Differentiation of stem cells into mature cells through the use of physical approaches is of great interest. Here, we prepared smart nanoenvironments by cell-imprinted substrates based on chondrocytes, tenocytes, and semifibroblasts as templates and demonstrated their potential for differentiation, redifferentiation, and transdifferentiation. Analysis of shape and upregulation/downregulation of specific genes of stem cells, which were seeded on these cell-imprinted substrates, confirmed that imprinted substrates have the capability to induce specific shapes and molecular characteristics of the cell types that were used as templates for cell-imprinting. Interestingly, immunofluorescent staining of a specific protein in chondrocytes (i.e., collagen type II) confirmed that adipose-derived stem cells, semifibroblasts, and tenocytes can acquire the chondrocyte phenotype after a 14 day culture on chondrocyte-imprinted substrates. In summary, we propose that common polystyrene tissue culture plates can be replaced by this imprinting technique as an effective and promising way to regulate any cell phenotype in vitro with significant potential applications in regenerative medicine and cell-based therapies.

A microfluidic platform is developed for the synthesis of monodisperse, 100 nm, chitosan based nanoparticles using nanogelation with ATP. The resulting nanoparticles tuned and enhanced transport and electrochemical properties of Nafion based nanocomposite membranes, which is highly favorable for fuel cell applications.

Nanochannel conductance measurements are commonly performed to characterize nanofluidic devices Theoretical analysis and experimental investigations imply that the nanochannel conductance does not follow the macro-scale models. It is generally accepted that the conductance of nanochannels deviates from the bulk and trend to a constant value at low concentrations. In this work, we present an improved model for the nanochannel conductance that takes into account the surface chemistry of the nanochannel wall. It figured out that the nanochannel conductance is no longer constant at low concentrations. The model predictions were compared with the experimental measurements and showed a very good agreement between the model and the experiments.

Electrical measurement is a widely used technique for the characterization of nanofluidic devices. The electrical conductivity of electrolytes is known to be dependent on temperature. However, the similarity of the temperature sensitivity of the electrical conductivity for bulk and nanochannels has not been validated. In this work, we present the results from experimental measurements as well as analytical modeling that show the significant difference between bulk and nanoscale. The temperature sensitivity of the electrical conductance of nanochannel is higher at low ionic concentration where the nanofluidic transport is governed by the electrostatic effects from the wall. Neglecting this effect can result in significant errors for high temperature measurements. Additionally, the temperature sensitivity of the nanochannel conductance allows to measure the enthalpy change of surface reactions at low ionic concentrations.

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