ABSTRACT
Researchers have made a significant breakthrough by merging the energy-saving attribute of organic solvent nanofiltration (OSN) with the remarkable solvent permeance and solute rejection of two-dimensional (2D) laminated membranes. This innovative approach brings forth a new era of sustainable and cost-effective separation techniques, presenting a promising solution to the issue of industrial solvents contaminating the environment. This development paves the way for new opportunities in building a sustainable future. Specifically, our mini-review has cast a spotlight on the separation and recovery of methanol-a solvent abundantly used in industrial processes. We systematically evaluated a diverse array of free-standing 2D nanolaminate OSN membranes. The analysis encompasses the assessment of pure methanol permeance, solute rejection capabilities, and the simultaneous evaluation of methanol permeance and solute rejection performance. Notably, this study sheds light on the considerable potential of 2D laminated OSN membranes in revolutionizing separation processes for the industrial use of methanol.
ABSTRACT
Outstanding water/ion selectivity of aquaporins paves the way for bioinspired desalination membranes. Since the amino acid asparagine (Asn) plays a critical role in the fast water conduction of aquaporins through hydrogen bonding interactions, we adapted this feature by functionalizing carbon nanotubes (CNTs) with Asn. We also studied a nonpolar amino acid and carboxylate functional groups for comparison. Computation of the ideal performance of individual CNTs at atomistic scale is a powerful tool for probing the effect of tip-functionalized CNTs on water and ion transport mechanism. Molecular simulation study suggests that steric effects required for ion rejection compromise fast water conductivity; however, an Asn functional group having polarity and hydrogen bonding capability can be used to balance this trade-off to some extent. To test our hypothesis, we incorporated functionalized CNTs (f-CNTs) into the in situ polymerized selective polyamide (PA) layer of thin film nanocomposite membranes and compared their experimental RO desalination performance. The f-CNTs were found to change the separation environment through modification of cross-linking density, thickness, and hydrophilicity of the PA layer. Asn functionalization led to more cross-linked and thinner PA layer while hydrophilicity is improved compared to other functional groups. Accordingly, water permeance is increased by 25% relative to neat PA with a salt rejection above 98%. Starting from the nanomaterial itself and benefiting from molecular simulation, it is possible to design superior membranes suited for practical applications.
ABSTRACT
BACKGROUND: Carbon nanotubes (CNTs) show great promise as theranostic agents due to their drug delivery properties, intrinsic near-infrared radiation-responsiveness, and magnetic functionalization. However, temperature elevation caused by these external stimuli during drug delivery should be considered for the evaluation of CNT-based systems loaded with temperature-sensitive biomolecules. METHODS: We examine the thermal stability of a 33 nucleotides long hairpin miRNA encapsulated in (20,20) CNT using all-atom molecular dynamics simulations in explicit water. We systematically increase the temperature as 298, 310, 327, and 343 K, reaching the melting temperature of miRNA. To emphasize the effect of the aromatic confined space, we compare the dynamics of miRNA inside the CNT to its dynamics free in the solution at the same temperatures, reaching a total simulation time of 7.9 µs. RESULTS: miRNA hairpin mostly maintains its double-stranded structure in the confined CNT, even at elevated temperatures. Binding free energies and potential of mean force calculations also underline the strong π-π interactions between the biomolecule and the CNT for 298-343 K. CONCLUSION: The let-7 miRNA mimic, which represents a wide family of RNAi-based therapeutics, can be transported in the CNT under medically applied hyperthermic conditions. GENERAL SIGNIFICANCE: This study shows how the structure and dynamics of miRNA hairpin are affected when encapsulated in an aromatic tube, during a systematic increase of temperature. It also indicates the high potential of CNT-based systems for the delivery of oligonucleotide therapeutics while simultaneous imaging/magnetic field guiding to the target tissue is achieved.
