Single‐beam dual‐color alternate‐pathway two‐photon spectroscopy: Toward an optical toolbox for redox biology

Abstract

We demonstrate a versatile single-laser platform for single-beam dual-color two-photon spectroscopy that combines a short-pulse laser source with a tunable broadband wavelength converter based on a highly nonlinear photoniccrystal fiber (PCF). We show that the short-pulse PCF output can be tailored, via dispersion and nonlinearity management, to deliver a broadband optical driver whose spectral structure is ideally suited for a single-beam two-photon absorption (2PA) spectroscopy of the next-generation genetically encodable fluorescent-protein (FP) sensors of pH and redox-responsive contrast agents. As a promising spectroscopic resource for redox biology, the short-pulse PCF output can be finely sculpted to alternately drive an FP system via a one of its two 2PA-allowed quantum pathways, yielding a high-contrast fluorescence readout for a highly sensitive detection of redox reactions and signaling, pH sensing, and oxidative-stress diagnosis.

Real‐time fiber‐optic recording of acute‐ischemic‐stroke signatures

“…MCAO-driven stroke dynamics is studied via a real-time fiber-optic readout of the fluorescence return from genetically encoded HyPer7 and SypHer3s sensors, providing a quantitative measure for, respectively, ROS buildup and pH variations in the targeted brain area. Serving as sources of optical excitation of these sensors via pathways A and B are 2 light-emitting diodes (LED1 and LED2 in Figure 1A), whose output wavelengths of λ A ≈ 490 and λ B ≈ 405 nm (M490F and M405F1, Thorlabs, or equivalent) are well suited (Figure 3A) for pathway A and pathway B excitations of HyPer7 and SypHer3s [88,94]. The average power of LEDs was kept below 1 μW, which excluded any photobleaching within the entire time span (up to 3-4 hours) needed to record full traces of pathway A-and pathway B-driven fluorescence readouts from all the fiber probes used in a given measurement for a meaningful characterization of pH and H 2 O 2 dynamics.…”

ECONOS/ECW 2020: In memoriam Marcus Motzkus

“…With his frequent invited talks and contributions, he truly shaped the meetings and delivered memorable highlights. Therefore, it is no surprise that so many groups associated with ECONOS/ECW immediately committed to contribute to this special issue, [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] which happens to be the largest collection of papers in this annual series in more than a decade.…”