Excellence in Research: Investigation of Enhancer-Free Photogenerated Singlet Oxygen

该项目旨在研究光在氧分子激发中的作用。被激发的氧分子，正式名称为单线态氧，在细胞生存和死亡的基本机制中发挥着至关重要的作用。新的有希望的癌症治疗方法和用于食品和药品消毒的先进技术使用单线态氧产生来消除病毒、细菌和其他微生物。正常情况下，被称为光敏剂的介体分子能够将能量从入射光转移到附近的氧分子。本项目研究在不使用光敏剂的情况下，在水环境中产生单线态氧的机理。如果成功，该方法将在环境科学、食品安全、生物制药和医学中得到广泛应用，因为它提供了对阳光如何产生微生物灭活、光产生的单线态氧的理解，并提供了一种高效、低成本的无光敏剂方法来灭活食品、生物和药品中的病原体。这项工作是特拉华州立大学、美国农业部、农业研究服务局(USDA ARS)食品安全和干预技术研究单位以及巴尔的摩县马里兰大学(UMBC)光子研究高级研究中心(CASPR)的科学家们合作的成果。该项目涉及特拉华州立大学，这是一所历史悠久的黑人大学(HBCU)。私人投资机构通过吸引STEM中代表性不足的学生，纳入了多样性并扩大了参与度。这项研究试图确认和表征水中无单线态氧增强剂的产生，并随后研究其产生的物理化学机制，考虑可见光的直接单光子吸收或通过间接双光子拉曼过程产生可检测的斯托克斯位移光子。这项研究还调查了病毒在单线态氧分子产生中的作用。用激光研究溶液中的溶解氧到活性氧的转化以前还没有进行过。光谱蓝区的连续波和脉冲激光光源将用于直接和间接基于拉曼的水环境中单线态氧的检测。这项研究将为单线态氧的检测和鉴定提供新的见解和思路，并可能为活性和可控的分子生产铺平道路。这一研究项目的成功完成将带来新的发现，潜在地应用于食品和生物制品的无化学消毒以及疾病治疗。初步证据表明，蓝色激光无光敏剂、非热产生单线态氧是导致病毒活性显着降低的原因。这项研究将扩大最初的结果，并为仅使用光产生高效的单线态氧设定最佳条件。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project aims to study the role of light in the excitation of oxygen molecules. Excited molecules of oxygen, formally called singlet oxygen, play a crucial role in the fundamental mechanisms of cell life and death. New promising methods for cancer treatment and advanced techniques to sanitize food and pharmaceuticals use singlet oxygen generation to eliminate viruses, bacteria, and other microorganisms. Normally, mediator molecules, called photosensitizers, enable the shift of energy from the incident light to nearby oxygen molecules. This project studies the mechanisms of production of singlet oxygen in a water environment without the use of photosensitizers. If successful, the method will find widespread applications in environmental sciences, food safety, bio-pharmaceuticals, and medicine by providing an understanding of how microbe-inactivating, light-generated singlet oxygen is produced by sunlight and by providing an efficient and low-cost photosensitizer-free method to inactivate pathogens within foods, bio- and pharmaceutical products. The effort is a collaboration between scientists of Delaware State University, United States Department of Agriculture, Agriculture Research Service (USDA ARS) Food Safety and Intervention Technologies Research Units, and the Center for Advanced Studies in Photonics Research (CASPR) of the University of Maryland, Baltimore County (UMBC). The project involves Delaware State University, a Historically Black university (HBCU). The PIs incorporate diversity and broaden participation by attracting underrepresented students in STEM. This study seeks to confirm and characterize singlet oxygen enhancer-free production in water and to subsequently investigate the physical-chemical mechanisms of its creation, considering a direct one-photon absorption of visible light or through an indirect two-photon Raman process with the generation of a detectable Stokes-shifted photon. The study also investigates the role of the virus in the production of singlet oxygen molecules. Use of lasers to study the conversion of dissolved oxygen to reactive oxygen species in solution has not been previously undertaken. Continuous wave and pulsed laser sources in the blue region of the spectrum will be used to conduct direct and indirect Raman-based detection of singlet oxygen in water-settings. The research should provide new insights and ideas for detection and identification of singlet oxygen and will perhaps lay the pathway for an active and controllable production of the molecule. Successful completion of this research project would result in novel findings with potential applications for chemical-free sanitization of food, and bioproducts, as well as for disease treatments. Preliminary evidence shows that photosensitizer-free non-thermal generation of singlet oxygen by blue laser light is responsible for a significant reduction of virus activity. The study will expand the initial results and set the best set of conditions for an efficient singlet oxygen generation by using only light.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.