Abstract
This paper presents a novel compact fiberoptic based singlet oxygen near‐infrared luminescence probe coupled to an InGaAs/InP single photon avalanche diode (SPAD) detector. Patterned time gating of the single‐photon detector is used to limit unwanted dark counts and eliminate the strong photosensitizer luminescence background. Singlet oxygen luminescence detection at 1270 nm is confirmed through spectral filtering and lifetime fitting for Rose Bengal in water, and Photofrin in methanol as model photosensitizers. The overall performance, measured by the signal‐to‐noise ratio, improves by a factor of 50 over a previous system that used a fiberoptic‐coupled superconducting nanowire single‐photon detector. The effect of adding light scattering to the photosensitizer is also examined as a first step towards applications in tissue in vivo. figureWiley-VCH Verlag & Co.KGaA
Highlights
Singlet oxygen (1O2), the first electronic excited state of the oxygen molecule, is involved in many biological processes [1, 2], including serving as a major cytotoxic photoproduct in photodynamic therapy (PDT) for treatment of cancer, vascular pathologies, skin conditions and localized infection [3]
The first output is a single pulse sent to the sync or ‘start’ channel of the time-correlated singlephoton counter (TCSPC, PicoQuant HydraHarp), while the second is a pattern of pulses sent to the single photon avalanche diode (SPAD) control module
Whenever the latter receives a pulse from the pulse pattern generator (PPG), the SPAD is turned on for a pre-determined duration, referred to here as the gate-width
Summary
Singlet oxygen (1O2), the first electronic excited state of the oxygen molecule, is involved in many biological processes [1, 2], including serving as a major cytotoxic photoproduct in photodynamic therapy (PDT) for treatment of cancer, vascular pathologies, skin conditions and localized infection [3]. The most detailed studies of singlet oxygen luminescence dosimetry (SOLD) used extended-wavelength photomultiplier tubes as the bestavailable detector, the quantum efficiency was typically
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