Externally sensitized deprotection of PPG-masked carbonyls as a spatial proximity probe in photoamplified detection of binding events

Abstract

Externally-sensitized electron-transfer fragmentation in dithiane PPG-protected carbonyls is adopted for detection and amplification of molecular recognition events. The new methodology allows for detection of as low as 50 attomoles of avidin utilizing an imager based on a low sensitivity mass-produced consumer CCD camera. Numeric modelling is carried out to demonstrate the intrinsic limitations of 2D amplification on surfaces and the advantages of unconstrained amplification in a compartmentalized volume of spatially addressable 3D solutions.

Reactive Oxygen Species Mediated Activation of a Dormant Singlet Oxygen Photosensitizer: From Autocatalytic Singlet Oxygen Amplification to Chemicontrolled Photodynamic Therapy

“…Continuous irradiation of an air-equilibrated solution of 7 in acetonitrile within a fluorimeter exciting at 532 nm displayed a sigmoidal enhancement in emission (see Figure 7 and Figure S9 for the raw data). [41][42][43][44]78 In order to avoid the preoxidation of 7, we next added 0.12 μM of sacrificial PMHC (2% equivalents of 7) to the solvent. Fluorescence intensity enhancements of ∼30-fold were recorded in the latter case.…”

“…Consistent with an autocatalytic activation mechanism, the Φ Δ recorded following direct 532 nm laser excitation of an air-equilibrated acetonitrile solution of 7 was observed to increase over time following a sigmoidal behavior (Figure ). − A ca. 6-fold increase in Φ Δ was initially recorded.…”

“…Although 7 is sparingly emissive (Φ f ≤ 0.008), the activated form would have similar emission to that of control 4 , characterized by a Φ f = 0.20, thus enabling tracing the activation over time via the increase of fluorescence emission intensity. Continuous irradiation of an air-equilibrated solution of 7 in acetonitrile within a fluorimeter exciting at 532 nm displayed a sigmoidal enhancement in emission (see Figure and Figure S9 for the raw data). − , In order to avoid the preoxidation of 7 , we next added 0.12 μM of sacrificial PMHC (2% equivalents of 7 ) to the solvent. Fluorescence intensity enhancements of ∼30-fold were recorded in the latter case.…”

“…Oxidation of the trap segment with ROS restores the ability of the compound to sensitize 1 O 2 and aborts its ability to scavenge 1 O 2 effectively activating the otherwise dormant photosensitizer (Scheme ). The photophysical and reactivity studies described herein show that Br 2 B–PMHC is a versatile ROS-activatable photosensitizer of potential application in tissues where metabolic imbalance leads to a large ROS production, such as in cancer cells − and wounded tissue. − The juxtaposed antioxidant-pro-oxidant antagonistic chemistry of Br 2 B–PMHC enables the autocatalytic − ROS ( 1 O 2 ) amplification under continuous photoexcitation as ROS (including 1 O 2 ) consumption triggers the photosensitization of 1 O 2 .…”

Photoactive spatial proximity probes for binding pairs with epigenetic marks

“…22 The length of the tether was previously shown to be adequate for the photo induced dithiane release in the avidin-biotin binding pair.…”