Microfluidics for Production of Particles: Mechanism, Methodology, and Applications

Microfluidic preparation and optimization of (Kollicoat ® IR-b-PCL) polymersome for co-delivery of Nisin-Curcumin in breast cancer application

This work aimed to develop amphiphilic nanocarriers such as polymersome based diblock copolymer of Kollicoat ® IR -block-poly(ε-caprolactone) (Kollicoat ® IR-b-PCL) for potential co-delivery of Nisin (Ni) and Curcumin (CUR) for treatment of breast cancer. To generate multi-layered nanocarriers of uniform size and morphology, microfluidics was used as a new technology. In order to characterise and optimize polymersome, design of experiments (Design-Expert) software with three levels full factorial design (3-FFD) method was used. Finally, the optimized polymersome was produced with a spherical morphology, small particle size (dH < 200 nm), uniform size distribution (PDI < 0.2), and high drug loading efficiency (Ni 78 % and CUR 93 %). Furthermore, the maximum release of Ni and CUR was found to be roughly 60 % and 80 % in PBS, respectively. Cytotoxicity assays showed a slight cytotoxicity of Ni and CUR -loaded polymersome (N- Ni /CUR) towards normal cells while demonstrating inhibitory activity against cancer cells compared to the free drugs. Also, the apoptosis assays and cellular uptake confirmed the obtained results from cytotoxic analysis. In general, this study demonstrated a microfluidic approach for preparation and optimization of polymersome for co-delivery of two drugs into cancer cells.

Microfluidic-Based dsRNA Delivery Nanoplatform for Efficient Spodoptera exigua Control

Nanotechnology-based RNA interference (RNAi) offers a promising approach to pest control. However, current methods for producing RNAi nanopesticides are mainly implemented in a batch-to-batch manner, lacking consistent quality control. Herein, we present a microfluidic-based nanoplatform for RNA nanopesticide preparation using lipid nanoparticles (LNPs) as nanocarriers, taking advantage of the enhanced mass transfer and continuous processing capabilities of microfluidic technology. The dsRNA@LNPs were rapidly formed within seconds, which showed uniform size distribution, improved leaf wettability, and excellent dispersion properties. The delivery efficiency of dsRNA@LNPs was evaluated by targeting the chitin synthetase B (CHSB) gene ofSpodoptera exigua. The dsRNA@LNPs can effectively resist nuclease-rich midgut fluid degradation. Importantly, dsCHSB@LNPs exhibited increased mortality rates, significant reduction of larvae growth, and enhanced gene suppression efficiency. Therefore, a continuous nanoplatform for RNAi nanopesticide preparation is demonstrated by utilizing microfluidic technology, representing a new route to produce RNAi nanopesticides with enhanced quality control and might accelerate their practical applications.

Synthesis, modifications, and applications of iron-based nanoparticles

Magnetic nanoparticles (MNPs) are appealing materials as assistant to resolve environmental pollution issues and as recyclable catalysts for the oxidative degradation of resistant contaminants. Moreover, they can significantly influence the advancement of medical applications for imaging, diagnostics, medication administration, and biosensing. On the other hand, due to unique features, excellent biocompatibility, high curie temperatures and low cytotoxicity of the Iron-based nanoparticles, they have received increasing attention in recent years. Using an external magnetic field, in which the ferrite magnetic nanoparticles (FMNPs) in the reaction mixtures can be easily removed, make them more efficient approach than the conventional method for separating the catalyst particles by centrifugation or filtration. Ferrite magnetic nanoparticles (FMNPs) provide various advantages in food processing, environmental issues, pharmaceutical industry, sample preparation, wastewater management, water purification, illness therapy, identification of disease, tissue engineering, and biosensor creation for healthcare monitoring. Modification of FMNPs with the proper functional groups and surface modification techniques play a significant role in boosting their capability. Due to flexibility of FMNPs in functionalization and synthesis, it is possible to make customized FMNPs that can be utilized in variety of applications. This review focuses on synthesis, modifications, and applications of Iron-based nanoparticles.

Microfluidic strategies for engineering oxygen-releasing biomaterials

In the field of tissue engineering, local hypoxia in large-cell structures (larger than 1 mm3) poses a significant challenge. Oxygen-releasing biomaterials supply an innovative solution through oxygen ⁠ delivery in a sustained and controlled manner. Compared to traditional methods such as emulsion, sonication, and agitation, microfluidic technology offers distinct benefits for oxygen-releasing material production, including controllability, flexibility, and applicability. It holds enormous potential in the production of smart oxygen-releasing materials. This review comprehensively covers the fabrication and application of microfluidic-enabled oxygen-releasing biomaterials. To begin with, the physical mechanism of various microfluidic technologies and their differences in oxygen carrier preparation are explained. Then, the distinctions among diverse oxygen-releasing components in regards for oxygen-releasing mechanism, oxygen-carrying capacity, and duration of oxygen release are presented. Finally, the present obstacles and anticipated development trends are examined together with the application outcomes of oxygen-releasing biomaterials based on microfluidic technology in the biomedical area. STATEMENT OF SIGNIFICANCE: Oxygen is essential for sustaining life, and hypoxia (a condition of low oxygen) is a significant challenge in various diseases. Microfluidic-based oxygen-releasing biomaterials offer precise control and outstanding performance, providing unique advantages over traditional approaches for tissue engineering. However, comprehensive reviews on this topic are currently lacking. In this review, we provide a comprehensive analysis of various microfluidic technologies and their applications for developing oxygen-releasing biomaterials. We compare the characteristics of organic and inorganic oxygen-releasing biomaterials and highlight the latest advancements in microfluidic-enabled oxygen-releasing biomaterials for tissue engineering, wound healing, and drug delivery. This review may hold the potential to make a significant contribution to the field, with a profound impact on the scientific community.

Revolutionizing targeting precision: microfluidics-enabled smart microcapsules for tailored delivery and controlled release

As promising delivery systems, smart microcapsules have garnered significant attention owing to their targeted delivery loaded with diverse active materials. By precisely manipulating fluids on the micrometer scale, microfluidic has emerged as a powerful tool for tailoring delivery systems based on potential applications. The desirable characteristics of smart microcapsules are associated with encapsulation capacity, targeted delivery capability, and controlled release of encapsulants. In this review, we briefly describe the principles of droplet-based microfluidics for smart microcapsules. Subsequently, we summarize smart microcapsules as delivery systems for efficient encapsulation and focus on target delivery patterns, including passive targets, active targets, and microfluidics-assisted targets. Additionally, based on release mechanisms, we review controlled release modes adjusted by smart membranes and on/off gates. Finally, we discuss existing challenges and potential implications associated with smart microcapsules.

Design of charge converting lipid nanoparticles via a microfluidic coating technique

It was the aim of this study to design charge converting lipid nanoparticles (LNP) via a microfluidic mixing technique used for the preparation and coating of LNP. LNP consisting of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), cholesterol, N-(carbonyl-methoxypolyethyleneglycol-2000)-1,2-distearoyl-sn-glycero-3-phosphoethanolamine (MPEG-2000-DSPE), and various cationic surfactants were prepared at diverging flow rate ratios (FRR) via microfluidic mixing. Utilizing a second chip in the microfluidic set-up, LNP were coated with polyoxyethylene (9) nonylphenol monophosphate ester (PNPP). LNP were examined for their stability in different physiologically relevant media as well as for hemolytic and cytotoxic effects. Finally, phosphate release and charge conversion of PNPP-coated LNP were evaluated after incubation with alkaline phosphatase and on Caco2-cells. LNP produced at an FRR of 5:1 exhibited a size between 80 and 150 nm and a positive zeta potential. Coating with PNPP within the second chip led to LNP exhibiting a negative zeta potential. After incubation with 1 U/ml alkaline phosphatase for 4 h, zeta potential of the LNP containing 1,2-dioleoyloxy-3-trimethylammonium-propane chloride (DOTAP) as cationic component shifted from - 35 mV to approximately + 5 mV. LNP prepared with other cationic surfactants remained slightly negative after enzymatic phosphate cleavage. Manufacturing of LNP containing PNPP and DOTAP via connection of two chips in a microfluidic instrument proves to show efficient change in zeta potential from negative to positive after incubation with alkaline phosphatase.

Intracellular Trafficking of Size-Tuned Nanoparticles for Drug Delivery

Polymeric nanoparticles (NPs) are widely used as drug delivery systems in nanomedicine. Despite their widespread application, a comprehensive understanding of their intracellular trafficking remains elusive. In the present study, we focused on exploring the impact of a 20 nm difference in size on NP performance, including drug delivery capabilities and intracellular trafficking. For that, poly(ethylene glycol) methyl ether-block-poly(lactide-co-glycolide) (PLGA-PEG) NPs with sizes of 50 and 70 nm were precisely tailored. To assess their prowess in encapsulating and releasing therapeutic agents, we have employed doxorubicin (Dox), a well-established anticancer drug widely utilized in clinical settings, as a model drug. Then, the beneficial effect of the developed nanoformulations was evaluated in breast cancer cells. Finally, we performed a semiquantitative analysis of both NPs' uptake and intracellular localization by immunostaining lysosomes, early endosomes, and recycling endosomes. The results show that the smaller NPs (50 nm) were able to reduce the metabolic activity of cancer cells more efficiently than NPs of 70 nm, in a time and concentration-dependent manner. These findings are corroborated by intracellular trafficking studies that reveal an earlier and higher uptake of NPs, with 50 nm compared to the 70 nm ones, by the breast cancer cells. Consequently, this study demonstrates that NP size, even in small increments, has an important impact on their therapeutic effect.

Microfluidic synthesis of nanomaterials for biomedical applications

The field of nanomaterials has progressed dramatically over the past decades with important contributions to the biomedical area. The physicochemical properties of nanomaterials, such as the size and structure, can be controlled through manipulation of mass and heat transfer conditions during synthesis. In particular, microfluidic systems with rapid mixing and precise fluid control are ideal platforms for creating appropriate synthesis conditions. One notable example of microfluidics-based synthesis is the development of lipid nanoparticle (LNP)-based mRNA vaccines with accelerated clinical translation and robust efficacy during the COVID-19 pandemic. In addition to LNPs, microfluidic systems have been adopted for the controlled synthesis of a broad range of nanomaterials. In this review, we introduce the fundamental principles of microfluidic technologies including flow field- and multiple field-based methods for fabricating nanoparticles, and discuss their applications in the biomedical field. We conclude this review by outlining several major challenges and future directions in the implementation of microfluidic synthesis of nanomaterials.

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.

Multi-Bioinspired MOF Delivery Systems from Microfluidics for Tumor Multimodal Therapy

Metal-organic framework (MOF)-based drug delivery systems have demonstrated values in oncotherapy. Current research endeavors are centralized on the functionality enrichment of featured MOF materials with designed versatility for synergistic multimodal treatments. Here, inspired by the multifarious biological functions including ferroptosis pattern, porphyrins, and cancer cell membrane (CCM) camouflage technique, novel multi-biomimetic MOF nanocarriers from microfluidics are prepared. The Fe3+ , meso-tetra(4-carboxyphenyl)porphine and oxaliplatin prodrug are incorporated into one MOF nano-system (named FeTPt), which is further cloaked by CCM to obtain a "Trojan Horse"-like vehicle (FeTPt@CCM). Owing to the functionalization with CCM, FeTPt@CCM can target and accumulate at the tumor site via homologous binding. After being internalized by cancer cells, FeTPt@CCM can be activated by a Fenton-like reaction as well as a redox reaction between Fe3+ and glutathione and hydrogen peroxide to generate hydroxyl radical and oxygen. Thus, the nano-platform effectively initiates ferroptosis and improves photodynamic therapy performance. Along with the Pt-drug chemotherapy, the nano-platform exhibits synergistic multimodal actions for inhibiting cancer cell proliferation in vitro and suppressing tumor growth in vivo. These features indicate that such a versatile biomimetic MOF delivery system from microfluidics has great potential for synergistic cancer treatment.

Engineering Metal-Phenolic Network Nanoparticles via Microfluidics

Microfluidics opens new avenues for materials engineering, as it enables scalable synthesis and provides highly controllable environments for reactions. Herein, we leverage microfluidics to engineer the properties of (bioactive) metal-phenolic network nanoparticles (MPN NPs), an emerging and highly modular nanoparticle platform for the incorporation and delivery of bioactive cargo. By varying the microfluidics operating parameters (flow rate ratio, total flow rate, temperature) and NP composition, we assemble MPN NPs, which consist of poly(ethylene glycol), biomacromolecules, metal ions, and polyphenols. Compared to MPN NPs prepared via bulk assembly, the microfluidics-assembled MPN NPs possess a broader tunable size range (i.e., ∼40-330 nm vs ∼45-220 nm for bulk-assembled NPs) and a higher (by ∼30%) protein loading. The bulk-assembled MPN NPs show pH-responsive protein release behavior (e.g., ∼50% at pH 7; ∼25% at pH 9; 48 h). Likewise, the MPN NPs prepared via microfluidics at a flow rate ratio of 1:1 display similar pH-responsive protein release behavior. For the microfluidics-assembled MPN NPs, protein release is also dependent on temperature (e.g., 30% at 4 °C, and ∼50% at 20 and 37 °C). Furthermore, assembly at a 1:1 flow rate ratio overall enables greater tunability of protein release profiles than that at higher flow rate ratios. While bulk-assembled NPs display a higher degree of cell association, NPs assembled via both strategies can be internalized by cells after 24 h. These findings provide new insights into engineering the properties of metal-organic materials via microfluidics, which is expected to advance their development and application.

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.

Photothermal Responsive Digital Polymerase Chain Reaction Resolving Exosomal microRNAs Expression in Liver Cancer

Exosomal microRNAs have been studied as a good source of noninvasive biomarkers due to their functions in genetic exchange between cells and have been already well documented in many biological activities; however, inaccuracy remains a key challenge for liver cancer surveillance. Herein, a versatile duplex photothermal digital polymerase chain reaction (PCR) strategy combined with a lipid nanoparticle-based exosome capture approach is proposed to profile microRNAs expression through a 3-h easy-to-operate process. The microfluidically-generated molybdenum disulfide-nanocomposite-doped gelatin microcarriers display attractive properties as a 2-4 °C s^-1 ramping-up rate triggered by near-infrared and reversible sol-gel transforming in step with PCR activation. To achieve PCR thermocycling, the corresponding irradiation coordinating with fan cooling are automatically performed via a homemade control module with programs. Thus, taking the multiplexing capability of dual-color labeling, 19-31 folds higher in exosomal microRNA-200b-3p and microRNA-21-5p, and tenfold lower in microRNA-22-3p expressions relative to the control microRNA-26a-5p are quantified in two liver cancer cells (Huh7 and HepG2) than in those from the healthy cells. It is believed that this exosomal microRNA genotyping method would be highly applicable for liver cancer diagnostics.

Synthesis and Application of Fluorescent Polymer Micro- and Nanoparticles

Fluorescent polymer particles have witnessed an increasing interest in recent years, owing to their fascinating physicochemical properties as well as wide-ranging applications. In this review, the state-of-the-art research progress of fluorescent polymer particles in the past five years is summarized. First, the synthesis protocols for fluorescent polymer particles, including emulsion polymerization, precipitation polymerization, dispersion polymerization, suspension polymerization, nanoprecipitation, self-assembly, and post-polymerization modification, are presented in detail. Then, the applications of the resulting beguiling particles in anticounterfeiting, chemical sensing, and biomedicine, are illustrated. Finally, the challenges and opportunities that exist in the field are pointed out. This review aims to offer important guidance and stimulate more research attention to this rapidly developing field.

Microfluidic preparation and optimization of sorafenib-loaded poly(ethylene glycol-block-caprolactone) nanoparticles for cancer therapy applications

The use of amphiphilic block copolymers to generate colloidal delivery systems for hydrophobic drugs has been the subject of extensive research, with several formulations reaching the clinical development stages. However, to generate particles of uniform size and morphology, with high encapsulation efficiency, yield and batch-to-batch reproducibility remains a challenge, and various microfluidic technologies have been explored to tackle these issues. Herein, we report the development and optimization of poly(ethylene glycol)-block-(ε-caprolactone) (PEG-b-PCL) nanoparticles for intravenous delivery of a model drug, sorafenib. We developed and optimized a glass capillary microfluidic nanoprecipitation process and studied systematically the effects of formulation and process parameters, including different purification techniques, on product quality and batch-to-batch variation. The optimized formulation delivered particles with a spherical morphology, small particle size (d_H < 80 nm), uniform size distribution (PDI < 0.2), and high drug loading degree (16 %) at 54 % encapsulation efficiency. Furthermore, the stability and in vitro drug release were evaluated, showing that sorafenib was released from the NPs in a sustained manner over several days. Overall, the study demonstrates a microfluidic approach to produce sorafenib-loaded PEG-b-PCL NPs and provides important insight into the effects of nanoprecipitation parameters and downstream processing on product quality.

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

Recent years have witnessed an increased interest in the development of nanoparticles (NPs) owing to their potential use in a wide variety of biomedical applications, including drug delivery, imaging agents, gene therapy, and vaccines, where recently, lipid nanoparticle mRNA-based vaccines were developed to prevent SARS-CoV-2 causing COVID-19. NPs typically fall into two broad categories: organic and inorganic. Organic NPs mainly include lipid-based and polymer-based nanoparticles, such as liposomes, solid lipid nanoparticles, polymersomes, dendrimers, and polymer micelles. Gold and silver NPs, iron oxide NPs, quantum dots, and carbon and silica-based nanomaterials make up the bulk of the inorganic NPs. These NPs are prepared using a variety of top-down and bottom-up approaches. Microfluidics provide an attractive synthesis alternative and is advantageous compared to the conventional bulk methods. The microfluidic mixing-based production methods offer better control in achieving the desired size, morphology, shape, size distribution, and surface properties of the synthesized NPs. The technology also exhibits excellent process repeatability, fast handling, less sample usage, and yields greater encapsulation efficiencies. In this article, we provide a comprehensive review of the microfluidic-based passive and active mixing techniques for NP synthesis, and their latest developments. Additionally, a summary of microfluidic devices used for NP production is presented. Nonetheless, despite significant advancements in the experimental procedures, complete details of a nanoparticle-based system cannot be deduced from the experiments alone, and thus, multiscale computer simulations are utilized to perform systematic investigations. The work also details the most common multiscale simulation methods and their advancements in unveiling critical mechanisms involved in nanoparticle synthesis and the interaction of nanoparticles with other entities, especially in biomedical and therapeutic systems. Finally, an analysis is provided on the challenges in microfluidics related to nanoparticle synthesis and applications, and the future perspectives, such as large-scale NP synthesis, and hybrid formulations and devices.

Microfluidics in drug delivery: review of methods and applications

Microfluidics technology has emerged as a promising methodology for the fabrication of a wide variety of advanced drug delivery systems. Owing to its ability for accurate handling and processing of small quantities of fluidics as well as immense control over physicochemical properties of fabricated micro and nanoparticles (NPs), microfluidic technology has significantly improved the pharmacokinetics and pharmacodynamics of drugs. This emerging technology has offered numerous advantages over the conventional drug delivery methods for fabricating of a variety of micro and nanocarriers for poorly soluble drugs. In addition, a microfluidic system can be designed for targeted drug delivery aiming to increase the local bioavailability of drugs. This review spots the light on the recent advances made in the area of microfluidics including various methods of fabrication of drug carriers, their characterization, and unique features. Furthermore, applications of microfluidic technology for the robust fabrication and development of drug delivery systems, the existing challenges associated with conventional fabrication methodologies as well as the proposed solutions offered by microfluidic technology have been discussed in details.HighlightsMicrofluidic technology has revolutionized fabrication of tunable micro and nanocarriers.Microfluidic platforms offer several advantages over the conventional fabrication methods.Microfluidic devices hold great promise in controlling the physicochemical features of fabricated drug carriers.Micro and nanocarriers with controllable release kinetics and site-targeting efficiency can be fabricated.Drug carriers fabricated by microfluidic technology exhibited improved pharmacokinetic and pharmacodynamic profiles.

Recent Trends of Microfluidics in Food Science and Technology: Fabrications and Applications

The development of novel materials with microstructures is now a trend in food science and technology. These microscale materials may be applied across all steps in food manufacturing, from raw materials to the final food products, as well as in the packaging, transport, and storage processes. Microfluidics is an advanced technology for controlling fluids in a microscale channel (1~100 μm), which integrates engineering, physics, chemistry, nanotechnology, etc. This technology allows unit operations to occur in devices that are closer in size to the expected structural elements. Therefore, microfluidics is considered a promising technology to develop micro/nanostructures for delivery purposes to improve the quality and safety of foods. This review concentrates on the recent developments of microfluidic systems and their novel applications in food science and technology, including microfibers/films via microfluidic spinning technology for food packaging, droplet microfluidics for food micro-/nanoemulsifications and encapsulations, etc.

A pH-Responsive Cluster Metal-Organic Framework Nanoparticle for Enhanced Tumor Accumulation and Antitumor Effect

As a result of the deficient tumor-specific antigens, potential off-target effect, and influence of protein corona, metal-organic framework nanoparticles have inadequate accumulation in tumor tissues, limiting their therapeutic effects. In this work, a pH-responsive linker (L) is prepared by covalently modifying oleylamine (OA) with 3-(bromomethyl)-4-methyl-2,5-furandione (MMfu) and poly(ethylene glycol) (PEG). Then, the L is embedded into a solid lipid nanoshell to coat apilimod (Ap)-loaded zeolitic imidazolate framework (Ap-ZIF) to form Ap-ZIF@SLN#L. Under the tumor microenvironment, the hydrophilic PEG and MMfu are removed, exposing the hydrophobic OA on Ap-ZIF@SLN#L, increasing their uptake in cancer cells and accumulation in the tumor. The ZIF@SLN#L nanoparticle induces reactive oxygen species (ROS). Ap released from Ap-ZIF@SLN#L significantly promotes intracellular ROS and lactate dehydrogenase generation. Ap-ZIF@SLN#L inhibits tumor growth, increases the survival rate in mice, activates the tumor microenvironment, and improves the infiltration of macrophages and T cells in the tumor, as demonstrated in two different tumor-bearing mice after injections with Ap-ZIF@SLN#TL. Furthermore, mice show normal tissue structure of the main organs and the normal serum level in alanine aminotransferase and aspartate aminotransferase after treatment with the nanoparticles. Overall, this pH-responsive targeting strategy improves nanoparticle accumulation in tumors with enhanced therapeutic effects.

The diffusion-driven microfluidic process to manufacture lipid-based nanotherapeutics with stealth properties for siRNA delivery

Our study investigated the manufacturing of lipid-based nanotherapeutics with stealth properties for siRNA delivery by employing a diffusion-driven microfluidic process in one or two-steps strategies to produce siRNA-loaded lipid nanocarriers and lipoplexes, respectively. In the one-step synthesis, siRNA in the aqueous phase is introduced from one inlet, while phospholipids dispersed in anhydrous ethanol are introduced from other inlets, generating the lipid nanocarriers. In the two-steps strategies, the pre-formed liposomes are complexed with siRNA. The process configuration with an aqueous diffusion barrier exerts a significant effect on the nanoaggregates synthesis. Dynamic light scattering data showed that lipid nanocarriers had a bigger particle diameter (298 ± 24 nm) and surface charge (43 ± 6 mV) compared to lipoplexes (194 ± 7 nm and 37.0 ± 0.4 mV). Moreover, DSPE-PEG(2000) was included in the formulation to synthesize lipid-based nanotherapeutics containing siRNA with stealth characteristics. The inclusion of PEG-lipid resulted in an increase in the surface charge of lipoplexes (from 33.7 ± 4.4-54.3 ± 1.6 mV), while a significant decrease was observed in the surface charge of lipid nanocarriers (30.3 ± 8.7 mV). The different structural assemblies were identified for lipoplex and lipid nanocarriers using Synchrotron SAXS. Lipid nanocarriers present a lower amount of multilayers than lipoplexes. Lipid-PEG insertion significantly influenced lipid nanocarriers' characteristics, drastically decreasing the number of multilayers. This effect was not observed in lipoplexes. The association between process configuration, lipid composition, and its effect on the characteristics of lipid-based vector systems can generate fundamental insights, contributing to gene-based nanotherapeutics development.

Biodegradable Microparticles for Regenerative Medicine: A State of the Art and Trends to Clinical Application

Tissue engineering and cell therapy are very attractive in terms of potential applications but remain quite challenging regarding the clinical aspects. Amongst the different strategies proposed to facilitate their implementation in clinical practices, biodegradable microparticles have shown promising outcomes with several advantages and potentialities. This critical review aims to establish a survey of the most relevant materials and processing techniques to prepare these micro vehicles. Special attention will be paid to their main potential applications, considering the regulatory constraints and the relative easiness to implement their production at an industrial level to better evaluate their application in clinical practices.

A novel magnetophoretic-based device for magnetometry and separation of single magnetic particles and magnetized cells

The use of magnetic micro- and nanoparticles in medicine and biology is expanding. One important example is the transport of magnetic microparticles and magnetized cells in lab-on-a-chip systems. The magnetic susceptibility of the particles is a key factor in determining their response to the externally applied magnetic field. Typically, to measure this parameter, their magnetophoretic mobility is studied. However, the particle tracking system for accurately determining the traveled distance in a certain time may be too complicated. Here, we introduce a lithographically fabricated chip composed of an array of thin magnetic micro-disks for evaluating the magnetic susceptibility of numerous individual magnetic particles simultaneously. The proposed novel magnetometer works based on the phase change in the trajectory of microparticles circulating around the disks in a rotating in-plane magnetic field. We explain that the easily detectable transition between the "phase-locked" and the "phase-slipping" regimes and the frequency at which it happens are appropriate parameters for measuring the magnetic susceptibility of the magnetic particles at the single-particle level. We show that this high-throughput (i.e., ∼ten thousand particles on a 1 cm² area) single-particle magnetometry method has various crucial applications, including i) magnetic characterization of magnetic beads as well as magnetically labeled living cells, ii) determining the magnetization rate of the cells taking up magnetic nanoparticles with respect to time, iii) evaluating the rate of degradation of magnetic nanoparticles in cells over time, iv) detecting the number of target cells in a sample, and v) separating particles based on their size and magnetic susceptibility.

Microfluidic technologies for nanoparticle formation

Functional nanoparticles (NPs) hold immense promise in diverse fields due to their unique biological, chemical, and physical properties associated with size or morphology. Microfluidic technologies featuring precise fluid manipulation have become versatile toolkits for manufacturing NPs in a highly controlled manner with low batch-to-batch variability. In this review, we present the fundamentals of microfluidic fabrication strategies, including mixing-, droplet-, and multiple field-based microfluidic methods. We highlight the formation of functional NPs using these microfluidic reactors, with an emphasis on lipid NPs, polymer NPs, lipid-polymer hybrid NPs, supramolecular NPs, metal and metal-oxide NPs, metal-organic framework NPs, covalent organic framework NPs, quantum dots, perovskite nanocrystals, biomimetic NPs, etc. we discuss future directions in microfluidic fabrication for accelerated development of functional NPs, such as device parallelization for large-scale NP production, highly efficient optimization of NP formulations, and AI-guided design of multi-step microfluidic reactors.

A microfluidic valve with bubble trap and zero dead volume

We present a technique to swiftly change the contents of a small sample chamber using only a few times the chamber volume. Our design has no dead volume and functions as a manifold that minimizes mixing between consecutive liquids at one inlet. Thereby, it is ideal for minimizing sample consumption. In addition, our fluidic circuit works as an efficient bubble trap. These properties make our design an exciting alternative to standard solutions using multiple valves and junctions.

Design and synthesis of gold nanostars-based SERS nanotags for bioimaging applications

Surface-enhanced Raman spectroscopy (SERS) nanotags hold a unique place among bioimaging contrast agents due to their fingerprint-like spectra, which provide one of the highest degrees of detection specificity. However, in order to achieve a sufficiently high signal intensity, targeting capabilities, and biocompatibility, all components of nanotags must be rationally designed and tailored to a specific application. Design parameters include fine-tuning the properties of the plasmonic core as well as optimizing the choice of Raman reporter molecule, surface coating, and targeting moieties for the intended application. This review introduces readers to the principles of SERS nanotag design and discusses both established and emerging protocols of their synthesis, with a specific focus on the construction of SERS nanotags in the context of bioimaging and theranostics.

Fullerol-hydrogel microfluidic spheres for in situ redox regulation of stem cell fate and refractory bone healing

The balance of redox homeostasis is key to stem cell maintenance and differentiation. However, this balance is disrupted by the overproduced reactive oxygen species (ROS) in pathological conditions, which seriously impair the therapeutic efficacy of stem cells. In the present study, highly dispersed fullerol nanocrystals with enhanced bioreactivity were incorporated into hydrogel microspheres using one-step innovative microfluidic technology to construct fullerol-hydrogel microfluidic spheres (FMSs) for in situ regulating the redox homeostasis of stem cells and promoting refractory bone healing. It was demonstrated that FMSs exhibited excellent antioxidant activity to quench both intracellular and extracellular ROS, sparing stem cells from oxidative stress damage. Furthermore, these could effectively promote the osteogenic differentiation of stem cells with the activation of FoxO1 signaling, indicating the intrinsically osteogenic property of FMSs. By injecting the stem cells-laden FMSs into rat calvarial defects, the formation of new bone was remarkably reinforced, which is a positive synergic effect from modulating the ROS microenvironment and enhancing the osteogenesis of stem cells. Collectively, the antioxidative FMSs, as injectable stem cell carriers, hold enormous promise for refractory bone healing, which can also be expanded to deliver a variety of other cells, targeting diseases that require in situ redox regulation.

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.

Microfluidicmixing system for precise PLGA-PEG nanoparticles size control

In this study, a microfluidic device was employed to produce polymeric nanoparticles (NPs) with well-controlled sizes. The influence of several parameters in the synthesis process, namely, polymer concentration, flow rate and flow rate ratio between the aqueous and organic solutions was investigated. To evaluate the NPs size effect, three diameters were selected (30, 50 and 70nm). Their cytocompatibility was demonstrated on endothelial cells and macrophages. Additionally, their efficacy to act as drug carriers was assessed in an in vitro inflammatory scenario. NPs loaded and released diclofenac (DCF) in a size-dependent profile (smaller sizes presented lower DCF content and higher release rate). Moreover, 30nm NPs were the most effective in reducing prostaglandin E₂ concentration. Therefore, this study demonstrates that microfluidics can generate stable NPs with controlled sizes, high monodispersity and enhanced batch-to-batch reproducibility. Indeed, NPs size is a crucial parameter for drug encapsulation, release and overall biological efficacy.

Lipid in Chips: A Brief Review of Liposomes Formation by Microfluidics

Liposomes are ubiquitous tools in biomedical applications, such as drug delivery, membrane science and artificial cell. Micro- and nanofabrication techniques have revolutionized the preparation of liposomes on the microscale. State-of-the-art liposomal formation on microfluidic chips and its associated applications are introduced in this review. We attempt to provide a reference for liposomal researchers by comparing various microfluidic techniques for liposomes formation.

Microfluidic encapsulation for controlled release and its potential for nanofertilisers

Nanotechnology is increasingly being utilized to create advanced materials with improved or new functional attributes. Converting fertilizers into a nanoparticle-form has been shown to improve their efficacy but the current procedures used to fabricate nanofertilisers often have poor reproducibility and flexibility. Microfluidic systems, on the other hand, have advantages over traditional nanoparticle fabrication methods in terms of energy and materials consumption, versatility, and controllability. The increased controllability can result in the formation of nanoparticles with precise and complex morphologies (e.g., tuneable sizes, low polydispersity, and multi-core structures). As a result, their functional performance can be tailored to specific applications. This paper reviews the principles, formation, and applications of nano-enabled delivery systems fabricated using microfluidic approaches for the encapsulation, protection, and release of fertilizers. Controlled release can be achieved using two main routes: (i) nutrients adsorbed on nanosupports and (ii) nutrients encapsulated inside nanostructures. We aim to highlight the opportunities for preparing a new generation of highly versatile nanofertilisers using microfluidic systems. We will explore several main characteristics of microfluidically prepared nanofertilisers, including droplet formation, shell fine-tuning, adsorbate fine-tuning, and sustained/triggered release behavior.

Microfluidic preparation and in vitro evaluation of iRGD-functionalized solid lipid nanoparticles for targeted delivery of paclitaxel to tumor cells

Solid lipid nanoparticles (SLNs) can combine the advantages of different colloidal carriers and prevent some of their disadvantages. The production of nanoparticles by means of microfluidics represents a successful platform for industrial scale-up of nanoparticle manufacture in a reproducible way. The realisation of a microfluidic technique to obtain SLNs in a continuous and reproducible manner encouraged us to create surface functionalised SLNs for targeted drug release using the same procedure. A tumor homing peptide, iRGD, owning a cryptic C-end Rule (CendR) motif is responsible for neuropilin-1 (NRP-1) binding and for triggering extravasation and tumor penetration of the peptide. In this study, the Paclitaxel loaded-SLNs produced by microfluidics were functionalized with the iRGD peptide. The SLNs proved to be stable in aqueous medium andwere characterized by a Z-average under 150 nm, a polydispersity index below 0.2, a zeta-potential between -20 and -35 mV and a drug encapsulation efficiency around 40%. Moreover, in vitro cytotoxic effects and cellular uptake have been assessed using 2D and 3D tumour models of U87 glioblastoma cell lines. Overall, these results demonstrate that the surface functionalization of SLNs with iRGD allow better cellular uptake and cytotoxicity ability.

Advances in Magnetic Nanoparticles Engineering for Biomedical Applications-A Review

Magnetic iron oxide nanoparticles (MNPs) have been developed and applied for a broad range of biomedical applications, such as diagnostic imaging, magnetic fluid hyperthermia, targeted drug delivery, gene therapy and tissue repair. As one key element, reproducible synthesis routes of MNPs are capable of controlling and adjusting structure, size, shape and magnetic properties are mandatory. In this review, we discuss advanced methods for engineering and utilizing MNPs, such as continuous synthesis approaches using microtechnologies and the biosynthesis of magnetosomes, biotechnological synthesized iron oxide nanoparticles from bacteria. We compare the technologies and resulting MNPs with conventional synthetic routes. Prominent biomedical applications of the MNPs such as diagnostic imaging, magnetic fluid hyperthermia, targeted drug delivery and magnetic actuation in micro/nanorobots will be presented.

Hyaluronic Acid-Based Nanoparticles for Protein Delivery: Systematic Examination of Microfluidic Production Conditions

Hyaluronic acid-based nanoparticles (HA NPs) can be used to deliver a protein cargo to cells overexpressing HA receptors such as CD44 since they combine the low toxicity of the carrier and the retention of the protein integrity with the receptor-mediated internalization. HA properties play a crucial but sometimes unclear role in managing the formation and stability of the meshwork, cell interactions, and ultimately the protein entrapment efficacy. Nowadays, microfluidic is an innovative technology that allows to overcome limits linked to the NPs production, guaranteeing reproducibility and control of individual batches. Taking advantage of this technique, in this research work, the role of HA weight average molecular weight (Mw) in NPs formation inside a microfluidic device has been specifically faced. Based on the relationship between polymer Mw and solution viscosity, a methodological approach has been proposed to ensure critical quality attributes (size of 200 nm, PDI ≤ 0.3) to NPs made by HA with different Mw (280, 540, 710 and 820 kDa). The feasibility of the protein encapsulation was demonstrated by using Myoglobin, as a model neutral protein, with an encapsulation efficiency always higher than 50%. Lastly, all NPs samples were successfully internalized by CD44-expressing cells.

Microfluidic Network Simulations Enable On-Demand Prediction of Control Parameters for Operating Lab-on-a-Chip-Devices

Reliable operation of lab-on-a-chip systems depends on user-friendly, precise, and predictable fluid management tailored to particular sub-tasks of the microfluidic process protocol and their required sample fluids. Pressure-driven flow control, where the sample fluids are delivered to the chip from pressurized feed vessels, simplifies the fluid management even for multiple fluids. The achieved flow rates depend on the pressure settings, fluid properties, and pressure-throughput characteristics of the complete microfluidic system composed of the chip and the interconnecting tubing. The prediction of the required pressure settings for achieving given flow rates simplifies the control tasks and enables opportunities for automation. In our work, we utilize a fast-running, Kirchhoff-based microfluidic network simulation that solves the complete microfluidic system for in-line prediction of the required pressure settings within less than 200 ms. The appropriateness of and benefits from this approach are demonstrated as exemplary for creating multi-component laminar co-flow and the creation of droplets with variable composition. Image-based methods were combined with chemometric approaches for the readout and correlation of the created multi-component flow patterns with the predictions obtained from the solver.

Non-viral nanoparticles for RNA interference: Principles of design and practical guidelines

Ribonucleic acid interference (RNAi) is an innovative treatment strategy for a myriad of indications. Non-viral synthetic nanoparticles (NPs) have drawn extensive attention as vectors for RNAi due to their potential advantages, including improved safety, high delivery efficiency and economic feasibility. However, the complex natural process of RNAi and the susceptible nature of oligonucleotides render the NPs subject to particular design principles and requirements for practical fabrication. Here, we summarize the requirements and obstacles for fabricating non-viral nano-vectors for efficient RNAi. To address the delivery challenges, we discuss practical guidelines for materials selection and NP synthesis in order to maximize RNA encapsulation efficiency and protection against degradation, and to facilitate the cytosolic release of oligonucleotides. The current status of clinical translation of RNAi-based therapies and further perspectives for reducing the potential side effects are also reviewed.

Particle engineering principles and technologies for pharmaceutical biologics

The global market of pharmaceutical biologics has expanded significantly during the last few decades. Currently, pharmaceutical biologic products constitute an indispensable part of the modern medicines. Most pharmaceutical biologic products are injections either in the forms of solutions or lyophilized powders because of their low oral bioavailability. There are certain pharmaceutical biologic entities formulated into particulate delivery systems for the administration via non-invasive routes or to achieve prolonged pharmaceutical actions to reduce the frequency of injections. It has been well documented that the design of nano- and microparticles via various particle engineering technologies could render pharmaceutical biologics with certain benefits including improved stability, enhanced intracellular uptake, prolonged pharmacological effect, enhanced bioavailability, reduced side effects, and improved patient compliance. Herein, we review the principles of the particle engineering technologies based on bottom-up approach and present the important formulation and process parameters that influence the critical quality attributes with some mathematical models. Subsequently, various nano- and microparticle engineering technologies used to formulate or process pharmaceutical biologic entities are reviewed. Lastly, an array of commercialized products of pharmaceutical biologics accomplished based on various particle engineering technologies are presented and the challenges in the development of particulate delivery systems for pharmaceutical biologics are discussed.

Microfluidic Synthesis, Control, and Sensing of Magnetic Nanoparticles: A Review

Magnetic nanoparticles have attracted significant attention in various disciplines, including engineering and medicine. Microfluidic chips and lab-on-a-chip devices, with precise control over small volumes of fluids and tiny particles, are appropriate tools for the synthesis, manipulation, and evaluation of nanoparticles. Moreover, the controllability and automation offered by the microfluidic chips in combination with the unique capabilities of the magnetic nanoparticles and their ability to be remotely controlled and detected, have recently provided tremendous advances in biotechnology. In particular, microfluidic chips with magnetic nanoparticles serve as sensitive, high throughput, and portable devices for contactless detecting and manipulating DNAs, RNAs, living cells, and viruses. In this work, we review recent fundamental advances in the field with a focus on biomedical applications. First, we study novel microfluidic-based methods in synthesizing magnetic nanoparticles as well as microparticles encapsulating them. We review both continues-flow and droplet-based microreactors, including the ones based on the cross-flow, co-flow, and flow-focusing methods. Then, we investigate the microfluidic-based methods for manipulating tiny magnetic particles. These manipulation techniques include the ones based on external magnets, embedded micro-coils, and magnetic thin films. Finally, we review techniques invented for the detection and magnetic measurement of magnetic nanoparticles and magnetically labeled bioparticles. We include the advances in anisotropic magnetoresistive, giant magnetoresistive, tunneling magnetoresistive, and magnetorelaxometry sensors. Overall, this review covers a wide range of the field uniquely and provides essential information for designing "lab-on-a-chip" systems for synthesizing magnetic nanoparticles, labeling bioparticles with them, and sorting and detecting them on a single chip.

A Survey on Analytical Methods for the Characterization of Green Synthesized Nanomaterials

Nowadays, nanotechnologies are well established and the uses of a great variety of nanomaterials show exponential growth. The development of green synthesis procedures experienced a great development thanks to the contribution of researchers of diverse origins. The versatility of green chemistry allows producing a wide range of organic and inorganic nanomaterials with numerous promising applications. In all cases, it is of paramount importance to carefully characterize the resulting nanomaterials because their properties will determine their correct performance to accomplish the function to which they were synthesized or even their detrimental effects like nanotoxicological behavior. This review provides an overview of frequently employed characterization methods and their applications for green synthesized nanomaterials. However, while several different nanoscale materials and their associated green construction methodology are being developed, other important techniques would be extensively incorporated into this field soon. The aim is to encourage researchers in the field to employ a variety of these techniques for achieving an exhaustive characterization of new nanomaterials and for contributing to the development of validated green synthesis procedures.

Acetalated dextran based nano- and microparticles: synthesis, fabrication, and therapeutic applications

Acetalated dextran (Ac-DEX) is a pH-responsive dextran derivative polymer. Prepared by a simple acetalation reaction, Ac-DEX has tunable acid-triggered release profile. Despite its relatively short research history, Ac-DEX has shown great potential in various therapeutic applications. Furthermore, the recent functionalization of Ac-DEX makes versatile derivatives with additional properties. Herein, we summarize the cutting-edge development of Ac-DEX and related polymers. Specifically, we focus on the chemical synthesis, nano- and micro-particle fabrication techniques, the controlled-release mechanisms, and the rational design Ac-DEX-based of drug delivery systems in various biomedical applications. Finally, we briefly discuss the challenges and future perspectives in the field.

Self-Driving Laboratories for Development of New Functional Materials and Optimizing Known Reactions

Innovations often play an essential role in the acceleration of the new functional materials discovery. The success and applicability of the synthesis results with new chemical compounds and materials largely depend on the previous experience of the researcher himself and the modernity of the equipment used in the laboratory. Artificial intelligence (AI) technologies are the next step in developing the solution for practical problems in science, including the development of new materials. Those technologies go broadly beyond the borders of a computer science branch and give new insights and practical possibilities within the far areas of expertise and chemistry applications. One of the attractive challenges is an automated new functional material synthesis driven by AI. However, while having many years of hands-on experience, chemistry specialists have a vague picture of AI. To strengthen and underline AI's role in materials discovery, a short introduction is given to the essential technologies, and the machine learning process is explained. After this review, this review summarizes the recent studies of new strategies that help automate and accelerate the development of new functional materials. Moreover, automatized laboratories' self-driving cycle could benefit from using AI algorithms to optimize new functional nanomaterials' synthetic routes. Despite the fact that such technologies will shape material science in the nearest future, we note the intelligent use of algorithms and automation is required for novel discoveries.

Micro-/Nano-Structures on Biodegradable Magnesium@PLGA and Their Cytotoxicity, Photothermal, and Anti-Tumor Effects

The size and structural control of particulate carriers for imaging agents and therapeutics are constant themes in designing smart delivery systems. This is motivated by the causal relationship between geometric parameters and functionalities of delivery vehicles. Here, both in vitro and in vivo, the controlling factors for cytotoxicity, photothermal, and anti-tumor effects of biodegradable magnesium@poly(lactic-co-glycolic acid (Mg@PLGA) particulate carriers with different sizes and shell thicknesses are investigated. Mg@PLGA microspheres fabricated by microfluidic emulsification are shown to have higher Mg encapsulation efficiency, 87%, than nanospheres by ultrasonic homogenization, 50%. The photothermal and anti-tumor effects of Mg@PLGA spheres are found to be dictated by their Mg content, irrelevant to size and structural features, as demonstrated in both in vitro cell assays and in vivo mice models. These results also provide important implications for designing and fabricating stimuli-responsive drug delivery vehicles.

Tunable Harmonic Flow Patterns in Microfluidic Systems through Simple Tube Oscillation

Generation of tunable harmonic flows at low cost in microfluidic systems is a persistent and significant obstacle to this field, substantially limiting its potential to address major scientific questions and applications. This work introduces a simple and elegant way to overcome this obstacle. Harmonic flow patterns can be generated in microfluidic structures by simply oscillating the inlet tubes. Complex rib and vortex patterns can be dynamically modulated by changing the frequency and magnitude of tube oscillation and the viscosity of liquid. Highly complex rib patterns and synchronous vortices can be generated in serially connected microfluidic chambers. Similar dynamic patterns can be generated using whole or diluted blood samples without damaging the sample. This method offers unique opportunities for studying complex fluids and soft materials, chemical synthesis of various compounds, and mimicking harmonic flows in biological systems using compact, tunable, and low-cost devices.

Synthesis and Surface Engineering of Inorganic Nanomaterials Based on Microfluidic Technology

The controlled synthesis and surface engineering of inorganic nanomaterials hold great promise for the design of functional nanoparticles for a variety of applications, such as drug delivery, bioimaging, biosensing, and catalysis. However, owing to the inadequate and unstable mass/heat transfer, conventional bulk synthesis methods often result in the poor uniformity of nanoparticles, in terms of microstructure, morphology, and physicochemical properties. Microfluidic technologies with advantageous features, such as precise fluid control and rapid microscale mixing, have gathered the widespread attention of the research community for the fabrication and engineering of nanomaterials, which effectively overcome the aforementioned shortcomings of conventional bench methods. This review summarizes the latest research progress in the microfluidic fabrication of different types of inorganic nanomaterials, including silica, metal, metal oxides, metal organic frameworks, and quantum dots. In addition, the surface modification strategies of nonporous and porous inorganic nanoparticles based on microfluidic method are also introduced. We also provide the readers with an insight on the red blocks and prospects of microfluidic approaches, for designing the next generation of inorganic nanomaterials.

Core/Shell PEGS/HA Hybrid Nanoparticle Via Micelle-Coordinated Mineralization for Tumor-Specific Therapy

Nanomicelles, by virtue of their prominent biocompatibility, degradability, and ability to solubilize hydrophobic drugs, have been widely used as the most effective delivery platform for anticancer drugs. However, undesirable drug-loading capacity, unfeasible modification, poor in vivo stability, and intratumoral penetration remain to be addressed. Herein, we introduce a novel core/shell PEGylated poly(glycerol sebacate) (PEGS)/hydroxyapatite (HA) hybrid nanomicelle based on a unique triblock PEGS substrate with functional carboxyls in terminals and free hydroxyls as pendant groups. The hydrophobic doxorubicin (DOX) can be controllably encapsulated in the core of nanomicelles via hydrogen bonding, and ensuing in situ mineralization of HA occurs as a shell layer with the electrostatic effect between the carboxylate radical (COO^-) and calcium ion (Ca²⁺). Through optimizing the coordination of PEGS nanomicelles and HA mineralization, 20-30 nm spherical nanoparticles can be formed with considerable drug loading (0.38 mg DOX/1 mg nanoparticles) and a sensitive pH-responsive release (about 50% release amount at pH 5.6 while <5% release amount at pH 7.4 in 24 h). In further in vitro studies, this PEGS/HA hybrid nanoparticle system exhibits excellent selective tumor inhibitory efficacy, while in in vivo studies, high efficacy of tumor suppression and low incidence of toxicity can be evidenced in a DOX-loaded PEGS/HA group (71.7% decrease in average tumor volume compared to a control group after 15 day hypodermic treatment). The core/shell PEGS/HA nanoparticle coordinated with PEGS nanomicelles and in situ HA mineralization represents high drug-loading capacity, multifunctional possibility, and tumor-selective and responsive release profiles and could offer a highly promising platform for tumor therapy in clinical application.

Thermodynamic, Spatial and Methodological Considerations for the Manufacturing of Therapeutic Polymer Nanoparticles

PURPOSE

Evaluate fundamental parameters that dictate the effectiveness of drug loading.

METHODS

A model water-soluble drug lacking ionizable groups, pirfenidone (PFD), was encapsulated through nanoprecipitation in poly(ethylene glycol)-poly(lactic acid) (PEG-PLA)-poly(lactic-co-glycolic acid) (PLGA) NPs. Firstly, the thermodynamic parameters predicting drug-polymer miscibility were determined to assess the system's suitability. Then, the encapsulation was evaluated experimentally by two different techniques, bulk and microfluidic (MF) nanoprecipitation. Additionally, the number of molecules that fit in a particle core were calculated and the loading determined experimentally for different core sizes. Lastly, the effect of co-encapsulation of α-lipoic acid (LA), a drug with complementary therapeutic effects and enhanced lipophilicity, was evaluated.

RESULTS

The thermodynamic miscibility parameters predicted a good suitability of the selected system. MF manufacturing enhanced the encapsulation efficiency by 60-90% and achieved a 2-fold higher NP cellular uptake. Considering spatial constrictions for drug encapsulation and increasing the size of the PLGA core the number of PFD molecules per NP was raised from under 500 to up to 2000. More so, the co-encapsulation of LA increased the number of drug molecules per particle by 96%, with no interference with the release profile.

CONCLUSIONS

Thermodynamic, spatial and methodological parameters should be considered to optimize drug encapsulation.

Step emulsification in microfluidic droplet generation: mechanisms and structures

Step emulsification for micro- and nano-droplet generation is reviewed in brief, including the emulsion mechanisms and microfluidic devices.