Static micromixer-coaxial electrospray synthesis of theranostic lipoplexes

Microfluidic Roadmap for Translational Nanotheranostics

Nanotheranostic materials (NTMs) shed light on the mechanisms responsible for complex diseases such as cancer because they enable making a diagnosis, monitoring the disease progression, and applying a targeted therapy simultaneously. However, several issues such as the reproducibility and mass production of NTMs hamper their application for clinical practice. To address these issues and facilitate the clinical application of NTMs, microfluidic systems have been increasingly used. This perspective provides a glimpse into the current state-of-art of NTM research, emphasizing the methods currently employed at each development stage of NTMs and the related open problems. This work reviews microfluidic technologies used to develop NTMs, ranging from the fabrication and testing of a single NTM up to their manufacturing on a large scale. Ultimately, a step-by-step vision on the future development of NTMs for clinical practice enabled by microfluidics techniques is provided.

Parametric Study of the Factors Influencing Liposome Physicochemical Characteristics in a Periodic Disturbance Mixer

Liposomes encapsulate different substances ranging from drugs to genes. Control over the average size and size distribution of these nanoparticles is vital for biomedical applications since these characteristics determine to a high degree where liposomes will accumulate in the human body. Micromixers enable the continuous flow synthesis of liposomes, improving size control and reproducibility. Recently, Dean flow dynamics-based micromixers, such as the periodic disturbance mixer (PDM), have been shown to produce controlled-size liposomes in a scalable and reproducible way. However, contrary to micromixers based on molecular diffusion or chaotic advection, their production factors and their influence over liposome properties have not yet been addressed thoroughly. In this work, we present a comprehensive parametric study of the effects of flow conditions and molecular changing factors such as concentration, lipid type, and temperature on the physicochemical characteristics of liposomes. Numerical models and confocal images are used to quantitatively and qualitatively evaluate mixing performance under different liposome production conditions and their relationship with vesicle properties. The total flow rate (TFR) and, to a lesser extent, the flow rate ratio (FRR) control the liposome size and size distribution. Effects on liposome size are also observed by changing the molecular factors. Moreover, the liposome ζ potential is independent of the factors studied here. The micromixer presented in this work enables the production of liposomes as small as 24 nm, with monodispersed to low or close to low polydispersed liposome populations as well as a production rate as high as 41 mg/h.

Ultrafast Detection of Exosomal RNAs via Cationic Lipoplex Nanoparticles in a Micromixer Biochip for Cancer Diagnosis

Exosomes are cell-derived, nanosized extracellular vesicles for intercellular communication. Exosomal RNAs have been shown as one type of promising cancer liquid biopsy biomarkers. Conventional methods to characterize exosomal RNAs such as quantitative reverse transcription polymerase chain reaction (qRT-PCR) are limited by low sensitivity, large sample consumption, time-consuming process, and high cost. Many technologies have been developed to overcome these challenges; however, many hours are still required to complete the assays, especially when exosome lysis and RNA extraction are required. We have developed a microfluidic cationic lipoplex nanoparticles (mCLN) assay that utilizes a micromixer biochip to allow for the effective capture of exosomes by cationic lipoplex nanoparticles and thus enables ultrafast and sensitive exosomal RNA detection for cancer diagnosis. The sensing performance and diagnostic performance of the mCLN assay were investigated using non-small cell lung cancer (NSCLC) as the disease model and exosomal microRNA-21 and TTF-1 mRNA as the biomarkers. The limits of detection of the mCLN assay were 2.06 × 10⁹ and 3.71 × 10⁹ exosomes/mL for microRNA-21 and TTF-1 mRNA, respectively, indicating that the mCLN assay may require as low as 1 μL of serum for exosomal RNA detection. The mCLN assay successfully distinguished NSCLC from normal controls by detecting significantly higher microRNA-21 and TTF-1 mRNA levels in exosomes from both NSCLC patient serum samples and A549 NSCLC cells than those from normal controls and BEAS-2B normal bronchial epithelial cells. Compared with conventional qRT-PCR assay, the mCLN assay showed a higher diagnostic accuracy in lung cancer, required less sample volume (30 vs 100 μL), and consumed much less time (10 min vs 4 h).

Ultrashort Peptide Theranostic Nanoparticles by Microfluidic-Assisted Rapid Solvent Exchange

Ultrashort peptides (USPs), composed of three to seven amino acids, can self-assemble into nanofibers in pure water. Here, using hydrodynamic focusing and a solvent exchange method on a microfluidic setup, we convert these nanofibers into globular nanoparticles with excellent dimensional control and polydispersity. Thanks to USP nanocarriers' structure, different drugs can be loaded. We used Curcumin as a model drug to evaluate the performance of USP nanocarriers as a novel drug delivery vehicle. These nanoparticles can efficiently cross the cell membrane and possess nonlinear optical properties. Therefore, we envisage USP nanoparticles as promising future theranostic nanocarriers.

Progress in Polymeric Nano-Medicines for Theranostic Cancer Treatment

Cancer is a life-threatening disease killing millions of people globally. Among various medical treatments, nano-medicines are gaining importance continuously. Many nanocarriers have been developed for treatment, but polymerically-based ones are acquiring importance due to their targeting capabilities, biodegradability, biocompatibility, capacity for drug loading and long blood circulation time. The present article describes progress in polymeric nano-medicines for theranostic cancer treatment, which includes cancer diagnosis and treatment in a single dosage form. The article covers the applications of natural and synthetic polymers in cancer diagnosis and treatment. Efforts were also made to discuss the merits and demerits of such polymers; the status of approved nano-medicines; and future perspectives.

Surface Response Based Modeling of Liposome Characteristics in a Periodic Disturbance Mixer

Liposomes nanoparticles (LNPs) are vesicles that encapsulate drugs, genes, and imaging labels for advanced delivery applications. Control and tuning liposome physicochemical characteristics such as size, size distribution, and zeta potential are crucial for their functionality. Liposome production using micromixers has shown better control over liposome characteristics compared with classical approaches. In this work, we used our own designed and fabricated Periodic Disturbance Micromixer (PDM). We used Design of Experiments (DoE) and Response Surface Methodology (RSM) to statistically model the relationship between the Total Flow Rate (TFR) and Flow Rate Ratio (FRR) and the resulting liposomes physicochemical characteristics. TFR and FRR effectively control liposome size in the range from 52 nm to 200 nm. In contrast, no significant effect was observed for the TFR on the liposomes Polydispersity Index (PDI); conversely, FRR around 2.6 was found to be a threshold between highly monodisperse and low polydispersed populations. Moreover, it was shown that the zeta potential is independent of TFR and FRR. The developed model presented on the paper enables to pre-establish the experimental conditions under which LNPs would likely be produced within a specified size range. Hence, the model utility was demonstrated by showing that LNPs were produced under such conditions.

Electrospraying preparation of metal germanate nanospheres for high-performance lithium-ion batteries and room-temperature gas sensors

Metal germanate nanospheres including Ca₂Ge₇O₁₆, Zn₂GeO₄ and SrGe₄O₉ were successfully synthesized by a direct and large-scale electrospraying method. As anodes for lithium ion batteries, the prepared metal germanate nanospheres showed high electrochemical lithium storage performance including excellent cycling stability and high rate capacity. Especially, the Ca₂Ge₇O₁₆ nanosphere anode delivered a high specific capacity of ∼ 670 mA h g^-1 at 0.2 A g^-1. The capacity retention was maintained around 71% even after 500 cycles. Moreover, when applied as room-temperature ammonia gas sensors, all three prepared germinate nanospheres showed significant sensing response values (6.04 for SrGe₄O₉, 2.73 for Zn₂GeO₄ and 1.70 for Ca₂Ge₇O₁₆), fast response-recovery time, excellent stability and outstanding selectivity.

Electrospray Functionalization of Titanium Dioxide Nanoparticles with Transferrin for Cerenkov Radiation Induced Cancer Therapy

Titanium dioxide (TiO₂) nanoparticles have shown success as photosensitizers in the form of light-based cancer therapy called Cerenkov radiation induced therapy (CRIT). While TiO₂ nanoparticles have been reported to be an effective therapeutic agent, there has been little work to control their functionalization and stability in aqueous suspension. In this work, the controlled coating of 25 nm diameter TiO₂ nanoparticles with the glycoprotein transferrin (Tf) for application in CRIT was demonstrated using an electrospray system. Monodisperse nanoscale droplets containing TiO₂ and Tf were dried during flight, coating the proteins on the surface of the metal oxide nanoparticles. Real-time scanning mobility particle sizing, dynamic light scattering, and transmission electron microscopy show efficient control of the Tf coating thickness when varying the droplet size and the ratio of Tf to TiO₂ in the electrospray precursor suspension. Further, the functionality of Tf-coated TiO₂ nanoparticles was demonstrated, and these particles were found to have enhanced targeting activity of Tf to the Tf receptor after electrospray processing. The electrospray-coated Tf/TiO₂ particles were also found to be more effective at killing the multiple myeloma cell line MM1.S than that of nanoparticles prepared by other reported functionalization methods. In summary, this investigation not only provides a single-step functionalization technique for nanomaterials used in Cerenkov radiation induced therapy but also elucidates an electrospray coating technique for nanomaterials that can be used for a wide range of drug design and delivery purposes.

Influence of Solvent Selection in the Electrospraying Process of Polycaprolactone

Electrosprayed polycaprolactone (PCL) microparticles are widely used in medical tissueengineering, drug control release delivery, and food packaging due to their prominent structuresand properties. In electrospraying, the selection of a suitable solvent system as the carrier of PCL isfundamental and a prerequisite for the stabilization of electrospraying, and the control ofmorphology and structure of electrosprayed particles. The latter is not only critical for diversifyingthe characteristics of electrosprayed particles and achieving improvement in their properties, butalso promotes the efficiency of the process and deepens the applications of electrosprayed particlesin various fields. In order to make it systematic and more accessible, this review mainly concludesthe effects of different solution properties on the operating parameters in electrospraying on theformation of Taylor cone and the final structure as well as the morphology. Meanwhile,correlations between operating parameters and electrospraying stages are summarized as well.Finally, this review provides detailed guidance on the selection of a suitable solvent systemregarding the desired morphology, structure, and applications of PCL particles.

Electrospraying an enabling technology for pharmaceutical and biomedical applications: A review

Electrospraying (ES) is a robust and versatile technique for the fabrication of micro- and nanoparticulate materials of various compositions, morphologies, shapes, textures and sizes. The physics of ES provides a great degree of flexibility towards the materials design of choice with desired physicochemical and biological properties. Not surprising, this technology has become an important tool for the production of micro- and nanostructured materials, especially in the pharmaceutical and biomedical arena. In this review, a basic introduction to the fundamentals of ES along with a brief description of the experimental parameters that can be manipulated to obtain micro- and nanostructured materials of desired composition, size, and configuration are outlined. A greater focus of this review is to bring to light the broad range of electrosprayed materials and their applications in drug delivery, biomedical imaging, implant coating, tissue engineering, and sensing. Taken together, this review will provide an appreciation of this unique technology, which can be used to fabricate micro- and nanostructured materials with tremendous applications in the pharmaceutical and biomedical fields.

Current developments and applications of microfluidic technology toward clinical translation of nanomedicines

Nanoparticulate drug delivery systems hold great potential for the therapy of many diseases, especially cancer. However, the translation of nanoparticulate drug delivery systems from academic research to industrial and clinical practice has been slow. This slow translation can be ascribed to the high batch-to-batch variations and insufficient production rate of the conventional preparation methods, and the lack of technologies for rapid screening of nanoparticulate drug delivery systems with high correlation to the in vivo tests. These issues can be addressed by the microfluidic technologies. For example, microfluidics can not only produce nanoparticles in a well-controlled, reproducible, and high-throughput manner, but also create 3D environments with continuous flow to mimic the physiological and/or pathological processes. This review provides an overview of the microfluidic devices developed to prepare nanoparticulate drug delivery systems, including drug nanosuspensions, polymer nanoparticles, polyplexes, structured nanoparticles and theranostic nanoparticles. We also highlight the recent advances of microfluidic systems in fabricating the increasingly realistic models of the in vivo milieu for rapid screening of nanoparticles. Overall, the microfluidic technologies offer a promise approach to accelerate the clinical translation of nanoparticulate drug delivery systems.

Biomaterials Meet Microfluidics: From Synthesis Technologies to Biological Applications

Microfluidics is characterized by laminar flow at micro-scale dimension, high surface to volume ratio, and markedly improved heat/mass transfer. In addition, together with advantages of large-scale integration and flexible manipulation, microfluidic technology has been rapidly developed as one of the most important platforms in the field of functional biomaterial synthesis. Compared to biomaterials assisted by conventional strategies, functional biomaterials synthesized by microfluidics are with superior properties and performances, due to their controllable morphology and composition, which have shown great advantages and potential in the field of biomedicine, biosensing, and tissue engineering. Take the significance of microfluidic engineered biomaterials into consideration; this review highlights the microfluidic synthesis technologies and biomedical applications of materials. We divide microfluidic based biomaterials into four kinds. According to the material dimensionality, it includes: 0D (particulate materials), 1D (fibrous materials), 2D (sheet materials), and 3D (construct forms of materials). In particular, micro/nano-particles and micro/nano-fibers are introduced respectively. This classification standard could include all of the microfluidic biomaterials, and we envision introducing a comprehensive and overall evaluation and presentation of microfluidic based biomaterials and their applications.

Controllable synthesis of functional nanoparticles by microfluidic platforms for biomedical applications - a review

Nanoparticles have drawn significant attention in biomedicine due to their unique optical, thermal, magnetic and electrical properties which are highly related to their size and morphologies. Recently, microfluidic systems have shown promising potential to modulate critical stages in nanosynthesis, such as nucleation, growth and reaction conditions so that the size, size distribution, morphology, and reproducibility of nanoparticles are optimized in a high throughput manner. In this review, we put an emphasis on a decade of developments of microfluidic systems for engineering nanoparticles in various applications including imaging, biosensing, drug delivery, and theranostic applications.

Microfluidic Hydrodynamic Focusing for Synthesis of Nanomaterials

Microfluidics expands the synthetic space such as heat transfer, mass transport, and reagent consumption to conditions not easily achievable in conventional batch processes. Hydrodynamic focusing in particular enables the generation and study of complex engineered nanostructures and new materials systems. In this review, we present an overview of recent progress in the synthesis of nanostructures and microfibers using microfluidic hydrodynamic focusing techniques. Emphasis is placed on distinct designs of flow focusing methods and their associated mechanisms, as well as their applications in material synthesis, determination of reaction kinetics, and study of synthetic mechanisms.

Cells Respond to Distinct Nanoparticle Properties with Multiple Strategies As Revealed by Single-Cell RNA-Seq

The impact of distinct nanoparticle (NP) properties on cellular response and ultimately human health is unclear. This gap is partially due to experimental difficulties in achieving uniform NP loads in the studied cells, creating heterogeneous populations with some cells "overloaded" while other cells are loaded with few or no NPs. Yet gene expression studies have been conducted in the population as a whole, identifying generic responses, while missing unique responses due to signal averaging across many cells, each carrying different loads. Here, we applied single-cell RNA-Seq to alveolar epithelial cells carrying defined loads of aminated or carboxylated quantum dots (QDs), showing higher or lower toxicity, respectively. Interestingly, cells carrying lower loads responded with multiple strategies, mostly with up-regulated processes, which were nonetheless coherent and unique to each QD type. In contrast, cells carrying higher loads responded more uniformly, with mostly down-regulated processes that were shared across QD types. Strategies unique to aminated QDs showed strong up-regulation of stress responses, coupled in some cases with regulation of cell cycle, protein synthesis, and organelle activities. In contrast, strategies unique to carboxylated QDs showed up-regulation of DNA repair and RNA activities and decreased regulation of cell division, coupled in some cases with up-regulation of stress responses and ATP-related functions. Together, our studies suggest scenarios where higher NP loads lock cells into uniform responses, mostly shutdown of cellular processes, whereas lower loads allow for unique responses to each NP type that are more diversified proactive defenses or repairs of the NP insults.

Coaxial electrospray of microparticles and nanoparticles for biomedical applications

Coaxial electrospray is an electrohydrodynamic process that produces multilayer microparticles and nanoparticles by introducing coaxial electrified jets. In comparison with other microencapsulation/nanoencapsulation processes, coaxial electrospray has several potential advantages such as high encapsulation efficiency, effective protection of bioactivity and uniform size distribution. However, process control in coaxial electrospray is challenged by the multiphysical nature of the process and the complex interplay of multiple design, process and material parameters. This paper reviews the previous works and the recent advances in design, modeling and control of a coaxial electrospray process. The review intends to provide general guidance for coaxial electrospray and stimulate further research and development interests in this promising microencapsulation/nanoencapsulation process.