A new technique for parallel recording of reflection photoplethysmography (PPG) signals in a broad spectral band (violet to near-infrared) has been developed, and its potential for assessment of blood microcirculation at various depths from the skin surface is discussed. PPG signals have been simultaneously detected at cw laser wavelength sets comprising 405, 532, 645, 807, and 1064 nm. Various signal baseline responses to breath holding and different shapes of the PPG pulses originated from the same heartbeat but recorded at different wavelengths have been observed, indicating a depth variety of the skin blood pulsation dynamics.
The ability to produce cell patterning through precise surface engineering has stimulated the development of cellular bioassays that offer new insights on the mechanisms of cell adhesion, proliferation, differentiation and molecular signaling pathways. Here we describe a simple micropatterning technique combining supersonic cluster beam deposition of nanostructured titania films on bovine serum albumin functionalized substrates. A standard lift-off process enables us to generate complementary micropatterns of hydrophobic bovine serum albumin (cell-repellent) and hydrophilic nanostructured TiO x (cell-adhesive). We demonstrate the selective PC12 cell adhesion and growth on biocompatible nanostructured TiO x . We also observed that these functional micropatterned substrates promote a considerable enhancement of cell attachment and proliferation.
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