Droplet based microfluidics
A nanocrystal (NC) is a tiny object, composed mostly of crystalline elements, that has at least one dimension smaller than 1,000 nanometers1. Nanocrystals (Fig. 1) can be classified as a subset of nanoparticles, specifically referring to solid particles with crystalline structures at the nanoscale. These materials exhibit distinct properties that stem from their small size and ordered atomic arrangements, making them essential components in a wide range of scientific and technological fields.
A diverse range of microreactor types and configurations available offer researchers versatile tools to explore novel synthesis routes and advance the field of nanocrystal synthesis. To date, different microfluidics systems, including continuous and segmented-flow microfluidic systems have been used to synthesize NCs of various sizes, shapes, and with narrow size distributions.6
A microfluidic tube-based reactor adopts the single-phase continuous flow type microfluidic regime. The synthesis of nanocrystals using microcapillary tube-based reactors has emerged as a promising approach in nanoscience and materials synthesis. These reactors offer precise control over reaction conditions and enable the production of nanocrystals with tailored properties. By confining the reaction within microcapillary tubes, researchers can achieve high reproducibility and scalability in the synthesis process. Tube-based reactors are selected for the synthesis of nanocrystals over chip-based configurations due to their fabrication and operational simplicity, while offering opportunities for facile scale-out production.7
Yang et al. developed a method for the controlled synthesis of CdSe quantum dots (NB: quantum dots are a specific type of nanocrystal). In their experimental setup, two syringes were filled with cadmium and selenium precursor solutions, which were then loaded into syringe pumps. Upon activation of the syringe pumps, the precursor solutions were injected into separate PTFE capillaries with a 300 µm inner diameter and subsequently combined using a Y-shaped junction (Fig. 3). The combined solution underwent mixing in a mixer to ensure homogeneity before passing through a heated tubing section immersed in an oil bath to initiate the reaction. The resulting nanocrystalline product was collected at the outlet of the reactor. 7
Whilst continuous phase reactors are attractive for their relative ease of implementation, they suffer from two principal drawbacks that can hinder their application to nanocrystal synthesis. Firstly, they have a propensity to foul after extended operation; and, secondly, viscous drag at the channel walls causes the fluid to flow at different velocities across the channel, with the central fluid moving fastest and periphery fluid moving progressively slower as the walls are approached.7
Nightingale et. al described a versatile capillary-based droplet reactor for the controlled synthesis of metal, metal-oxide and compound semiconductor nanocrystals. The reactor exhibits stable droplet flow over a wide range of flow rates and temperatures and resists fouling even in the presence of solid intermediates or side-products. The non-dispersive flow-dynamics and the exceptional control and stability of the reactor combine to offer a near-ideal environment for performing nanocrystal synthesis. Finally we note that, whilst we have focused here on nanocrystal synthesis, the reactor is also amenable to many other solution phase synthesis procedures where tight control over reaction conditions is required.12 The reactor was successfully applied to the synthesis of metal (Ag), metal oxide (TiO2) and compound semiconductor (CdSe) nanoparticles, and in each case exhibited stable droplet flow over many hours of operation without fouling, even for reactions involving solid intermediates.12
Microfluidics has significantly impacted the synthesis of nanocrystals, providing precise control over reaction conditions, and enabling its application in the production of a wide range of compounds.
Jun et al. presented a novel approach to synthesizing hierarchical Cu2O nanocrystals with a focus on their application as electrocatalysts for the selective reduction of CO2 to C2 products. The study describes the fabrication of a unique hierarchical structure of Cu2O, termed h-Cu2O ONS, achieved through the modulation of nanocrystal growth kinetics using flow chemistry in a microfluidic system.
This innovative synthesis method aims to enhance the catalytic performance of Cu2O nanocrystals in the electrochemical reduction of CO2, particularly towards the selective generation of C2 products. The hierarchical Cu2O nanocrystals synthesized through microfluidics hold promise as efficient electrocatalysts for the conversion of CO2 into valuable C2 products, such as C2H4 and C2H6. By leveraging the advantages of microfluidic-assisted synthesis, the research contributes to the development of advanced materials for CO2 reduction applications, offering potential solutions for sustainable energy conversion and storage.13
The transformation of drug microcrystals into drug nanoparticles can result in the production of either a crystalline or an amorphous product, depending on the method of production. While an amorphous drug nanoparticle technically should not be classified as a nanocrystal, it is commonly referred to as “nanocrystals in the amorphous state.” This process of producing drug nanocrystals offers the advantage of reducing the size of poorly water-soluble drug particles to the nanometer scale, thereby altering the drug’s thermodynamic and kinetic properties and addressing challenges related to its biopharmaceutical delivery.14
Drug nanocrystals exhibit enhanced adhesion to surface/cell membranes compared to microparticles due to their smaller size and increased surface area, facilitating improved interactions. Additionally, drug nanocrystal suspensions demonstrate long-term physical stability when appropriately stabilized, preventing aggregation of the nanocrystals and inhibiting the Ostwald ripening phenomenon.14
Furthermore, the application of microfluidics in nanocrystal synthesis extends to the use for the synthesis of advanced drug delivery systems15,16. Liu et al. introduces a novel approach that combines the advantages of polymeric nanoparticles and drug nanocrystals in a nano-in-nano vector. This innovative vector aims to leverage the strengths of both polymeric nanoparticles and drug nanocrystals to enhance drug delivery systems. By merging these two components, the nano-in-nano vector offers a promising strategy for optimizing drug therapeutic efficacy, improving drug stability, and achieving controlled drug release. The study highlights the potential of this hybrid approach in advancing drug delivery systems and highlights the synergistic benefits of integrating polymeric nanoparticles and drug nanocrystals in a single vector for enhanced pharmaceutical applications.17
Sorafenib (SFN) and itraconazole (ICZ) nanocrystals encapsulated by folic acid (FA) conjugated spermine-functionalized acetylated dextran (ADS), HSFN@ADS-FA and ICZ@ADS-FA, were produced through multistep microfluidics nanoprecipitation configuration same as the one depicted in (Fig. 6). The PTX@HF and SFN@HF nanocrystals showed ultrahigh drug loading degree (42.6 and 45.2%, respectively), pH sensitive drug release, an increased drug dissolution kinetics, and high-throughput production rate at ~700 g/day on a single device.14
Nanocrystalline semiconductors are of considerable scientific and commercial interest owing to their tunable optical and electronic properties, and potential applications in a wide range of electronic devices. Physical characteristics of nanocrystallites are determined primarily by spatial confinement effects with properties such as the optical band gap often differing considerably from the bulk semiconductor.18
The semiconductor nanocrystal has been widely investigated for three decades now and forms one of the centerpieces of the modern nanoscience revolution19. CdSe nanocrystals possess exceptional optical and electronic properties that render them valuable in diverse semiconductor applications, including biological labeling, light-emitting diodes, and solar cells. Hirokuyi et.al. presented a study that focuses on the preparation of CdSe nanocrystals in a micro-flow-reactor. The research explores the synthesis of CdSe nanocrystals using a microfluidic system, aiming to investigate the efficient production of these nanocrystals in a controlled environment. By utilizing microfluidics, the researchers aim to enhance the reproducibility and scalability of the synthesis process, potentially leading to the production of high-quality CdSe nanocrystals with tailored properties for various applications.20
Moreover, the application of microfluidics in nanocrystal synthesis extends to the fabrication of composite materials like α-CsPbI3/m-SiO2 nanocomposites for solid-state lighting applications.
Guo et.al. presented a microfluidic-based continuous large-scale fabrication of CsPbI3– mesoporous SiO2 (CPI/m-SiO2) nanocomposites to solve the problem of large-scale continuous production of stable, repeatable, high-quality perovskite NCs.21 CsPbI3 perovskite nanocrystals are known for their limited chemical stability compared to other CsPbX3 perovskite nanocrystals due to their thermodynamically metastable nature. The research aims to address this limitation by synthesizing α-CsPbI3/m-SiO2 nanocomposites in a continuous manner using a microfluidics reactor. The resulting nanocomposites exhibit enhanced stability and are intended for use in solid-state lighting applications.
The utilization of microfluidics in the synthesis of nanocrystals has revolutionized the field, offering numerous advantages and opportunities for advancements in nanomaterial production. This technology has been instrumental in the production of various nanomaterials, including semiconductor nanocrystals, drug nanoparticles, and perovskite nanocrystals, showcasing its versatility and impact across different disciplines. The use of microfluidics has not only enhanced the reproducibility and efficiency of nanocrystal synthesis but has also facilitated the exploration of novel synthesis techniques and the development of advanced materials with unique characteristics. Overall, the integration of microfluidics in nanocrystal synthesis represents a promising avenue for the future of nanotechnology, offering new possibilities for the design, fabrication, and application of nanomaterials in diverse fields.
Email* I hereby agree than Elveflow uses my personal data
Do you want tips on how to best set up your microfluidic experiment? Do you need inspiration or a different angle to take on your specific problem? Well, we probably have an application note just for you, feel free to check them out!
Centrifugal microfluidics, or "Lab-on-a-CD," leverages centrifugal force to manipulate fluids on a microscale.
The integration of CRISPR-Cas9 with microfluidics has led to the development of innovative techniques for genetic editing and screening.
Pharmacogenomics is the study of how an individual’s genetic variants influence drug responses and treatment efficacy.
The Dynamics of Fungal Spore Dispersal: Insights from Microfluidic Models
Free-flow electrophoresis (FFE) is a technique that enables the continuous separation of analytes as they flow through a planar channel.
Specifically, we will explore a mechanical force known as shear stress and its role in modulating cellular responses through a process known as mechanosensing.
The profile of laminar flow through a small straight pipe may be approximated by small concentric cylinders towards the direction of the flow.
Finding the right technique for particle encapsulation using micro and nanoparticles is key for a successful particle encapsulation protocol.
This review demonstrates the development of microfluidic techniques and their capability in performing various types of chemical synthesis.
A guide to calculate the flow resistance of your microfluidic circuit.
One of the key criteria to choose your microfluidic device material is its chemical resistance. This review will help you choose one depending on your application.
Microfluidics: definitions. This short review aims to cover the main microfluidics definitions from the simple word by word science to the advantages & applications
Introduction to thermoelectric sensor | Microfluidics immunosensors offer multiple advantages over the conventional immunoassays that include improved reaction rate, reduced time for incubation of the reactants, and decreased reagents and sample consumption. Moreover, miniaturization and integration of the multiple assay components permit automation, precise flow control, increased reproducibility, and the possibility for high-throughput analysis.
Get a quote
Name*
Email*
Message
Newsletter subscription
We will answer within 24 hours
By filling in your info you accept that we use your data.
Collaborations
Need customer support?
Serial Number of your product
Support Type AdviceHardware SupportSoftware Support
Subject*
I hereby agree that Elveflow uses my personal data Newsletter subscription
How can we help you?
Message I hereby agree that Elveflow uses my personal data Newsletter subscription