Microfluidics for nano-drug delivery systems: From fundamentals to industrialization

New avenues for cancer immunotherapy: Cell-mediated drug delivery systems

Cancer research has become increasingly complex over the past few decades as knowledge of the heterogeneity of cancer cells, their proliferative ability, and their tumor microenvironments has become available. Although conventional therapies remain the most compelling option for cancer treatment to date, immunotherapy is a promising way to harness natural immune defenses to target and kill cancer cells. Cell-mediated drug delivery systems (CDDSs) have been an active line of research for enhancing the therapeutic efficacy and specificity of cancer immunotherapy. These systems can be tailored to different types of immune cells, allowing immune evasion and accumulation in the tumor microenvironment. By enabling the targeted delivery of therapeutic agents such as immune stimulants, cytokines, antibodies, and antigens, CDDSs have improved the survival of some patients with cancer. This review summarizes the research status of CDDSs, with a focus on their underlying mechanisms of action, biology, and clinical applications. We also discuss opportunities and challenges for implementation of CDDSs into mainstream cancer immunotherapy.

Controlled preparation of curcumin nanocrystals by detachable stainless steel microfluidic chip

Microfluidic technology has not been extensively utilized in nanocrystals manufacture, although it has been used in the production of liposomes and LNPs. This is mainly due to concerns including blockage of narrow pipes and corrosion of organic solvents on chips. In this study, a detachable stainless steel microfluidic chip with split-and-recombine (SAR) structure was engraved and used to prepare curcumin nanocrystal suspensions by a microfluidic-antisolvent precipitation method. A simulation study of the mixing activities of three chip structures was conducted by COMSOL Multiphysics software. Then the curcumin nanocrystals preparation was optimized by Box-Behnken design to screen different stabilizers and solvents. Two curcumin nanocrystals formulations with an average particle size of 59.29 nm and 168.40 nm were obtained with PDIs of 0.131 and 0.058, respectively. Compared to curcumin powder, the formulation showed an increase in dissolution rate in 0.1 M HCL while pharmacokinetic study indicated that Cmax was increased by 4.47 and 3.14 times and AUC0-∞ were 4.26 and 3.14 times greater. No clogging or deformation of the chip was observed after long usage. The results demonstrate that the stainless steel microfluidic chips with SAR structure have excellent robustness and controllability. It has the potential to be applied in GMP manufacturing of nanocrystals.

Berberine-loaded nanoemulsions as a natural food preservative; the impact of femtosecond laser irradiation on the antibacterial activity

There is a growing concern among food safety regulators, the food industry, and consumers about foodborne illnesses. To improve food safety and increase shelf life, it is necessary to use natural preservatives. Natural antimicrobials are safer than artificial preservatives because they can prevent microbial resistance while also meeting consumers' demands for healthier food. This study used Berberine to enhance the antibacterial activity of Satureja Khuzistanica essential oil nanoemulsions (SKEO NE) against Staphylococcus aureus (S. aureus) bacteria, making them a promising option as preservatives. Response Surface Methodology (RSM) was employed to determine the optimized Berberine loaded SKEO NE (Berberine/SKEO NE), resulting in a mean droplet size of 88.60 nm at 6.91, 3.21, and 0.08% w/w of surfactant, essential oil, and Berberine, respectively. Berberine utilization in SKEO NE has led to an increase in antibacterial activity. The nanoemulsion samples significantly ruptured the S. aureus bacterial cell membrane, rapidly discharging cell contents. The use of a microfluidic system in tandem based on the conventional approach significantly accelerated this process. Enhancing the interaction between nanodroplets and the bacterial membrane can be achieved through the nanoemulsification process of EOs, which involves modifying their surface characteristics. This enhancement is particularly pronounced when employing microfluidic systems due to their substantial contact surface area. We investigated the potential of using femtosecond laser irradiation at a wavelength of 1040 nm to augment the antibacterial action of nanoemulsions. The combined treatment of laser and nanoemulsions significantly increased the antibacterial effect of nanoemulsions by approximately 15% for each bacterium, suggesting the potential utility of this treatment to bolster the antibacterial activity of nanoemulsions. Bacteria were trapped using optical tweezers for up to 20 min, with bacterial destruction observed starting at 3 min and exhaustive destruction evident after 20 min.

Periodic Flows in Microfluidics

Microfluidics, the science and technology of manipulating fluids in microscale channels, offers numerous advantages, such as low energy consumption, compact device size, precise control, fast reaction, and enhanced portability. These benefits have led to applications in biomedical assays, disease diagnostics, drug discovery, neuroscience, and so on. Fluid flow within microfluidic channels is typically in the laminar flow region, which is characterized by low Reynolds numbers but brings the challenge of efficient mixing of fluids. Periodic flows are time-dependent fluid flows, featuring repetitive patterns that can significantly improve fluid mixing and extend the effective length of microchannels for submicron and nanoparticle manipulation. Besides, periodic flow is crucial in organ-on-a-chip (OoC) for accurately modeling physiological processes, advancing disease understanding, drug development, and personalized medicine. Various techniques for generating periodic flows have been reported, including syringe pumps, peristalsis, and actuation based on electric, magnetic, acoustic, mechanical, pneumatic, and fluidic forces, yet comprehensive reviews on this topic remain limited. This paper aims to provide a comprehensive review of periodic flows in microfluidics, from fundamental mechanisms to generation techniques and applications. The challenges and future perspectives are also discussed to exploit the potential of periodic flows in microfluidics.

Production of 5-fluorouracil-loaded PLGA nanoparticles with toroidal microfluidic system and optimization of process variables by design of experiments

In recent decades, microfluidics has presented new opportunities for the production of nanoparticles (NPs). However, to achieve rapid clinical translation, the production of PLGA NPs in a single microfluidic channel for both the pharmaceutical research and industry without the need for scaling is still limited. The aim of this study was to accomplish the production of reproducible and stable 5-FU loaded Poly(lactic-co-glycolic acid) (PLGA) NPs, using an innovative toroidal microfluidic system, for cancer therapy. The toroidal microfluidic system enabled the production of spherical NPs ranging from 100 to 150 nm by adjusting both the TFR within the range of 5-15 mL/min and FRR between 1:3 and 1:7. A systematic assessment of critical process variables (total flow rate; TFR, flow rate ratio; FRR) for the production of PLGA NPs was conducted using Design of Experiment (DoE). The NPs, which exhibit a uniform size distribution, remained stable even after centrifugation and storage for 3 months at 4 °C. The encapsulation efficiency of drug and the concentration of NPs were not affected by changing process parameters. The effective 5-FU encapsulation into NPs resulted in a controlled in vitro drug release. Due to the controlled release profile of the 5-FU loaded PLGA NPs, the formulation was a promising candidate for mitigating the toxic side effects of free 5-FU and improving cancer treatment. In conclusion, toroidal microfluidic system enables high-volume production of stable PLGA NPs, both with and without 5-FU.

Aided Porous Medium Emulsification for Functional Hydrogel Microparticles Synthesis

Despite the substantial advancement in developing various hydrogel microparticle (HMP) synthesis methods, emulsification through porous medium to synthesize functional hybrid protein-polymer HMPs has yet to be addressed. Here, the aided porous medium emulsification for hydrogel microparticle synthesis (APME-HMS) system, an innovative approach drawing inspiration from porous medium emulsification is introduced. This method capitalizes on emulsifying immiscible phases within a 3D porous structure for optimal HMP production. Using the APME-HMS system, synthesized responsive bovine serum albumin (BSA) and polyethylene glycol diacrylate (PEGDA) HMPs of various sizes are successfully synthesized. Preserving protein structural integrity and functionality enable the formation of cytochrome c (cyt c) - PEGDA HMPs for hydrogen peroxide (H2O2) detection at various concentrations. The flexibility of the APME-HMS system is demonstrated by its ability to efficiently synthesize HMPs using low volumes (≈50 µL) and concentrations (100 µm) of proteins within minutes while preserving proteins' structural and functional properties. Additionally, the capability of the APME-HMS method to produce a diverse array of HMP types enriches the palette of HMP fabrication techniques, presenting it as a cost-effective, biocompatible, and scalable alternative for various biomedical applications, such as controlled drug delivery, 3D printing bio-inks, biosensing devices, with potential implications even in culinary applications.

Albumin Nanoparticle-Based Drug Delivery Systems

Nanoparticle-based systems are extensively investigated for drug delivery. Among others, with superior biocompatibility and enhanced targeting capacity, albumin appears to be a promising carrier for drug delivery. Albumin nanoparticles are highly favored in many disease therapies, as they have the proper chemical groups for modification, cell-binding sites for cell adhesion, and affinity to protein drugs for nanocomplex generation. Herein, this review summarizes the recent fabrication techniques, modification strategies, and application of albumin nanoparticles. We first discuss various albumin nanoparticle fabrication methods, from both pros and cons. Then, we provide a comprehensive introduction to the modification section, including organic albumin nanoparticles, metal albumin nanoparticles, inorganic albumin nanoparticles, and albumin nanoparticle-based hybrids. We finally bring further perspectives on albumin nanoparticles used for various critical diseases.

Tailored micromixing in chemically patterned microchannels undergoing electromagnetohydrodynamic flow

The study unveils a simple, non-invasive method to perform micromixing with the help of spatiotemporal variation in the Lorentz force inside a microchannel decorated with chemically heterogeneous walls. Computational fluid dynamics simulations have been utilized to investigate micromixing under the coupled influence of electric and magnetic fields, namely, electromagnetohydrodynamics, to alter the direction of the Lorentz force at the specific locations by creating the reverse flow zones where the pressure gradient, ∇ p = 0 . The study explores the impact of periodicity, distribution, and size of electrodes alongside the magnitude of applied field intensity, the flow rate of the fluid, and the nature of the electric field on the generation of the mixing vortices and their strength inside the microchannels. The results illustrate that the wall heterogeneities can indeed enforce the formation of localized on-demand vortices when the strength of the localized reverse flow overcomes the inertia of the mainstream flow. In such a scenario, while the vortex size and strength are found to increase with the size of the heterogeneous electrodes and field intensities, the number of vortices increases with the number of heterogeneous electrodes decorated on the channel wall. The presence of a non-zero pressure-driven inflow velocity is found to subdue the strength of the vortices to restrict the mixing facilitated by the localized variation of the Lorentz force. Interestingly, the usage of an alternating current (AC) electric field is found to provide an additional non-invasive control on the mixing vortices by enabling periodic changes in their direction of rotation. A case study in this regard discloses the possibility of rapid mixing with the usage of an AC electric field for a pair of miscible fluids inside a microchannel.

Conventional and microfluidic methods: Design and optimization of lipid-polymeric hybrid nanoparticles for gene therapy

Gene therapy holds significant promise as a therapeutic approach for addressing a diverse range of diseases through the suppression of overexpressed proteins and the restoration of impaired cell functions. Developing a nanocarrier that can efficiently load and release genetic material into cells remains a challenge. The primary goal of this study is to develop formulations aimed to enhance the therapeutic potential of GapmeRs through technological approaches. To this end, lipid-polymeric hybrid nanoparticles (LPHNPs) with PLGA, DC-cholesterol, and DOPE-mPEG2000 were produced by conventional single-step nanoprecipitation (SSN) and microfluidic (MF) methods. The optimized nanoparticles by SSN have a size of 149.9 ± 18.07 nm, a polydispersity index (PdI) of 0.23 ± 0.02, and a zeta potential of (ZP) of 29.34 ± 2.44 mV, while by MF the size was 179.8 ± 6.3, a PdI of 0.24 ± 0.01, and a ZP of 32.25 ± 1.36 mV. Furthermore, LPHNPs prepared with GapmeR-protamine by both methods exhibit a high encapsulation efficiency of approximately 90%. The encapsulated GapmeR is completely released in 24 h. The LPHNP suspensions are stable for up to 6 h in 10% FBS at pH 5.4 and 7.4. By contrast, LPHNPs remain stable in suspension in 4.5% albumin at pH 7.4 for 24 h. Additionally, LPHNPs were successfully freeze-dried using trehalose in the range of 2.5-5% as cryoprotectant The LPHNPs produced by MF and SSN increase, 6 and 12 fold respectively, GapmeR cell uptake, and both of them reduce by 60-70% expression of Tob1 in 48 h.Our study demonstrates the efficacy of the developed LPHNPs as carriers for oligonucleotide delivery, offering valuable insights for their scale up production from a conventional bulk methodology to a high-throughput microfluidic technology.

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.

Microfluidics for personalized drug delivery

This review highlights the transformative impact of microfluidic technology on personalized drug delivery. Microfluidics addresses issues in traditional drug synthesis, providing precise control and scalability in nanoparticle fabrication, and microfluidic platforms show high potential for versatility, offering patient-specific dosing and real-time monitoring capabilities, all integrated into wearable technology. Covalent conjugation of antibodies to nanoparticles improves bioactivity, driving innovations in drug targeting. The integration of microfluidics with sensor technologies and artificial intelligence facilitates real-time feedback and autonomous adaptation in drug delivery systems. Key challenges, such as droplet polydispersity and fluidic handling, along with future directions focusing on scalability and reliability, are essential considerations in advancing microfluidics for personalized drug delivery.

Extracellular Vesicles: A New Star for Gene Drug Delivery

Recently, gene therapy has become a subject of considerable research and has been widely evaluated in various disease models. Though it is considered as a stand-alone agent for COVID-19 vaccination, gene therapy is still suffering from the following drawbacks during its translation from the bench to the bedside: the high sensitivity of exogenous nucleic acids to enzymatic degradation; the severe side effects induced either by exogenous nucleic acids or components in the formulation; and the difficulty to cross the barriers before reaching the therapeutic target. Therefore, for the successful application of gene therapy, a safe and reliable transport vector is urgently needed. Extracellular vesicles (EVs) are the ideal candidate for the delivery of gene drugs owing to their low immunogenicity, good biocompatibility and low toxicity. To better understand the properties of EVs and their advantages as gene drug delivery vehicles, this review covers from the origin of EVs to the methods of EVs generation, as well as the common methods of isolation and purification in research, with their pros and cons discussed. Meanwhile, the engineering of EVs for gene drugs is also highlighted. In addition, this paper also presents the progress in the EVs-mediated delivery of microRNAs, small interfering RNAs, messenger RNAs, plasmids, and antisense oligonucleotides. We believe this review will provide a theoretical basis for the development of gene drugs.

Microfluidic Formulation for Biomedical Applications

Microfluidic technology was recognized in the 1980s when the first micropumps and micro-valves were developed to manipulate fluids for biological applications [...].

The Other Side of Plastics: Bioplastic-Based Nanoparticles for Drug Delivery Systems in the Brain

Plastics have changed human lives, finding a broad range of applications from packaging to medical devices. However, plastics can degrade into microscopic forms known as micro- and nanoplastics, which have raised concerns about their accumulation in the environment but mainly about the potential risk to human health. Recently, biodegradable plastic materials have been introduced on the market. These polymers are biodegradable but also bioresorbable and, indeed, are fundamental tools for drug formulations, thanks to their transient ability to pass through biological barriers and concentrate in specific tissues. However, this "other side" of bioplastics raises concerns about their toxic potential, in the form of micro- and nanoparticles, due to easier and faster tissue accumulation, with unknown long-term biological effects. This review aims to provide an update on bioplastic-based particles by analyzing the advantages and drawbacks of their potential use as components of innovative formulations for brain diseases. However, a critical analysis of the literature indicates the need for further studies to assess the safety of bioplastic micro- and nanoparticles despite they appear as promising tools for several nanomedicine applications.

Microfluidic Synthesis of Magnetite Nanoparticles for the Controlled Release of Antibiotics

Magnetite nanoparticles (MNPs) have been intensively studied for biomedical applications, especially as drug delivery systems for the treatment of infections. Additionally, they are characterized by intrinsic antimicrobial properties owing to their capacity to disrupt or penetrate the microbial cell wall and induce cell death. However, the current focus has shifted towards increasing the control of the synthesis reaction to ensure more uniform nanoparticle sizes and shapes. In this context, microfluidics has emerged as a potential candidate method for the controlled synthesis of nanoparticles. Thus, the aim of the present study was to obtain a series of antibiotic-loaded MNPs through a microfluidic device. The structural properties of the nanoparticles were investigated through X-ray diffraction (XRD) and, selected area electron diffraction (SAED), the morphology was evaluated through transmission electron microscopy (TEM) and high-resolution TEM (HR-TEM), the antibiotic loading was assessed through Fourier-transform infrared spectroscopy (FT-IR) and, and thermogravimetry and differential scanning calorimetry (TG-DSC) analyses, and. the release profiles of both antibiotics was determined through UV-Vis spectroscopy. The biocompatibility of the nanoparticles was assessed through the MTT assay on a BJ cell line, while the antimicrobial properties were investigated against the S. aureus, P. aeruginosa, and C. albicans strains. Results proved considerable uniformity of the antibiotic-containing nanoparticles, good biocompatibility, and promising antimicrobial activity. Therefore, this study represents a step forward towards the microfluidic development of highly effective nanostructured systems for antimicrobial therapies.