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Advances in Microreactor Devices for Biomedicine, Nanoparticle Synthesis, Catalysis and Energy Processes

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Electronic Materials".

Deadline for manuscript submissions: closed (15 December 2021) | Viewed by 18999

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Special Issue Editor

Dr. Victor Sebastian

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Guest Editor

1. Department of Chemical and Environmental Engineering, University of Zaragoza, 50018 Zaragoza, Spain
2. Aragon Nanoscience Institute, University of Zaragoza, 50018 Zaragoza, Spain
Interests: manoscience; catalyst; molecules
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Microreactors are defined as miniaturized reaction systems fabricated using microtechnology and precision engineering methods. However, the term “microreactor” is the name that is generally used to describe a wide variety of devices that have small dimensions that are further classified according to their complexity, integration level, physical and chemical principles and the fields of application. Reducing the dimensions of the reaction system under the millimeter scale favors rapid reaction rates and minimizes the heat and mass transport limitations that usually limits conventional reactor systems.

Over the past decade, microreactor technology has evolved from simple devices for basic chemical transformations to more complex systems for a great number of applications in the fields of catalysis, energy processes, nanomaterial production, biomedicine and sensors. The use of microreactor devices enables us to perform reactions with an unprecedented control over mixing, mass- and heat-transfer, safety, reaction residence time and other process parameters, which results in enhanced reproducibility. In addition, they allow us to utilize extreme reaction conditions, which are far from the common laboratory practice (e.g., high temperature, pressure, and reactant concentration), in a safe and reliable fashion. In microreactors, the reaction rates can be accelerated by orders of magnitude and the reaction times shrink from hours to minutes and seconds. Microreactor devices are key contributors to chemical discovery and development, for instance by the well-known continuous flow chemistry. Continuous-flow chemistry is a relatively new field that has rapidly gained ground in the last couple of years. The use of microreactor devices has received a lot of attention, as these devices provide novel and unprecedented opportunities for synthetic chemists with regard to reaction safety, mixing efficiency, and reproducibility.

The low energy densities of even state of the art batteries are a major hindrance to the lengthy use of portable consumer electronics and portable equipment. Much ongoing research is therefore focused on developing microsystem generators that can take advantage of the high energy density of the fuels, while being both portable and producing sufficiently high power levels. The small size of microreactors allows for their easier transportation and rapid, on-site installation in contrast to large, centralized stations.

The functionality of nanomaterials depends on their dimensions, shape and chemical composition. This implies that attaining the desired dimensions and composition through controlled synthesis is the key to retaining the properties that make these materials functional. The continuous-flow synthesis of functional nanomaterials not only paves the way to achieving consistency in properties, but is also scalable and yet decentralized, providing it with flexible on-site, on-demand production.

Microreactor technology has played a fundamental role in biomedicine, where all types of drugs, both hydrophobic and hydrophilic, and small molecules, proteins and nucleic acids, can be encapsulated into the nanoengineered carriers. Microreactor devices can also be used for local drug delivery. Wearable or implantable microreactor devices can be loaded with drugs and can precisely control the release of payloads in a sustained or stimuli-responsive manner. Microreactors are a valuable tool in tissue engineering, promoting the migration, proliferation and differentiation of cells in controlled situations. Finally, the so-called micro-total-analysis-systems (μ-TAS) or lab-on-chip (LOC), are a vital influence for clinical and environmental diagnostics.

This Special Issue on “Advances in Microreactor Devices for Biomedicine, Nanoparticle Synthesis, Catalysis and Energy Processes” is a timely approach to survey recent progress in the area of microreactor devices and their applications. The articles presented in this Special Issue will cover various topics, ranging from the application of microreactor devices in biomedicine (drug delivery, nanovector production, tissue engineering, and diagnostics), nanomaterial production (inorganic, organic, and hybrid nanomaterials), catalysis (new reaction approaches and flow chemistry) and energy processes (process intensification and new microreactor designs). In this context, the research published in this issue will offer a unique glimpse of what has been achieved and what remains to be explored in micoreactor technology.

It is my pleasure to invite you to submit a manuscript to this Special Issue. Full papers, communications, and reviews are all welcome.

Assoc. Prof. Dr. Victor Sebastian
Guest Editor

Manuscript Submission Information

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Keywords

Microreactor design
Biomedicine
Drug delivery
Tissue engineering
Nanomaterial production
Catalysis
Flow chemistry
Scale-up
Energy process

Published Papers (4 papers)

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Research

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23 pages, 5608 KiB

Open AccessArticle

Microflow Nanoprecipitation of Positively Charged Gastroresistant Polymer Nanoparticles of Eudragit^® RS100: A Study of Fluid Dynamics and Chemical Parameters

by Cristina Yus, Manuel Arruebo, Silvia Irusta and Victor Sebastián

Materials 2020, 13(13), 2925; https://doi.org/10.3390/ma13132925 - 30 Jun 2020

Cited by 5 | Viewed by 2982

Abstract

The objective of the present work was to produce gastroresistant Eudragit^® RS100 nanoparticles by a reproducible synthesis approach that ensured mono-disperse nanoparticles under the size of 100 nm. Batch and micromixing nanoprecipitation approaches were selected to produce the demanded nanoparticles, identifying the critical parameters affecting the synthesis process. To shed some light on the formulation of the targeted nanoparticles, the effects of particle size and homogeneity of fluid dynamics, and physicochemical parameters such as polymer concentration, type of solvent, ratio of solvent to antisolvent, and total flow rate were studied. The physicochemical characteristics of resulting nanoparticles were studied applying dynamic light scattering (DLS) particle size analysis and electron microscopy imaging. Nanoparticles produced using a micromixer demonstrated a narrower and more homogenous distribution than the ones obtained under similar conditions in conventional batch reactors. Besides, fluid dynamics ensured that the best mixing conditions were achieved at the highest flow rate. It was concluded that nucleation and growth events must also be considered to avoid uncontrolled nanoparticle growth and evolution at the collection vial. Further, rifampicin-encapsulated nanoparticles were prepared using both approaches, demonstrating that the micromixing-assisted approach provided an excellent control of the particle size and polydispersity index. Not only the micromixing-assisted nanoprecipitation promoted a remarkable control in the nanoparticle formulation, but also it enhanced drug encapsulation efficiency and loading, as well as productivity. To the best of our knowledge, this was the very first time that drug-loaded Eudragit^® RS100 nanoparticles (NPs) were produced in a continuous fashion under 100 nm (16.5 ± 4.3 nm) using microreactor technology. Furthermore, we performed a detailed analysis of the influence of various fluid dynamics and physicochemical parameters on the size and uniformity of the resulting nanoparticles. According to these findings, the proposed methodology can be a useful approach to synthesize a myriad of nanoparticles of alternative polymers. Full article

(This article belongs to the Special Issue Advances in Microreactor Devices for Biomedicine, Nanoparticle Synthesis, Catalysis and Energy Processes)

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19 pages, 2898 KiB

Open AccessFeature PaperArticle

A Modular Millifluidic Platform for the Synthesis of Iron Oxide Nanoparticles with Control over Dissolved Gas and Flow Configuration

by Luca Panariello, Gaowei Wu, Maximilian O. Besenhard, Katerina Loizou, Liudmyla Storozhuk, Nguyen Thi Kim Thanh and Asterios Gavriilidis

Materials 2020, 13(4), 1019; https://doi.org/10.3390/ma13041019 - 25 Feb 2020

Cited by 21 | Viewed by 4229

Abstract

Gas–liquid reactions are poorly explored in the context of nanomaterials synthesis, despite evidence of significant effects of dissolved gas on nanoparticle properties. This applies to the aqueous synthesis of iron oxide nanoparticles, where gaseous reactants can influence reaction rate, particle size and crystal structure. Conventional batch reactors offer poor control of gas–liquid mass transfer due to lack of control on the gas–liquid interface and are often unsafe when used at high pressure. This work describes the design of a modular flow platform for the water-based synthesis of iron oxide nanoparticles through the oxidative hydrolysis of Fe²⁺ salts, targeting magnetic hyperthermia applications. Four different reactor systems were designed through the assembly of two modular units, allowing control over the type of gas dissolved in the solution, as well as the flow pattern within the reactor (single-phase and liquid–liquid two-phase flow). The two modular units consisted of a coiled millireactor and a tube-in-tube gas–liquid contactor. The straightforward pressurization of the system allows control over the concentration of gas dissolved in the reactive solution and the ability to operate the reactor at a temperature above the solvent boiling point. The variables controlled in the flow system (temperature, flow pattern and dissolved gaseous reactants) allowed full conversion of the iron precursor to magnetite/maghemite nanocrystals in just 3 min, as compared to several hours normally employed in batch. The single-phase configuration of the flow platform allowed the synthesis of particles with sizes between 26.5 nm (in the presence of carbon monoxide) and 34 nm. On the other hand, the liquid–liquid two-phase flow reactor showed possible evidence of interfacial absorption, leading to particles with different morphology compared to their batch counterpart. When exposed to an alternating magnetic field, the particles produced by the four flow systems showed ILP (intrinsic loss parameter) values between 1.2 and 2.7 nHm²/kg. Scale up by a factor of 5 of one of the configurations was also demonstrated. The scaled-up system led to the synthesis of nanoparticles of equivalent quality to those produced with the small-scale reactor system. The equivalence between the two systems is supported by a simple analysis of the transport phenomena in the small and large-scale setups. Full article

(This article belongs to the Special Issue Advances in Microreactor Devices for Biomedicine, Nanoparticle Synthesis, Catalysis and Energy Processes)

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12 pages, 2058 KiB

Open AccessArticle

Photocatalytic Microporous Membrane against the Increasing Problem of Water Emerging Pollutants

by Pedro M. Martins, Joana M. Ribeiro, Sara Teixeira, Dmitri. Y. Petrovykh, Gianaurelio Cuniberti, Luciana Pereira and Senentxu Lanceros-Méndez

Materials 2019, 12(10), 1649; https://doi.org/10.3390/ma12101649 - 21 May 2019

Cited by 32 | Viewed by 3233

Abstract

Emerging pollutants are an essential class of recalcitrant contaminants that are not eliminated from water after conventional treatment. Here, a photocatalytic microporous membrane based on polyvinylidene difluoride-co-trifluoroethylene (PVDF−TrFE) with immobilised TiO₂ nanoparticles, prepared by solvent casting, was tested against representative emerging pollutants. The structure and composition of these polymeric membranes were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, porosimetry, and contact angle goniometry. The nanocomposites exhibited a porous structure with a uniform distribution of TiO₂ nanoparticles. The addition of TiO₂ did not change the structure of the polymeric matrix; however, it increased the wettability of the nanocomposite. The nanocomposites degraded 99% of methylene blue (MB), 95% of ciprofloxacin (CIP), and 48% of ibuprofen (IBP). The microporous nanocomposite exhibited no photocatalytic efficiency loss after four use cycles, corresponding to 20 h of UV irradiation. The reusability of this system confirms the promising nature of polymer nanocomposites as the basis for cost-effective and scalable treatments of emerging pollutants. Full article

(This article belongs to the Special Issue Advances in Microreactor Devices for Biomedicine, Nanoparticle Synthesis, Catalysis and Energy Processes)

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Review

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25 pages, 2959 KiB

Open AccessReview

Continuous Ultrasonic Reactors: Design, Mechanism and Application

by Zhengya Dong, Claire Delacour, Keiran Mc Carogher, Aniket Pradip Udepurkar and Simon Kuhn

Materials 2020, 13(2), 344; https://doi.org/10.3390/ma13020344 - 11 Jan 2020

Cited by 84 | Viewed by 7524

Abstract

Ultrasonic small scale flow reactors have found increasing popularity among researchers as they serve as a very useful platform for studying and controlling ultrasound mechanisms and effects. This has led to the use of these reactors for not only research purposes, but also various applications in biological, pharmaceutical and chemical processes mostly on laboratory and, in some cases, pilot scale. This review summarizes the state of the art of ultrasonic flow reactors and provides a guideline towards their design, characterization and application. Particular examples for ultrasound enhanced multiphase processes, spanning from immiscible fluid–fluid to fluid–solid systems, are provided. To conclude, challenges such as reactor efficiency and scalability are addressed. Full article

(This article belongs to the Special Issue Advances in Microreactor Devices for Biomedicine, Nanoparticle Synthesis, Catalysis and Energy Processes)

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