Theranostic Near-Infrared-Active Conjugated Polymer Nanoparticles.

Conjugated polymer nanoparticles (CPNs) based on a common solar cell material (PTB7) have been prepared, and their potential in theranostic applications based on bioimaging and photosensitizing capabilities has been evaluated. The main absorption and emission bands of the prepared CPNs both fell within the NIR-I (650-950 nm) transparency window, allowing facile and efficient implementation of our CPNs as bioimaging agents, as demonstrated in this work for A549 human lung cancer cell cultures. The prepared CPN samples were also shown to produce reactive oxygen species (ROS) upon photoexcitation in the near-infrared or ultraviolet spectral regions, both in aqueous solutions and in HaCaT keratinocyte cell cultures. Importantly, we show that the photosensitizing ability of our CPNs was largely determined by the nature of the stabilizing shell: coating the CPNs with a Pluronic F-127 copolymer led to an improvement of photoinitiated ROS production, while using poly[styrene-co-maleic anhydride] instead completely quenched said process. This work therefore demonstrates that the photosensitizing capability of CPNs can be modulated via an appropriate selection of stabilizing material and highlights the significance of this parameter for the on-demand design of theranostic probes based on CPNs.

Large-scale fabrication of free-standing and sub-µm PDMS through-hole membranes.

Free-standing polydimethylsiloxane (PDMS) through-hole membranes have been studied extensively in recent years for chemical and biomedical applications. However, robust fabrication of such membranes with sub-µm through-holes, and at a sub-µm thickness over large areas is challenging. In this paper, we report a robust and simple method for large-scale fabrication of free-standing and sub-µm PDMS through-hole membranes, combining soft-lithography with reactive plasma etching techniques. First, arrays of sub-µm photoresist (PR) columns were patterned on another spin-coated sacrificial PR layer, using conventional photolithography processes. Subsequently, a solution of PDMS : hexane at a 1 : 10 ratio was spin-coated over these fabricated arrays. The cured PDMS membrane was etched in a plasma mixture of sulfur hexafluoride (SF6) and oxygen (O2) to open the through-holes. This PDMS membrane can be smoothly released with a supporting ring by completely dissolving the sacrificial PR structures in acetone. Using this fabrication method, we demonstrated the fabrication of free-standing PDMS membranes at various sub-µm thicknesses down to 600 ± 20 nm, and nanometer-sized through-hole (810 ± 20 nm diameter) densities, over areas as large as 3 cm in diameter. Furthermore, we demonstrated the potential of the as-prepared membranes as cell-culture substrates for biomedical applications by culturing endothelial cells on these membranes in a Transwell-like set-up.