Self-Assembly Kinetics of Colloidal Particles inside Monodispersed Micro-Droplet and Fabrication of Anisotropic Photonic Crystal Micro-Particles

Erythrocyte-Inspired Functional Materials for Biomedical Applications

Erythrocytes are the most abundant cells in the blood. As the results of long-term natural selection, their specific biconcave discoid morphology and cellular composition are responsible for gaining excellent biological performance. Inspired by the intrinsic features of erythrocytes, various artificial biomaterials emerge and find broad prospects in biomedical applications such as therapeutic delivery, bioimaging, and tissue engineering. Here, a comprehensive review from the fabrication to the applications of erythrocyte-inspired functional materials is given. After summarizing the biomaterials mimicking the biological functions of erythrocytes, the synthesis strategies of particles with erythrocyte-inspired morphologies are presented. The emphasis is on practical biomedical applications of these bioinspired functional materials. The perspectives for the future possibilities of the advanced erythrocyte-inspired biomaterials are also discussed. It is hoped that the summary of existing studies can inspire researchers to develop novel biomaterials; thus, accelerating the progress of these biomaterials toward clinical biomedical applications.

Shaping in the Third Direction; Fabrication of Hemispherical Micro-Concavity Array by Using Large Size Polystyrene Spheres as Template for Direct Self-Assembly of Small Size Silica Spheres

Silica and polystyrene spheres with a small size ratio (r = 0.005) form by sequential hanging drop self-assembly, a binary colloidal crystal through which calcination transforms in a silica-ordered concavity array. These arrays are capable of light Bragg diffraction and shape dependent optical phenomena, and they can be transformed into inverse-opal structures. Hierarchical 2D and 3D super-structures with ordered concavities as structural units were fabricated in this study.

Boston Ivy-Inspired Disc-Like Adhesive Microparticles for Drug Delivery

Microparticles with strong adherence are expected as efficient drug delivery vehicles. Herein, we presented an ingenious hydrogel microparticle recapitulating the adhesion mechanism of Boston ivy tendrils adhesive discs (AD) for durable drug delivery. The particles were achieved by replicating a silica colloidal crystal aggregates assembled in a droplet template after rapid solvent extraction. Due to their unique shape, the nanostructure, and the sticky hydrogel component, such novel microparticles exhibited prominent adhesive property to the wet tissue environment. It was demonstrated that the bioinspired microcarriers loading with dexamethasone had a good therapeutic effect for ulcerative colitis due to the strong adhesion ability for prolonging the maintenance of drug availability. These virtues make the biomimetic microparticles potentially ideal for many practical clinical applications, such as drug delivery, bioimaging, and biodiagnostics.

Making Photonic Crystals via Evaporation of Nanoparticle-Laden Droplets on Superhydrophobic Microstructures

We employed a convenient evaporation approach to fabricate photonic crystals by naturally drying droplets laden with nanoparticles on a superhydrophobic surface. The final drying morphology could be controlled by the concentration of nanoparticles. A dilute droplet resulted in a torus, whereas a quasi-spherical cap with a bottom cavity was made from a concentrated droplet. Remarkably, the nanofluid droplets maintained high contact angles (≳120°) during the entire evaporation process because of inhomogeneous surface wetting. Bottom-view snapshots revealed that during evaporation the color of the contact area changed sequentially from white to red, orange, yellow, and eventually to green. Scanning electron microscopy and Voronoi analysis demonstrated that nanoparticles were self-assembled to a hexagonal pattern. Finally, based on the effects of particle size, material, and volume concentration on the reflected wavelengths, a model has been developed to successfully predict the reflected wavelength peaks from the contact area of evaporating colloidal droplets. Our model can be easily adopted as a manufacturing guide for functional photonic crystals to predict the optimal reflected color made by evaporation-driven self-assembly of photonic crystals.

Colloidal Crystals from Microfluidics

Colloidal crystals are of great interest to researchers because of their excellent optical properties and broad applications in barcodes, sensors, displays, drug delivery, and other fields. Therefore, the preparation of high quality colloidal crystals in large quantities with high speed is worth investigating. After decades of development, microfluidics have been developed that provide new choices for many fields, especially for the generation of functional materials in microscale. Through the design of microfluidic chips, colloidal crystals can be prepared controllably with the advantages of fast speed and low cost. In this Review, research progress on colloidal crystals from microfluidics is discussed. After summarizing the classifications, the generation of colloidal crystals from microfluidics is discussed, including basic colloidal particles preparation, and their assembly inside or outside of microfluidic devices. Then, applications of the achieved colloidal crystals from microfluidics are illustrated. Finally, the future development and prospects of microfluidic-based colloidal crystals are summarized.

Self-assembly of colloids based on microfluidics

Self-assembly of colloids provides a powerful way for the construction of complex multi-scale materials. Microfluidic techniques possess great potential to precisely control the assembly of micro- and nano-scale building blocks via the rational design of various microfluidic environments. In this review, we first discuss the self-assembly of colloids without templates by using the laminar microfluidic technique. The self-assembly of colloids based on a droplet as a template was subsequently summarized and discussed via droplet microfluidic technique. Moreover, the evaporation-driven self-assembly of colloids in microfluidic channels has been discussed and analysed. Finally, the representative applications in this field have been pointed out. The aim of this review is to summarize the state-of-art on the self-assembly of colloids based on various microfluidic techniques, exhibit their representative applications, and point out the current challenges in this field, hoping to inspire and guide future work.

One-step fabrication of silica colloidosomes with in situ drug encapsulation

In situ modification, drug encapsulation and fabrication of hollow silica colloidosomes in microfluidic device.