Nitric Oxide Photorelease from Silicone Films Doped with N-Nitroso BODIPY.

Nitric oxide (NO) is a unique biochemical mediator involved in the regulation of vital processes. Light-controllable NO releasers show promise in the development of smart therapies. Here, we present a novel biocompatible material based on polydimethylsiloxane (PDMS) doped with BODIPY derivatives containing an N-nitroso moiety that is capable of the photoinduced generation of NO. We study the green-light-induced NO-release properties with the following three methods: electrochemical gas-phase sensor, liquid-phase sensor, and the Griess assay. Prolonged release of NO from the polymer films after short irradiation by narrow-band LED light sources and a laser beam is demonstrated. Importantly, this was accompanied by no or little release of the parent compound (BODIPY-based photodonor). Silicone films with the capability of controllable and clean NO release can potentially be used as a highly portable NO delivery system for different therapeutic applications.

Singlet oxygen luminescence detector based on low-cost InGaAs avalanche photodiode.

Molecular oxygen excited to singlet state (Singlet oxygen, 1O2) becomes highly reactive and cytotoxic chemical. 1O2 is commonly generated by photoexcitation of dyes (photosensitizers), including the photodynamic therapy and diagnostics of cancer. However, the formation of singlet oxygen is often unwanted for various light-sensitive compounds, e.g. it causes the photobleaching of fluorescent probes. In either case, during a development of new photosensitive chemicals and drugs there is a need to evaluate the amount of 1O2 formed during photoexcitation. The direct approach in measuring the amount of singlet oxygen is based on the detection of its luminescence at 1270 nm. However, this luminescence is usually weak, which implies the use of highly sensitive single-photon detectors. Thus the existing instruments are commonly complicated and expensive. Here we suggest an approach and report a device to measure the 1O2 luminescence using low-cost InGaAs avalanche photodiode and simple electronics. The measurements can be performed in stationary (not time-resolved) mode in organic solvents such as tetrachloromethane (CCl4), ethanol and DMSO. In particular, we performed spectral-resolved measurements of the singlet oxygen luminescence in CCl4 with the device and demonstrated high complementarity to literature data. The simple setup allows to evaluate the efficiency (or speed) of singlet oxygen generation and hence facilitates the development and characterization of new photosensitizers and other photosensitive chemicals.