ABSTRACT
Cells are the basic building units of living organisms, which are bounded by intricate plasma membrane guarding the cell interior. Life or death of a cell critically depends on the intactness of outer membrane whose structure and function are intense research curiosity and also, a potential source of developing various technologies for biomedical and industrial applications. Over the years, considerable understanding of cell membrane structure and function has been obtained but much remains to be learned. It is fairly well established that plasma membrane of mammalian cell mainly consists of lipids, proteins, and cholesterol, and a bilayer of lipids forms the core structure separating the cell interior from the exterior surroundings. The recent impetus in biotechnology has propelled membrane research to unravel the molecular design and function of cellular membrane with the hope to developing novel products and processes. A few tools and devices based on membrane have already been developed and employed for practical applications in medicine, industry, and biotechnology. Modeled after cell membrane, liposomes have been prepared in laboratory, which have found numerous biological, medical, and industrial applications. The precision, speed, and sensitivity with which real cell membranes regulate molecular transport, sense tiny concentration of substances, carry out intermolecular communications have much to offer in developing strategic and biocompatible materials, sensor devices, and signal processor technologies. Extensive recent research has provided a few physical and chemical methods to overcome natural transport barrier of membrane, opening many new prospects for cellular engineering and membrane biotechnology. For example, methods have been developed to introduce exogenous molecules into a variety of plant, bacterial, and mammalian cells but some limitations are encountered. Obviously, gaining access to the cell interior without affecting cell viability holds enormous potential to basic research in exploring the tiny internal world of living cells and in providing exciting new opportunities to modify cellular composition in controlled fashion with prospects in nanoscience, biomolecular engineering, cell membrane fusion and intermembrane trafficking and communication, signaling, sensing processes, etc. that are at work in living cell function. To cope with the harsh variable surroundings, cells have evolved antenna network and implanted microswitches on their membrane surface, which allow them to sort specific ligands and deal with the external stresses for maintaining their survival. The precise steps involved in these functions have remained intriguing but they may offer a whole new opportunity for developing devices to recognize and sort out ensemble of molecules required for numerous applications in diagnostic medicine, pollution science, signal processing, and cell biotechnology. The key to success in achieving newer practical applications largely lies in delineation of molecular design of membrane architecture and in accomplishing the controlled permeabilization of plasma membrane. Advanced imaging methods have aided enormously in learning the intricate dynamic structure and function of cellular membrane, which have generated a host of new opportunities for biomolecular engineering, medicine, and structural science.
