Thermomechanical Response of a Representative Porin for Biomimetics

Abstract

The thermomechanical response of Omp2a, a representative porin used for the fabrication of smart biomimetic nanomembranes, has been characterized using microcantilever technology and compared with standard proteins. For this purpose, thermally induced transitions involving the conversion of stable trimers to bigger aggregates, local reorganizations based on the strengthening or weakening of intermolecular interactions, and protein denaturation have been detected by the microcantilever resonance frequency and deflection as a function of the temperature. Measurements have been carried out on arrays of 8-microcantilevers functionalized with proteins (Omp2a, lysozyme and bovine serum albumin). To interpret the measured nanofeatures, the response of proteins to temperature has been also examined using other characterization techniques, including real time wide angle X-ray diffraction. Results not only demonstrate the complex behavior of porins, which exhibit multiple local thermal transitions before undergoing denaturation at temperatures higher than 105 °C, but also suggest a posttreatment to control the orientation of immobilized Omp2a molecules in functionalized biomimetic nanomembranes and, thus, increase their efficacy in ion transport.

Temperature effect on the SARS-CoV-2: A molecular dynamics study of the spike homotrimeric glycoprotein

“…ideally, around –5 kcal/mol), the roughly retention of the shape at 373 K should be related to stronger noncovalent interactions. In fact, the average amount of SBs increases ~ 11% (closed down) / ~18% (open up) when the temperature rises from 298 to 373 K, supporting that SBs are responsible for the global shape retention observed at 373 K. Indeed, it is well known that SBs not only provide rigidity to thermophilic proteins [53] , [54] , [55] , [56] but also help to retain the global shape of thermostable membrane proteins when are subjected to temperatures similar to those considered in this work, as was experimentally observed in recent work [26] .…”

“…However, the response of proteins to changes in the temperature conditions can be very different. For example, some proteins have high thermal stability while others can unfold or even denature at moderate temperature [24] , [25] , [26] .…”

Nanofeatures affect the thermal transitions of polymer thin films: a microcantilever-based investigation

“…This possibility is consistent with previous results on cantilevers non-uniformly coated with protein aggregates. 8 Finally, the third possibility is a combination of the previous two (i.e. a change in the thermal expansion coefficient and the effect of the discontinuities).…”

“…proteins, DNA and polymers) at small scale, due to their high sensitivity and little sample mass requirement (from nano to attograms). For example, these technologies have been applied to study how such large systems can react to pH changes, 1,2 wetting and moisture uptake, 3,4 swelling and de-swelling, 5 the interfacial tension, 6 the molecular folding, 7,8 and the hydration of selfassembled monolayers, 9 among others. Most significantly, NEMs and MEMs can also capture the effect induced by airsample or liquid-sample interfaces.…”

“…15 Several parameters, including the T g , the amorphous a and b relaxations, the liquid crystalline transitions of polymers, 16 as well as the apparent denaturation temperature (T ad ) and other thermal transitions, have been determined for different proteins by means of MEMs technology. 8 In recent studies, we developed PLA free-standing nanomembranes (FSNMs) with nanopores crossing the entire thin film thickness to act as a solid support for several applications. 17,18 Nanopores were obtained by combining spin-coating and the phase segregation that occurs in immiscible PLA:poly(vinyl alcohol) (PVA) mixtures; subsequently, PVA domains were removed via selective solvent etching.…”