Microfluidic force spectroscopy for characterization of biomolecular interactions with piconewton resolution.

In this paper we present a scalable method based on the use of microfluidics and shear force spectroscopy which can be used for determining the affinity between molecules. Our method involves the use of functionalization of the surface of microfluidic channels with ligand molecules, and the surface of microspheres with receptor molecules. Bound beads are detached from the surface of the microchannels using pressure driven flow. The drag force required to detach the beads is used to determine the affinity of the bond holding the two molecules together. The minimum force we are able to detect is 5 pN. We have used this method to determine the binding force between protein-protein interactions and DNA base-pair interactions. We also have shown the ability of this technique to distinguish between strong and weak protein-protein interactions. Using this approach, it may be possible to multiplex an array of these functionalized channels onto a chip and probe the interactions between large varieties of biomolecules.

Population screening for association of mitochondrial haplogroups BM, J, K and M with multiple sclerosis: interrelation between haplogroup J and MS in Persian patients.

BACKGROUND: Multiple sclerosis (MS) is an immunological inflammatory disease of the central nervous system (CNS) which is chronically observed in young adults. On the basis of earlier studies, potential relatedness between MS and mitochondrial DNA (mtDNA) mutations was postulated. MATERIALS AND METHODS: 246 individuals were screened using the PCR-RFLP method, including 70 MS patients examined for mitochondrial haplogroups BM, J, K and M and 176, 149 and 70 normal controls examined for haplogroups BM and M, J and K, respectively. RESULTS AND DISCUSSION: Our analysis revealed a relatively high proportion of haplogroup BM in MS patients (approximately 26%) compared to normal controls ( approximately 13%). In addition, a slightly significant increase of MS patients of haplogroup J (20% in MS patients versus 9.39% in normal controls at P =0.049), while haplogroups M and K did not show contribution to MS contingency (2.85 and 2.27%, respectively at P = 1.000 in haplogroup M and 12.85 and 7.14% respectively at P =0.399 in haplogroup K).