be scale up.

Photodynamic Activity of Fullerene Derivatives Solubilized in Water by Natural-Product-Based Solubilizing Agents

Water-soluble fullerenes prepared by using solubilizing agents based on natural products are promising photosensitizers for photodynamic therapy. Cyclodextrin, β-1,3-glucan, lysozyme, and liposomes can stably solubilize not only C₆₀ and C₇₀ , but also some C₆₀ derivatives in water. To improve the solubilities of fullerenes, specific methods have been developed for each solubilizing agent. Water-soluble C₆₀ and C₇₀ exhibit photoinduced cytotoxicity under near-ultraviolet irradiation, but not at wavelengths over 600 nm, which are the appropriate wavelengths for photodynamic therapy. However, dyad complexes of solubilized C₆₀ derivatives combined with light-harvesting antenna molecules improve the photoinduced cytotoxicities at wavelengths over 600 nm. Furthermore, controlling the fullerene and antenna molecule positions within the solubilizing agents affects the performance of the photosensitizer.

High-Throughput Continuous Flow Production of Nanoscale Liposomes by Microfluidic Vertical Flow Focusing

Liposomes represent a leading class of nanoparticles for drug delivery. While a variety of techniques for liposome synthesis have been reported that take advantage of microfluidic flow elements to achieve precise control over the size and polydispersity of nanoscale liposomes, with important implications for nanomedicine applications, these methods suffer from extremely limited throughput, making them impractical for large-scale nanoparticle synthesis. High aspect ratio microfluidic vertical flow focusing is investigated here as a new approach to overcoming the throughput limits of established microfluidic nanoparticle synthesis techniques. Here the vertical flow focusing technique is utilized to generate populations of small, unilamellar, and nearly monodisperse liposomal nanoparticles with exceptionally high production rates and remarkable sample homogeneity. By leveraging this platform, liposomes with modal diameters ranging from 80 to 200 nm are prepared at production rates as high as 1.6 mg min(-1) in a simple flow-through process.

Large-scale preparation of clove essential oil and eugenol-loaded liposomes using a membrane contactor and a pilot plant

Based on our previous study where optimal conditions were defined to encapsulate clove essential oil (CEO) into liposomes at laboratory scale, we scaled-up the preparation of CEO and eugenol (Eug)-loaded liposomes using a membrane contactor (600 mL) and a pilot plant (3 L) based on the principle of ethanol injection method, both equipped with a Shirasu Porous Glass membrane for injection of the organic phase into the aqueous phase. Homogenous, stable, nanometric-sized and multilamellar liposomes with high phospholipid, Eug loading rates and encapsulation efficiency of CEO components were obtained. Saturation of phospholipids and drug concentration in the organic phase may control the liposome stability. Liposomes loaded with other hydrophobic volatile compounds could be prepared at large scale using the ethanol injection method and a membrane for injection.

Formulation of resveratrol entrapped niosomes for topical use

A new approach to the formulation of resveratrol (RSV) entrapped niosomes for topical use is proposed in this work. Niosomes were formulated with Gelot 64 (G64) as surfactant, and two skin-compatible unsaturated fatty acids (oleic and linoleic acids), commonly used in pharmaceutical formulations, as penetration enhancers. Niosomes were prepared by two different methods: a thin film hydration method with minor modifications followed by a sonication stage (TFH-S), and an ethanol injection modified method (EIM). Niosomes prepared with the EIM method were in the range of 299-402 nm, while the TFH-S method produced larger niosomes in the range of 293-496 nm. Moreover, niosomes with higher RSV entrapment efficiency (EE) and better stability were generated by the EIM method. Ex vivo transdermal experiments, carried out in Franz diffusion cells on newborn pig skin, indicated that niosomes prepared by the EIM method were more effective for RSV penetration in epidermis and dermis (EDD), with values up to 21% for both penetration enhancers tested. The EIM method, which yielded the best RSV-entrapped niosomes, seems to be the most suitable for scaling up.

Porphyrin-uptake in liposomes and living cells using an exchange method with cyclodextrin

A preparation of a lipid-membrane-incorporated tetraphenylporphyrin was achieved from the corresponding tetraphenylporphyrin·cyclodextrin complexes using an exchange method in both liposomes and cells.

A facile route to the synthesis of monodisperse nanoscale liposomes using 3D microfluidic hydrodynamic focusing in a concentric capillary array

A novel microscale device has been developed to enable the one-step continuous flow assembly of monodisperse nanoscale liposomes using three-dimensional microfluidic hydrodynamic focusing (3D-MHF) in a concentric capillary array. The 3D-MHF flow technique displays patent advantages over conventional methods for nanoscale liposome manufacture (i.e., bulk-scale alcohol injection and/or sonication) through the on-demand synthesis of consistently uniform liposomes without the need for post-processing strategies. Liposomes produced by the 3D-MHF device are of tunable size, have a factor of two improvement in polydispersity, and a production rate that is four orders of magnitude higher than previous MHF methods, which can be attributed to entirely radially symmetric diffusion of alcohol-solvated lipid into an aqueous flow stream. Moreover, the 3D-MHF platform is simple to construct from low-cost, commercially-available components, which obviates the need for advanced microfabrication strategies necessitated by previous MHF nanoparticle synthesis platforms.

Development and antitumor activity of a BCL-2 targeted single-stranded DNA oligonucleotide

PNT100 is a 24-base, chemically unmodified DNA oligonucleotide sequence that is complementary to a region upstream of the BCL-2 gene. Exposure of tumor cells to PNT100 results in suppression of proliferation and cell death by a process called DNA interference. PNT2258 is PNT100 that is encapsulated in protective amphoteric liposomes developed to efficiently encapsulate the PNT100 oligonucleotide, provide enhanced serum stability, optimized pharmacokinetic properties and antitumor activity of the nanoparticle both in vivo and in vitro. PNT2258 demonstrates broad antitumor activity against BCL-2-driven WSU-DLCL2 lymphoma, highly resistant A375 melanoma, PC-3 prostate, and Daudi-Burkitt’s lymphoma xenografts. The sequence specificity of PNT100 was demonstrated against three control sequences (scrambled, mismatched, and reverse complement) all encapsulated in a lipid formulation with identical particle characteristics, and control sequences did not demonstrate antiproliferative activity in vivo or in vitro. PNT2258 is currently undergoing clinical testing to evaluate safety and antitumor activity in patients with recurrent or refractory non-Hodgkin’s lymphoma and additional studies are planned.

Microfluidic preparation of liposomes to determine particle size influence on cellular uptake mechanisms

PURPOSE

This study investigates the cellular uptake and trafficking of liposomes in Caco-2 cells, using vesicles with distinct average diameters ranging from 40.6 nm to 276.6 nm. Liposomes were prepared by microfluidic hydrodynamic flow focusing, producing nearly-monodisperse populations and enabling size-dependent uptake to be effectively evaluated.

METHODS

Populations of PEG-conjugated liposomes of various distinct sizes were prepared in a disposable microfluidic device using a simple continuous-flow microfluidic technique. Liposome cellular uptake was investigated using flow cytometry and confocal microscopy.

RESULTS

Liposome uptake by Caco-2 cells was observed to be strongly size-dependent for liposomes with mean diameters ranging from 40.6 nm to 276.6 nm. When testing these liposomes against endocytosis inhibitors, cellular uptake of the largest (97.8 nm and 162.1 nm in diameter) liposomes were predominantly subjected to clathrin-dependent uptake mechanisms, the medium-sized (72.3 nm in diameter) liposomes seemed to be influenced by all investigated pathways and the smallest liposomes (40.6 nm in diameter) primarily followed a dynamin-dependent pathway. In addition, the 40.6 nm, 72.3 nm, and 162.1 nm diameter liposomes showed slightly decreased accumulation within endosomes after 1 h compared to liposomes which were 97.8 nm in diameter. Conversely, liposome co-localization with lysosomes was consistent for liposomes ranging from 40.6 nm to 97.8 nm in diameter.

CONCLUSIONS

The continuous-flow synthesis of nearly-monodisperse populations of liposomes of distinct size via a microfluidic hydrodynamic flow focusing technique enabled unique in vitro studies in which specific effects of particle size on cellular uptake were elucidated. The results of this study highlight the significant influence of liposome size on cellular uptake mechanisms and may be further exploited for increasing specificity, improving efficacy, and reducing toxicity of liposomal drug delivery systems.