Protein and cell micropatterning and its integration with micro/nanoparticles assembly.

Micropatterning of proteins and cells has become very popular over the past decade due to its importance in the development of biosensors, microarrays, tissue engineering and cellular studies. This article reviews the techniques developed for protein and cell micropatterning and its biomedical applications. The prospect of integrating micro and nanoparticles with protein and cell micropatterning is discussed. The micro/nanoparticles are assembled into patterns and form the substrate for proteins and cell attachment. The assembled particles create a micro or nanotopography, depending on the size of the particles employed. The nonplanar structure can increase the surface area for biomolecules attachment and therefore enhance the sensitivity for detection in biosensors. Furthermore, a nanostructured substrate can influence the conformation and functionality of protein attached to it, while cellular response in terms of morphology, adhesion, proliferation, differentiation, etc. can be affected by a surface expressing micro or nanoscale structures. Proteins and cells tend to lose their normal functions upon attachment to substrate. By recognizing the types of topography that are favourable for preserving proteins and cell behaviour, and integrating it with micropattering will lead to the development of functional protein and cell patterns.

Elastic modulus of resin-based dental restorative materials: a microindentation approach.

This research aimed to determine the elastic modulus of resin-based dental composite restoratives using the microindentation test method. Results were then compared with those obtained with the ISO three-point bending test method. Five materials from the same manufacturer (3M ESPE) were selected for the study. They included microfill (A110), minifill (Z100 and Filtek Z250), poly-acid modified (F2000), and flowable (Filtek Flowable [FF]) composites. The indentation moduli of the composites were determined using a custom-designed microindentation test set up after conditioning in water at 37 degrees C for 1 week and 1 month. The indentation test was carried out at peak load of 10 N and Oliver & Pharr's method was used to determine the maximum projected contact area. Data was analyzed using ANOVA/post-hoc Scheffe's test at significance level 0.05 and Pearson's correlation at significance level 0.01. The mean indentation modulus ranged from 5.80 to 15.64 GPa and 5.71 to 15.35 GPa at 1 week and 1 month, respectively. At both time periods, the indentation modulus of Z100 was significantly higher than all other materials. F2000 was significantly higher than Z250, which was significantly stiffer than A110 and FF. The rankings were in good agreement with the ISO flexural test. A significant, positive, and strong correlation (r = 0.93 and 0.94 at 1 week and 1 month, respectively) in modulus between ISO three-point bending and microindentation test methods was observed. In view of the small specimen size and good reproducibility, the microindentation reflects a potential test method for determining the elastic properties of dental composite restoratives.