Microfluidics: a transformational tool for nanomedicine development and production

Recent advances in microfluidic technology of arterial thrombosis investigations

Microfluidic technology has emerged as a powerful tool in studying arterial thrombosis, allowing researchers to construct artificial blood vessels and replicate the hemodynamics of blood flow. This technology has led to significant advancements in understanding thrombosis and platelet adhesion and aggregation. Microfluidic models have various types and functions, and by studying the fabrication methods and working principles of microfluidic chips, applicable methods can be selected according to specific needs. The rapid development of microfluidic integrated system and modular microfluidic system makes arterial thrombosis research more diversified and automated, but its standardization still needs to be solved urgently. One key advantage of microfluidic technology is the ability to precisely control fluid flow in microchannels and to analyze platelet behavior under different shear forces and flow rates. This allows researchers to study the physiological and pathological processes of blood flow, shedding light on the underlying mechanisms of arterial thrombosis. In conclusion, microfluidic technology has revolutionized the study of arterial thrombosis by enabling the construction of artificial blood vessels and accurately reproducing hemodynamics. In the future, microfluidics will place greater emphasis on versatility and automation, holding great promise for advancing antithrombotic therapeutic and prophylactic measures.

Innovative Formulation Platform: Paving the Way for Superior Protein Therapeutics with Enhanced Efficacy and Broadened Applications

Protein therapeutics offer high therapeutic potency and specificity; the broader adoptions and development of protein therapeutics, however, have been constricted by their intrinsic limitations such as inadequate stability, immunogenicity, suboptimal pharmacokinetics and biodistribution, and off-target effects. This review describes a platform technology that formulates individual protein molecules with a thin formulation layer of crosslinked polymers, which confers the protein therapeutics with high activity, enhanced stability, controlled release capability, reduced immunogenicity, improved pharmacokinetics and biodistribution, and ability to cross the blood brain barriers. Based on currently approved protein therapeutics, this formulating platform affords the development of a vast family of superior protein therapeutics with improved efficacy and broadened indications at significantly reduced cost.

Liposome-Hydrogel Composites for Controlled Drug Delivery Applications

Various controlled delivery systems (CDSs) have been developed to overcome the shortcomings of traditional drug formulations (tablets, capsules, syrups, ointments, etc.). Among innovative CDSs, hydrogels and liposomes have shown great promise for clinical applications thanks to their cost-effectiveness, well-known chemistry and synthetic feasibility, biodegradability, biocompatibility and responsiveness to external stimuli. To date, several liposomal- and hydrogel-based products have been approved to treat cancer, as well as fungal and viral infections, hence the integration of liposomes into hydrogels has attracted increasing attention because of the benefit from both of them into a single platform, resulting in a multifunctional drug formulation, which is essential to develop efficient CDSs. This short review aims to present an updated report on the advancements of liposome-hydrogel systems for drug delivery purposes.

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.

Tunable rigidity of PLGA shell-lipid core nanoparticles for enhanced pulmonary siRNA delivery in 2D and 3D lung cancer cell models

Faced with the threat of lung cancer-related deaths worldwide, small interfering RNA (siRNA) can silence tumor related messenger RNA (mRNA) to tackle the issue of drug resistance with enhanced anti-tumor effects. However, how to increase lung tumor targeting and penetration with enhanced gene silencing are the issues to be addressed. Thus, the objective of this study is to explore the feasibility of designing non-viral siRNA vectors for enhanced lung tumor therapy via inhalation. Here, shell-core based polymer-lipid hybrid nanoparticles (HNPs) were prepared via microfluidics by coating PLGA on siRNA-loaded cationic liposomes (Lipoplexes). Transmission electron microscopy and energy dispersive spectroscopy study demonstrated that HNP consists of a PLGA shell and a lipid core. Atomic force microscopy study indicated that the rigidity of HNPs could be well tuned by changing thickness of the PLGA shell. The designed HNPs were muco-inert with increased stability in mucus and BALF, good safety, enhanced mucus penetration and cellular uptake. Crucially, HNP1 with the thinnest PLGA shell exhibited superior transfection efficiency (84.83%) in A549 cells, which was comparable to that of lipoplexes and Lipofectamine 2000, and its tumor permeability was 1.88 times that of lipoplexes in A549-3T3 tumor spheroids. After internalization of the HNPs, not only endosomal escape but also lysosomal exocytosis was observed. The transfection efficiency of HNP1 (39.33%) was 2.26 times that of lipoplexes in A549-3T3 tumor spheroids. Moreover, HNPs exhibited excellent stability during nebulization via soft mist inhaler. In conclusion, our study reveals the great potential of HNP1 in siRNA delivery for lung cancer therapy via inhalation.

Recent advances in nanoantibiotics against multidrug-resistant bacteria

Multidrug-resistant (MDR) bacteria-caused infections have been a major threat to human health. The abuse of conventional antibiotics accelerates the generation of MDR bacteria and makes the situation worse. The emergence of nanomaterials holds great promise for solving this tricky problem due to their multiple antibacterial mechanisms, tunable antibacterial spectra, and low probabilities of inducing drug resistance. In this review, we summarize the mechanism of the generation of drug resistance, and introduce the recently developed nanomaterials for dealing with MDR bacteria via various antibacterial mechanisms. Considering that biosafety and mass production are the major bottlenecks hurdling the commercialization of nanoantibiotics, we introduce the related development in these two aspects. We discuss urgent challenges in this field and future perspectives to promote the development and translation of nanoantibiotics as alternatives against MDR pathogens to traditional antibiotics-based approaches.

Design of PLGA nanoparticles for sustained release of hydroxyl-FK866 by microfluidics

The use of nanoparticle (NP) delivery systems in cancer treatment has received significant interest, however use of such systems in delivery of cytotoxic chemotherapy agents can be limited by low encapsulation efficiency and burst release of the cytotoxin, as well issues with throughput and reproducibility during the fabrication of drug-loaded NPs. In this study, we used a hydrodynamic flow-focusing microfluidic system to successfully produce poly(lactic-co-glycolic acid) (PLGA) NPs. The physico-chemical properties of PLGA NPs were controlled by changing the manufacturing parameters, such as flow rate ratio, total flow rate, PLGA and surfactant concentration. The NAMPT inhibitor-polymer conjugate, hydroxyl-FK866-PLGA, was synthesized and used to fabricate hydroxyl-FK866-PLGA NPs for the formulation of localized delivery systems able to release low doses of cytotoxins and enhance the efficacy of NAMPT inhibitors. Hydroxyl-FK866-PLGA NPs were prepared with optimized fabrication parameters, having average Z-size of 128 ± 8 nm (PDI < 0.2), ζ-potential of -14.8 ± 5.3 mV and high encapsulation efficiency (98.6 ± 5.8 %). The pH-dependent release of hydroxyl-FK866 was monitored over time in conditions mimicking the normal (pH 7.4) and inflamed/tumor (pH 6.4) microenvironments, observing a sustained release pattern (over two months) without any initial burst release. Finally, toxicity of hydroxyl-FK866-PLGA NPs were tested in selected human cell lines, the human leukemia monocytic cell line (THP-1), and the human triple negative breast cancer cell line (MDA-MB-231). Our work suggests that microfluidic systems are a promising technology for a rapid and efficient manufacturing of PLGA-based NPs for the controlled release of cytotoxins. Moreover, the use of drug-polymer conjugates is an effective approach for the manufacturing of polymeric NPs enabling high encapsulation efficiency and a prolonged and sustained pH-dependent drug release.

Establishing and testing a robot-based platform to enable the automated production of nanoparticles in a flexible and modular way

Robotic systems facilitate relatively simple human-robot interaction for non-robot experts, providing the flexibility to implement different processes. In this context, shorter process times, as well as an increased product and process quality could be achieved. Robots short time-consuming processes, take over ergonomically unfavorable tasks and work efficiently all the time. In addition, flexible production is possible while maintaining or even increasing safety. This study describes the successful development of a dual-arm robot-based modular infrastructure and the establishment of an automated process for the reproducible production of nanoparticles. As proof of concept, a manual synthesis protocol for silica nanoparticle preparation with a diameter of about 200 nm as building blocks for photonic crystals was translated into a fully automated process. All devices and components of the automated system were optimized and adapted according to the synthesis requirements. To demonstrate the benefit of the automated nanoparticle production, manual (synthesis done by lab technicians) and automated syntheses were benchmarked. To this end, different processing parameters (time of synthesis procedure, accuracy of dosage etc.) and the properties of the produced nanoparticles were compared. We demonstrate that the use of the robot not only increased the synthesis accuracy and reproducibility but reduced the personnel time and costs up to 75%.

Solid Lipid Nanoparticles vs. Nanostructured Lipid Carriers: A Comparative Review

Solid-lipid nanoparticles and nanostructured lipid carriers are delivery systems for the delivery of drugs and other bioactives used in diagnosis, therapy, and treatment procedures. These nanocarriers may enhance the solubility and permeability of drugs, increase their bioavailability, and extend the residence time in the body, combining low toxicity with a targeted delivery. Nanostructured lipid carriers are the second generation of lipid nanoparticles differing from solid lipid nanoparticles in their composition matrix. The use of a liquid lipid together with a solid lipid in nanostructured lipid carrier allows it to load a higher amount of drug, enhance drug release properties, and increase its stability. Therefore, a direct comparison between solid lipid nanoparticles and nanostructured lipid carriers is needed. This review aims to describe solid lipid nanoparticles and nanostructured lipid carriers as drug delivery systems, comparing both, while systematically elucidating their production methodologies, physicochemical characterization, and in vitro and in vivo performance. In addition, the toxicity concerns of these systems are focused on.

3D Printing Technologies in Personalized Medicine, Nanomedicines, and Biopharmaceuticals

3D printing technologies enable medicine customization adapted to patients' needs. There are several 3D printing techniques available, but majority of dosage forms and medical devices are printed using nozzle-based extrusion, laser-writing systems, and powder binder jetting. 3D printing has been demonstrated for a broad range of applications in development and targeting solid, semi-solid, and locally applied or implanted medicines. 3D-printed solid dosage forms allow the combination of one or more drugs within the same solid dosage form to improve patient compliance, facilitate deglutition, tailor the release profile, or fabricate new medicines for which no dosage form is available. Sustained-release 3D-printed implants, stents, and medical devices have been used mainly for joint replacement therapies, medical prostheses, and cardiovascular applications. Locally applied medicines, such as wound dressing, microneedles, and medicated contact lenses, have also been manufactured using 3D printing techniques. The challenge is to select the 3D printing technique most suitable for each application and the type of pharmaceutical ink that should be developed that possesses the required physicochemical and biological performance. The integration of biopharmaceuticals and nanotechnology-based drugs along with 3D printing ("nanoprinting") brings printed personalized nanomedicines within the most innovative perspectives for the coming years. Continuous manufacturing through the use of 3D-printed microfluidic chips facilitates their translation into clinical practice.

Liposomes or Extracellular Vesicles: A Comprehensive Comparison of Both Lipid Bilayer Vesicles for Pulmonary Drug Delivery

The rapid and non-invasive pulmonary drug delivery (PDD) has attracted great attention compared to the other routes. However, nanoparticle platforms, like liposomes (LPs) and extracellular vesicles (EVs), require extensive reformulation to suit the requirements of PDD. LPs are artificial vesicles composed of lipid bilayers capable of encapsulating hydrophilic and hydrophobic substances, whereas EVs are natural vesicles secreted by cells. Additionally, novel LPs-EVs hybrid vesicles may confer the best of both. The preparation methods of EVs are distinguished from LPs since they rely mainly on extraction and purification, whereas the LPs are synthesized from their basic ingredients. Similarly, drug loading methods into/onto EVs are distinguished whereby they are cell- or non-cell-based, whereas LPs are loaded via passive or active approaches. This review discusses the progress in LPs and EVs as well as hybrid vesicles with a special focus on PDD. It also provides a perspective comparison between LPs and EVs from various aspects (composition, preparation/extraction, drug loading, and large-scale manufacturing) as well as the future prospects for inhaled therapeutics. In addition, it discusses the challenges that may be encountered in scaling up the production and presents our view regarding the clinical translation of the laboratory findings into commercial products.

Mechanisms and challenges of nanocarriers as non-viral vectors of therapeutic genes for enhanced pulmonary delivery

With the rapid development of biopharmaceuticals and the outbreak of COVID-19, the world has ushered in a frenzy to develop gene therapy. Therefore, therapeutic genes have received enormous attention. However, due to the extreme instability and low intracellular gene expression of naked genes, specific vectors are required. Viral vectors are widely used attributed to their high transfection efficiency. However, due to the safety concerns of viral vectors, nanotechnology-based non-viral vectors have attracted extensive investigation. Still, issues of low transfection efficiency and poor tissue targeting of non-viral vectors need to be addressed. Especially, pulmonary gene delivery has obvious advantages for the treatment of inherited lung diseases, lung cancer, and viral pneumonia, which can not only enhance lung targeting and but also reduce enzymatic degradation. For systemic diseases therapy, pulmonary gene delivery can enhance vaccine efficacy via inducing not only cellular, humoral immunity but also mucosal immunity. This review provides a comprehensive overview of nanocarriers as non-viral vectors of therapeutic genes for enhanced pulmonary delivery. First of all, the characteristics and therapeutic mechanism of DNA, mRNA, and siRNA are provided. Thereafter, the advantages and challenges of pulmonary gene delivery in exerting local and systemic effects are discussed. Then, the inhalation dosage forms for nanoparticle-based drug delivery systems are introduced. Moreover, a series of materials used as nanocarriers for pulmonary gene delivery are presented, and the endosomal escape mechanisms of nanocarriers based on different materials are explored. The application of various non-viral vectors for pulmonary gene delivery are summarized in detail, with the perspectives of nano-vectors for pulmonary gene delivery.

Droplet-based microfluidic synthesis of nanogels for controlled drug delivery: tailoring nanomaterial properties via pneumatically actuated flow-focusing junction

Conventional batch syntheses of polymer-based nanoparticles show considerable shortcomings in terms of scarce control over nanomaterials morphology and limited lot-to-lot reproducibility. Droplet-based microfluidics represents a valuable strategy to overcome these constraints, exploiting the formation of nanoparticles within discrete microdroplets. In this work, we synthesized nanogels (NGs) composed of hyaluronic acid and polyethyleneimine using a microfluidic flow-focusing device endowed with a pressure-driven micro-actuator. The actuator achieves real-time modulation of the junction orifice width, thereby regulating the microdroplet diameter and, as a result, the NG size. Acting on process parameters, NG hydrodynamic diameter could be tuned in the range 92-190 nm while preserving an extremely low polydispersity (0.015); those values are hardly achievable in batch syntheses and underline the strength of our toolbox for the continuous in-flow synthesis of nanocarriers. Furthermore, NGs were validated in vitro as a drug delivery system in a representative case study still lacking an effective therapeutic treatment: ovarian cancer. Using doxorubicin as a chemotherapeutic agent, we show that NG-mediated release of the drug results in an enhanced antiblastic effect vs. the non-encapsulated administration route even at sublethal dosages, highlighting the wide applicability of our microfluidics-enabled nanomaterials in healthcare scenarios.

Novel microfluidic swirl mixers for scalable formulation of curcumin loaded liposomes for cancer therapy

Liposomes have been widely used in nanomedicine for the delivery of hydrophobic and hydrophilic anticancer agents. The most common applications of these formulations are vaccines and anticancer formulations (e.g., mRNA, small molecule drugs). However, large-scale production with precise control of size and size distribution of the lipid-based drug delivery systems (DDSs) is one of the major challenges in the pharmaceutical industry. In this study, we used newly designed microfluidic swirl mixers with simple 3D mixing chamber structures to prepare liposomes at a larger scale (up to 320 mL/min or 20 L/h) than the commercially available devices. This design demonstrated high productivity and better control of liposome size and polydispersity index (PDI) than conventional liposome preparation methods. The microfluidic swirl mixer devices were used to produce curcumin-loaded liposomes under different processing conditions which were later characterized and studied in vitro to evaluate their efficiency as DDSs. The obtained results demonstrated that the liposomes can effectively deliver curcumin into cancer cells. Therefore, the microfluidic swirl mixers are promising devices for reproducible and scalable manufacturing of DDSs.

Improving Antibacterial Activity of a HtrA Protease Inhibitor JO146 against Helicobacter pylori: A Novel Approach Using Microfluidics-Engineered PLGA Nanoparticles

Nanoparticle drug delivery systems have emerged as a promising strategy for overcoming limitations of antimicrobial drugs such as stability, bioavailability, and insufficient exposure to the hard-to-reach bacterial drug targets. Although size is a vital colloidal feature of nanoparticles that governs biological interactions, the absence of well-defined size control technology has hampered the investigation of optimal nanoparticle size for targeting bacterial cells. Previously, we identified a lead antichlamydial compound JO146 against the high temperature requirement A (HtrA) protease, a promising antibacterial target involved in protein quality control and virulence. Here, we reveal that JO146 was active against Helicobacter pylori with a minimum bactericidal concentration of 18.8–75.2 µg/mL. Microfluidic technology using a design of experiments approach was utilized to formulate JO146-loaded poly(lactic-co-glycolic) acid nanoparticles and explore the effect of the nanoparticle size on drug delivery. JO146-loaded nanoparticles of three different sizes (90, 150, and 220 nm) were formulated with uniform particle size distribution and drug encapsulation efficiency of up to 25%. In in vitro microdilution inhibition assays, 90 nm nanoparticles improved the minimum bactericidal concentration of JO146 two-fold against H. pylori compared to the free drug alone, highlighting that controlled engineering of nanoparticle size is important in drug delivery optimization.

Microfluidic Technology for the Production of Hybrid Nanomedicines

Microfluidic technologies have recently been applied as innovative methods for the production of a variety of nanomedicines (NMeds), demonstrating their potential on a global scale. The capacity to precisely control variables, such as the flow rate ratio, temperature, total flow rate, etc., allows for greater tunability of the NMed systems that are more standardized and automated than the ones obtained by well-known benchtop protocols. However, it is a crucial aspect to be able to obtain NMeds with the same characteristics of the previously optimized ones. In this study, we focused on the transfer of a production protocol for hybrid NMeds (H-NMeds) consisting of PLGA, Cholesterol, and Pluronic® F68 from a benchtop nanoprecipitation method to a microfluidic device. For this aim, we modified parameters such as the flow rate ratio, the concentration of core materials in the organic phase, and the ratio between PLGA and Cholesterol in the feeding organic phase. Outputs analysed were the chemico-physical properties, such as size, PDI, and surface charge, the composition in terms of %Cholesterol and residual %Pluronic® F68, their stability to lyophilization, and the morphology via atomic force and electron microscopy. On the basis of the results, even if microfluidic technology is one of the unique procedures to obtain industrial production of NMeds, we demonstrated that the translation from a benchtop method to a microfluidic one is not a simple transfer of already established parameters, with several variables to be taken into account and to be optimized.

Galenic Lab-on-a-Chip concept for lipid nanocapsules production

The continuous production of drug delivery systems assisted by microfluidics has drawn a growing interest because of the high reproducibility, low batch-to-batch variations, narrow and controlled particle size distributions and scale-up ease induced by this kind of processes. Besides, microfluidics offers opportunities for high throughput screening of process parameters and the implementation of process characterization techniques as close to the product as possible. In this context, we propose to spotlight the GALECHIP concept through the development of an instrumented microfluidic pilot considered as a Galenic Lab-on-a-Chip to formulate nanomedicines, such as lipid nanocapsules (LNCs), under controlled process conditions. In this paper we suggest an optimal rational development in terms of chip costs and designs. First, by using two common additive manufacturing techniques, namely fused deposition modelling and multi-jet modelling to prototype customized 3D microfluidic devices (chips and connectors). Secondly, by manufacturing transparent Silicon (Si)/Glass chips with similar channel geometries but obtained by a new approach of deep reactive ion etching (DRIE) technology suitable with in situ small angle X-ray scattering characterizations. LNCs were successfully produced by a phase inversion composition (PIC) process with highly monodispersed sizes from 25 nm to 100 nm and formulated using chips manufactured by 3D printing and DRIE technologies. The transparent Si/Glass chip was also used for the small angle X-ray scattering (SAXS) analysis of the LNC formulation with the PIC process. The 3D printing and DRIE technologies and their respective advantages are discussed in terms of cost, easiness to deploy and process developments in a GALECHIP point of view.

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

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

Microfluidic formulation of nanoparticles for biomedical applications

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

Excipient-Free Pure Drug Nanoparticles Fabricated by Microfluidic Hydrodynamic Focusing

Nanoprecipitation is one of the most versatile methods to produce pure drug nanoparticles (PDNPs) owing to the ability to optimize the properties of the product. Nevertheless, nanoprecipitation may result in broad particle size distribution, low physical stability, and batch-to-batch variability. Microfluidics has emerged as a powerful tool to produce PDNPs in a simple, reproducible, and cost-effective manner with excellent control over the nanoparticle size. In this work, we designed and fabricated T- and Y-shaped Si-made microfluidic devices and used them to produce PDNPs of three kinase inhibitors of different lipophilicity and water-solubility, namely imatinib, dasatinib and tofacitinib, without the use of colloidal stabilizers. PDNPs display hydrodynamic diameter in the 90-350 nm range as measured by dynamic light scattering and a rounded shape as visualized by high-resolution scanning electron microscopy. Powder X-ray diffraction and differential scanning calorimetry confirmed that this method results in highly amorphous nanoparticles. In addition, we show that the flow rate of solvent, the anti-solvent, and the channel geometry of the device play a key role governing the nanoparticle size.

Microfluidic synthesis of protein-loaded nanogels in a coaxial flow reactor using a design of experiments approach

Ionic gelation is commonly used to generate nanogels but often results in poor control over size and polydispersity. In this work we present a novel approach to the continuous manufacture of protein-loaded chitosan nanogels using microfluidics whereby we demonstrate high control and uniformity of the product characteristics. Specifically, a coaxial flow reactor (CFR) was employed to control the synthesis of the nanogels, comprising an inner microcapillary of internal diameter (ID) 0.595 mm and a larger outer glass tube of ID 1.6 mm. The CFR successfully facilitated the ionic gelation process via chitosan and lysozyme flowing through the inner microcapillary, while cross-linkers sodium tripolyphosphate (TPP) and 1-ethyl-2-(3-dimethylaminopropyl)-carbodiimide (EDC) flowed through the larger outer tube. In conjunction with the CFR, a four-factor three-level face-centered central composite design (CCD) was used to ascertain the relationship between various factors involved in nanogel production and their responses. Specifically, four factors including chitosan concentration, TPP concentration, flow ratio and lysozyme concentration were investigated for their effects on three responses (size, polydispersity index (PDI) and encapsulation efficiency (% EE)). A desirability function was applied to identify the optimum parameters to formulate nanogels in the CFR with ideal characteristics. Nanogels prepared using the optimal parameters were successfully produced in the nanoparticle range at 84 ± 4 nm, showing a high encapsulation efficiency of 94.6 ± 2.9% and a high monodispersity of 0.26 ± 0.01. The lysis activity of the protein lysozyme was significantly enhanced in the nanogels at 157.6% in comparison to lysozyme alone. Overall, the study has demonstrated that the CFR is a viable method for the synthesis of functional nanogels containing bioactive molecules.

Bile acid-based dual-functional prodrug nanoparticles for bone regeneration through hydrogen peroxide scavenging and osteogenic differentiation of mesenchymal stem cells

A high level of reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂) upregulates pro-inflammatory cytokines and inhibits the osteogenic differentiation of mesenchymal stem cells (MSCs), which are key factors in bone regeneration. Ursodeoxycholic acid (UDCA), a hydrophilic bile acid, has antioxidant and anti-inflammatory activities and also plays beneficial roles in bone regeneration by stimulating the osteogenic differentiation of MSCs while suppressing their adipogenic differentiation. Despite its remarkable capacity for bone regeneration, multiple injections of UDCA induce adverse side effects such as mechanical stress and contamination in bone defects. To fully exploit the beneficial roles of UDCA, a concept polymeric prodrug was developed based on the hypothesis that removal of overproduced H₂O₂ will potentiate the osteogenic functions of UDCA. In this work, we report bone regenerative nanoparticles (NPs) formulated from a polymeric prodrug of UDCA (PUDCA) with UDCA incorporated in its backbone through H₂O₂-responsive peroxalate linkages. The PUDCA NPs displayed potent antioxidant and anti-inflammatory activities in MSCs and induced osteogenic rather than adipogenic differentiation of the MSCs. In rat models of bone defect, the PUDCA NPs exhibited significantly better bone regeneration capacity and anti-inflammatory effects than equivalent amounts of UDCA. We anticipate that PUDCA NPs have tremendous translational potential as bone regenerative agents.

Synthesis of Nanoscale Liposomes via Low-Cost Microfluidic Systems

We describe the manufacture of low-cost microfluidic systems to produce nanoscale liposomes with highly uniform size distributions (i.e., low polydispersity indexes (PDI)) and acceptable colloidal stability. This was achieved by exploiting a Y-junction device followed by a serpentine micromixer geometry to facilitate the diffusion between the mixing phases (i.e., continuous and dispersed) via advective processes. Two different geometries were studied. In the first one, the microchannels were engraved with a laser cutting machine on a polymethyl methacrylate (PMMA) sheet and covered with another PMMA sheet to form a two-layer device. In the second one, microchannels were not engraved but through-hole cut on a PMMA sheet and encased by a top and a bottom PMMA sheet to form a three-layer device. The devices were tested out by putting in contact lipids dissolved in alcohol as the dispersed phase and water as the continuous phase to self-assemble the liposomes. By fixing the total flow rate (TFR) and varying the flow rate ratio (FRR), we obtained most liposomes with average hydrodynamic diameters ranging from 188 ± 61 to 1312 ± 373 nm and 0.30 ± 0.09 PDI values. Such liposomes were obtained by changing the FRR from 5:1 to 2:1. Our results approached those obtained by conventional bulk synthesis methods such as a thin hydration bilayer and freeze-thaw, which produced liposomes with diameters ranging from 200 ± 38 to 250 ± 38 nm and 0.30 ± 0.05 PDI values. The produced liposomes might find several potential applications in the biomedical field, particularly in encapsulation and drug delivery.

Microfluidic Manufacturing of Multitargeted PLGA/PEG Nanoparticles for Delivery of Taxane Chemotherapeutics

Taxane chemotherapeutics have played a key role in the treatment of various types of cancer throughout the past years. However, the drawbacks inherent to the pharmaceutical formulation of taxanes are still a reality and mainly due to the low aqueous solubility of these medicines, as well as to the nontargeted therapy and consequent side effects. Nanoparticles (NPs) of poly(lactic-co-glycolic acid) (PLGA) and polyethylene glycol (PEG) have sparked broad interest in this field and demonstrated capacity of improving taxanes' formulation. If, in one hand, the PLGA core of these NPs is able to solubilize drugs, on the other hand, the PEG shell promotes immune escape and presents chemical end groups for the attachment of targeting ligands. Advances in the design of these nanosystems resulted in the development of multitargeted PLGA/PEG NPs achieved by dual-ligand functionalization. The multitargeting offers a promising alternative to the delivery of taxanes across successive cell types or compartments and to the synergetic exploitation of more than one transporter on the cell surface. Besides the upgrade in the design of multitargeted PLGA/PEG NPs, their manufacturing has also evolved from bulk assembly to continuous-flow, high-throughput technologies such as microfluidics. This technology relies on microchannel platforms described to enable the production of large-scale batches of NPs in a better time-saving manner, with higher drug loading, reproducibility, and lower polydispersity. Herein, a detailed microfluidic method for the preparation of multitargeted, taxane-loaded PLGA/PEG NPs is described. Focus is given to the setting up of the microfluidic system and conditions required to manufacture these NPs by using polymers of PLGA and PEG previously elsewhere functionalized with two generic targeting ligands.

Czaplewska J, Hoeppener S, Werz O, S. Schubert U. Optimized Encapsulation of the FLAP/PGES-1 Inhibitor BRP-187 in PVA-Stabilized PLGA Nanoparticles Using Microfluidics

The dual inhibitor of the 5-lipoxygenase-activating protein (FLAP) and the microsomal prostaglandin E2 synthase-1 (mPGES-1), named BRP-187, represents a promising drug candidate due to its improved anti-inflammatory efficacy along with potentially reduced side effects in comparison to non-steroidal anti-inflammatory drugs (NSAIDs). However, BRP-187 is an acidic lipophilic drug and reveals only poor water solubility along with a strong tendency for plasma protein binding. Therefore, encapsulation in polymeric nanoparticles is a promising approach to enable its therapeutic use. With the aim to optimize the encapsulation of BRP-187 into poly(lactic-co-glycolic acid) (PLGA) nanoparticles, a single-phase herringbone microfluidic mixer was used for the particle preparation. Various formulation parameters, such as total flow rates, flow rate ratio, the concentration of the poly(vinyl alcohol) (PVA) as a surfactant, initial polymer concentration, as well as presence of a co-solvent on the final particle size distribution and drug loading, were screened for best particle characteristics and highest drug loading capacities. While the size of the particles remained in the targeted region between 121 and 259 nm with low polydispersities (0.05 to 0.2), large differences were found in the BRP-187 loading capacities (LC = 0.5 to 7.29%) and drug crystal formation during the various formulations.

Addressing the challenges to increase the efficiency of translating nanomedicine formulations to patients

INTRODUCTION

Nanotechnology is in a growth phase for drug delivery and medical imaging. Nanomaterials with unique properties present opportunities for encapsulation of therapeutics and imaging agents, along with conjugation to ligands for targeting. Favorable chemistry of nanomaterials can create formulations that address critical challenges for therapeutics, such as insolubility and a low capacity to cross the blood-brain-barrier (BBB) and intestinal wall.

AREAS COVERED

The authors investigate challenges faced during translation of nanomedicines while suggesting reasons as to why some nanoformulations have under-performed in clinical trials. They assess physiological barriers such as the BBB and gut mucus that nanomedicines must overcome to deliver cargos. They also provide an overview with examples of how nanomedicines can be designed to improve localization and site-specific delivery (e.g., encapsulation, bioconjugation, and triggered-release).

EXPERT OPINION

There are examples where nanomedicines have demonstrated improved efficacy of payload in humans; however, most of the advantages conferred were in improved pharmacokinetics and reduced toxicity. Problematic data show susceptibility of nanoformulations against natural protective mechanisms present in the body, including distribution impediment by physiological barriers and activation of the reticuloendothelial system. Further initiatives should address current challenges while expanding the scope of nanomedicine into advanced biomedical imaging and antibiotic delivery.

Comparative Nanofabrication of PLGA-Chitosan-PEG Systems Employing Microfluidics and Emulsification Solvent Evaporation Techniques

Poor circulation stability and inadequate cell membrane penetration are significant impediments in the implementation of nanocarriers as delivery systems for therapeutic agents with low bioavailability. This research discusses the fabrication of a biocompatible poly(lactide-co-glycolide) (PLGA) based nanocarrier with cationic and hydrophilic surface properties provided by natural polymer chitosan and coating polymer polyethylene glycol (PEG) for the entrapment of the hydrophobic drug disulfiram. The traditional emulsification solvent evaporation method was compared to a microfluidics-based method of fabrication, with the optimisation of the parameters for each method, and the PEGylation densities on the experimental nanoparticle formulations were varied. The size and surface properties of the intermediates and products were characterised and compared by dynamic light scattering, scanning electron microscopy and X-ray diffraction, while the thermal properties were investigated using thermogravimetric analysis and differential scanning calorimetry. Results showed optimal particle properties with an intermediate PEG density and a positive surface charge for greater biocompatibility, with nanoparticle surface characteristics shielding physical interaction of the entrapped drug with the exterior. The formulations prepared using the microfluidic method displayed superior surface charge, entrapment and drug release properties. The final system shows potential as a component of a biocompatible nanocarrier for poorly soluble drugs.

Liposomes: Advancements and innovation in the manufacturing process

Liposomes are well recognised as effective drug delivery systems, with a range of products approved, including follow on generic products. Current manufacturing processes used to produce liposomes are generally complex multi-batch processes. Furthermore, liposome preparation processes adopted in the laboratory setting do not offer easy translation to large scale production, which may delay the development and adoption of new liposomal systems. To promote advancement and innovation in liposome manufacturing processes, this review considers the range of manufacturing processes available for liposomes, from laboratory scale and scale up, through to large-scale manufacture and evaluates their advantages and limitations. The regulatory considerations associated with the manufacture of liposomes is also discussed. New innovations that support leaner scalable technologies for liposome fabrication are outlined including self-assembling liposome systems and microfluidic production. The critical process attributes that impact on the liposome product attributes are outlined to support potential wider adoption of these innovations.

Recent advancements in liposome technology

The liposomes have continued to be well-recognized as an important nano-sized drug delivery system with attractive properties, such a characteristic bilayer structure assembling the cellular membrane, easy-to-prepare and high bio-compatibility. Extensive effort has been devoted to the development of liposome-based drug delivery systems during the past few decades. Many drug candidates have been encapsulated in liposomes and investigated for reduced toxicity and extended duration of therapeutic effect. The liposomal encapsulation of hydrophilic and hydrophobic small molecule therapeutics as well as other large molecule biologics have been established among different academic and industrial research groups. To date, there has been an increasing number of FDA-approved liposomal-based therapeutics together with more and more undergoing clinical trials, which involve a wide range of applications in anticancer, antibacterial, and antiviral therapies. In order to meet the continuing demand for new drugs in clinics, more recent advancements have been investigated for optimizing liposomal-based drug delivery system with more reproducible preparation technique and a broadened application to novel modalities, including nucleic acid therapies, CRISPR/Cas9 therapies and immunotherapies. This review focuses on the recent liposome' preparation techniques, the excipients of liposomal formulations used in various novel studies and the routes of administration used to deliver liposomes to targeted areas of disease. It aims to update the research in liposomal delivery and highlights future nanotechnological approaches.

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.

Nanostructured Lipid Carriers for Delivery of Chemotherapeutics: A Review

The efficacy of current standard chemotherapy is suboptimal due to the poor solubility and short half-lives of chemotherapeutic agents, as well as their high toxicity and lack of specificity which may result in severe side effects, noncompliance and patient inconvenience. The application of nanotechnology has revolutionized the pharmaceutical industry and attracted increasing attention as a significant means for optimizing the delivery of chemotherapeutic agents and enhancing their efficiency and safety profiles. Nanostructured lipid carriers (NLCs) are lipid-based formulations that have been broadly studied as drug delivery systems. They have a solid matrix at room temperature and are considered superior to many other traditional lipid-based nanocarriers such as nanoemulsions, liposomes and solid lipid nanoparticles (SLNs) due to their enhanced physical stability, improved drug loading capacity, and biocompatibility. This review focuses on the latest advances in the use of NLCs as drug delivery systems and their preparation and characterization techniques with special emphasis on their applications as delivery systems for chemotherapeutic agents and different strategies for their use in tumor targeting.

High Frequency Sonoprocessing: A New Field of Cavitation-Free Acoustic Materials Synthesis, Processing, and Manipulation

Ultrasound constitutes a powerful means for materials processing. Similarly, a new field has emerged demonstrating the possibility for harnessing sound energy sources at considerably higher frequencies (10 MHz to 1 GHz) compared to conventional ultrasound (⩽3 MHz) for synthesizing and manipulating a variety of bulk, nanoscale, and biological materials. At these frequencies and the typical acoustic intensities employed, cavitation-which underpins most sonochemical or, more broadly, ultrasound-mediated processes-is largely absent, suggesting that altogether fundamentally different mechanisms are at play. Examples include the crystallization of novel morphologies or highly oriented structures; exfoliation of 2D quantum dots and nanosheets; polymer nanoparticle synthesis and encapsulation; and the possibility for manipulating the bandgap of 2D semiconducting materials or the lipid structure that makes up the cell membrane, the latter resulting in the ability to enhance intracellular molecular uptake. These fascinating examples reveal how the highly nonlinear electromechanical coupling associated with such high-frequency surface vibration gives rise to a variety of static and dynamic charge generation and transfer effects, in addition to molecular ordering, polarization, and assembly-remarkably, given the vast dimensional separation between the acoustic wavelength and characteristic molecular length scales, or between the MHz-order excitation frequencies and typical THz-order molecular vibration frequencies.

Nose-to-brain delivery of enveloped RNA - cell permeating peptide nanocomplexes for the treatment of neurodegenerative diseases

Direct nose-to-brain (N-to-B) delivery enables the rapid transport of drugs to the brain, while minimizing systemic exposure. The objective of this work was to engineer a nanocarrier intended to enhance N-to-B delivery of RNA and to explore its potential utility for the treatment of neurological disorders. Our approach involved the formation of electrostatically driven nanocomplexes between a hydrophobic derivative of octaarginine (r8), chemically conjugated with lauric acid (C12), and the RNA of interest. Subsequently, these cationic nanocomplexes were enveloped (enveloped nanocomplexes, ENCPs) with different protective polymers, i.e. polyethyleneglycol - polyglutamic acid (PEG-PGA) or hyaluronic acid (HA), intended to enhance their stability and mucodiffusion across the olfactory nasal mucosa. These rationally designed ENCPs were produced in bulk format and also using a microfluidics-based technique. This technique enabled the production of a scalable nanoformulation, exhibiting; (i) a unimodal size distribution with a tunable mean size, (ii) the capacity to highly associate (100%) and protect RNA from degradation, (iii) the ability to preserve its physicochemical properties in biorelevant media and prevent the premature RNA release. Moreover, in vitro cell culture studies showed the capacity of ENCPs to interact and be efficiently taken-up by CHO cells. Finally, in vivo experiments in a mouse model of Alzheimer's disease provided evidence of a statistically significant increase of a potentially therapeutic miRNA mimic in the hippocampus area and its further effect on two mRNA targets, following its intranasal administration. Overall, these findings stress the value of the rational design of nanocarriers towards overcoming the biological barriers associated to N-to-B RNA delivery and reveal their potential value as therapeutic strategies in Alzheimer's disease.

Comparison of bulk and microfluidics methods for the formulation of poly-lactic-co-glycolic acid (PLGA) nanoparticles modified with cell-penetrating peptides of different architectures

The efficient and reproducible production of nanoparticles using bulk nanoprecipitation methods is still challenging because of low batch to batch reproducibility. Here, we optimize a bulk nanoprecipitation method using design of experiments and translate to a microfluidic device to formulate surface-modified poly-lactic-co-glycolic (PLGA) nanoparticles. Cell-penetrating peptides (CPPs) with a short, long linear or branched architecture were used for the surface modification of PLGA nanoparticles. The microfluidics method was more time efficient than the bulk nanoprecipitation method and allowed the formulation of uniform PLGA nanoparticles with a size of 150 nm, a polydispersity index below 0.150 and with better reproducibility in comparison to the bulk nanoprecipitation method. After surface modification the size of CPP-tagged PLGA nanoparticles increased to 160–180 nm and the surface charge of the CPP-tagged PLGA nanoparticles varied between −24 mV and +3 mV, depending on the architecture and concentration of the conjugated CPP. Covalent attachment of CPPs to the PLGA polymer was confirmed with FTIR by identifying the formation of an amide bond. The conjugation efficiency of CPPs to the polymeric PLGA nanoparticles was between 32 and 80%. The development and design of reproducible nanoformulations with tuneable surface properties is crucial to understand interactions at the nano-bio interface.

Successful oral delivery of poorly water-soluble drugs both depends on the intraluminal behavior of drugs and of appropriate advanced drug delivery systems

Poorly water-soluble drugs continue to be a problematic, yet important class of pharmaceutical compounds for treatment of a wide range of diseases. Their prevalence in discovery is still high, and their development is usually limited by our lack of a complete understanding of how the complex chemical, physiological and biochemical processes that occur between administration and absorption individually and together impact on bioavailability. This review defines the challenge presented by these drugs, outlines contemporary strategies to solve this challenge, and consequent in silico and in vitro evaluation of the delivery technologies for poorly water-soluble drugs. The next steps and unmet needs are proposed to present a roadmap for future studies for the field to consider enabling progress in delivery of poorly water-soluble compounds.

Lipid Nanoparticles for Delivery of Therapeutic RNA Oligonucleotides

Gene therapy is an exciting field that has the potential to address emerging scientific and therapeutic tasks. RNA-based gene therapy has made remarkable progress in recent decades. Nevertheless, efficient targeted delivery of RNA therapeutics is still a prerequisite for entering the clinics. In this review, we introduce current delivery methods for RNA gene therapeutics based on lipid nanoparticles (LNPs). We focus on the clinical appeal of recent RNA NPs and discuss existing challenges of fabrication and screening LNP candidates for effective translation into drugs of human metabolic diseases and cancer.

Microfluidic manufacturing of surface-functionalized graphene oxide nanoflakes for gene delivery

Graphene oxide (GO) is a single-atomic-layered material made of a sheet of oxidized carbon atoms arranged in a honeycomb structure. Thanks to the notable physical and chemical properties of GO, GO-based nanomaterials have applications in many fields of research, including gene delivery. It has been reported that pristine GO can absorb single-stranded DNA and RNA through π-π stacking, which cannot be used as a gene carrier because it is hard to load double-stranded DNA (dsDNA). To tackle this issue, this work was aimed at developing a hybrid nanoparticle (NP) system made of GO coated with cationic lipids (hereafter referred to as GOCL) with suitable physical-chemical properties for gene delivery applications. To this end, nanosized GO flakes (nGO) were coated with the cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) by microfluidic mixing. Comprehensive characterization of GOCL NPs was performed by a combination of dynamic light scattering (DLS), micro-electrophoresis and atom force microscopy (AFM). Our results show that GOCL NPs exhibit adequate size (<150 nm) and surface charge (ξ = +15 mV) for gene delivery purposes. Complexes made of GOCL NPs and plasmid DNA (pDNA) were used to transfect human cervical cancer cells (HeLa) and human embryonic kidney (HEK-293) cells. Pristine nGO and DOTAP cationic liposomes were used as a reference. GOCL NPs exhibited a similar TE but a much higher cell viability compared with DOTAP cationic liposomes. Confocal fluorescence microscopy provided a reasonable explanation for the superior performance of GOCL/DNA complexes showing that they are much more numerous, regular in size and homogeneously distributed than DOTAP/DNA complexes, thus splitting their gene payload over the entire cell population. Because of the imperative demand for efficient and safe nanocarriers, this study will contribute to the development of novel surface-functionalized GO-based hybrid gene vectors.

Evaluating nanomedicine with microfluidics

Nanomedicines are engineered nanoscale structures that have an extensive range of application in the diagnosis and therapy of many diseases. Despite the rapid progress in and tremendous potential of nanomedicines, their clinical translational process is still slow, owing to the difficulty in understanding, evaluating, and predicting their behavior in complex living organisms. Microfluidic techniques offer a promising way to resolve these challenges. Carefully designed microfluidic chips enable in vivo microenvironment simulation and high-throughput analysis, thus providing robust platforms for nanomedicine evaluation. Here, we summarize the recent developments and achievements in microfluidic methods for nanomedicine evaluation, categorized into four sections based on their target systems: single cell, multicellular system, organ, and organism levels. Finally, we provide our perspectives on the challenges and future directions of microfluidics-based nanomedicine evaluation.

A novel microfluidic liposomal formulation for the delivery of the SN-38 camptothecin: characterization and in vitro assessment of its cytotoxic effect on two tumor cell lines

PURPOSE

Irinotecan (CPT-11) and SN-38 - its active metabolite - are alkaloid-derived topoisomerase I interactive compounds widely used in various cancer therapy protocols. To solve the problems associated with the instability of their lactone ring at physiological pH and with the extreme insolubility of SN-38, the development of delivery carriers (eg, liposomes) has been considered a subject of unquestionable medical interest. This article focuses on the development of an alternative protocol to the classical lipid-film hydration procedures to obtain a pharmaceutical formulation for SN-38.

METHODS

SN-38-loaded liposomes (SN-38lip) were produced by microemulsification, without a prior lipid-film preparation step, and characterized by different methods. Formulation parameters were determined by photon correlation spectroscopy, and the SN-38 entrapment efficiency was evaluated by absorbance spectroscopy. SN-38lip was obtained as a dry, white powder by lyophilization. MTT and LDH assays were conducted to assess the cytotoxic effect of SN-38, both in liposomal (SN-38lip) and solubilized form (SN-38sol); flow cytometry was used to quantify SN-38 uptake and to analyze cell-cycle phase distribution after drug exposure.

RESULTS

Microfluidic, stable, and controlled sized, negatively charged liposomes, with high SN-38 incorporation efficiency into egg yolk phosphatidylcholine (EPC)/L-α-dioleoyl-phospathidylserine (DOPS) (9:1) vesicles (SN-38lip), were prepared. A lyophilized powder of SN-38lip, easily reconstitutable while retaining physicochemical parameters, was finally obtained. The efficacy of SN-38lip was assessed by in vitro studies with two tumor cell lines (HeLa and Caco-2) and compared with that of SN-38sol. It demonstrated the highest uptake of SN-38lip, in accordance with its highest cytotoxicity effect, in comparison with that of SN-38sol. In addition, different cell-cycle alterations were induced in both cell lines by the liposomal formulation.

CONCLUSION

The results highlight the potential usefulness of the procured SN-38 liposomal formulation and provide the basis for conducting in vivo studies that allow the development of alternative strategies for colorectal cancer treatment.

Cationic lipid/DNA complexes manufactured by microfluidics and bulk self-assembly exhibit different transfection behavior

Recent advances in biochemical and biophysical research have been achieved through the employment of microfluidic devices. Microfluidic mixing of therapeutic agents with biomaterials yields systems with finely tuned physical-chemical properties for applications in drug and gene delivery. Here, we investigate the role of preparation technology (microfluidic mixing vs. bulk self-assembly) on the transfection efficiency (TE) and cytotoxicity of multicomponent cationic liposome/DNA complexes (lipoplexes) in live Chinese hamster ovarian (CHO) cells. Decoupling TE and cytotoxicity allowed us to combine them in a unique coherent vision. While bulk self-assembly produces highly efficient and highly toxic MC lipoplexes, microfluidics manufacture leads to less efficient, but less cytotoxic complexes. This discrepancy is ascribed to two main factors controlling lipid-mediated cell transfection, i.e. the lipoplex concentration at the cell surface and the lipoplex arrangement at the nanoscale. Further research is required to optimize microfluidic manufacturing of lipoplexes to obtain highly efficient and not cytotoxic gene delivery systems.

Translation of combination nanodrugs into nanomedicines: lessons learned and future outlook

The concept of nanomedicine is not new. For instance, some nanocrystals and colloidal drug molecules are marketed that improve pharmacokinetic characteristics of single-agent therapeutics. For the past two decades, the number of research publications on single-agent nanoformulations has grown exponentially. However, formulations advancing to pre-clinical and clinical evaluations that lead to therapeutic products has been limited. Chronic diseases such as cancer and HIV/AIDS require drug combinations, not single agents, for durable therapeutic responses. Therefore, development and clinical translation of drug combination nanoformulations could play a significant role in improving human health. Successful translation of promising concepts into pre-clinical and clinical studies requires early considerations of the physical compatibility, pharmacological synergy, as well as pharmaceutical characteristics (e.g. stability, scalability and pharmacokinetics). With this approach and robust manufacturing processes in place, some drug-combination nanoparticles have progressed to non-human primate and human studies. In this article, we discuss the rationale and role of drug-combination nanoparticles, the pre-clinical and clinical research progress made to date and the key challenges for successful clinical translation. Finally, we offer insight to accelerate clinical translation through leveraging robust nanoplatform technologies to enable implementation of personalised and precision medicine.

Lipofection of plasmid DNA into human mast cell lines using lipid nanoparticles generated by microfluidic mixing

Mast cells are important immune cells that have significant roles in mediating allergy and asthma. Therefore, studying the molecular mechanisms regulating these and other processes in mast cells is important to elucidate. Methods such as lipofection, transduction, and electroporation are often employed to dissect these mechanisms by disrupting gene expression in mast cell lines. However, as with other leukocytes, human mast cells (HMCs) are often refractory to the delivery of plasmids by lipofection. In this study, we investigated the utility of lipid nanoparticles (LNPs) containing the ionizable cationic lipids 1,2-dioleoyloxy-3-dimethylaminopropane, 1,2-dioleyloxy-3-dimethylaminopropane, or 2,2-dilinoleyl-4-(2-dimethylaminoethyl)-[1,3]-dioxolane for the delivery of plasmid DNA into HMC lines. Herein, we demonstrate for the first time the use of LNPs to achieve significant and reproducible levels of plasmid DNA transfection in HMC-1.2 and laboratory of allergic diseases 2 (LAD2) cells. These levels reached 53.2% and 16.0% in HMC-1.2 and LAD2 cells, respectively; and outperformed Lipofectamine 3000 in both cases. Moreover, cell viability in the transfected cells remained above 65% for all LNP conditions tested. Together, these observations illustrate the efficacy of this technique for mast cell researchers and further support the use of LNPs for nucleic acid delivery into leukocytes.

Design and Development of Biomimetic Nanovesicles Using a Microfluidic Approach

The advancement of nanotechnology toward more sophisticated bioinspired approaches has highlighted the gap between the advantages of biomimetic and biohybrid platforms and the availability of manufacturing processes to scale up their production. Though the advantages of transferring biological features from cells to synthetic nanoparticles for drug delivery purposes have recently been reported, a standardizable, batch-to-batch consistent, scalable, and high-throughput assembly method is required to further develop these platforms. Microfluidics has offered a robust tool for the controlled synthesis of nanoparticles in a versatile and reproducible approach. In this study, the incorporation of membrane proteins within the bilayer of biomimetic nanovesicles (leukosomes) using a microfluidic-based platform is demonstrated. The physical, pharmaceutical, and biological properties of microfluidic-formulated leukosomes (called NA-Leuko) are characterized. NA-Leuko show extended shelf life and retention of the biological functions of donor cells (i.e., macrophage avoidance and targeting of inflamed vasculature). The NA approach represents a universal, versatile, robust, and scalable tool, which is extensively used for the assembly of lipid nanoparticles and adapted here for the manufacturing of biomimetic nanovesicles.

Optimization and scale up of microfluidic nanolipomer production method for preclinical and potential clinical trials

Background

The process of optimization and fabrication of nanoparticle synthesis for preclinical studies can be challenging and time consuming. Traditional small scale laboratory synthesis techniques suffer from batch to batch variability. Additionally, the parameters used in the original formulation must be re-optimized due to differences in fabrication techniques for clinical production. Several low flow microfluidic synthesis processes have been reported in recent years for developing nanoparticles that are a hybrid between polymeric nanoparticles and liposomes. However, use of high flow microfluidic synthetic techniques has not been described for this type of nanoparticle system, which we will term as nanolipomer. In this manuscript, we describe the successful optimization and functional assessment of nanolipomers fabricated using a microfluidic synthesis method under high flow parameters.

Results

The optimal total flow rate for synthesis of these nanolipomers was found to be 12 ml/min and flow rate ratio 1:1 (organic phase: aqueous phase). The PLGA polymer concentration of 10 mg/ml and a DSPE-PEG lipid concentration of 10% w/v provided optimal size, PDI and stability. Drug loading and encapsulation of a representative hydrophobic small molecule drug, curcumin, was optimized and found that high encapsulation efficiency of 58.8% and drug loading of 4.4% was achieved at 7.5% w/w initial concentration of curcumin/PLGA polymer. The final size and polydispersity index of the optimized nanolipomer was 102.11 nm and 0.126, respectively. Functional assessment of uptake of the nanolipomers in C4-2B prostate cancer cells showed uptake at 1 h and increased uptake at 24 h. The nanolipomer was more effective in the cell viability assay compared to free drug. Finally, assessment of in vivo retention in mice of these nanolipomers revealed retention for up to 2 h and were completely cleared at 24 h.

Conclusions

In this study, we have demonstrated that a nanolipomer formulation can be successfully synthesized and easily scaled up through a high flow microfluidic system with optimal characteristics. The process of developing nanolipomers using this methodology is significant as the same optimized parameters used for small batches could be translated into manufacturing large scale batches for clinical trials through parallel flow systems.

Using microfluidic platforms to develop CNS-targeted polymeric nanoparticles for HIV therapy

The human immunodeficiency virus (HIV) uses the brain as reservoir, which turns it as a promising target to fight this pathology. Nanoparticles (NPs) of poly(lactic-co-glycolic) acid (PLGA) are potential carriers of anti-HIV drugs to the brain, since most of these antiretrovirals, as efavirenz (EFV), cannot surpass the blood-brain barrier (BBB). Forasmuch as the conventional production methods lack precise control over the final properties of particles, microfluidics emerged as a prospective alternative. This study aimed at developing EFV-loaded PLGA NPs through a conventional and microfluidic method, targeted to the BBB, in order to treat HIV neuropathology. Compared to the conventional method, NPs produced through microfluidics presented reduced size (73 nm versus 133 nm), comparable polydispersity (around 0.090), less negative zeta-potential (-14.1 mV versus -28.0 mV), higher EFV association efficiency (80.7% versus 32.7%) and higher drug loading (10.8% versus 3.2%). The microfluidics-produced NPs also demonstrated a sustained in vitro EFV release (50% released within the first 24 h). NPs functionalization with a transferrin receptor-binding peptide, envisaging BBB targeting, proved to be effective concerning nuclear magnetic resonance analysis (δ = -0.008 ppm; δ = -0.017 ppm). NPs demonstrated to be safe to BBB endothelial and neuron cells (metabolic activity above 70%), as well as non-hemolytic (1-2% of hemolysis, no morphological alterations on erythrocytes). Finally, functionalized nanosystems were able to interact more efficiently with BBB cells, and permeability of EFV associated with NPs through a BBB in vitro model was around 1.3-fold higher than the free drug.