Fundamental studies on throughput capacities of hydrodynamic flow-focusing microfluidics for producing monodisperse polymer nanoparticles

Navigating the future: Microfluidics charting new routes in drug delivery

Microfluidics has emerged as a transformative force in the field of drug delivery, offering innovative avenues to produce a diverse range of nano drug delivery systems. Thanks to its precise manipulation of small fluid volumes and its exceptional command over the physicochemical characteristics of nanoparticles, this technology is notably able to enhance the pharmacokinetics of drugs. It has initiated a revolutionary phase in the domain of drug delivery, presenting a multitude of compelling advantages when it comes to developing nanocarriers tailored for the delivery of poorly soluble medications. These advantages represent a substantial departure from conventional drug delivery methodologies, marking a paradigm shift in pharmaceutical research and development. Furthermore, microfluidic platformsmay be strategically devised to facilitate targeted drug delivery with the objective of enhancing the localized bioavailability of pharmaceutical substances. In this paper, we have comprehensively investigated a range of significant microfluidic techniques used in the production of nanoscale drug delivery systems. This comprehensive review can serve as a valuable reference and offer insightful guidance for the development and optimization of numerous microfluidics-fabricated nanocarriers.

Targeted delivery and apoptosis induction of CDK-4/6 inhibitor loaded folic acid decorated lipid-polymer hybrid nanoparticles in breast cancer cells

Targeted drug delivery is an advanced approach for active targeting of tumor that can enhance the concentration of the drug at the site of action and reduce the off-target toxicity and non-specific effects of the drug. Folate receptors (FR) are membrane-bound surface proteins, over-expressed in numerous solid tumors, folate and folate conjugates bind to FR with higher affinity. In the present investigation, we fabricated Folic acid (FA) decorated Palbociclib loaded lipid-polymer hybrid nanoparticles (FA-PLPHNPs) using quality by design (QbD) approach and evaluated its anti-cancer activity in folate receptor-positive breast cancer cell lines. 1HNMR, ATR-FTIR spectroscopic techniques confirmed the formation of DSPE-PEG-FA ligand. The optimized FA-PLPHNPs formulation exhibited 143.36 ± 5.24 nm, 0.172 ± 0.004, -16.84 ± 0.27 mV, and 93.12 ± 0.43 % of particle size, PDI, zeta potential and % entrapment efficiency, respectively. The FA-PLPHNPs exhibited an approximately 9, 11-fold reduction in IC50 values than free Palbociclib in MCF-7 and MDA-MB-231 cells at 48 h. The role of FA in targeting breast cancer was studied by means of a receptor-blocking assay, and concluded that FA-PLPHNPs were internalized into MCF-7 and MDA-MB-231 cells by folate receptor-mediated endocytosis. FA-PLPHNPs showed higher anti-cancer efficiency and caused enhanced reactive oxygen species generation, apoptosis (Acridine orange/ ethidium bromide dual staining and Annexin V/PI staining), reduced cell migration, and colony formation. Thus, the fabricated Palbociclib-loaded FA-conjugated lipid polymer hybrid nanoparticles could act as a potential nanocarrier for the treatment of breast cancer.

Design, development, and evaluation of CDK-4/6 inhibitor loaded 4-carboxy phenyl boronic acid conjugated pH-sensitive chitosan lecithin nanoparticles in the management of breast cancer

Our main aim to design and develop a novel 4-carboxy phenyl boronic acid (4-CPBA) conjugated Palbociclib (PALB) loaded pH-sensitive chitosan lipid nanoparticles (PPCL) to enhance the anti-cancer efficacy of the PALB in in-vitro cell line studies by loading into 4-CPBA conjugated chitosan lipid nanoparticles. 4-CPBA was conjugated to chitosan by carbodiimide chemistry and formation of conjugate was confirmed by 1HNMR, ATR-FTIR spectroscopic techniques. Ionic-gelation method was used for the fabrication of PPCL and particles size, PDI, zeta potential were found to be 226.5 ± 4.3 nm, 0.271 ± 0.014 and 5.03 ± 0.42 mV. Presence of pH-sensitive biological macromolecule i.e. chitosan in the carrier system provides pH-sensitivity to PPCL and sustainedly released the drug upto 144 h. The PPCL exhibited approximately 7.2, 6.6, and 5-fold reduction in IC50 values than PALB in MCF-7, MDA-MB-231 and 4T1 cells. Receptor blocking assay concluded that the fabricated nanoparticles were internalized into MCF-7 cells might be through sialic acid-mediated endocytosis. PPCL caused extensive mitochondrial depolarization, enhanced ROS generation, apoptosis (DAPI nuclear staining, acridine orange/ ethidium bromide dual staining), and reduced % cell migration than pure PALB. It was concluded that the hybrid lipid-polymer nanoparticles provides an optimistic approach for the treatment of breast cancer.

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.

Lipid-Based Nanoparticles for Drug/Gene Delivery: An Overview of the Production Techniques and Difficulties Encountered in Their Industrial Development

Over the past decade, the therapeutic potential of nanomaterials as novel drug delivery systems complementing conventional pharmacology has been widely acknowledged. Among these nanomaterials, lipid-based nanoparticles (LNPs) have shown remarkable pharmacological performance and promising therapeutic outcomes, thus gaining substantial interest in preclinical and clinical research. In this review, we introduce the main types of LNPs used in drug formulations such as liposomes, nanoemulsions, solid lipid nanoparticles, nanostructured lipid carriers, and lipid polymer hybrid nanoparticles, focusing on their main physicochemical properties and therapeutic potential. We discuss computational studies and modeling techniques to enhance the understanding of how LNPs interact with therapeutic cargo and to predict the potential effectiveness of such interactions in therapeutic applications. We also analyze the benefits and drawbacks of various LNP production techniques such as nanoprecipitation, emulsification, evaporation, thin film hydration, microfluidic-based methods, and an impingement jet mixer. Additionally, we discuss the major challenges associated with industrial development, including stability and sterilization, storage, regulatory compliance, reproducibility, and quality control. Overcoming these challenges and facilitating regulatory compliance represent the key steps toward LNP's successful commercialization and translation into clinical settings.

Nanohybrids Composed of Tannic Acid Cross-Linked by Metal Ions Obtained by a Microfluidic Technique

Naturally occurring compounds, such as tannic acid (TA), are perfect for constructing nanohybrids (NHs) with metal ions due to their anticarcinogenic, antimicrobial, and antioxidant properties. To date, the batch methods are the ones in which such NHs were constructed; however, those methods possess many drawbacks, such as low reproducibility or size variations. To overcome this limitation, microfluidic preparation is proposed for NHs construction composed of TA and iron (III). The spherical particles with a size between 70 and 150 nm and antimicrobial properties can be easily fabricated in a controlled manner.

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

In recent years, owing to the miniaturization of the fluidic environment, microfluidic technology offers unique opportunities for the implementation of nano drug delivery systems (NDDSs) production processes. Compared with traditional methods, microfluidics improves the controllability and uniformity of NDDSs. The fast mixing and laminar flow properties achieved in the microchannels can tune the physicochemical properties of NDDSs, including particle size, distribution and morphology, resulting in narrow particle size distribution and high drug-loading capacity. The success of lipid nanoparticles encapsulated mRNA vaccines against coronavirus disease 2019 by microfluidics also confirmed its feasibility for scaling up the preparation of NDDSs via parallelization or numbering-up. In this review, we provide a comprehensive summary of microfluidics-based NDDSs, including the fundamentals of microfluidics, microfluidic synthesis of NDDSs, and their industrialization. The challenges of microfluidics-based NDDSs in the current status and the prospects for future development are also discussed. We believe that this review will provide good guidance for microfluidics-based NDDSs.

Generation of Photopolymerized Microparticles Based on PEGDA Hydrogel Using T-Junction Microfluidic Devices: Effect of the Flow Rates

The formation of microparticles (MPs) of biocompatible and biodegradable hydrogels such as polyethylene glycol diacrylate (PEGDA) utilizing microfluidic devices is an attractive option for entrapment and encapsulation of active principles and microorganisms. Our research group has presented in previous studies a formulation to produce these hydrogels with adequate physical and mechanical characteristics for their use in the formation of MPs. In this work, hydrogel MPs are formed based on PEGDA using a microfluidic device with a T-junction design, and the MPs become hydrogel through a system of photopolymerization. The diameters of the MPs are evaluated as a function of the hydrodynamic condition flow rates of the continuous (Qc) and disperse (Qd) phases, measured by optical microscopy, and characterized through scanning electron microscopy. As a result, the following behavior is found: the diameter is inversely proportional to the increase in flow in the continuous phase (Qc), and it has a significant statistical effect that is greater than that in the flow of the disperse phase (Qd). While the diameter of the MPs is proportional to Qd, it does not have a significant statistical effect on the intervals of flow studied. Additionally, the MPs' polydispersity index (PDI) was measured for each experimental hydrodynamic condition, and all values were smaller than 0.05, indicating high homogeneity in the MPs. The microparticles have the potential to entrap pharmaceuticals and microorganisms, with possible pharmacological and bioremediation applications.

A timescale-guided microfluidic synthesis of tannic acid-FeIII network nanocapsules of hydrophobic drugs

Many drugs are poorly water-soluble and suffer from low bioavailability. Metal-phenolic network (MPN), a hydrophilic thin layer such as tannic acid (TA)-FeIII network, has been recently used to encapsulate hydrophobic drugs to improve their bioavailability. However, it remains challenging to synthesize nanocapsules of a wide variety of hydrophobic drugs and to scale up the production in a continuous manner. Here, we present a microfluidic synthesis method to continuously produce TA-FeIII network nanocapsules of hydrophobic drugs. We hypothesize that nanocapsules can continuously be formed only when the microfluidic mixing timescale is shorter than the drug's nucleation timescale. The hypothesis was tested on three hydrophobic drugs - paclitaxel, curcumin, and vitamin D with varying solubility and nucleation timescale. The proposed mechanism was validated by successfully predicting the synthesis outcomes. The microfluidically-synthesized nanocapsules had well-controlled sizes of 100-200 nm, high drug loadings of 40-70%, and a throughput of up to 70 mg hr-1 per channel. The release kinetics, cellular uptake, and cytotoxicity were further evaluated. The effect of coating constituents on nanocapsule properties were characterized. Fe content of nanocapsules was reported. The stability of nanocapsules at different temperatures and pHs were also tested. The results suggest that the present method can provide a quantitative guideline to predictively design a continuous synthesis scheme for hydrophobic drug encapsulation via MPN nanocapsules with scaled-up capability.

Design of functional nanoparticles by microfluidic platforms as advanced drug delivery systems for cancer therapy

Nanoparticle systems are functional carriers that can be used in the cancer therapy field for the delivery of a variety of hydrophobic and/or hydrophilic drugs. Recently, the advent of microfluidic platforms represents an advanced approach to the development of new nanoparticle-based drug delivery systems. Particularly, microfluidics can simplify the design of new nanoparticle-based systems with tunable physicochemical properties such as size, size distribution and morphology, ensuring high batch-to-batch reproducibility and consequently, an enhanced therapeutic effect in vitro and in vivo. In this perspective, we present accurate state-of-the-art microfluidic platforms focusing on the fabrication of polymer-based, lipid-based, lipid/polymer-based, inorganic-based and metal-based nanoparticles for biomedical applications.

Can histamine cause an enhancement of the cellular uptake and cytotoxicity of doxorubicin-loaded polylactide nanoparticles?

Histamine (His) in humans is physiologically involved in neurotransmission and increases vascular permeability during the development of inflammatory response and immunity. It could be used to enhance drug-loaded nanoparticles (NPs) distribution. However, it cannot be freely delivered due to the risk of His-dose-dependent deleterious effects. His can be attached to the polymeric backbone during polymerization to overcome this limitation. In this study, His was used as an initiator of lactide polymerization, and the obtained macromolecules were subsequently used to prepare doxorubicin (DOX)-loaded NPs by nanoprecipitation and microfluidics for examination of anti-cancer properties. Notably, the in vitro activity towards gastric cancer cells (AGS) of the NPs composed of histamine-functionalized polylactides (PLAs) was greatly enhanced compared to control NPs built from hydroxy‑functionalized PLAs. Furthermore, Zonula occludens-1 (ZO-1) tight junction protein production was significantly diminished after treating cells with DOX-loaded NPs assembled with PLAs with histamine residues. These results demonstrate the synergistic effect in cytotoxicity towards gastric cancer cells of DOX and the histamine that are carried by NPs. It is believed that His-DOX NPs strategy may lead to effective, targeted, and low-toxic delivery of drugs into cancer cells.

Intravascular Imaging of Atherosclerosis by Using Engineered Nanoparticles

Atherosclerosis is a leading cause of morbidity and mortality, and high-risk atherosclerotic plaques can result in myocardial infarction, stroke, and/or sudden death. Various imaging and sensing techniques (e.g., ultrasound, optical coherence tomography, fluorescence, photoacoustic) have been developed for scanning inside blood vessels to provide accurate detection of high-risk atherosclerotic plaques. Nanoparticles have been utilized in intravascular imaging to enable targeted detection of high-risk plaques, to enhance image contrast, and in some applications to also provide therapeutic functions of atherosclerosis. In this paper, we review the recent progress on developing nanoparticles for intravascular imaging of atherosclerosis. We discuss the basic nanoparticle design principles, imaging modalities and instrumentations, and common targets for atherosclerosis. The review is concluded and highlighted with discussions on challenges and opportunities for bringing nanoparticles into in vivo (pre)clinical intravascular applications.

Effects of Particle Geometry for PLGA-Based Nanoparticles: Preparation and In Vitro/In Vivo Evaluation

The physicochemical properties (size, shape, zeta potential, porosity, elasticity, etc.) of nanocarriers influence their biological behavior directly, which may result in alterations of the therapeutic outcome. Understanding the effect of shape on the cellular interaction and biodistribution of intravenously injected particles could have fundamental importance for the rational design of drug delivery systems. In the present study, spherical, rod and elliptical disk-shaped PLGA nanoparticles were developed for examining systematically their behavior in vitro and in vivo. An important finding is that the release of the encapsulated human serum albumin (HSA) was significantly higher in spherical particles compared to rod and elliptical disks, indicating that the shape can make a difference. Safety studies showed that the toxicity of PLGA nanoparticles is not shape dependent in the studied concentration range. This study has pioneering findings on comparing spherical, rod and elliptical disk-shaped PLGA nanoparticles in terms of particle size, particle size distribution, colloidal stability, morphology, drug encapsulation, drug release, safety of nanoparticles, cellular uptake and biodistribution. Nude mice bearing non-small cell lung cancer were treated with 3 differently shaped nanoparticles, and the accumulation of nanoparticles in tumor tissue and other organs was not statistically different (p > 0.05). It was found that PLGA nanoparticles with 1.00, 4.0 ± 0.5, 7.5 ± 0.5 aspect ratios did not differ on total tumor accumulation in non-small cell lung cancer.

Non-fouling flow reactors for nanomaterial synthesis

This review provides a holistic description of flow reactor fouling for wet-chemical nanomaterial syntheses. Fouling origins and consequences are discussed together with the variety of flow reactors for its prevention.

Placental Nanoparticle Uptake-On-a-Chip: The Impact of Trophoblast Syncytialization and Shear Stress

The placenta is a dynamic and complex organ that plays an essential role in the health and development of the fetus. Placental disorders can affect the health of both the mother and the fetus. There is currently an unmet clinical need to develop nanoparticle-based therapies to target and treat placental disorders. However, little is known about the interaction of nanoparticles (NPs) with the human placenta under biomimetic conditions. Specifically, the impact of shear stress exerted on the trophoblasts (placental epithelial cells) by the maternal blood flow, the gradual fusion of the trophoblasts along the gestation period (syncytialization), and the impact of microvilli formation on the cell uptake of NPs is not known. To this end, we designed dynamic placenta-on-a-chip models using BeWo cells to recapitulate the micro-physiological environment, and we induced different degrees of syncytialization via chemical induction with forskolin. We characterized the degree of syncytialization quantitatively by measuring beta human chorionic gonadotropin (β-hCG) secretion, as well as qualitatively by immunostaining the tight junction protein, ZO-1, and counter nuclear staining. We also characterized microvilli formation under static and dynamic conditions via F-actin staining. We used these models to measure the cell uptake of chondroitin sulfate a binding protein (CSA) conjugated and control liposomes using confocal microscopy, followed by image analysis. Interestingly, exposure of the cells to a dynamic flow of media intrinsically induced syncytialization and microvilli formation compared to static controls. Under dynamic conditions, BeWo cells produced more β-hCG in conditions that increased the cell exposure time to forskolin (p < 0.005). Our cell uptake results clearly show a combined effect of the exerted shear stress and forskolin treatment on the cell uptake of liposomes as uptake increased in forskolin exposed conditions (p < 0.05). Overall, the difference in the extent of cell uptake of liposomes among the different conditions clearly displays a need for the development of dynamic models of the placenta that consider the changes in the placental cell phenotype along the gestation period, including syncytialization, microvilli formation, and the expression of different transport and uptake receptors. Knowledge generated from this work will inform future research aiming at developing drug delivery systems targeting the placenta.

Microfluidic Nanoparticles for Drug Delivery

Nanoparticles (NPs) have attracted tremendous interest in drug delivery in the past decades. Microfluidics offers a promising strategy for making NPs for drug delivery due to its capability in precisely controlling NP properties. The recent success of mRNA vaccines using microfluidics represents a big milestone for microfluidic NPs for pharmaceutical applications, and its rapid scaling up demonstrates the feasibility of using microfluidics for industrial-scale manufacturing. This article provides a critical review of recent progress in microfluidic NPs for drug delivery. First, the synthesis of organic NPs using microfluidics focusing on typical microfluidic methods and their applications in making popular and clinically relevant NPs, such as liposomes, lipid NPs, and polymer NPs, as well as their synthesis mechanisms are summarized. Then, the microfluidic synthesis of several representative inorganic NPs (e.g., silica, metal, metal oxide, and quantum dots), and hybrid NPs is discussed. Lastly, the applications of microfluidic NPs for various drug delivery applications are presented.

Microfluidic synthesis of optically responsive materials for nano- and biophotonics

Recently, nanomaterials demonstrating optical response under illumination, the so-called optically responsive nanoparticles (NPs), have found their broad application as optical switchers, gas adsorbents, data storage devices, and optical and biological sensors. Unique optical properties of such nanomaterials are strongly related to their chemical composition, geometrical parameters and morphology. Microfluidic approaches for NPs' synthesis allow overcoming the known critical stages in conventional synthesis of NPs due to a high rate of heat/mass transfer and precise regulation of synthesis conditions, which results in reproducible synthesis outcomes with the desired physico-chemical properties. Here, we review the recent advances in microfluidic approach for synthesis of optically responsive nanomaterials (plasmonic, photoluminescent, shape-changeable NPs), highlighting the general background of microfluidics, common considerations in the design of microfluidic chips (MFCs), and theoretical models of the NPs' formation mechanisms. Comparative analysis of microfluidic synthesis with conventional synthesis methods is provided further, along with the recent applications of optically responsive NPs in nano- and biophotonics.

Microfluidic based nanoparticle synthesis and their potential applications

A lot of substantial innovation in advancement of microfluidic field in recent years to produce nanoparticle reveals a number of distinctive characteristics for instance compactness, controllability, fineness in process, and stability along with minimal reaction amount. Recently, a prompt development, as well as realization in production of nanoparticles in microfluidic environs having dimension of micro to nanometers and constituents extending from metals, semiconductors to polymers, has been made. Microfluidics technology integrates fluid mechanics for production of nanoparticles having exclusive with homogenous sizes, shapes, and morphology, which are utilized in several bioapplications such as biosciences, drug delivery, healthcare, including food engineering. Nanoparticles are usually well-known for having fine and rough morphology because of their small dimensions including exceptional physical, biological, chemical, and optical properties. Though the orthodox procedures need huge instruments, costly autoclaves, use extra power, extraordinary heat loss, as well as take surplus time for synthesis. Additionally, this is fascinating in order to systematize, assimilate, in addition, to reduce traditional tools onto one platform to produce micro and nanoparticles. The synthesis of nanoparticles by microfluidics permits fast handling besides better efficacy of method utilizing the smallest components for process. Herein, we will focus on synthesis of nanoparticles by means of microfluidic devices intended for different bioapplications. This article is protected by copyright. All rights reserved.

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.

Formulation of tunable size PLGA-PEG nanoparticles for drug delivery using microfluidic technology

Amphiphilic block co-polymer nanoparticles are interesting candidates for drug delivery as a result of their unique properties such as the size, modularity, biocompatibility and drug loading capacity. They can be rapidly formulated in a nanoprecipitation process based on self-assembly, resulting in kinetically locked nanostructures. The control over this step allows us to obtain nanoparticles with tailor-made properties without modification of the co-polymer building blocks. Furthermore, a reproducible and controlled formulation supports better predictability of a batch effectiveness in preclinical tests. Herein, we compared the formulation of PLGA-PEG nanoparticles using the typical manual bulk mixing and a microfluidic chip-assisted nanoprecipitation. The particle size tunability and controllability in a hydrodynamic flow focusing device was demonstrated to be greater than in the manual dropwise addition method. We also analyzed particle size and encapsulation of fluorescent compounds, using the common bulk analysis and advanced microscopy techniques: Transmission Electron Microscopy and Total Internal Reflection Microscopy, to reveal the heterogeneities occurred in the formulated nanoparticles. Finally, we performed in vitro evaluation of obtained NPs using MCF-7 cell line. Our results show how the microfluidic formulation improves the fine control over the resulting nanoparticles, without compromising any appealing property of PLGA nanoparticle. The combination of microfluidic formulation with advanced analysis methods, looking at the single particle level, can improve the understanding of the NP properties, heterogeneities and performance.

Applications of Microfluidic Devices in the Diagnosis and Treatment of Cancer: A Review Study

Many cancer-related deaths are reported annually due to a lack of appropriate diagnosis and treatment strategies. Microfluidic technology, as new creativity has a great impact on automation and miniaturization via handling a small volume of materials and samples (in microliter to femtoliter range) to set up the system. Microfluidic devices not only detect various cancer-diagnostic factors from biological fluids but also can produce proper nanoparticles for drug delivery. With the contribution of microfluidics; multiple treatments for cancer such as chemotherapy, radiation therapy, and gene delivery can be implemented and studied. Hence, Microfluidics can be worth for the cancer field because of its high Throughput, high sensitivity, less material use, and low expense. In this review study, we intend to look at positive microfluidics prospects, features, benefits, and clinical applications.

Microfluidic Assembly: An Innovative Tool for the Encapsulation, Protection, and Controlled Release of Nutraceuticals

Nutraceuticals have been gradually accepted as food ingredients that can offer health benefits and provide protection against several diseases. It is widely accepted due to potential nutritional benefits, safety, and therapeutic effects. Most nutraceuticals are vulnerable to the changes in the external environment, which leads to poor physical and chemical stability and absorption. Several researchers have designed various encapsulation technologies to promote the use of nutraceuticals. Microfluidic technology is an emerging approach which can be used for nutraceutical delivery with precise control. The delivery systems using microfluidic technology have obtained much interest in recent years. In this review article, we have summarized the recently introduced nutraceutical delivery platforms including emulsions, liposomes, microspheres, microgels, and polymer nanoparticles based on microfluidic techniques. Emphasis has been made to discuss the advantages, preparations, characterizations, and applications of nutraceutical delivery systems. Finally, the challenges, several up-scaling methods, and future expectations are discussed.

Microfluidic-assisted nanoprecipitation of biodegradable nanoparticles composed of PTMC/PCL (co)polymers, tannic acid and doxorubicin for cancer treatment

This study was aimed towards the development of a novel microfluidic approach for the preparation of (co)polymeric and hybrid nanoparticles (NPs) composed of (co)polymers/tannic acid (TA) in the microfluidic flow-focusing glass-capillary device. The MiliQ water was used as water phase, whereas the organic phase was composed of poly(ε-caprolactone) (PCL) and poly(trimethylene carbonate) (PTMC) homopolymers and (co)polymers with different proportion of comonomers which were prepared via enzymatic polymerization that allows avoiding the usage of potentially toxic catalyst. To prepare hybrid NPs, TA was additionally added to the organic phase. Subsequently, as a result of mixing between these distinct phases in microfluidic channels, the nanoprecipitation in the form of spherical NPs occurs. The size of NPs was tuned over the range of 140-230 nm by controlling phase flow rates and the composition of NPs. Moreover, the release studies of the encapsulated anticancer drug doxorubicin (DOX) demonstrated that the drug release is greatly influenced by the (co)polymers composition, their molecular weight, NPs size, and the presence of TA. The antitumor activities of the (co)polymeric and hybrid NPs toward breast cancer cells (MCF-7) were tested in vitro. Among all tested formulation, the NPs composed of PCL/TA most efficiently inhibit the cell proliferation of MCF-7 cells, most importantly, their efficiency was higher than free DOX. The proposed strategy may provide an efficient alternative for the construction of nanocarriers with great potential in anticancer therapy.

Integrated nanoparticle size with membrane porosity for improved analytical performance in sandwich immunochromatographic assay

The use of luminescent nanobeads to improve the sensitivity of sandwich immunochromatographic assay (ICA) has obtained increasing concern. Illustrating the relationship among luminescent intensity, nanobead size, nitrocellulose membrane aperture, and ICA sensitivity is important for achieving the optimal target detection. Thus, we synthesized six differently sized quantum dot beads (QBs) (95, 140, 180, 235, 325, and 405 nm) as ICA labels and applied them in three aperture membranes (10, 15, and 25 μm). Results indicate that increasing the QB size to less than an appropriate size of 235 nm is beneficial for ICA sensitivity because of the increased fluorescence. However, oversized QBs result in reduced sensitivity due to the decreased diffusion or settlement of the QB on the membrane that causes obvious background signal. The small aperture membrane perfectly matching the QB size contributes to ICA sensitivity by decreasing the migration velocity of the QB probe for increased binding of the QB@analyte complex at the T zone. Consequently, the best detection of hepatitis B surface antigen with a sensitivity of 0.156 ng/mL is achieved using 235 nm QBs in 15 μm membrane. Further performance evaluation of our QB₂₃₅-ICA_CN95 demonstrates excellent accuracy, selectivity, and practicability. This work provides a new idea to manipulate the sensitivity of sandwich ICA by tuning the QB size and the membrane aperture, and a theoretical guidance for selecting the probe and membrane to achieve the best detection of target analytes.

Polymer based nanoparticles for biomedical applications by microfluidic techniques: from design to biological evaluation

The development of microfluidic technologies represents a new strategy to produce and test drug delivery systems.

Development of High-Drug-Loading Nanoparticles

Formulating drugs into nanoparticles offers many attractive advantages over free drugs including improved bioavailability, minimized toxic side effects, enhanced drug delivery, feasibility of incorporating other functions such as controlled release, imaging agents for imaging, targeting delivery, and loading more than one drug for combination therapies. One of the key parameters is drug loading, which is defined as the mass ratio of drug to drug-loaded nanoparticles. Currently, most nanoparticle systems have relatively low drug loading (<10 wt%), and developing methods to increase drug loading remains a challenge. This Minireview presents an overview of recent research on developing nanoparticles with high drug loading (>10 wt%) from the perspective of synthesis strategies, including post-loading, co-loading, and pre-loading. Based on these three different strategies, various nanoparticle systems with different materials and drugs are summarized and discussed in terms of their synthesis methods, drug loadings, encapsulation efficiencies, release profiles, stabilities, and their applications in drug delivery. The advantages and disadvantages of these strategies are presented with an objective of providing useful design rules for future development of high-drug-loading nanoparticles.

Microfluidics for pharmaceutical nanoparticle fabrication: The truth and the myth

Using micro-sized channels to manipulate fluids is the essence of microfluidics which has wide applications from analytical chemistry to material science and cell biology research. Recently, using microfluidic-based devices for pharmaceutical research, in particular for the fabrication of micro- and nano-particles, has emerged as a new area of interest. The particles that can be prepared by microfluidic devices can range from micron size droplet-based emulsions to nano-sized drug loaded polymeric particles. Microfluidic technology poses unique advantages in terms of the high precision of the mixing regimes and control of fluids involved in formulation preparation. As a result of this, monodispersity of the particles prepared by microfluidics is often recognised as being a particularly advantageous feature in comparison to those prepared by conventional large-scale mixing methods. However, there is a range of practical drawbacks and challenges of using microfluidics as a direct micron- and nano-particle manufacturing method. Technological advances are still required before this type of processing can be translated for application by the pharmaceutical industry. This review focuses specifically on the application of microfluidics for pharmaceutical solid nanoparticle preparation and discusses the theoretical foundation of using the nanoprecipitation principle to generate particles and how this is translated into microfluidic design and operation.

Continuous, high-throughput production of artemisinin-loaded supramolecular cochleates using simple off-the-shelf flow focusing device

Lipid cochleates are gaining increasing interest as drug-carriers. However, their preparation relies on conventional batch processes that are complex, time consuming and lack batch-to-batch reproducibility; presenting a bottleneck for clinical translation. We report an efficient continuous preparation process for artemisinin-loaded cochleates (ART-cochleates) using inexpensive off-the-shelf flow focusing device. By carefully controlling the flow focusing parameters, we showed along with the mechanism that, ART-cochleates of uniform and tuneable size (~180 nm in width and ~1030 nm in length) were obtained with low dispersity (0.18 in width and 0.27 in length), narrow size distribution and high reproducibility compared to the batch process. The device achieved high throughput of 11.5 g/day with ART encapsulation of 64.24 ± 2.5% and loading of 83.37 ± 3.68 mg ART/g of cochleates. Art-cochleates were non-toxic and showed sustained in-vitro release of ART with effective transepithelial permeability across intestinal Caco-2 monolayer (~60% and ~25% transport for pure ART and ART-cochleates, respectively) resulting in better in-vitro bioavailability. The off-the-shelf device is envisioned to be highly promising platform for continuous and high-throughput manufacturing of drug-loaded cochleates in a controlled and reproducible manner. It has potential to enable clinical translation of drug-loaded cochleates with predicable drug release, absorption and bioavailability.

Modelling protein therapeutic co-formulation and co-delivery with PLGA nanoparticles continuously manufactured by microfluidics

Formulating protein therapeutics into nanoparticles (NPs) of poly(lactic-co-glycolic acid) (PLGA) provides key features such as protection against clearance, sustained release and less side effects by possible attachment of targeting ligands.

Formulation Strategies for Folate-Targeted Liposomes and Their Biomedical Applications

The folate receptor (FR) is a tumor-associated antigen that can bind with folic acid (FA) and its conjugates with high affinity and ingests the bound molecules inside the cell via the endocytic mechanism. A wide variety of payloads can be delivered to FR-overexpressed cells using folate as the ligand, ranging from small drug molecules to large DNA-containing macromolecules. A broad range of folate attached liposomes have been proven to be highly effective as the targeted delivery system. For the rational design of folate-targeted liposomes, an intense conceptual understanding combining chemical and biomedical points of view is necessary because of the interdisciplinary nature of the field. The fabrication of the folate-conjugated liposomes basically involves the attachment of FA with phospholipids, cholesterol or peptides before liposomal formulation. The present review aims to provide detailed information about the design and fabrication of folate-conjugated liposomes using FA attached uncleavable/cleavable phospholipids, cholesterol or peptides. Advances in the area of folate-targeted liposomes and their biomedical applications have also been discussed.

Disulfide-Mediated Bioconjugation: Disulfide Formation and Restructuring on the Surface of Nanomanufactured (Microfluidics) Nanoparticles

This study is about (1) nanomanufacturing (focusing on microfluidic-assisted nanoprecipitation), (2) advanced colloid characterization (focusing on field flow fractionation), and (3) the possible restructuring of surface disulfides. Disulfides are dynamic and exchangeable groups, and here we specifically focus, first, on their use to introduce biofunctional groups and, second, on their re-organization, which may lead to variable surface chemistries and uncontrolled cell interactions. The particles were obtained via microfluidic-assisted (flow-focused) nanoprecipitation of poly(ethylene glycol)-b-poly(ε-caprolactone) bearing or not a 2-pyridyl disulfide (PDS) terminal group, which quantitatively exchanges with thiols in solution. In this study, we have paid specific attention to size characterization, thereby also demonstrating the limitations of dynamic light scattering (DLS) as a stand-alone technique. By using asymmetric flow field flow fractionation coupled with DLS, static light scattering (SLS), and refractive index detectors, we show that relatively small amounts of >100 nm aggregates (cryogenic transmission electron microscopy and SLS/DLS comparison suggesting them to be wormlike micelles) dominated the stand-alone DLS results, whereas the "real" size distributions picked <50 nm. Our key result is that the kinetics of the conjugation based on PDS-thiol exchange was controlled by the thiol pK_a, and this also determined the rate of the exchange between the resulting disulfides and glutathione (GSH). In particular, more acidic thiols (e.g., peptides, where a cysteine is flanked by cationic residues) react faster with PDS, but their disulfides hardly exchange with GSH; the reverse applies to thiols with a higher pK_a. Disulfides that resist against restructuring via thiol-disulfide exchange allow for a stable bioconjugation, although they may be bad news for payload release under reducing conditions. However, experiments of both thiol release and nanoparticles uptake in cells (HCT116) show that also the disulfides formed from less-acidic and, therefore, less-reactive, and more exchangeable thiols were stable for at least a few hours even in a GSH-rich (10 mM) environment; this suggests a sufficiently long stability of surface groups to achieve, for example, a cell-targeting effect.

Finding key nanoprecipitation variables for achieving uniform polymeric nanoparticles using neurofuzzy logic technology

Nanoprecipitation is a simple and fast method to produce polymeric nanoparticles (Np); however, most applications require filtration or another separation technique to isolate the nanosuspension from aggregates or polydisperse particle production. In order to avoid variability introduced by these additional steps, we report here a systematic study of the process to yield monomodal and uniform Np production with the nanoprecipitation method. To further identify key variables and their interactions, we used artificial neural networks (ANN) to investigate the multiple variables which influence the process. In this work, a polymethacrylate derivative was used for Np (NpERS) and a database with several formulations and conditions was developed for the ANN model. The resulting ANN model had a high predictability (> 70%) for NpERS characteristics measured (mean size, PDI, zeta potential, and number of particle populations). Moreover, the model identified production variables leading to polymer supersaturation, such as mixing time and turbulence, as key in achieving monomodal and uniform NpERS in one production step. Polymer concentration and type of solvent, modifiers of polymer diffusion and supersaturation, were also shown to control NpERS characteristics. The ANN study allowed the identification of key variables and their interactions and resulted in a predictive model to study the NpERS production by nanoprecipitation. In turn, we have achieved an optimized method to yield uniform NpERS which could pave way for polymeric nanoparticle production methods with potential in biological and drug delivery applications.