Instant formation of nanopores on flexible polymer membranes using intense pulsed light and nanoparticle templates

The development of simple and high-throughput approaches to yield solid-state nanopores on large surface membranes may facilitate the prevalence of nanopore analysis technology and in-vitro diagnosis using portable devices.However,solidstate nanopores are typically realized by complex and highend nanofabrication equipments.Here,we present a method to achieve nanopores on polymer membranes using,silver nanoparticles(AgNPs)as templates and intense pulsed light(IPL)as a heating source.The density and size of nanopores are controllable by adjusting the spin coating rate,the concentration of nanoparticle suspension,and the size of nanoparticles(NPs).The temperature of the AgNPs can rapidly reach 1132 K under instant heating of photothermal effect through light irradiation in 2 ms,resulting in localized melting and decomposition of an underneath polycarbonate(PC)membrane to yield nanopores with sizes ranging from 10 to 270 nm.After removing the nanoparticle residues,the flexible membrane with nanopores can be integrated into a flow cell to achieve a nanopore sensor that has been used to measure the translocation behaviors of bovine serum albumin(BSA).The results have demonstrated the capability of the sensor in protein denaturation identification.This low-cost and highthroughput technique to fabricate solid-state nanopores on flexible polymeric membranes may facilitate the development of more nanopore-based flexible sensors that can be integrated with other flexible components for wearable diagnosis.

SOLUTION CRYSTALLIZATION BEHAVIOR OF LINEAR AND STAR-SHAPED POLY(ETHYLENE GLYCOL)-b-POLY(ε-CAPROLACTONE) BLOCK COPOLYMERS

Lamellar crystals of diblock, triblock and four-arm poly（ethylene glycol）-b-poly（ε-caprolactone） （PEG-b-PCL） crystalline-crystalline copolymers were successfully obtained from their solution. Morphology and structure of lamellar crystals of crystalline-crystalline copotymers were investigated using tapping-mode atomic force microscopy （AFM） and selected area electron diffraction （SAED）. All of these samples showed the truncated-lozenge multilayer basal shapes with central screw dislocation or central stack, which were all obtained simultaneously from the oil bath. The diffraction pattern of PEG block lamellar crystal is attributed to the （120） diffracting planes and the pattern of PCL block lamellar crystal is attributed to the （1 I0） diffracting planes and （200） diffracting planes according to the SAED results. Four （110） crystal growth planes and two （200） crystal growth planes are discovered for the PCL blocks, but the （120） crystal growth planes of PEG blocks are hided in the figure of AFM. The crystalline structure of the four-arm copolymers （FA） is more disorder and confused than that of the diblock （DI） copolymer and the striated fold surface structures of lamellar crystals of four-arm copolymers （FA） are smoother than these of linear analogues, owing to the confused crystallization of blocks caused by the mutual restriction of blocks and the hindrance of the dendritic cores. In addition, the aspect ratio of FA is greater than that of the others. It is hypothesized that there are two reasons for the change of aspect ratios. First, the （200） diffracting planes of PCL crystals grew slowly compared to their （110） diffracting planes because of difference in the energy barrier. Secondly, edge dislocations on the （200） diffracting planes are also responsible for the variation of the aspect ratio. Consequently, the crystalline defects are augmented by the competing blocks crystallized simultaneously and the hindrance of the dendritic cores.