Understanding biophysical behaviours of microfluidic-synthesized nanoparticles at nano-biointerface

Effect of polymer concentration on the morphology of the PHPMAA-g-PLA graft copolymer nanoparticles produced by microfluidics nanoprecipitation

Successful generation of micelles, vesicles, and/or worms with controllable sizes was achieved through the self-assembly process of the poly[N-(2-hydroxypropyl)]methacrylamide-g-polylactide (PHPMAA-g-PLA) graft copolymer within a microfluidic channel. A product diagram was created to illustrate various morphologies associated with different polymer concentrations, all while maintaining a constant flow velocity ratio between water and the polymer solution.

Microfluidic-Assisted Formulation of ε-Polycaprolactone Nanoparticles and Evaluation of Their Properties and In Vitro Cell Uptake

The nanoprecipitation method was used to formulate ε-polycaprolactone (PCL) into fluorescent nanoparticles. Two methods of mixing the phases were evaluated: introducing the organic phase into the aqueous phase dropwise and via a specially designed microfluidic device. As a result of the nanoprecipitation process, fluorescein-loaded nanoparticles (NPs) with a mean diameter of 127 ± 3 nm and polydispersity index (PDI) of 0.180 ± 0.009 were obtained. The profiles of dye release were determined in vitro using dialysis membrane tubing, and the results showed a controlled release of the dye from NPs. In addition, the cytotoxicity of the NPs was assessed using an MTT assay. The PCL NPs were shown to be safe and non-toxic to L929 and MG63 cells. The results of the present study have revealed that PCL NPs represent a promising system for developing new drug delivery systems.

Microfluidic-driven mixing of high molecular weight polymeric complexes for precise nanoparticle downsizing

Chitosan (CHIT) and hyaluronic acid (HA) are two polysaccharides (PSs) with high value in several biomedical applications. In this study, we present a microfluidic method to synthetize CHIT-HA NPs to overcome the disadvantages of the dropwise approach generally used for nanoprecipitation of polyelectrolyte complexes. The proposed microfluidic approach enables to generate monodisperse suspensions of NPs with ≈100 nm of size compared to the dropwise method that generated ≈2 times bigger NPs. Finally, we evaluated the potential of obtained NPs in an inflammatory scenario. The treatment with NPs led to the reduction of the main inflammatory molecules produced by macrophages (PGE₂, IL-6, IL-8, MCAF and TNF-α) and fibroblasts (IL-1 α, PGE₂, TNF-α) stimulated with lipopolysaccharide or conditioned medium, respectively. This study demonstrates that our approach can be used to enhance the synthesis of nanocarriers based on bioactive macromolecules.

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

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

Tuning Size and Morphology of mPEG-b-p(HPMA-Bz) Copolymer Self-Assemblies Using Microfluidics

The careful design of nanoparticles, in terms of size and morphology, is of great importance to developing effective drug delivery systems. The ability to precisely tailor nanoparticles in size and morphology during polymer self-assembly was therefore investigated. Four poly(ethylene glycol)-b-poly(N-2-benzoyloxypropyl methacrylamide) mPEG-b-p(HPMA-Bz) block copolymers with a fixed hydrophilic block of mPEG 5 kDa and a varying molecular weight of the hydrophobic p(HPMA-Bz) block (A: 17.1, B: 10.0, C: 5.2 and D: 2.7 kDa) were self-assembled into nanoparticles by nanoprecipitation under well-defined flow conditions, using microfluidics, at different concentrations. The nanoparticles from polymer A, increased in size from 55 to 90 nm using lower polymer concentrations and slower flow rates and even polymer vesicles were formed along with micelles. Similarly, nanoparticles from polymer D increased in size from 35 to 70 nm at slower flow rates and also formed vesicles along with micelles, regardless of the used concentration. Differently, polymers B and C mainly self-assembled into micelles at the different applied flow rates with negligible size difference. In conclusion, this study demonstrates that the self-assembly of mPEG-b-p(HPMA-Bz) block copolymers can be easily tailored in size and morphology using microfluidics and is therefore an attractive option for further scaled-up production activities.

Understanding the Factors Influencing Chitosan-Based Nanoparticles-Protein Corona Interaction and Drug Delivery Applications

Chitosan is a polymer that is extensively used to prepare nanoparticles (NPs) with tailored properties for applications in many fields of human activities. Among them, targeted drug delivery, especially when cancer therapy is the main interest, is a major application of chitosan-based NPs. Due to its positive charges, chitosan is used to produce the core of the NPs or to cover NPs made from other types of polymers, both strategies aiming to protect the carried drug until NPs reach the target sites and to facilitate the uptake and drug delivery into these cells. A major challenge in the design of these chitosan-based NPs is the formation of a protein corona (PC) upon contact with biological fluids. The composition of the PC can, to some extent, be modulated depending on the size, shape, electrical charge and hydrophobic / hydrophilic characteristics of the NPs. According to the composition of the biological fluids that have to be crossed during the journey of the drug-loaded NPs towards the target cells, the surface of these particles can be changed by covering their core with various types of polymers or with functionalized polymers carrying some special molecules, that will preferentially adsorb some proteins in their PC. The PC's composition may change by continuous processes of adsorption and desorption, depending on the affinity of these proteins for the chemical structure of the surface of NPs. Beside these, in designing the targeted drug delivery NPs one can take into account their toxicity, initiation of an immune response, participation (enhancement or inhibition) in certain metabolic pathways or chemical processes like reactive oxygen species, type of endocytosis of target cells, and many others. There are cases in which these processes seem to require antagonistic properties of nanoparticles. Products that show good behavior in cell cultures may lead to poor in vivo results, when the composition of the formed PC is totally different. This paper reviews the physico-chemical properties, cellular uptake and drug delivery applications of chitosan-based nanoparticles, specifying the factors that contribute to the success of the targeted drug delivery. Furthermore, we highlight the role of the protein corona formed around the NP in its intercellular fate.

In situ bone tissue engineering using gene delivery nanocomplexes

Gene delivery offers promising outcomes for functional recovery or regeneration of lost tissues at cellular and tissue levels. However, more efficient carriers are needed to safely and locally delivery of genetic materials. Herein, we demonstrate microfluidic-assisted synthesis of plasmid DNA (pDNA)-based nanocomplexe (NC) platforms for bone tissue regeneration. pDNA encoding human bone morphogenesis protein-2 (BMP-2) was used as a gene of interest. Formation and fine-tuning of nanocomplexes (NCs) between pDNA and chitosan (CS) as carriers were performed using a micromixer platform. Flow characteristics were adjusted to tune mixing time and consequently size, zeta potential, and compactness of assembled NCs. Subsequently, NCs were immobilized on a nanofibrous Poly(ε-caprolactone) (PCL) scaffold functionalized with metalloprotease-sensitive peptide (MMP-sensitive). This construct can provide an environmental-sensitive and localized gene delivery platform. Osteogenic differentiation of bone marrow-derived mesenchymal stem cells (MSCs) was studied using chemical and biological assays. The presented results converge to indicate a great potential of the developed methodology for in situ bone tissue engineering using immobilized microfluidic-synthesized gene delivery nanocomplexes, which is readily expandable in the field of regenerative nanomedicine. STATEMENT OF SIGNIFICANCE: In this study, we demonstrate microfluidic-assisted synthesis of plasmid DNA (pDNA)-based nanocomplexes (NCs) platforms for bone tissue regeneration. We used pDNA encoding human bone morphogenesis protein-2 (BMP-2) as the gene of interest. Using micromixer platform nanocomplexes (NCs) between pDNA and chitosan (CS) were fabricated and optimized. NCs were immobilized on a nanofibrous polycaprolactone scaffold functionalized with metalloprotease-sensitive peptide. In vitro and in vivo assays confirmed the osteogenic differentiation of mesenchymal stem cells (MSCs). The obtained data indicated great potential of the developed methodology for in situ bone tissue engineering using immobilized microfluidic-synthesized gene delivery nanocomplexes, which is readily expandable in the field of regenerative nanomedicine.

Microfluidic Generation of Nanomaterials for Biomedical Applications

As nanomaterials (NMs) possess attractive physicochemical properties that are strongly related to their specific sizes and morphologies, they are becoming one of the most desirable components in the fields of drug delivery, biosensing, bioimaging, and tissue engineering. By choosing an appropriate methodology that allows for accurate control over the reaction conditions, not only can NMs with high quality and rapid production rate be generated, but also designing composite and efficient products for therapy and diagnosis in nanomedicine can be realized. Recent evidence implies that microfluidic technology offers a promising platform for the synthesis of NMs by easy manipulation of fluids in microscale channels. In this Review, a comprehensive set of developments in the field of microfluidics for generating two main classes of NMs, including nanoparticles and nanofibers, and their various potentials in biomedical applications are summarized. Furthermore, the major challenges in this area and opinions on its future developments are proposed.

Combinational drug delivery using nanocarriers for breast cancer treatments: A review

Breast cancer (BC) is the most common cancer in women that requires special attention due to low response to conventional treatments. The common method for treating cancer (especially BC) is applying a single anticancer agent, however, due to some disadvantages including cytotoxicity, side effects, and multidrug resistance, the efficiency and application of this method are limited. To overcome these challenges, the combinational delivery of anticancer drugs (including chemical agents, genetic materials, etc.) has been introduced. To increase the efficacy of this new method, several nanocarriers including inorganic nanoparticles (such as, magnetic nanoparticles, silica nanoparticles, etc.) and organic ones (e.g., dendrimers, liposomes, micelles, and polymeric nanoparticles) have been used. Based on the literature, combinational delivery using nanocarriers showed promising results in the treatment of BC. In this review, combination regimens for the treatment of BC, nanocarriers containing combinations of pharmaceutical agents (including small molecule chemotherapeutic, biological, and gene therapy agents) as an opportunity to overcome chemotherapy challenges and, finally, examples of these formulations have been presented. This review aims to provide a better understanding of these increasingly important new methods of cancer treatment and the main issues and key considerations for a rational design of nanocarriers used in combinational delivery of different synergistic anticancer agents. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2272-2283, 2018.

Label-free in-flow detection of receptor recognition motifs on the biomolecular corona of nanoparticles

Nanomedicine, nanotargeting and nanotherapeutics have in the last few years faced several difficulties in translating the promising results obtained in vitro to an in vivo scenario. The origin of this discrepancy might be found in the lack of a detailed and realistic characterization of the biological surface of nanoparticles. Despite the capability to engineer nanomaterials with a great variety and a precise control of the surface functionalization, the targeting capability is lost when the nanoparticles are embedded in complex biological media, due to the formation of a biological layer (biomolecular corona). This biological layer represents the ultimate nanoparticle surface, likely to interact with the cell machinery. Therefore, in addition to traditional nanoparticle characterization techniques, a more insightful investigation of the biomolecular corona is needed, including the capability to assess the orientation and functionality of specific key molecular features. Here we present a method for the rapid screening of exposed protein recognition motifs on the surface of nanoparticles exploiting quartz crystal microbalance (QCM). We quantify accessible functional epitopes of transferrin-coated nanoparticles and correlate them to differences in nanoparticle size and functionalization. The target recognition occurs label free in flow, thereby pushing our investigation into a more in vivo-like scenario. Our method is applicable to a wide array of nanoparticles and therefore holds the potential to become an advanced technique for the classification of all kinds of nanobioconstructs based on their biological external functionality.

The effect of surface charge and pH on the physiological behaviour of cobalt, copper, manganese, antimony, zinc and titanium oxide nanoparticles in vitro

The precise knowledge on various interactions of metal nanoparticles (NP) in a living organism is scarce. It is expected that metals can bind to nucleic acids, peptides and proteins (e.g. enzymes), and modify the functioning of vital cellular compartments after entering the organism. The predictive factors for quantitative nanostructure-activity relationship (QNAR) analysis could enhance efficient and harmless usage of nanoparticles (NPs) in the industry as well in the medicine. The studies value the composition of the NP corona determined by time, temperature and source of protein which has been found to implicate the physiological behaviour of NPs. One has largely been ignored: the NPs specific isoelectric point (IEP) and pH at the state of measurement. Herein, this study investigates the effect of pH and surface charge of six metal oxide (MeOx) NPs on time dependency of cytotoxicity. Several aspects of the characterization of ultrafine particles in the actual test system which is the most relevant for the interpretation of the toxicological data are referred: (i) the difference of pH in the room temperature and in the incubation conditions (ii) the difference of dispersions in MilliQ and complete cell media; (iii) the need to exemplify also the pH and isoelectric point when the hydrodynamic size is measured; (iv) the importance of time due to the time-dependent equilibration and changes of NPs corona. The surface charge determines the formation of corona and could be modified by pH. MeOx NPs without fully charge equilibrated corona might play the main role of MeOx NPs entering into the cell and consequently the time dependent manifestation of the cellular effect.

Particle Targeting in Complex Biological Media

Over the past few decades, nanoengineered particles have gained increasing interest for applications in the biomedical realm, including diagnosis, imaging, and therapy. When functionalized with targeting ligands, these particles have the potential to interact with specific cells and tissues, and accumulate at desired target sites, reducing side effects and improve overall efficacy in applications such as vaccination and drug delivery. However, when targeted particles enter a complex biological environment, the adsorption of biomolecules and the formation of a surface coating (e.g., a protein corona) changes the properties of the carriers and can render their behavior unpredictable. For this reason, it is of importance to consider the potential challenges imposed by the biological environment at the early stages of particle design. This review describes parameters that affect the targeting ability of particulate drug carriers, with an emphasis on the effect of the protein corona. We highlight strategies for exploiting the protein corona to improve the targeting ability of particles. Finally, we provide suggestions for complementing current in vitro assays used for the evaluation of targeting and carrier efficacy with new and emerging techniques (e.g., 3D models and flow-based technologies) to advance fundamental understanding in bio-nano science and to accelerate the development of targeted particles for biomedical applications.

Palmitoyl ascorbate and doxorubicin co-encapsulated liposome for synergistic anticancer therapy

Combination therapy with two drugs and nanoparticle-based drug delivery systems are widely applied to reduce the adverse effects of traditional treatment by chemotherapeutic drugs. Palmitoyl ascorbate (PA) as a lipophilic derivative of ascorbic acid shows the advantages in cancer treatment. The aim of the study was to prepare a doxorubicin (DOX) and PA co-loaded liposome to synergistically treat tumor and effectively alleviate the toxicity caused by DOX. The effects were evaluated by in vitro and in vivo studies. The liposomes (weight ratio of DOX to PA=1:20, DOX₁/PA₂₀-LPs) exhibited the strongest synergistic effects, combination index was 0.38, 0.56, and 0.05 in MCF-7, HepG2, and A549 cells, respectively. In vitro cellular uptake study, the intercellular concentration of DOX in DOX₁/PA₂₀-LPs was 2.5-fold greater than DOX loaded liposome, and DOX₁/PA₂₀-LPs was taken in not only by macropinocytosis, but also by clathrin-mediated endocytosis. Intracellular distribution experiment showed that DOX₁/PA₂₀-LPs efficiently concentrated in the nucleus. In vivo studies indicated that co-encapsulated liposome not only showed the strongest antitumor ability by tumor growth suppression, but also significantly enhanced the safety by the change of body weight and reduced damages to other tissues (evidenced by histopathology study). These results indicated that DOX and PA co-delivery liposome successfully enhanced the anticancer efficacy and mitigated the toxicities of DOX, which displayed potential for clinical application with enhanced safety and efficacy.

Gold nanoparticles, radiations and the immune system: Current insights into the physical mechanisms and the biological interactions of this new alliance towards cancer therapy

Considering both cancer's serious impact on public health and the side effects of cancer treatments, strategies towards targeted cancer therapy have lately gained considerable interest. Employment of gold nanoparticles (GNPs), in combination with ionizing and non-ionizing radiations, has been shown to improve the effect of radiation treatment significantly. GNPs, as high-Z particles, possess the ability to absorb ionizing radiation and enhance the deposited dose within the targeted tumors. Furthermore, they can convert non-ionizing radiation into heat, due to plasmon resonance, leading to hyperthermic damage to cancer cells. These observations, also supported by experimental evidence both in vitro and in vivo systems, reveal the capacity of GNPs to act as radiosensitizers for different types of radiation. In addition, they can be chemically modified to selectively target tumors, which renders them suitable for future cancer treatment therapies. Herein, a current review of the latest data on the physical properties of GNPs and their effects on GNP circulation time, biodistribution and clearance, as well as their interactions with plasma proteins and the immune system, is presented. Emphasis is also given with an in depth discussion on the underlying physical and biological mechanisms of radiosensitization. Furthermore, simulation data are provided on the use of GNPs in photothermal therapy upon non-ionizing laser irradiation treatment. Finally, the results obtained from the application of GNPs at clinical trials and pre-clinical experiments in vivo are reported.

Interactions of organic nanoparticles with proteins in physiological conditions

The efficacy of nanoparticles in biomedical applications is strongly influenced by their ability to bind proteins onto their surface. The analysis of organic nanoparticles interacting with proteins in physiological conditions may help in the successful design of next generation nanoparticles with improved biodistributions and therapeutic performances.

Nanoparticle-based drug delivery in cancer: the role of cell membrane structures

Development of novel drug-delivery systems aims to specifically deliver anticancer drugs to tumor tissues and improve the efficiency of chemotherapy, while minimizing side effects of drugs on healthy tissues and organs. However, drug-delivery systems are confronted by membrane barriers and multiple drug resistance in cancer cells. In recent years, the obtained results indicate an important role of lipids, proteins and carbohydrates in apoptosis, drug transport and the process of cellular uptake of nanoparticles via endocytosis. This article discusses the hypothesis of the relationship between cell membrane structure and nanoparticles in cancer cells.