Surface-functionalizations are of essential importance for diverse areas from biomedicine to biosensing, nanocomposites, water treatment, and energy harvesting devices. One facile and rapid way to functionalize any materials surface is by mussel inspired polydopamine (PDA) coating. It has been realized that dopamine (DA), the precursor, can be coated virtually on any substrates in presence of a buffer of pH ~ 8.5. Over the past 20 years, an overwhelming interest has been noticed around cellulose based materials specially nanofibers (CNFs) shown due to its many unique characteristics including high stiffness and modulus, great transparency well biodegradability, biocompatibility and low production cost. Despite of the facts, pristine cellulose often suffers from certain characteristic limitations in biomaterial applications due to the lack of appropriate surface functionalities. This research therefore aims to develop cellulose based composite materials suitable for biomedical applications, precisely electrode material for biosensors. The electrodes were made of controlled amount of polydopamine treated cellulose nanofiber composite. When investigated the mechanical properties of the composites, significant improvement was observed. Moreover, the composites exhibited good sensing behaviors under electrochemical investigations, leading them to be a promising material for biosensing applications.
Being a naturally occurring biopolymer, cellulose is popular and deeply explored for its amazing mechanical properties. Cellulose nanofibers are modelled and molecular dynamics simulations conducted using GROMACS and All-Optimized Potential for Liquid Simulations (OPLS-AA) force field is used for parameterization. The mechanical properties and structural stability of the cellulose nanofibers are investigated via the simulations. We explore the hydrogen bonding disparities on the CNF structure as it is subjected to different pull forces. The results show that the hydrogen bonds decrease every time a pull force is increased, with the decrement more significant when large pull forces are applied than low pull forces.
Cellulose is the most naturally occurring biomolecular polymers ensemble into cellulose nanofibers that has both amorphous and crystalline domains in proportions dependent on the source. Cellulose nanofibrils have raised significant interest as excellent structural materials with exceptional mechanical properties. It is important to understand the structure of CNF and its synergy. This study entails molecular dynamics simulations of the cellulose nanofibrils to give insightful understanding of its atomic details in response to temperature. GROningen Machine for Chemical Simulations (GROMACS) is used as the simulations software and All-Atom Optimized Potential for Liquid Simulations (OPLS-AA) force field is chosen for the simulation. To understand the thermally induced structural changes, lattice parameters, crystal density, hydrogen bonding network and other parameters are critically analyzed. The total number of hydrogen bonds is also observed.
Atomic force microscopy (AFM) is known for measuring the mechanical properties of nanomaterials. It has been used for measuring the mechanical properties of few kinds of fibers, such as carbon nanotubes, gold nanofibers, graphene. In this study, the effect of various sources on the elastic modulus of cellulose nanofibers (CNFs) was investigated by using AFM three-points bending test. The CNFs were extracted from hardwood, softwood, bamboo and cotton by using aqueous counter collision (ACC) system and the morphology of CNFs were studied by AFM. CNFs were successfully transferred to the AFM calibration chip and the three-points bending test was performed. CNFs were considered to be circular shape by taking into account the AFM tip radius and the Young’s modulus was calculated. The calculation results indicate that the range of Young’s modulus is between 102 and 131 GPa varying upon the cellulose resources.