A review on microfluidic-assisted nanoparticle synthesis, and their applications using multiscale simulation methods

Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) for the delivery of bioactives sourced from plants: part I - composition and production methods

INTRODUCTION

Nanoparticles (NPs) are widely used in the pharmaceutical field to treat various human disorders. Among these, lipid-based NPs (LNPs), including solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), are favored for drug/bioactive delivery due to their high stability, biocompatibility, encapsulation efficiency, and sustained/controlled release. These properties make them particularly suitable as carriers of compounds derived from plant sources.

AREAS COVERED

This study comprehensively explores updated literature knowledge on SLN and NLC, focusing on their composition and production methods for the specific delivery of drug/bioactive compounds derived from plant sources of interest in pharmaceutical and biomedical fields.

EXPERT OPINION

SLN and NLC facilitate the development of more effective natural product-based therapies, aiming to reduce dosage and minimize side effects. These delivery systems align with the consumer demands for safer and more sustainable products, as there are also based on biocompatible and biodegradable raw materials, thereby posing minimal toxicological risks while also meeting regulatory guidelines.

Enhancing siRNA cancer therapy: Multifaceted strategies with lipid and polymer-based carrier systems

Cancers are increasing in prevalence and many challenges remain for their treatment, such as chemoresistance and toxicity. In this context, siRNA-based therapeutics have many potential advantages for cancer therapies as a result of their ability to reduce or prevent expression of specific cancer-related genes. However, the direct delivery of naked siRNA is hindered by issues like enzymatic degradation, insufficient cellular uptake, and poor pharmacokinetics. Hence, the discovery of a safe and efficient delivery vehicle is essential. This review explores various lipid and polymer-based delivery systems for siRNA in cancer treatment. Both polymers and lipids have garnered considerable attention as carriers for siRNA delivery. While all of these systems protect siRNA and enhance transfection efficacy, each exhibits its unique strengths. Lipid-based delivery systems, for instance, demonstrate high entrapment efficacy and utilize cost-effective materials. Conversely, polymeric-based delivery systems offer advantages through chemical modifications. Nonetheless, certain drawbacks still limit their usage. To address these limitations, combining different materials in formulations (lipid, polymer, or targeting agent) could enhance pharmaceutical properties, boost transfection efficacy, and reduce side effects. Furthermore, co-delivery of siRNA with other therapeutic agents presents a promising strategy to overcome cancer resistance. Lipid-based delivery systems have been demonstrated to encapsulate many therapeutic agents and with high efficiency, but most are limited in terms of the functionalities they display. In contrast, polymeric-based delivery systems can be chemically modified by a wide variety of routes to include multiple components, such as release or targeting elements, from the same materials backbone. Accordingly, by incorporating multiple materials such as lipids, polymers, and/or targeting agents in RNA formulations it is possible to improve the pharmaceutical properties and therapeutic efficacy while reducing side effects. This review focuses on strategies to improve siRNA cancer treatments and discusses future prospects in this important field.

Integration of acoustic micromixing with cyclic olefin copolymer microfluidics for enhanced lab-on-a-chip applications in nanoscale liposome synthesis

The integration of acoustic wave micromixing with microfluidic systems holds great potential for applications in biomedicine and lab-on-a-chip technologies. Polymers such as cyclic olefin copolymer (COC) are increasingly utilized in microfluidic applications due to its unique properties, low cost, and versatile fabrication methods, and incorporating them into acoustofluidics significantly expands their potential applications. In this work, for the first time, we demonstrated the integration of polymer microfluidics with acoustic micromixing utilizing oscillating sharp edge structures to homogenize flowing fluids. The sharp edge mixing platform was entirely composed of COC fabricated in a COC-hydrocarbon solvent swelling based microfabrication process. As an electrical signal is applied to a piezoelectric transducer bonded to the micromixer, the sharp edges start to oscillate generating vortices at its tip, mixing the fluids. A 2D numerical model was implemented to determine the optimum microchannel dimensions for experimental mixing assessment. The system was shown to successfully mix fluids at flow rates up to 150µl h-1and has a modest effect even at the highest tested flow rate of 600µl h-1. The utility of the fabricated sharp edge micromixer was demonstrated by the synthesis of nanoscale liposomes.

Crafting Docetaxel-Loaded Albumin Nanoparticles Through a Novel Thermal-Driven Self-Assembly/Microfluidic Combination Technology: Formulation, Process Optimization, Stability, and Bioavailability

Background

The commercial docetaxel (DTX) formulation causes severe side effects due to polysorbate 80 and ethanol. Novel surfactant-free nanoparticle (NP) systems are needed to improve bioavailability and reduce side effects. However, controlling the particle size and stability of NPs and improving the batch-to-batch variation are the major challenges.

Methods

DTX-loaded bovine serum albumin nanoparticles (DTX-BSA-NPs) were prepared by a novel thermal-driven self-assembly/microfluidic technology. Single-factor analysis and orthogonal test were conducted to obtain the optimal formulation of DTX-BSA-NPs in terms of particle size, encapsulation efficiency (EE), and drug loading (DL). The effects of oil/water flow rate and pump pressure on the particle size, EE, and DL were investigated to optimize the preparation process of DTX-BSA-NPs. The drug release, physicochemical properties, stability, and pharmacokinetics of NPs were evaluated.

Results

The optimized DTX-BSA-NPs were uniform, with a particle size of 118.30 nm, EE of 89.04%, and DL of 8.27%. They showed a sustained release of 70% over 96 hours and an increased stability. There were some interactions between the drug and excipients in DTX-BSA-NPs. The half-life, mean residence time, and area under the curve (AUC) of DTX-BSA-NPs increased, but plasma clearance decreased when compared with DTX.

Conclusion

The thermal-driven self-assembly/microfluidic combination method effectively produces BSA-based NPs that improve the bioavailability and stability of DTX, offering a promising alternative to traditional formulations.

Versatile hybrid technique for passive straight micromixer manufacturing by combining pulsed laser ablation, stereolithographic 3D printing and computational fluid dynamics

There is a need to develop new and versatile fabrication methods to achieve efficient mixing of fluids in microfluidic channels using microstructures. This work presents a new technique that combines stereolithography (SLA) and pulsed laser ablation (PLA) to manufacture a straight micromixer for uniform mixing of two samples. Computational fluid dynamics (CFD) simulation is performed to deeply understand the physical mechanisms of the process. The results suggest that this new optical technique holds the potential to become a versatile hybrid technique for manufacturing remarkable mixing microfluidic devices.

Cavity-agnostic acoustofluidic manipulations enabled by guided flexural waves on a membrane acoustic waveguide actuator

This article presents an in-depth exploration of the acoustofluidic capabilities of guided flexural waves (GFWs) generated by a membrane acoustic waveguide actuator (MAWA). By harnessing the potential of GFWs, cavity-agnostic advanced particle manipulation functions are achieved, unlocking new avenues for microfluidic systems and lab-on-a-chip development. The localized acoustofluidic effects of GFWs arising from the evanescent nature of the acoustic fields they induce inside a liquid medium are numerically investigated to highlight their unique and promising characteristics. Unlike traditional acoustofluidic technologies, the GFWs propagating on the MAWA's membrane waveguide allow for cavity-agnostic particle manipulation, irrespective of the resonant properties of the fluidic chamber. Moreover, the acoustofluidic functions enabled by the device depend on the flexural mode populating the active region of the membrane waveguide. Experimental demonstrations using two types of particles include in-sessile-droplet particle transport, mixing, and spatial separation based on particle diameter, along with streaming-induced counter-flow virtual channel generation in microfluidic PDMS channels. These experiments emphasize the versatility and potential applications of the MAWA as a microfluidic platform targeted at lab-on-a-chip development and showcase the MAWA's compatibility with existing microfluidic systems.

Acoustohydrodynamic micromixers: Basic mixing principles, programmable mixing prospectives, and biomedical applications

Acoustohydrodynamic micromixers offer excellent mixing efficiency, cost-effectiveness, and flexible controllability compared with conventional micromixers. There are two mechanisms in acoustic micromixers: indirect influence by induced streamlines, exemplified by sharp-edge micromixers, and direct influence by acoustic waves, represented by surface acoustic wave micromixers. The former utilizes sharp-edge structures, while the latter employs acoustic wave action to affect both the fluid and its particles. However, traditional micromixers with acoustic bubbles achieve significant mixing performance and numerous programmable mixing platforms provide excellent solutions with wide applicability. This review offers a comprehensive overview of various micromixers, elucidates their underlying principles, and explores their biomedical applications. In addition, advanced programmable micromixing with impressive versatility, convenience, and ability of cross-scale operations is introduced in detail. We believe this review will benefit the researchers in the biomedical field to know the micromixers and find a suitable micromixing method for their various applications.

On chip synthesis of a pH sensitive gefitinib anticancer drug nanocarrier based on chitosan/alginate natural polymers

In this research, using a microfluidic chip, a nanocarrier for the anticancer drug gefitinib was synthesized. Chitosan and alginate natural polymers were utilized for the synthesis of the nanocarrier. The synthesis of the nanocarrier comprises the interaction of secondary amine functional groups of gefitinib molecules with carboxylate functional groups of alginate polymer to form the primary nucleus followed by the formation of the nanocarrier through the self-assembly of chitosan and alginate polymers on a fabricated microfluidic chip. The chip was fabricated by laser engraving poly(methyl methacrylate) polymer sheets. The nanocarrier was characterized by FT-IR, DLS, SEM, and TEM techniques. The synthesized nanocarrier had a size distribution of 5.30 ± 2.60 nm and the encapsulation efficiency percent was 68.4% in the optimum conditions. The loading efficiency was calculated as 50.2 mg g-1 of nanocarrier. Drug release studies showed that the nanocarrier is sensitive to pH and releases more gefitinib in acidic environments. Cytotoxicity of the synthesized nanocarrier was studied on the A549 non-small cell lung cancer, and the MTT test showed that the synthesized nanocarrier has a lower IC50 value than the free drug. Also, the cytotoxicity studies showed that the materials used for the synthesis of nanocarrier do not show significant cytotoxicity. Compared to the previously reported method, the developed microfluidic-assisted method showed advantages such as a faster synthesis procedure and comparable encapsulation efficiency and loading capacity.

Microfluidics-mediated Liposomal Nanoparticles for Cancer Therapy: Recent Developments on Advanced Devices and Technologies

Liposomes, spherical particles with phospholipid double layers, have been extensively studied over the years as a means of drug administration. Conventional manufacturing techniques like thin-film hydration and extrusion have limitations in controlling liposome size and distribution. Microfluidics enables superior tuning of parameters during the self-assembly of liposomes, producing uniform populations. This review summarizes microfluidic methods for engineering liposomes, including hydrodynamic flow focusing, jetting, micro mixing, and double emulsions. The precise control over size and lamellarity afforded by microfluidics has advantages for cancer therapy. Liposomes created through microfluidics and designed to encapsulate chemotherapy drugs have exhibited several advantageous properties in cancer treatment. They showcase enhanced permeability and retention effects, allowing them to accumulate specifically in tumor tissues passively. This passive targeting of tumors results in improved drug delivery and efficacy while reducing systemic toxicity. Promising results have been observed in pancreatic, lung, breast, and ovarian cancer models, making them a potential breakthrough in cancer therapy. Surface-modified liposomes, like antibodies or carbohydrates, also achieve active targeting. Overall, microfluidic fabrication improves reproducibility and scalability compared to traditional methods while maintaining drug loading and biological efficacy. Microfluidics-engineered liposomal formulations hold significant potential to overcome challenges in nanomedicine-based cancer treatment.

Template-Free Manufacturing of Defined Structure and Size Polymeric Microparticles

Complex-structured polymeric microparticles hold significant promise as an advance in next-generation medicine mostly due to demand from developing targeted drug delivery. However, the conventional methods for producing these microparticles of defined size, shape, and sophisticated composition often face challenges in scalability, reliance on specialized components such as micro-patterned templates, or limited control over particle size distribution and cargo (functional payload) release kinetics. In this study, we introduce a novel and reliably scalable approach for manufacturing microparticles of defined structures and sizes with variable parameters. The concept behind this method involves the deposition of a specific number of polymer layers on a substrate with low surface energy. Each layer can serve as either the carrier for cargo or a programmable shell-former with predefined permeability. Subsequently, this layered structure is precisely cut into desired-size blanks (particle precursors) using a laser. The manufacturing process is completed by applying heat to the substrate, which results in sealing the edges of the blanks. The combination of the high surface tension of the molten polymer and the low surface energy of the substrate enables the formation of discrete particles, each possessing semi-spherical or other designed geometries determined by their internal composition. Such anisotropic microparticles are envisaged to have versatile applications.

Microfluidic-Assisted Formulation of ε-Polycaprolactone Nanoparticles and Evaluation of Their Properties and In Vitro Cell Uptake

The nanoprecipitation method was used to formulate ε-polycaprolactone (PCL) into fluorescent nanoparticles. Two methods of mixing the phases were evaluated: introducing the organic phase into the aqueous phase dropwise and via a specially designed microfluidic device. As a result of the nanoprecipitation process, fluorescein-loaded nanoparticles (NPs) with a mean diameter of 127 ± 3 nm and polydispersity index (PDI) of 0.180 ± 0.009 were obtained. The profiles of dye release were determined in vitro using dialysis membrane tubing, and the results showed a controlled release of the dye from NPs. In addition, the cytotoxicity of the NPs was assessed using an MTT assay. The PCL NPs were shown to be safe and non-toxic to L929 and MG63 cells. The results of the present study have revealed that PCL NPs represent a promising system for developing new drug delivery systems.

Detection of SARS-CoV-2 Based on Nucleic Acid Amplification Tests (NAATs) and Its Integration into Nanomedicine and Microfluidic Devices as Point-of-Care Testing (POCT)

The coronavirus SARS-CoV-2 has highlighted the criticality of an accurate and rapid diagnosis in order to contain the spread of the virus. Knowledge of the viral structure and its genome is essential for diagnosis development. The virus is still quickly evolving and the global scenario could easily change. Thus, a greater range of diagnostic options is essential to face this threat to public health. In response to the global demand, there has been a rapid advancement in the understanding of current diagnostic methods. In fact, innovative approaches have emerged, leveraging the benefits of nanomedicine and microfluidic technologies. Although this development has been incredibly fast, several key areas require further investigation and optimization, such as sample collection and preparation, assay optimization and sensitivity, cost effectiveness, scalability device miniaturization, and portability and integration with smartphones. Addressing these gaps in the knowledge and these technological challenges will contribute to the development of reliable, sensitive, and user-friendly NAAT-based POCTs for the diagnosis of SARS-CoV-2 and other infectious diseases, facilitating rapid and effective patient management. This review aims to provide an overview of current SARS-CoV-2 detection methods based on nucleic acid detection tests (NAATs). Additionally, it explores promising approaches that combine nanomedicine and microfluidic devices with high sensitivity and relatively fast 'time to answer' for integration into point-of-care testing (POCT).