Microfluidic technologies for accelerating the clinical translation of nanoparticles

Self-spinning nanoparticle laden microdroplets for sensing and energy harvesting

Exposure of a volatile organic vapour could set in powerful rotational motion a microdroplet composed of an aqueous salt solution loaded with metal nanoparticles. The solutal Marangoni motion on the surface originating from the sharp difference in the surface tension of water and organic vapour stimulated the strong vortices inside the droplet. The vapour sources of methanol, ethanol, diethyl ether, toluene, and chloroform stimulated motions of different magnitudes could easily be correlated to the surface tension gradient on the drop surface. Interestingly, when the nanoparticle laden droplet of aqueous salt solution was connected to an external electric circuit through a pair of electrodes, an ∼85-95% reduction in the electrical resistance was observed across the spinning droplet. The extent of reduction in the resistance was found to have a correlation with the difference in the surface tension of the vapour source and the water droplet, which could be employed to distinguish the vapour sources. Remarkably, the power density of the same prototype was estimated to be around 7 μW cm(-2), which indicated the potential of the phenomenon in converting surface energy into electrical in a non-destructive manner and under ambient conditions. Theoretical analysis uncovered that the difference in the ζ-potential near the electrodes was the major reason for the voltage generation. The prototype could also detect the repeated exposure and withdrawal of vapour sources, which helped in the development of a proof-of-concept detector to sense alcohol issuing out of the human breathing system.

Can microfluidics address biomanufacturing challenges in drug/gene/cell therapies?

Translation of any inventions into products requires manufacturing. Development of drug/gene/cell delivery systems will eventually face manufacturing challenges, which require the establishment of standardized processes to produce biologically-relevant products of high quality without incurring prohibitive cost. Microfluidicu technologies present many advantages to improve the quality of drug/gene/cell delivery systems. They also offer the benefits of automation. What remains unclear is whether they can meet the scale-up requirement. In this perspective, we discuss the advantages of microfluidic-assisted synthesis of nanoscale drug/gene delivery systems, formation of microscale drug/cell-encapsulated particles, generation of genetically engineered cells and fabrication of macroscale drug/cell-loaded micro-/nano-fibers. We also highlight the scale-up challenges one would face in adopting microfluidic technologies for the manufacturing of these therapeutic delivery systems.

Particle Trajectory-Dependent Ionic Current Blockade in Low-Aspect-Ratio Pores

Resistive pulse sensing with nanopores having a low thickness-to-diameter aspect-ratio structure is expected to enable high-spatial-resolution analysis of nanoscale objects in a liquid. Here we investigated the sensing capability of low-aspect-ratio pore sensors by monitoring the ionic current blockades during translocation of polymeric nanobeads. We detected numerous small current spikes due to partial occlusion of the pore orifice by particles diffusing therein reflecting the expansive electrical sensing zone of the low-aspect-ratio pores. We also found wide variations in the ion current line-shapes in the particle capture stage suggesting random incident angle of the particles drawn into the pore. In sharp contrast, the ionic profiles were highly reproducible in the post-translocation regime by virtue of the spatial confinement in the pore that effectively constricts the stochastic capture dynamics into a well-defined ballistic motion. These results, together with multiphysics simulations, indicate that the resistive pulse height is highly dependent on the nanoscopic single-particle trajectories involved in ultrathin pore sensors. The present finding indicates the importance of regulating the translocation pathways of analytes in low-aspect-ratio pores for improving the discriminability toward single-bioparticle tomography in liquid.

Chitosan microspheres with an extracellular matrix-mimicking nanofibrous structure as cell-carrier building blocks for bottom-up cartilage tissue engineering

Scaffolds for tissue engineering (TE) which closely mimic the physicochemical properties of the natural extracellular matrix (ECM) have been proven to advantageously favor cell attachment, proliferation, migration and new tissue formation. Recently, as a valuable alternative, a bottom-up TE approach utilizing cell-loaded micrometer-scale modular components as building blocks to reconstruct a new tissue in vitro or in vivo has been proved to demonstrate a number of desirable advantages compared with the traditional bulk scaffold based top-down TE approach. Nevertheless, micro-components with an ECM-mimicking nanofibrous structure are still very scarce and highly desirable. Chitosan (CS), an accessible natural polymer, has demonstrated appealing intrinsic properties and promising application potential for TE, especially the cartilage tissue regeneration. According to this background, we report here the fabrication of chitosan microspheres with an ECM-mimicking nanofibrous structure for the first time based on a physical gelation process. By combining this physical fabrication procedure with microfluidic technology, uniform CS microspheres (CMS) with controlled nanofibrous microstructure and tunable sizes can be facilely obtained. Especially, no potentially toxic or denaturizing chemical crosslinking agent was introduced into the products. Notably, in vitro chondrocyte culture tests revealed that enhanced cell attachment and proliferation were realized, and a macroscopic 3D geometrically shaped cartilage-like composite can be easily constructed with the nanofibrous CMS (NCMS) and chondrocytes, which demonstrate significant application potential of NCMS as the bottom-up cell-carrier components for cartilage tissue engineering.

Fabrication of complex PDMS microfluidic structures and embedded functional substrates by one-step injection moulding

We report a novel injection moulding technique for fabrication of complex multi-layer microfluidic structures, allowing one-step robust integration of functional components with microfluidic channels and fabrication of elastomeric valves.

Microfluidic platform for photodynamic therapy cytotoxicity analysis of nanoencapsulated indocyanine-type photosensitizers

The application of nanotechnology is important to improve research and development of alternative anticancer therapies. In order to accelerate research related to cancer diagnosis and to improve the effectiveness of cancer treatment, various nanomaterials are being tested. The main objective of this work was basic research focused on examination of the mechanism and effectiveness of the introduction of nanoencapsulated photosensitizers to human carcinoma (A549) and normal cells (MRC-5). Newly encapsulated hydrophobic indocyanine-type photosensitizer (i.e., IR-780) was subjected to in vitro studies to determine its release characteristics on a molecular level. The photosensitizers were delivered to carcinoma and normal cells cultured under model conditions using multiwell plates and with the use of the specially designed hybrid (poly(dimethylsiloxane) (PDMS)/glass) microfluidic system. The specific geometry of our microsystem allows for the examination of intercellular interactions between cells cultured in the microchambers connected with microchannels of precisely defined length. Our microsystem allows investigating various therapeutic procedures (e.g., photodynamic therapy) on monoculture, coculture, and mixed culture, simultaneously, which is very difficult to perform using standard multiwell plates. In addition, we tested the cellular internalization of nanoparticles (differing in size, surface properties) in carcinoma and normal lung cells. We proved that cellular uptake of nanocapsules loaded with cyanine IR-780 in carcinoma cells was more significant than in normal cells. We demonstrated non cytotoxic effect of newly synthesized nanocapsules built with polyelectrolytes (PEs) of opposite surface charges: polyanion-polysodium-4-styrenesulphonate and polycation-poly(diallyldimethyl-ammonium) chloride loaded with cyanine IR-780 on human lung carcinoma and normal cell lines. However, the differences observed in the photocytotoxic effect between two types of tested nanocapsules can result from the type of last PE layer and their different surface charge.

Combining microfluidics and FT-IR spectroscopy: towards spatially resolved information on chemical processes

This review outlines the combination of infrared spectroscopy and continuous microfluidic processes.

Green microfluidic synthesis of monodisperse silver nanoparticles via genetic algorithm optimization

A scalable and green procedure for the microfluidic flow synthesis of monodisperse silver nanoparticles is reported.

Recapitulation of complex transport and action of drugs at the tumor microenvironment using tumor-microenvironment-on-chip

Targeted delivery aims to selectively distribute drugs to targeted tumor tissues but not to healthy tissues. This can address many clinical challenges by maximizing the efficacy but minimizing the toxicity of anti-cancer drugs. However, a complex tumor microenvironment poses various barriers hindering the transport of drugs and drug delivery systems. New tumor models that allow for the systematic study of these complex environments are highly desired to provide reliable test beds to develop drug delivery systems for targeted delivery. Recently, research efforts have yielded new in vitro tumor models, the so called tumor-microenvironment-on-chip, that recapitulate certain characteristics of the tumor microenvironment. These new models show benefits over other conventional tumor models, and have the potential to accelerate drug discovery and enable precision medicine. However, further research is warranted to overcome their limitations and to properly interpret the data obtained from these models. In this article, key features of the in vivo tumor microenvironment that are relevant to drug transport processes for targeted delivery were discussed, and the current status and challenges for developing in vitro transport model systems were reviewed.

Nanomedicines for Endothelial Disorders

The endothelium lines the internal surfaces of blood and lymphatic vessels and has a critical role in maintaining homeostasis. Endothelial dysfunction is involved in the pathology of many diseases and conditions, including disorders such as diabetes, cardiovascular diseases, and cancer. Given this common etiology in a range of diseases, medicines targeting an impaired endothelium can strengthen the arsenal of therapeutics. Nanomedicine - the application of nanotechnology to healthcare - presents novel opportunities and potential for the treatment of diseases associated with an impaired endothelium. This review discusses therapies currently available for the treatment of these disorders and highlights the application of nanomedicine for the therapy of these major disease complications.

On-chip synthesis of fine-tuned bone-seeking hybrid nanoparticles

Aims: Here we report a one-step approach for reproducible synthesis of finely tuned targeting multifunctional hybrid nanoparticles (HNPs). Materials & methods: A microfluidic-assisted method was employed for controlled nanoprecipitation of bisphosphonate-conjugated poly(D,L-lactide-co-glycolide) chains, while coencapsulating superparamagnetic iron oxide nanoparticles and the anticancer drug Paclitaxel. Results: Smaller and more compact HNPs with narrower size distribution and higher drug loading were obtained at microfluidic rapid mixing regimen compared with the conventional bulk method. The HNPs were shown to have a strong affinity for hydroxyapatite, as demonstrated in vitro bone-binding assay, which was further supported by molecular dynamics simulation results. In vivo proof of concept study verified the prolonged circulation of targeted microfluidic HNPs. Biodistribution as well as noninvasive bioimaging experiments showed high tumor localization and suppression of targeted HNPs to the bone metastatic tumor. Conclusion: The hybrid bone-targeting nanoparticles with adjustable characteristics can be considered as promising nanoplatforms for various theragnostic applications.

Microfluidics-based single-step preparation of injection-ready polymeric nanosystems for medical imaging and drug delivery

Translation of therapeutic polymeric nanosystems to patients and industry requires simplified, reproducible and scalable methods for assembly and loading. A single-step in-line process based on nanocoprecipitation of oxazoline-siloxane block copolymers in flow-focusing poly(dimethylsiloxane) microfluidics was designed to manufacture injection-ready nanosystems. Nanosystem characteristics could be controlled by copolymer concentration, block length and chemistry, microchannel geometry, flow rate, aqueous/organic flow rate ratio and payload concentration. The well-tolerated nanosystems exhibited differential cell binding and payload delivery and could confer sensitivity to photodynamic therapy to HeLa cancer cells. Such injection-ready nanosystems carrying drugs, diagnostic or functional materials may facilitate translation to clinical application.

Control of polymeric nanoparticle size to improve therapeutic delivery

As nanoparticle (NP)-mediated drug delivery research continues to expand, understanding parameters that govern NP interactions with the biological environment becomes paramount. The principles identified from the study of these parameters can be used to engineer new NPs, impart unique functionalities, identify novel utilities, and improve the clinical translation of NP formulations. One key design parameter is NP size. New methods have been developed to produce NPs with increased control of NP size between 10 and 200nm, a size range most relevant to physical and biochemical targeting through both intravascular and site-specific deliveries. Three notable techniques best suited for generating polymeric NPs with narrow size distributions are highlighted in this review: self-assembly, microfluidics-based preparation, and flash nanoprecipitation. Furthermore, the effect of NP size on the biological fate and transport properties at the molecular scale (protein-NP interactions) and the tissue and systemic scale (convective and diffusive transport of NPs) are analyzed here. These analyses underscore the importance of NP size control in considering clinical translation and assessment of therapeutic outcomes of NP delivery vehicles.

Nanomedicine applied to translational oncology: A future perspective on cancer treatment

The high global incidence of cancer is associated with high rates of mortality and morbidity worldwide. By taking advantage of the properties of matter at the nanoscale, nanomedicine promises to develop innovative drugs with greater efficacy and less side effects than standard therapies. Here, we discuss both clinically available anti-cancer nanomedicines and those en route to future clinical application. The properties, therapeutic value, advantages and limitations of these nanomedicine products are highlighted, with a focus on their increased performance versus conventional molecular anticancer therapies. The main regulatory challenges toward the translation of innovative, clinically effective nanotherapeutics are discussed, with a view to improving current approaches to the clinical management of cancer. Ultimately, it becomes clear that the critical steps for clinical translation of nanotherapeutics require further interdisciplinary and international effort, where the whole stakeholder community is involved from bench to bedside. From the Clinical Editor: Cancer is a leading cause of mortality worldwide and finding a cure remains the holy-grail for many researchers and clinicians. The advance in nanotechnology has enabled novel strategies to develop in terms of cancer diagnosis and therapy. In this concise review article, the authors described current capabilities in this field and outlined comparisons with existing drugs. The difficulties in bringing new drugs to the clinics were also discussed.

Microfluidic Assembly of a Multifunctional Tailorable Composite System Designed for Site Specific Combined Oral Delivery of Peptide Drugs

Multifunctional tailorable composite systems, specifically designed for oral dual-delivery of a peptide (glucagon-like peptide-1) and an enzymatic inhibitor (dipeptidyl peptidase 4 (DPP4)), were assembled through the microfluidics technique. Both drugs were coloaded into these systems for a synergistic therapeutic effect. The systems were composed of chitosan and cell-penetrating peptide modified poly(lactide-co-glycolide) and porous silicon nanoparticles as nanomatrices, further encapsulated in an enteric hydroxypropylmethylcellulose acetylsuccinate polymer. The developed multifunctional systems were pH-sensitive, inherited by the enteric polymer, enabling the release of the nanoparticles only in the simulated intestinal conditions. Moreover, the encapsulation into this polymer prevented the degradation of the nanoparticles' modifications. These nanoparticles showed strong and higher interactions with the intestinal cells in comparison with the nonmodified ones. The presence of DPP4 inhibitor enhanced the peptide permeability across intestinal cell monolayers. Overall, this is a promising platform for simultaneously delivering two drugs from a single formulation. Through this approach peptides are expected to increase their bioavailability and efficiency in vivo both by their specific release at the intestinal level and also by the reduced enzymatic activity. The use of this platform, specifically in combination of the two antidiabetic drugs, has clinical potential for the therapy of type 2 diabetes mellitus.

Role of Physicochemical Properties in Nanoparticle Toxicity

With the recent rapid growth of technological comprehension in nanoscience, researchers have aimed to adapt this knowledge to various research fields within engineering and applied science. Dramatic advances in nanomaterials marked a new epoch in biomedical engineering with the expectation that they would have huge contributions to healthcare. However, several questions regarding their safety and toxicity have arisen due to numerous novel properties. Here, recent studies of nanomaterial toxicology will be reviewed from several physiochemical perspectives. A variety of physiochemical properties such as size distribution, electrostatics, surface area, general morphology and aggregation may significantly affect physiological interactions between nanomaterials and target biological areas. Accordingly, it is very important to finely tune these properties in order to safely fulfill a bio-user's purpose.

Composite nanoparticles for gene delivery

Nanoparticle-mediated gene and siRNA delivery has been an appealing area to gene therapists when they attempt to treat the diseases by manipulating the genetic information in the target cells. However, the advances in materials science could not keep up with the demand for multifunctional nanomaterials to achieve desired delivery efficiency. Researchers have thus taken an alternative approach to incorporate various materials into single composite nanoparticle using different fabrication methods. This approach allows nanoparticles to possess defined nanostructures as well as multiple functionalities to overcome the critical extracellular and intracellular barriers to successful gene delivery. This chapter will highlight the advances of fabrication methods that have the most potential to translate nanoparticles from bench to bedside. Furthermore, a major class of composite nanoparticle-lipid-based composite nanoparticles will be classified based on the components and reviewed in details.

Bubble pump: scalable strategy for in-plane liquid routing

We present an on-chip liquid routing technique intended for application in well-based microfluidic systems that require long-term active pumping at low to medium flowrates. Our technique requires only one fluidic feature layer, one pneumatic control line and does not rely on flexible membranes and mechanical or moving parts. The presented bubble pump is therefore compatible with both elastomeric and rigid substrate materials and the associated scalable manufacturing processes. Directed liquid flow was achieved in a microchannel by an in-series configuration of two previously described "bubble gates", i.e., by gas-bubble enabled miniature gate valves. Only one time-dependent pressure signal is required and initiates at the upstream (active) bubble gate a reciprocating bubble motion. Applied at the downstream (passive) gate a time-constant gas pressure level is applied. In its rest state, the passive gate remains closed and only temporarily opens while the liquid pressure rises due to the active gate's reciprocating bubble motion. We have designed, fabricated and consistently operated our bubble pump with a variety of working liquids for >72 hours. Flow rates of 0-5.5 μl min(-1), were obtained and depended on the selected geometric dimensions, working fluids and actuation frequencies. The maximum operational pressure was 2.9 kPa-9.1 kPa and depended on the interfacial tension of the working fluids. Attainable flow rates compared favorably with those of available micropumps. We achieved flow rate enhancements of 30-100% by operating two bubble pumps in tandem and demonstrated scalability of the concept in a multi-well format with 12 individually and uniformly perfused microchannels (variation in flow rate <7%). We envision the demonstrated concept to allow for the consistent on-chip delivery of a wide range of different liquids that may even include highly reactive or moisture sensitive solutions. The presented bubble pump may provide active flow control for analytical and point-of-care diagnostic devices, as well as for microfluidic cells culture and organ-on-chip platforms.

Shape Control in Engineering of Polymeric Nanoparticles for Therapeutic Delivery

Nanoparticle-mediated delivery of therapeutics holds great potential for the diagnosis and treatment of a wide range of diseases. Significant advances have been made in the design of new polymeric nanoparticle carriers through modulation of their physical and chemical structures and biophysical properties. Nanoparticle shape has been increasingly proposed as an important attribute dictating their transport properties in biological milieu. In this review, we highlight three major methods for preparing polymeric nanoparticles that allow for exquisite control of particle shape. Special attention is given to various approaches to controlling nanoparticle shape by tuning copolymer structural parameters and assembly conditions. This review also provides comparisons of these methods in terms of their unique capabilities, materials choices, and specific delivery cargos, and summarizes the biological effects of nanoparticle shape on transport properties at the tissue and cellular levels.

Increased tumor distribution and expression of histidine-rich plasmid polyplexes

Background

Selecting nonviral carriers for in vivo gene delivery is often dependent on determining the optimal carriers from transfection assays in vitro. The rationale behind this in vitro strategy is to cast a net sufficiently wide to identify the few effective carriers of plasmids for in vivo studies. Nevertheless, many effective in vivo carriers may be overlooked by this strategy because of the marked differences between in vitro and in vivo assays.

Methods

After solid-phase synthesis of linear and branched histidine/lysine (HK) peptides, the two peptide carriers were compared for their ability to transfect MDA-MB-435 tumor cells in vitro and then in vivo.

Results

By contrast to their transfection activity in vitro, the linear H2K carrier of plasmids was far more effective in vivo compared to the branch H2K4b. Surprisingly, negatively-charged polyplexes formed by the linear H2K peptide gave higher transfection in vivo than did those with a positive surface charge. To examine the distribution of plasmid expression within the tumor from H2K polyplexes, we found widespread expression by immunohistochemical staining. With a fluorescent tdTomato expressing-plasmid, we confirmed a pervasive distribution and gene expression within the tumor mediated by the H2K polyplex.

Conclusions

Although mechanisms underlying the efficiency of gene expression are probably multifactorial, unpacking of the H2K polyplex within the tumor appears to have a significant role. Further development of these H2K polyplexes represents an attractive approach for plasmid-based therapies of cancer. © 2014 The Authors. The Journal of Gene Medicine published by John Wiley & Sons, Ltd.

Delivery of oligonucleotides with lipid nanoparticles

Since their inception in the 1980s, oligonucleotide-based (ON-based) therapeutics have been recognized as powerful tools that can treat a broad spectrum of diseases. The discoveries of novel regulatory methods of gene expression with diverse mechanisms of action are still driving the development of novel ON-based therapeutics. Difficulties in the delivery of this class of therapeutics hinder their in vivo applications, which forces drug delivery systems to be a prerequisite for clinical translation. This review discusses the strategy of using lipid nanoparticles as carriers to deliver therapeutic ONs to target cells in vitro and in vivo. A discourse on how chemical and physical properties of the lipid materials could be utilized during formulation and the resulting effects on delivery efficiency constitutes the major part of this review.

Assessing potential peptide targeting ligands by quantification of cellular adhesion of model nanoparticles under flow conditions

Sophisticated drug delivery systems are coated with targeting ligands to improve the specific adhesion to surface receptors on diseased cells. In our study, we developed a method with which we assessed the potential of peptide ligands to specifically bind to receptor overexpressing target cells. Therefore, a microfluidic setup was used where the cellular adhesion of nanoparticles with ligand and of control nanoparticles was observed in parallel under the same experimental conditions. The effect of the ligand on cellular binding was quantified by counting the number of adhered nanoparticles with ligand and differently labeled control nanoparticles on single cells after incubation under flow conditions. To provide easy-to-synthesize, stable and reproducible nanoparticles which mimic the surface characteristics of drug delivery systems and meet the requirements for quantitative analysis, latex beads based on amine-modified polystyrene were used as model nanoparticles. Two short peptides were tested to serve as targeting ligand on the beads by increasing the specific binding to HuH7 cells. The c-Met binding peptide cMBP2 was used for hepatocyte growth factor receptor (c-Met) targeting and the peptide B6 for transferrin receptor (TfR) targeting. The impact of the targeting peptide on binding was investigated by comparing the beads with ligand to different internal control beads: 1) without ligand and tailored surface charge (electrostatic control) and 2) with scrambled peptide and similar surface charge, but a different amino acid sequence (specificity control). Our results demonstrate that the method is very useful to select suitable targeting ligands for specific nanoparticle binding to receptor overexpressing tumor cells. We show that the cMBP2 ligand specifically enhances nanoparticle adhesion to target cells, whereas the B6 peptide mediates binding to tumor cells mainly by nonspecific interactions. All together, we suggest that cMBP2 is a suitable choice for specific receptor targeting whereas the peptide B6 should not be considered as specific targeting moiety.

Single Cell Electrical Characterization Techniques

Electrical properties of living cells have been proven to play significant roles in understanding of various biological activities including disease progression both at the cellular and molecular levels. Since two decades ago, many researchers have developed tools to analyze the cell’s electrical states especially in single cell analysis (SCA). In depth analysis and more fully described activities of cell differentiation and cancer can only be accomplished with single cell analysis. This growing interest was supported by the emergence of various microfluidic techniques to fulfill high precisions screening, reduced equipment cost and low analysis time for characterization of the single cell’s electrical properties, as compared to classical bulky technique. This paper presents a historical review of single cell electrical properties analysis development from classical techniques to recent advances in microfluidic techniques. Technical details of the different microfluidic techniques are highlighted, and the advantages and limitations of various microfluidic devices are discussed.

Microengineered vascular systems for drug development

Recent advances in microfabrication technologies and advanced biomaterials have allowed for the development of in vitro platforms that recapitulate more physiologically relevant cellular components and function. Microengineered vascular systems are of particular importance for the efficient assessment of drug candidates to physiological barriers lining microvessels. This review highlights advances in the development of microengineered vascular structures with an emphasis on the potential impact on drug delivery studies. Specifically, this article examines the development of models for the study of drug delivery to the central nervous system and cardiovascular system. We also discuss current challenges and future prospects of the development of microengineered vascular systems.

A versatile and robust microfluidic platform toward high throughput synthesis of homogeneous nanoparticles with tunable properties

A versatile and robust microfluidic nanoprecipitation platform for high throughput synthesis of nanoparticles is fabricated. The versatility of this platform is proven through the successful preparation of different types of nanoparticles. This platform presents great robustness, with homogeneous nanoparticles always being obtained, regardless of the formulation parameters. The diameter and surface charge of the prepared nanoparticles can also be easily tuned.

Design attributes of long-circulating polymeric drug delivery vehicles

Following systemic administration polymeric drug delivery vehicles allow for a controlled and targeted release of the encapsulated medication at the desired site of action. For an elevated and organ specific accumulation of their cargo, nanocarriers need to avoid opsonization, activation of the complement system and uptake by macrophages of the mononuclear phagocyte system. In this respect, camouflaged vehicles revealed a delayed elimination from systemic circulation and an improved target organ deposition. For instance, a steric shielding of the carrier surface by poly(ethylene glycol) substantially decreased interactions with the biological environment. However, recent studies disclosed possible deficits of this approach, where most notably, poly(ethylene glycol)-modified drug delivery vehicles caused significant immune responses. At present, identification of novel potential carrier coating strategies facilitating negligible immune reactions is an emerging field of interest in drug delivery research. Moreover, physical carrier properties including geometry and elasticity seem to be very promising design attributes to surpass numerous biological barriers, in order to improve the efficacy of the delivered medication.

A method for concentrating lipid peptide DNA and siRNA nanocomplexes that retains their structure and transfection efficiency

Nonviral gene and small interfering RNA (siRNA) delivery formulations are extensively used for biological and therapeutic research in cell culture experiments, but less so in in vivo and clinical research. Difficulties with formulating the nanoparticles for uniformity and stability at concentrations required for in vivo and clinical use are limiting their progression in these areas. Here, we report a simple but effective method of formulating monodisperse nanocomplexes from a ternary formulation of lipids, targeting peptides, and nucleic acids at a low starting concentration of 0.2 mg/mL of DNA, and we then increase their concentration up to 4.5 mg/mL by reverse dialysis against a concentrated polymer solution at room temperature. The nanocomplexes did not aggregate and they had maintained their biophysical properties, but, importantly, they also mediated DNA transfection and siRNA silencing in cultured cells. Moreover, concentrated anionic nanocomplexes administered by convection-enhanced delivery in the striatum showed efficient silencing of the β-secretase gene BACE1. This method of preparing nanocomplexes could probably be used to concentrate other nonviral formulations and may enable more widespread use of nanoparticles in vivo.

Growth of nanoparticles and microparticles by controlled reaction-diffusion processes

The synthesis of different sizes of nanoparticles and microparticles is important in designing nanostructured materials with various properties. Wet synthesis methods lack the flexibility to create various sizes of particles (particle libraries) using fixed conditions without the repetition of the steps in the method with a new set of parameters. Here, we report a synthesis method based on nucleation and particle growth in the wake of a moving chemical front in a gel matrix. The process yields well-separated regions (bands) filled with nearly monodisperse nanoparticles and microparticles, with the size of the particles varying from band to band in a predictable way. The origin of the effect is due to an interplay of a precipitation reaction of the reagents and their diffusion that is controlled in space and time by the moving chemical front. The method represents a new approach and a promising tool for the fast and competitive synthesis of various sizes of colloidal particles.

Cancer nanomedicine: from targeted delivery to combination therapy

The advent of nanomedicine marks an unparalleled opportunity to advance the treatment of a variety of diseases, including cancer. The unique properties of nanoparticles, such as large surface-to volume ratio, small size, the ability to encapsulate a variety of drugs, and tunable surface chemistry, gives them many advantages over their bulk counterparts. This includes multivalent surface modification with targeting ligands, efficient navigation of the complex in vivo environment, increased intracellular trafficking, and sustained release of drug payload. These advantages make nanoparticles a mode of treatment potentially superior to conventional cancer therapies. This article highlights the most recent developments in cancer treatment using nanoparticles as drug-delivery vehicles, including promising opportunities in targeted and combination therapy.

Microfluidic platforms with monolithically integrated hierarchical apertures for the facile and rapid formation of cargo-carrying vesicles

We fabricated a simple yet robust microfluidic platform with monolithically integrated hierarchical apertures. This platform showed efficient diffusive mixing of the introduced lipids through approximately 8000 divisions with tiny pores (~5 μm in diameter), resulting in massive, real-time production of various cargo-carrying particles via multi-hydrodynamic focusing.

Microfluidic synthesis of barcode particles for multiplex assays

The increasing use of high-throughput assays in biomedical applications, including drug discovery and clinical diagnostics, demands effective strategies for multiplexing. One promising strategy is the use of barcode particles that encode information about their specific compositions and enable simple identification. Various encoding mechanisms, including spectroscopic, graphical, electronic, and physical encoding, have been proposed for the provision of sufficient identification codes for the barcode particles. These particles are synthesized in various ways. Microfluidics is an effective approach that has created exciting avenues of scientific research in barcode particle synthesis. The resultant particles have found important application in the detection of multiple biological species as they have properties of high flexibility, fast reaction times, less reagent consumption, and good repeatability. In this paper, research progress in the microfluidic synthesis of barcode particles for multiplex assays is discussed. After introducing the general developing strategies of the barcode particles, the focus is on studies of microfluidics, including their design, fabrication, and application in the generation of barcode particles. Applications of the achieved barcode particles in multiplex assays will be described and emphasized. The prospects for future development of these barcode particles are also presented.

Nanomanufacturing of Tobacco Mosaic Virus-Based Spherical Biomaterials Using a Continuous Flow Method

Nanomanufacturing of nanoparticles is critical for potential translation and commercialization. Continuous flow devices can alleviate this need through unceasing production of nanoparticles. Here we demonstrate the scaled-up production of spherical nanoparticles functionalized with biomedical cargos from the rod-shaped plant virus tobacco mosaic virus (TMV) using a mesofluidic, continued flow method. Production yields were increased 30-fold comparing the mesofluidic device versus batch methods. Finally, we produced MRI contrast agents of select sizes, with per particle relaxivity reaching 979,218 mM^–1 s^–1 at 60 MHz. These TMV-based spherical nanoparticle MRI contrast agents are in the top echelon of relaxivity per nanoparticle.

On-chip controlled surfactant-DNA coil-globule transition by rapid solvent exchange using hydrodynamic flow focusing

This paper presents a microfluidic method for precise control of the size and polydispersity of surfactant-DNA nanoparticles. A mixture of surfactant and DNA dispersed in 35% ethanol is focused between two streams of pure water in a microfluidic channel. As a result, a rapid change of solvent quality takes place in the central stream, and the surfactant-bound DNA molecules undergo a fast coil-globule transition. By adjusting the concentrations of DNA and surfactant, fine-tuning of the nanoparticle size, down to a hydrodynamic diameter of 70 nm with a polydispersity index below 0.2, can be achieved with a good reproducibility.

Nanoparticle approaches against bacterial infections

Despite the wide success of antibiotics, the treatment of bacterial infections still faces significant challenges, particularly the emergence of antibiotic resistance. As a result, nanoparticle drug delivery platforms including liposomes, polymeric nanoparticles, dendrimers, and various inorganic nanoparticles have been increasingly exploited to enhance the therapeutic effectiveness of existing antibiotics. This review focuses on areas where nanoparticle approaches hold significant potential to advance the treatment of bacterial infections. These areas include targeted antibiotic delivery, environmentally responsive antibiotic delivery, combinatorial antibiotic delivery, nanoparticle-enabled antibacterial vaccination, and nanoparticle-based bacterial detection. In each area we highlight the innovative antimicrobial nanoparticle platforms and review their progress made against bacterial infections.

Production of nanoparticle drug delivery systems with microfluidics tools

INTRODUCTION

Nowadays the development of composite nano- and microparticles is an extensively studied area of research. This interest is growing because of the potential use of such particles in drug delivery systems. Indeed they can be used in various medical disciplines depending upon their sizes and their size distribution, which determine their final biomedical applications.

AREAS COVERED

Amongst the different techniques to produce nanoparticles, microfluidic techniques allow preparing particles having a specific size, a narrow size distribution and high encapsulation efficiency with ease. This review covers the general description of microfluidics, its techniques, advantages and disadvantages with focus on the encapsulation of active principles in polymeric nanoparticles as well as on pure drug nanoparticles. Polymeric nanoparticles constitute the majority of the examples reported; however lipid nanoparticulate systems (DNA, SiRNA nanocarriers) are very comparable and their formulation processes are in most cases exactly similar. Accordingly this review focuses also on active ingredient nanoparticles formulated by nanoprecipitation processes in microfluidic devices in general. It also provides detailed description of the different geometries of most common microfluidic devices and the crucial parameters involved in techniques designed to obtain the desired properties.

EXPERT OPINION

Although the classical fabrication of nanoparticles drug delivery systems in batch is extremely well-described and developed, their production with microfluidic tools arises today as an emerging field with much more potential. In this review we present and discuss these new possibilities for biomedical applications through the current emerging developments.

Bionanotechnology. Colloidal nanoparticles as advanced biological sensors

Colloidal nanoparticle biosensors have received intense scientific attention and offer promising applications in both research and medicine. We review the state of the art in nanoparticle development, surface chemistry, and biosensing mechanisms, discussing how a range of technologies are contributing toward commercial and clinical translation. Recent examples of success include the ultrasensitive detection of cancer biomarkers in human serum and in vivo sensing of methyl mercury. We identify five key materials challenges, including the development of robust mass-scale nanoparticle synthesis methods, and five broader challenges, including the use of simulations and bioinformatics-driven experimental approaches for predictive modeling of biosensor performance. The resultant generation of nanoparticle biosensors will form the basis of high-performance analytical assays, effective multiplexed intracellular sensors, and sophisticated in vivo probes.