Microcontact Printing Techniques in Bioscience

The microcontact printing(μCP) technology available for patterning protein, DNA hybridization, immunoassay and cellular cocultures onto solid surface are reviewed. This review describes some of the techniques currently employed for creating two-dimensional biomolecular microarray, and the research results regarding their effectiveness. In addition, the applications of the impact of μCP technology in the field of biosciences are also presented.

CuSO_4 Micro-crystal Lattice Produced by Microcontact Printing

An elastic stamp was produced by molding poly(dimethylsiloxane)(PDMS) against a master with micro\|patterns on the surface. Then a procedure named microcontact printing was carried out on the glass substrate with the ink of an octadecylsiloxane(OTS) solution. The OTS reacted with the glass and formed a self\|assembly monolayer, and the process produced hydrophobic micro\|patterns on hydrophilic substrate. Owing to a simple hydrophobic interaction between the CuSO\-4 solution and the monolayer, a regular CuSO\-4 micro\|crystal lattice could be produced.

Wafer Scale Synthesis of Dense Aligned Arrays of Single-Walled Carbon Nanotubes

Here we present an easy one-step approach to pattern uniform catalyst lines for the growth of dense,aligned parallel arrays of single-walled carbon nanotubes(SWNTs)on quartz wafers by using photolithography or polydimethylsiloxane(PDMS)stamp microcontact printing(μCP).By directly doping an FeCl3/methanol solution into Shipley 1827 photoresist or polyvinylpyrrolidone(PVP),various catalyst lines can be well-patterned on a wafer scale.In addition,during the chemical vapor deposition(CVD)growth of SWNTs the polymer layers play a very important role in the formation of mono-dispersed nanoparticles.This universal and effi cient method for the patterning growth of SWNTs arrays on a surface is compatible with the micro-electronics industry,thus enabling of the fabrication highly integrated circuits of SWNTs.

Fabrication of microcapsule arrays on chemically patterned surfaces via covalent linking

A method for fabricating arrays of microcapsules covalently immobilized onto chemically patterned substrates was developed.The core-shell microparticles with poly(allylamine hydrochloride)(PAH) as the outermost layer were obtained by layer-by-layer (LbL) assembly,which were further treated with glutaraldehyde to endow the particles with abundant aldehyde groups on their surfaces.The particles were then covalently coupled to the chemically patterned regions with amino groups created by microcontact printing (μCP).After dissolution of the core particles,arrays of the hollow microcapsules with unchanged structures were obtained.These arrays could stand rigorous environmental conditions of higher ionic strength,and lower and higher pH values.Thus,the technique could be possibly applied to exploiting chips of microcontainers or microreactors in sensing technology.

Visualized Degradation of CO_(2)-Based Unsaturated Polyesters toward Structure-Controlled and High-Value-Added Fluorophores

In comparing with traditional polymer degradation toward unknown or unvalued products(i.e.,downcycling),new methods to degrade polymers into monomers or high-value-added materials(i.e.,upcycling)are preferable for sustainable developments.In this work,CO_(2)-based linear and cross-linked unsaturated polyesters,that is,poly(alkynoate)s,were successfully degraded by benzamidine into diols and high-value-added pyrimidone or imidazolone derivatives through controlled reaction conditions.The degradation process could be visualized under UV light via gradually increased luminescent intensity of the reaction mixtures and fluorescence patterns could be generated through microcontact printing of the stamp on the thin films of poly(alkynoate)s.Moreover,the pyrimidone derivatives could be applied in bioimaging and inhibiting bacteria,and the imidazolone derivatives could be used for the detection and recovery of gold(III)ions from electronic waste and serve as the fluorescent sensor to detect in situ-generated amines from food spoilage.Thus,this work presents a visualized and high value productselective degradation to solve the end-of-life issue of polymers.

Wafer scale direct-write of Ge and Si nanostructures with conducting stamps and a modified mask aligner

The broad availability of high throughput nanostructure fabrication is essential for advancement in nanoscale science. Large-scale manufacturing developed by the semiconductor industry is often too resource-intensive for medium scale laboratory prototyping. We demonstrate the inexpensive wafer scale direct- write of Ge and Si nanostructures with a 4-inch mask aligner retrofitted with a conducting microstructured stamp. A bias applied between the stamp and an underlying silicon substrate results in the reaction of diphenylgermane and diphenylsilane precursors at the stamp--substrate interface to yield the direct- write of Ge and Si nanostructures in determined locations. With the increasing number of outdated mask aligners available from the semiconductor industry and an extensive library of liquid precursors, this strategy provides facile, inexpensive, wafer scale semiconductor direct-write for applications such as electronics, photonics, and photovoltaics.

Tuning interfacial interactions for bottom-up assembly of surface-anchored metal-organic frameworks to tailor film morphology and pattern surface features

Surface-anchored metal-organic frameworks(surMOFs)integrate nanoporous supramolecular MOF materials directly into architectures for applications such as gas storage,chemical sensing,and energy storage.Layer-by-layer solution-phase deposition of the MOF-14 components(1,3,5-tris(4-carboxyphenyl)benzene and copper(II)dimers,respectively)produces a porous and conformal film on carboxylterminated self-assembled monolayers(SAMs).In this research,the formation of ultrathin(less than 25 nm)surMOF films on codeposited bicomponent SAMs and microcontact printed SAMs is investigated by atomic force microscopy,ellipsometry,infrared spectroscopy,and contact angle goniometry.SAMs composed of methyl-terminated alkanethiols assembled on gold substrates inhibit surMOF formation,whereas carboxyl-terminated alkanethiols promote MOF-14-based film growth.To tune the density of carboxyl groups that anchor the film,methyl-and carboxylterminated alkanethiols of varying concentrations are codeposited on gold.This systematic study demonstrates how surMOF film formation and morphology are impacted by these SAMs with mixed surface functionalities.Chemical patterning methods for SAMs,such as microcontact printing(μCP),commonly have mixed chemical functionalities within certain regions of the pattern.Insights gained regarding how mixed surface functionalities affect surMOF film formation are applied herein to optimize theμCP method to produce chemically patterned SAMs that selectively direct surMOF assembly to produce high-quality surMOF film features.