Contact-Free Online Monitoring of Bioreactor Cell Cultures with Magnetic Resonance Relaxometry.

Frequent, low-latency measurements of bioreactor culture growth are critical for achieving maximum culture efficiency and productivity. Typical cell density and viability measurements are made by manually removing a sample from the culture, but this approach is both slow and unsuitable for small culture volumes, which cannot support frequent destructive sampling. In this work, automated magnetic resonance relaxometry measurements of a sealed bioreactor system are used to estimate the cell density and provide qualitative information about the culture in near real-time.

Principal component analysis of alpha-helix deformations in transmembrane proteins.

α-helices are deformable secondary structural components regularly observed in protein folds. The overall flexibility of an α-helix can be resolved into constituent physical deformations such as bending in two orthogonal planes and twisting along the principal axis. We used Principal Component Analysis to identify and quantify the contribution of each of these dominant deformation modes in transmembrane α-helices, extramembrane α-helices, and α-helices in soluble proteins.