König K, Liu Y, Sonek G J, Berns M W, Tromberg B J
Beckman Laser Institute and Medical Clinic, University of California, Irvine 92715, USA.
Photochem Photobiol. 1995 Nov;62(5):830-5. doi: 10.1111/j.1751-1097.1995.tb09143.x.
Cellular autofluorescence spectra were monitored in a single-beam gradient force optical trap ("optical tweezers") in order to probe the physiological effects of near infrared and UVA (320-400 nm) microirradiation. Prior to trapping, Chinese hamster ovary cells exhibited weak UVA-excited autofluorescence with maxima at 455 nm characteristic of beta-nicotinamide adenine dinucleotide (phosphate) emission. No strong effect of a 1064 nm NIR microbeam on fluorescence intensity and spectral characteristics was found during trapping, even for power densities up to 70 MW/cm2 and radiant exposures of 100 GJ/cm2. In contrast to the 1064 nm trap, a 760 nm trapping beam caused a two-fold autofluorescence increase within 5 min (about 20 GJ/cm2). Exposure to 365 nm UVA (1 W/cm2) during 1064 nm trapping significantly altered cellular autofluorescence, causing, within 10 min, a five-fold increase and a 6 nm red shift versus initial levels. We conclude that 1064 nm microbeams can be applied for an extended period without producing autofluorescence changes characteristic of alterations in the cellular redox state. However, 760 nm effects may occur via a two-photon absorption mechanism, which, in a manner similar to UVA exposure, alters the redox balance and places the cell in a state of oxidative stress.
在单光束梯度力光阱（“光镊”）中监测细胞自发荧光光谱，以探究近红外和UVA（320 - 400 nm）微辐射的生理效应。在捕获之前，中国仓鼠卵巢细胞表现出较弱的UVA激发自发荧光，其最大值在455 nm，这是β - 烟酰胺腺嘌呤二核苷酸（磷酸）发射的特征。在捕获过程中，即使功率密度高达70 MW/cm²且辐射暴露量为100 GJ/cm²，也未发现1064 nm近红外微束对荧光强度和光谱特征有强烈影响。与1064 nm光阱相反，760 nm捕获光束在5分钟内（约20 GJ/cm²）使自发荧光增加了两倍。在1064 nm捕获期间暴露于365 nm UVA（1 W/cm²）会显著改变细胞自发荧光，在10分钟内使其相对于初始水平增加了五倍并出现6 nm的红移。我们得出结论，1064 nm微束可以长时间应用而不会产生细胞氧化还原状态改变所特有的自发荧光变化。然而，760 nm的效应可能通过双光子吸收机制发生，这与UVA暴露类似，会改变氧化还原平衡并使细胞处于氧化应激状态。
