Block copolymer assisted topochemical polymerization: A facile and efficient route to robust polymeric nanoporous membranes decorated with versatile amino acids

Freestanding Block Copolymer Membranes with Tunable Pore Sizes Promoted by Subnanometer Nanowires

Block copolymers (BCPs) have enduring appeal for its intriguing assembly behaviors. Nevertheless, the unsatisfactory mechanical properties of BCPs make it a problem to fabricate freestanding membranes and hindered practical applications. Herein, a freestanding membrane with tunable pore size is prepared simply by co-assembly of BCPs and subnanometer nanowires (SNWs), combining the abundant function of BCPs and prominent mechanical properties of SNWs. Benefited from synergy of the components and the hierarchical structure, the tensile strength of composite membrane is promoted by two orders of magnitude compared to that of BCPs. With the columnar pores aligning vertically to surfaces and the pore size regulated by processing conditions, the membranes exhibit precise size-selected effect in ultrafiltration of Au nanoparticles (Au NPs) and can distinct NPs with diameter difference as tiny as 5 nm, demonstrating the promising prospect in separation technology and even widespread fields.

Selective recognition of tryptophan by a methylpillar[5]arene-based supramolecular fuorescent probe

Herein we present a simple fluorescence quenching method to selectively recognise and determine L-tryptophan (L-Trp) out of other 19 natural amino acids. Methylpillar[5]arene (MeP5), which is employed as a macrocyclic fluorescent probe, exhibits fluorescence activity in the solution of poor solvents because of aggregation-induced emission (AIE) effect. Fluorescence quenching of MeP5 in the solution of EtOH/CH₂Cl₂ (98/2, v/v) was observed upon the addition of L-Trp whereas other 19 natural amino acids did not bring about obvious change in fluorescence intensity. ¹H NMR titration, fluorescence spectroscopy, mass spectrometry and theoretical analysis revealed that L-Trp can be encapsulated into the cavity of MeP5 to form a stable 1:1 host-guest inclusion complex which accounts for the quenching characteristics. The proposed procedure in this investigation offers an attractive and promising method for the selective detection of L-Trp in a mixture of natural amino acids.