Catalase plays an essential role in degrading hydrogen peroxide (H2O2), which is one of the major enzymatic ROS scavenging mechanisms. Here, using wild-type Candida albicans along with its catalase-deficient mutant, we report that catalase inside fungi could be effectively and universally inactivated by blue light 410 nm, subsequently rendering these pathogens extremely sensitive to H2O2 and ROS-generating agents. This strategy could also significantly eradicate multiple notorious clinical Candida strains, including Candida auris. The antimicrobial efficacy of catalase photoinactivation is further validated using immune cell co-culturing system and a Candida albicans-induced mouse model of skin abrasion. Taken together, our findings offer a novel catalase-targeting approach against multidrug-resistant fungal infections.
Volumetric chemical imaging is highly desired for investigating biochemical processes at the sub-cellular level. Here, we report bond-selective intensity diffraction tomography (BS-IDT) based on 3D quantitative phase detection of the mid-infrared photothermal effect. BS-IDT demonstrates volumetric chemical imaging with incoherent diffraction-limited resolution and a high speed up to ~6 Hz per volume. The mid-IR spectrum extracted from BS-IDT shows high fidelity compared with ground truth measured by an FTIR spectrometer. The 3D chemical imaging results from cancer cells and Caenorhabditis elegans validate BS-IDT’s superior performance.
Spectroscopic stimulated Raman scattering (SRS) imaging has become a useful tool finding a broad range of applications. Due to the limited spectral coverage of current SRS systems, most SRS applications utilized a narrow Raman band (<300 cm-1). Multi-window SRS imaging covering C-H, C-D and fingerprint regions offers richer chemical information. In this work, we present a multi-window SRS imaging system with a rapid widely tunable fiber laser. We implemented auto-balanced detection to enhance the signal-to-noise ratio of stimulated Raman loss by 23 times. We demonstrated SRS metabolic imaging of fungi, cancer cells, and Caenorhabditis elegans across the C-H, silent and fingerprint Raman windows. Our results showcase the potential of the multi-window SRS system for a broad range of applications.
We present a novel version of mid-infrared photothermal microscopy in which thermosensitive fluorescent probes are harnessed to sense the mid-infrared photothermal effect. The fluorescence intensity can be modulated at the level of 1% per Kelvin, which is 100 times larger than the modulation of scattering intensity. In addition, fluorescence emission is free of interference, thus much improving the image quality. Moreover, fluorophores can target specific organelles or biomolecules, thus augmenting the specificity of photothermal imaging. Spectral fidelity is confirmed by fingerprinting a single bacterium. A wide-field fluorescence-detected mid-infrared photothermal microscope developed allows video-rate bond-selective imaging of biological specimens.
Candida auris, the deadly infectious fungus, was reported to infest nearly 60 hospitals and more than 90 nursing homes in New York City. Moreover, these fungal species have developed resistance to all three major anti-fungal drugs. Drug-resistant Candida spp. and other non-albicans have developed multi-drug resistance around the world. Here, we show that, through efficient photoinactivation of an essential detoxifying enzyme which exists in most of the fungal strains, we could achieve significant eradication of those pathogens by subsequent administration of low-concentration of hydrogen peroxide and antifungal drugs. Noteworthy, hydrogen peroxide or antifungal alone is not effective to eradicate them.
Candidemia remains the fourth most common cause of nosocomial bloodstream infections. For more than a half-century, amphotericin B (Amp B) has been the last line of defense in the treatment of life-threatening fungal infections. However, during the past several years, severe infections due to Amp B-resistant Candida spp. isolates have been increasingly reported. Here, through polarization stimulated Raman scattering microscopy, Amp B was found to accumulate largely in the cell membrane of Candida spp. in a highly orientated approach, and the interaction between Amp B and ergosterol was investigated as well. Moreover, we found that the correlation between Amp B and ergosterol in Amp B-susceptible Candida spp. is different from that of Amp B-resistant Candida spp., which provides us important information to understand the working mechanism of Amp B, and to achieve fast determination of the Amp B susceptibility of Candida spp.
The rapid evolution of antibiotic resistance increasingly challenges the successful treatment of S. aureus infections. Here, we present an unconventional treatment approach by disassembly its membrane microdomains via pulsed laser photolysis of staphyloxanthin. After staphyloxanthin photolysis, membrane permeabilization, fluidification, and membrane protein detachment, were found the underlying mechanisms to malfunction its defense to several major classes of conventional antibiotics. Through resistance selection study, we found pulsed laser treatment completely depleted staphyloxanthin virulence. More importantly, laser treatment further inhibited development of resistance for several major classes of conventional antibiotics including fluoroquinolones, tetracyclines, aminoglycosides, and oxazolidinones. Collectively, this work highlights a novel platform to revive conventional antibiotics to treat S. aureus infections.
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