Microfluidics-enabled rational design of immunomagnetic nanomaterials and their shape effect on liquid biopsy

Microfluidic device-fabricated spiky nano-burflower shape gold nanomaterials facilitate large biomolecule delivery into cells using infrared light pulses

Photothermal nanoparticle-sensitised photoporation is an emerging approach, which is considered an efficient tool for the intracellular delivery of biomolecules. Nevertheless, using this method to achieve high transfection efficiency generally compromises cell viability and uneven distribution of nanoparticles results in non-uniform delivery. Here, we show that high aspect ratio gold nano-burflowers, synthesised in a microfluidic device, facilitate highly efficient small to very-large cargo delivery uniformly using infrared light pulses without sacrificing cell viability. By precisely controlling the flow rates of shaping reagent and reducing agent, high-density (24 numbers) sharply branched spikes (∼80 nm tip-to-tip length) of higher aspect ratios (∼6.5) with a small core diameter (∼45 nm) were synthesised. As produced gold burflower-shape nanoparticles are biocompatible, colloidally stable (large surface zeta potential value), and uniform in morphology with a higher plasmonic peak (max. 890 nm). Theoretical analysis revealed that spikes on the nanoparticles generate a higher electromagnetic field enhancement upon interaction with light pulses. It induces plasmonic nanobubbles in the vicinity of the cells, followed by pore formation on the membrane leading to diverse biomolecular delivery into cells. Our platform has been successfully implemented for uniform delivery of small to very large biomolecules, including siRNA (20-24 bp), plasmid DNA expressing green fluorescent protein (6.2 kbp), Cas-9 plasmid (9.3 kbp), and β-galactosidase enzyme (465 kDa) into diverse mammalian cells with high transfection efficiency and cell viability. For very large biomolecules such as enzymes, the best results were achieved as ∼100% transfection efficiency and ∼100% cell viability in SiHa cells. Together, our findings demonstrate that the spiky gold nano-burflower shape nanoparticles manufactured in a microfluidic system exhibited excellent plasmonic behaviour and could serve as an effective tool in manipulating cell physiology.

Gold Nanoparticle-Based Microfluidic Chips for Capture and Detection of Circulating Tumor Cells

Liquid biopsy has progressed to its current use to diagnose and monitor cancer. Despite the recent advances in investigating cancer detection and diagnosis strategies, there is still a room for improvements in capturing CTCs. We developed an efficient CTC detection system by integrating gold nanoparticles with a microfluidic platform, which can achieve CTC capture within 120 min. Here, we report our development of a simple and effective way to isolate CTCs using antibodies attached on gold nanoparticles to the surface of a lateral filter array (LFA) microdevice. Our method was optimized using three pancreatic tumor cell lines, enabling the capture with high efficiency (90% ± 3.2%). The platform was further demonstrated for isolating CTCs from patients with metastatic pancreatic cancer. Our method and platform enables the production of functionalized, patterned surfaces that interact with tumor cells, enhancing the selective capture of CTCs for biological assays.

Microfluidic Fabrication of Silica Microspheres Infused with Positron Emission Tomography Imaging Agents

Selective internal radiation therapy (SIRT) is a treatment which delivers radioactive therapeutic microspheres via the hepatic artery to destroy tumorigenic tissue of the liver. However, the dose required varies significantly from patient to patient due to nuances in individual biology. Therefore, a positron emission tomography (PET) imaging surrogate, or radiotracer, is used to predict in vivo behavior of therapeutic Y-90 spheres. The ideal surrogate should closely resemble Y-90 microspheres in morphology for highest predictive accuracy. This work presents the fabrication of positron-emitting silica microspheres infused with PET radiotracers copper, fluorine, and gallium. A quick one-pot synthesis is used to create precursor sol, followed by droplet formation with flow-focusing microfluidics, and finally thermal treatment to yield 10-50 μm microspheres with narrow size distribution. Loading of the infused element is controllable in the sol synthesis, while the final sphere size is tunable based on microfluidic flow rates and device channel width. The system is then employed to make radioactive Ga-68 microspheres, which are tested for radioactivity and stability. The fabrication method can be completed within a few hours, depending on the desired microsphere quantity. A microfluidic system is applied to fabricate silica particles loaded with diverse elemental infusions, including radioactive Ga-68.

Nanotechnology based drug delivery systems: Does shape really matter?

As of today, the era of nanomedicine has brought numerous breakthroughs and overcome challenges in the treatment of various disorders. Various factors like size, charge and surface hydrophilicity have garnered significant attention by nanotechnologists. However, more exploration in the field of nanoparticle shape and geometry, one of the basic physical phenomenon is required. Tuning nanoparticle shape and geometry could potentially overcome pitfalls in therapeutics and biomedical fields. Thus, in this article, we unveil the importance of tuning nanoparticle shape selection across the delivery platforms. This article provides an in-depth understanding of nanoparticle shape modulation and advise the researchers on the ideal morphology selection tailored for each implication. We deliberated the importance of nanoparticle shape selection for specific implications with respect to organ targeting, cellular internalization, pharmacokinetics and bio-distribution, protein corona formation as well as RES evasion and tumor targeting. An additional section on the significance of shape transformation, a recently introduced novel avenue with applications in drug delivery was discussed. Furthermore, regulatory concerns towards nanoparticle shape which need to be addressed for harnessing their clinical translation will be explained.

Toward continuous production of high-quality nanomaterials using microfluidics: nanoengineering the shape, structure and chemical composition

Over the last decade, a multitude of synthesis strategies has been reported for the production of high-quality nanoparticles. Wet-chemical methods are generally the most efficient synthesis procedures since high control of crystallinity and physicochemical properties can be achieved. However, a number of challenges remain from inadequate reaction control during the nanocrystallization process; specifically variability, selectivity, scalability and safety. These shortcomings complicate the synthesis, make it difficult to obtain a uniform product with desired properties, and present serious limitations for scaling the production of colloidal nanocrystals from academic studies to industrial applications. Continuous flow reactors based on microfluidic principles offer potential solutions and advantages. The reproducibility of reaction conditions in microfluidics and therefore product quality have proved to exceed those obtained by batch processing. Considering that in nanoparticles' production not only is it crucial to control the particle size distribution, but also the shape and chemical composition, this review presents an overview of the current state-of-the-art in synthesis of anisotropic and faceted nanostructures by using microfluidics techniques. The review surveys the available tools that enable shape and chemical control, including secondary growth methods, active segmented flow, and photoinduced shape conversion. In addition, emphasis is placed on the available approaches developed to tune the structure and chemical composition of nanomaterials in order to produce complex heterostructures in a continuous and reproducible fashion.

Microfluidic nanomaterials: From synthesis to biomedical applications

Microfluidic platforms gain popularity in biomedical research due to their attractive inherent features, especially in nanomaterials synthesis. This review critically evaluates the current state of the controlled synthesis of nanomaterials using microfluidic devices. We describe nanomaterials' screening in microfluidics, which is very relevant for automating the synthesis process for biomedical applications. We discuss the latest microfluidics trends to achieve noble metal, silica, biopolymer, quantum dots, iron oxide, carbon-based, rare-earth-based, and other nanomaterials with a specific size, composition, surface modification, and morphology required for particular biomedical application. Screening nanomaterials has become an essential tool to synthesize desired nanomaterials using more automated processes with high speed and repeatability, which can't be neglected in today's microfluidic technology. Moreover, we emphasize biomedical applications of nanomaterials, including imaging, targeting, therapy, and sensing. Before clinical use, nanomaterials have to be evaluated under physiological conditions, which is possible in the microfluidic system as it stimulates chemical gradients, fluid flows, and the ability to control microenvironment and partitioning multi-organs. In this review, we emphasize the clinical evaluation of nanomaterials using microfluidics which was not covered by any other reviews. In the future, the growth of new materials or modification in existing materials using microfluidics platforms and applications in a diversity of biomedical fields by utilizing all the features of microfluidic technology is expected.

Rational design of on-chip gold plasmonic nanoparticles towards ctDNA screening

This paper demonstrates the design, synthesis, simulation, and testing of three distinct geometries of plasmonic gold nanoparticles for on-chip DNA screening towards liquid biopsy. By employing a seed-mediated growth method, we have synthesized gold nanospheres, nanorods, and nanobipyramids. In parallel, we developed numerical simulations to understand the effects of nanoparticle geometry on the resonance features and refractive index sensitivity. Both experimental and simulation results were compared through a series of studies including in-solution and on-chip tests. We have thoroughly characterized the impact of nanoparticle geometry on the sensitivity to circulating tumor DNA, with immediate implications for liquid biopsy. The results agree well with theoretical predictions and simulations, including both bulk refractive index sensitivity and thin film sensitivity. Importantly, this work quantitatively establishes the link between nanoparticle geometry and efficacy in detecting rare circulating biomarkers. The nanobipyramids provided the highest sensitivity, approximately doubling the sensitivity compared to nanorods. To the best of our knowledge this is the first report carrying through geometric effects of simulation to clinically relevant biosensing. We put forth here synthesis and testing of three nanoparticle geometries, and a framework for both experimental and theoretical validation of plasmonic sensitivities towards liquid biopsy.

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.

Microfluidics for ZnO micro-/nanomaterials development: rational design, controllable synthesis, and on-chip bioapplications

Zinc oxide (ZnO) materials hold great promise in diverse applications due to their attractive physicochemical features. Recent years, especially the last decade, have witnessed considerable progress toward rational design and bioapplications of multiscale ZnO materials through microfluidic techniques. Design of a microfluidic device that allows for precise control over reaction conditions could not only yield ZnO particles with a fast production rate and high quality, but also permit downstream applications with desirable and superior performance. This review summarizes microfluidic approaches for the synthesis and applications of ZnO micro-/nanomaterials. In particular, we discuss the recent achievement of using microfluidic reactors in the controllable synthesis of ZnO structures (wire, rod, sphere, flower, sheet, flake, spindle, and ellipsoid), and highlight the unprecedented opportunities for applying them in biosensing, biological separation, and molecular catalysis applications through microfluidic chips. Finally, major challenges and potential opportunities are explored to guide future studies in this area.

Microfluidics-enabled rational design of ZnO micro-/nanoparticles with enhanced photocatalysis, cytotoxicity, and piezoelectric properties

Microfluidics-based reactors enables the controllable synthesis of micro-/nanostructures for a broad spectrum of applications from materials science, bioengineering to medicine. In this study, we first develop a facile and straightforward flow synthesis strategy to control zinc oxide (ZnO) of different shapes (sphere, ellipsoid, short rod, long rod, cube, urchin, and platelet) on a few seconds time scale, based on the 1.5-run spiral-shaped microfluidic reactor with a relative short microchannel length of ca. 92 mm. The formation of ZnO is realized simply by mixing reactants through two inlet flows, one containing zinc nitrate and the other sodium hydroxide. The structures of ZnO are tuned by choosing appropriate flow rates and reactant concentrations of two inlet fluids. The formation mechanism behind microfluidics is proposed. The photocatalysis, cytotoxicity, and piezoelectric capabilities of as-synthesized ZnO from microreactors are further examined, and the structure-dependent efficacy is observed, where higher surface area ZnO structures generally behave better performance. These results bring new insights not only in the rational design of functional micro-/nanoparticles from microfluidics, but also for deeper understanding of the structure-efficacy relationship when translating micro-/nanomaterials into practical applications.

Advances in diagnostic microfluidics

Microfluidics is an emerging field in diagnostics that allows for extremely precise fluid control and manipulation, enabling rapid and high-throughput sample processing in integrated micro-scale medical systems. These platforms are well-suited for both standard clinical settings and point-of-care applications. The unique features of microfluidics-based platforms make them attractive for early disease diagnosis and real-time monitoring of the disease and therapeutic efficacy. In this chapter, we will first provide a background on microfluidic fundamentals, microfluidic fabrication technologies, microfluidic reactors, and microfluidic total-analysis-systems. Next, we will move into a discussion on the clinical applications of existing and emerging microfluidic platforms for blood analysis, and for diagnosis and monitoring of cancer and infectious disease. Together, this chapter should elucidate the potential that microfluidic systems have in the development of effective diagnostic technologies through a review of existing technologies and promising directions.

Microfluidic continuous flow synthesis of functional hollow spherical silica with hierarchical sponge-like large porous shell

Microfluidics brings unique opportunities for engineering micro-/nanomaterials with well-controlled physicochemical properties. Herein, using a miniaturized multi-run spiral-shaped microreactor, we develop a flow synthesis strategy to continuously produce hollow spherical silica (HSS) with hierarchical sponge-like pore sizes ranging from several nanometers to over one hundred nanometers. The formation of HSS is realized by mixing two reactant flows, one containing cetyltrimethylammonium bromide (CTAB) and diluted ammonia and the other 1,3,5-trimethylbenzene (TMB) and diluted tetraethyl orthosilicate (TEOS), at a flow rate as high as 5 mL/min. The effect of the reactant concentration and the flow rate on the structural change of the resultant materials is examined. Functional small-sized nanoparticles (magnetic nanoparticle, quantum dot, and silver nanoparticle) can be separately assembled into HSS and high molecular weight protein (bovine serum albumin) can be successfully loaded into HSS and delivered into cancer cells afterward, making them promising in the fields of separation and purification, bioimaging, catalysis, and theranostics.

Microfluidics for silica biomaterials synthesis: opportunities and challenges

The rational design and controllable synthesis of silica nanomaterials bearing unique physicochemical properties is becoming increasingly important for a variety of biomedical applications from imaging to drug delivery. Microfluidics has recently emerged as a promising platform for nanomaterial synthesis, providing precise control over particle size, shape, porosity, and structure compared to conventional batch synthesis approaches. This review summarizes microfluidics approaches for the synthesis of silica materials as well as the design, fabrication and the emerging roles in the development of new classes of functional biomaterials. We highlight the unprecedented opportunities of using microreactors in biomaterial synthesis, and assess the recent progress of continuous and discrete microreactors and the associated biomedical applications of silica materials. Finally, we discuss the challenges arising from the intrinsic properties of microfluidics reactors for inspiring future research in this field.

Biomimetic human lung-on-a-chip for modeling disease investigation

The lung is the primary respiratory organ of the human body and has a complicated and precise tissue structure. It comprises conductive airways formed by the trachea, bronchi and bronchioles, and many alveoli, the smallest functional units where gas-exchange occurs via the unique gas-liquid exchange interface known as the respiratory membrane. In vitro bionic simulation of the lung or its microenvironment, therefore, presents a great challenge, which requires the joint efforts of anatomy, physics, material science, cell biology, tissue engineering, and other disciplines. With the development of micromachining and miniaturization technology, the concept of a microfluidics-based organ-on-a-chip has received great attention. An organ-on-a-chip is a small cell-culture device that can accurately simulate tissue and organ functions in vitro and has the potential to replace animal models in evaluations of drug toxicity and efficacy. A lung-on-a-chip, as one of the first proposed and developed organs-on-a-chip, provides new strategies for designing a bionic lung cell microenvironment and for in vitro construction of lung disease models, and it is expected to promote the development of basic research and translational medicine in drug evaluation, toxicological detection, and disease model-building for the lung. This review summarizes current lungs-on-a-chip models based on the lung-related cellular microenvironment, including the latest advances described in studies of lung injury, inflammation, lung cancer, and pulmonary fibrosis. This model should see effective use in clinical medicine to promote the development of precision medicine and individualized diagnosis and treatment.

Automation and artificial intelligence in the clinical laboratory

The daily operation of clinical laboratories will be drastically impacted by two disruptive technologies: automation and artificial intelligence (the development and use of computer systems able to perform tasks that normally require human intelligence). These technologies will also expand the scope of laboratory medicine. Automation will result in increased efficiency but will require changes to laboratory infrastructure and a shift in workforce training requirements. The application of artificial intelligence to large clinical datasets generated through increased automation will lead to the development of new diagnostic and prognostic models. Together, automation and artificial intelligence will support the move to personalized medicine. Changes in pathology and clinical doctoral scientist training will be necessary to fully participate in these changes. KEYWORDS: Automation; artificial intelligence; deep learning; laboratory medicine.

Ultrafast microfluidic synthesis of hierarchical triangular silver core-silica shell nanoplatelet toward enhanced cellular internalization

Microfluidic reactors represent a new frontier in the rational design and controllable synthesis of functional micro-/nanomaterials. Herein, we develop a continuous and ultrafast flow synthesis method to obtain triangular silver (tAg) nanoplatelet using a short range two-loop spiral-shaped laminar flow microfluidic reactor, with one inlet flow containing AgNO₃, trisodium citrate, and H₂O₂ and the other NaBH₄. The effect of the reactant concentration and flow rate on the structural changes of tAg is examined. Through the same miniaturized microreactor, hierarchical core-shell Ag@SiO₂ can be produced with tunable silica shell thickness using one inlet flow containing the as-synthesized Ag nanoparticles together with tetraethyl orthosilicate and the other ammonia. The enhanced cellular internalization efficiency of triangular nanoplatelets by PANC-1 and MCF-7 cells is further confirmed in comparison with the spherical ones. These results not only bring new insights for engineering nanomaterials from microreactors but also facilitate the rational design of functional nanostructures for enhancing their biological performance.

Microfluidic synthesis and on-chip enrichment application of two-dimensional hollow sandwich-like mesoporous silica nanosheet with water ripple-like surface

The merits of microfluidics bring new opportunities for engineering of nanomaterials with well controlled chemical, physical and biological properties for a variety of applications. Herein, using a two-run spiral-shaped microfluidic device, we first develop a facile and straightforward flow synthesis strategy to create two-dimensional mesoporous silica nanosheet (MSN). Such MSN exhibits typical hollow sandwich-like bilayer and unique water ripple-like wrinkle surface, which greatly increase the particulate accessibility for mass transfer. The enhanced on-chip enrichment performance of MSN is further confirmed toward different substrates (dye, protein, drug). These findings not only shed new light on microfluidics-enabled chemicals engineering, but also open up numerous new possibilities by microfluidics in adsorption, separation, and biomedical fields.

Microfluidics-enabled rapid manufacturing of hierarchical silica-magnetic microflower toward enhanced circulating tumor cell screening

The emergence of microfluidic techniques provides new opportunities for chemical synthesis and biomedical applications. Herein, we first develop a microfluidics-based flow and sustainable strategy to synthesize hierarchical silica-magnetic microflower with unique multilayered structure for the efficient capture of circulating tumor cells through our engineered microfluidic screening chip. The production of microflower materials can be realized within 94 milliseconds and a yield of nearly 5 grams per hour can be achieved. The enhanced bioaccessibility of such a multilayered microflower towards cancer cells (MCF-7 and MDA-MB-231) is demonstrated, and the cancer cell capture efficiency of this hierarchical immunomagnetic system in clinical blood samples is significantly increased compared with a standard CellSearch™ assay. These findings bring new insights for engineering functional micro-/nanomaterials in liquid biopsy.