Bioinspired Superwettability Micro/Nanoarchitectures: Fabrications and Applications

Understanding the relationship between liquid manipulation and micro‐/nanostructured interfaces has gained much attention due to the wide potential applications in many fields, such as chemical and biomedical assays, environmental protection, industry, and even daily life. Much work has been done to construct various materials with interfacial liquid manipulation abilities, leading to a range of interesting applications. Herein, different fabrication methods from the top‐down approach to the bottom‐up approach and subsequent surface modifications of micro‐/nanostructured interfaces are first introduced. Then, interactions between the surface and liquid, including liquid wetting, liquid transportation, and a number of corresponding models, together with the definition of hydrophilic/hydrophobic, oleophilic/olephobic, the definition and mechanism of superwetting, including superhydrophobicity, superhydrophilicity, and superoleophobicity, are presented. The micro‐/nanostructured interface, with major applications in self‐cleaning, antifogging, anti‐icing, anticorrosion, drag‐reduction, oil–water separation, water collection, droplet (micro)array, and surface‐directed liquid transport, is summarized, and the mechanisms underlying each application are discussed. Finally, the remaining challenges and future perspectives in this area are included.

Section: Introductionmentioning

confidence: 99%

Micro‐/Nanostructured Interface for Liquid Manipulation and Its Applications

Duan

Zheng

Zhao

et al. 2019

“…Another main strategy to impact microflow behaviors through surface effects is to construct physical structures on the inner surfaces of microchannels, including anisotropic wetting structures, and micro‐/nanostructures for wettability enhancement. A surface is said to be anisotropic in wettability if it shows distinct contact angles when measured in different directions . Anisotropic wetting occurs when liquid contact line encounters physical discontinuity and chemical heterogeneity present on solid surfaces.…”

Section: Inner Surface Design Of Microchannelsmentioning

confidence: 99%

“…A surface is said to be anisotropic in wettability if it shows distinct contact angles when measured in different directions. [51][52][53] Anisotropic wetting occurs when liquid contact line encounters physical discontinuity and chemical heterogeneity present on solid surfaces. In recent years, anisotropic wetting micro-/nanostructures have attracted wide scientific attention for practical applications, such as microfluidics, [24,54] fog harvesting, [55][56][57] and oil-water separation.…”

Section: Surface Structure Constructionmentioning

confidence: 99%

Inner Surface Design of Functional Microchannels for Microscale Flow Control

Wang

Yang

et al. 2019

Fluidic flow behaviors in microfluidics are dominated by the interfaces created between the fluids and the inner surface walls of microchannels. Microchannel inner surface designs, including the surface chemical modification, and the construction of micro‐/nanostructures, are good examples of manipulating those interfaces between liquids and surfaces through tuning the chemical and physical properties of the inner walls of the microchannel. Therefore, the microchannel inner surface design plays critical roles in regulating microflows to enhance the capabilities of microfluidic systems for various applications. Most recently, the rapid progresses in micro‐/nanofabrication technologies and fundamental materials have also made it possible to integrate increasingly complex chemical and physical surface modification strategies with the preparation of microchannels in microfluidics. Besides, a wave of researches focusing on the ideas of using liquids as dynamic surface materials is identified, and the unique characteristics endowed with liquid–liquid interfaces have revealed that the interesting phenomena can extend the scope of interfacial interactions determining microflow behaviors. This review extensively discusses the microchannel inner surface designs for microflow control, especially evaluates them from the perspectives of the interfaces resulting from the inner surface designs. In addition, prospective opportunities for the development of surface designs of microchannels, and their applications are provided with the potential to attract scientific interest in areas related to the rapid development and applications of various microchannel systems.

“…Producing defined hierarchical materials is difficult and in demand, since natural hierarchical structures are limited in both quantity and purity 1a,2. Currently, chemical synthesis such as assembling methods has become the primary approach in preparation of hierarchical materials considering the low cost and high yield, superior to conventional engineering methods 2d,3. Notably, development of advanced assembling in preparation of hierarchical materials relies on the following three major aspects: 1) the order for assembling of subunits toward complex structures;1b,2a,4 2) the linkage/conjugation manners among different subunits;2c,5 and 3) the selection of subunits with the size ranging from nano‐ to micrometers (e.g., from nanoparticles to microbeads) 2d,4b,6.…”

mentioning

confidence: 99%

“…Notably, development of advanced assembling in preparation of hierarchical materials relies on the following three major aspects: 1) the order for assembling of subunits toward complex structures;1b,2a,4 2) the linkage/conjugation manners among different subunits;2c,5 and 3) the selection of subunits with the size ranging from nano‐ to micrometers (e.g., from nanoparticles to microbeads) 2d,4b,6. Further the core–shell materials with diverse nanoshell structures can be emerging candidates to prepare hierarchical materials owing to the unique bio‐interfaces,1b,7 but present core–shell materials are usually in the nanoscale or sub‐micrometer size limiting their general application 3c,8. Considering the above aspects, assembling of hierarchical core–shell materials with microsizes for mass production is still very challenging and calling for application‐driven design toward practical use.…”

mentioning

confidence: 99%

Design of Hierarchical Beads for Efficient Label‐Free Cell Capture

Sun

Wang

Huang

et al. 2019

materials with diverse nanoshell structures can be emerging candidates to prepare hierarchical materials owing to the unique bio-interfaces, [1b,7] but present core-shell materials are usually in the nanoscale or sub-micrometer size limiting their general application. [3c,8] Considering the above aspects, assembling of hierarchical core-shell materials with microsizes for mass production is still very challenging and calling for applicationdriven design toward practical use.Cell analysis plays a key role in biomedical research for diagnostic purpose. [9] In real case cell analysis, cell capture tends to be essential owing to the high complexity of biological specimens. [9b,c,10] To date, there are two main categories including prelabeling [10a,11] and labelfree [9a,12] process for cell capture. Compared to the labeling process that needs specific probes (such as antibodies), label-free cell capture represents the next generation tool and usually requires smart materials or devices. [6c,13] Ideal materials and devices for efficient label-free cell capture may offer: 1) surface topology with strong adherence to cell membranes; [14] 2) surface chemistry with high biocompatibility and affinity; [3c,12a,15] 3) specific size to avoid cellular endocytosis; [16] and 4) structural stability during the whole cell capture process. [6c,11b,12a,17] Until now, most existing label-free techniques only addressed parts of these issues and usually applied in imaging or delivery. Therefore, it would be desirable to construct newer materials and devices as efficient platforms for label-free cell capture.In this work, we designed hierarchical beads for efficient label-free cell capture, as shown in Figure 1a. We coated silica nanoparticles (size of ≈15 nm) onto silica spheres (size of ≈200 nm) to achieve nanoscale surface roughness, and then combined the rough silica spheres with microbeads (≈150-1000 µm in diameter) to assemble hierarchical structures. We built complex hierarchical beads via electrostatic interaction, covalent bonding, and nanoparticle adherence. Further after functionalization by hyaluronic acid (HA), the hierarchical microbeads displayed desirable surface hydrophilicity, biocompatibility, and chemical/structural stability. Due to the controlled surface topology and chemistry, the functionalized microbeads showed high cell capture efficiency of 87.9-98.7% in a label-free manner. Our work contributed to the design of Defined hierarchical materials promise cell analysis and call for applicationdriven design in practical use. The further issue is to develop advanced materials and devices for efficient label-free cell capture with minimum instrumentation. Herein, the design of hierarchical beads is reported for efficient label-free cell capture. Silica nanoparticles (size of ≈15 nm) are coated onto silica spheres (size of ≈200 nm) to achieve nanoscale surface roughness, and then the rough silica spheres are combined with microbeads (≈150-1000 µm in diameter) to assemble hierarchical structures. These hierarch...