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Aquaporin (AQP) is a family of membrane proteins that enable water and small individual molecules to permeate cell membranes. Examples of these protein channels are aquaglyceroporin and aquaporin-1 (AQP1). Here, we investigate the permeability of carbon dioxide $$(\hbox {CO}_2)$$ through both aquglyceroporin and AQP1 channels and explain their selectivity mechanisms. We provide a mathematical model which determines the molecular interaction potential between carbon dioxide molecule and an AQP channel. We evaluate this interaction using two approaches, namely discrete-continuum and completed discrete approaches. Both calculations agree well and our results indicate the acceptance of $$(\hbox {CO}_2)$$ molecule into these channels which is in good agreement with other recent studies.

Aquaporin is a family of small membrane-proteins that are capable of transporting nano-sized materials. In the present paper, we investigate the structure of these channels and provide information about the mechanism of individual molecules being encapsulated into aquaglyceroporin (GlpF) and aquaporin-1 (AQP1) channels by calculating the potential energy. In particular, we presents a mathematical model to determine the total potential energy for the interaction of the ammonia and nitric oxide molecules and different aquaporin channels which we assume to have a symmetrical cylindrical structure. We propose to describe these interactions in two steps. Firstly, we model the nitrogen atom as a discrete point and secondly, we model the three hydrogen atoms on the surface of a sphere of a certain radius. Then, we find the total potential energy by summing these interactions. Next, by considering the nitric oxide molecule as two discrete atoms uniformly distributed interacting with GlpF and AQP1 channels then gathering all pairs of interaction to determine the potential energy. Our results show that the ammonia and nitric oxide molecules can be encapsulated into both GlpF and AQP1 channels Refereed/Peer-reviewed

Benzene molecules confined in carbon nanotubes of varying radii are employed as semiconductors in electronic nanodevices, and their orientation determines the electrical properties of the system. In this paper, we investigate the interaction energy of all the possible configurations of a benzene molecule inside various carbon nanotubes and then we determine the equilibrium configuration. We adopt the continuous approach together with the semi-empirical Lennard-Jones potential function to model van der Waals interaction between a benzene molecule and a carbon nanotube. This approach results in an analytical expression, which accurately approximates the interaction energy and can be readily used to generate numerical data. We find that horizontal, tilted and perpendicular configurations on the axis of the carbon nanotube are all possible equilibrium configurations of the benzene molecule when the radius of the carbon nanotube is less than 5.580 . However, when the radius of the carbon nanotube is larger than 5.580 an offset horizontal orientation is the only possible equilibrium configuration of the benzene molecule. In the limiting case, the orientation of a benzene molecule on a graphene sheet can be derived simply by letting the radius of the carbon nanotube tend to infinity. Refereed/Peer-reviewed

At the nanoscale a number of very high frequency oscillating systems involving relative motion with respect to a carbon nanotube have been identified. In this paper, we study the two-body systems of an atom and a fullerene C60 orbiting around a single infinitely long carbon nanotube and a fullerene C60 orbiting around a fullerene C1500. The van der Waals interaction forces are modeled using the Lennard–Jones potential together with the continuum approach for which carbon atoms are assumed to be uniformly distributed over the surfaces of both the fullerenes and the carbon nanotube. Some analytical and perturbation solutions are obtained for the regime where the attractive term of the potential energy dominates. Certain circular orbiting radii of these nanoscale systems are estimated using a stability argument and the corresponding circular orbiting frequencies can then be calculated by investigating the minimum energy configuration of their effective potential energies. We find that the circular orbiting frequencies of the various proposed nano-systems are in the gigahertz range. Finally, the classification of their orbiting paths is determined numerically.