Protein crosslinking photosensitized by rose Bengal (RB²⁻) has multiple medical applications and understanding the photosensitization mechanism can improve treatment effectiveness. To this end, we investigated the photochemical efficiencies of monomeric RB²⁻ (RB_M²⁻) and dimeric RB²⁻ (RB_D²⁻) and the optimal pH for anaerobic RB²⁻ photosensitization in cornea. Absorption spectra and dynamic light scattering (DLS) measurements were used to estimate the fractions of RB_M²⁻ and RB_D²⁻. RB²⁻ self-photosensitized bleaching was used to evaluate the photoactivity of RB_M²⁻ and RB_D²⁻. The pH dependence of anaerobic RB²⁻ photosensitization was evaluated in ex vivo rabbit corneas. The 549 nm/515 nm absorption ratio indicated that concentrations > 0.10 mm RB contained RB_D²⁻. Results from DLS gave estimated mean diameters for RB_M²⁻ and RB_D²⁻ of 0.70 ± 0.02 nm and 1.75 ± 0.13 nm, respectively, and indicated that 1 mm RB²⁻ contained equal fractions of RB_M²⁻ and RB_D²⁻. Quantum yields for RB²⁻ bleaching were not influenced by RB_D²⁻ in RB²⁻ solutions although accounting for RB²⁻ concentration effects on the reaction kinetics demonstrated that RB_D²⁻ is not a photosensitizer. Optimal anaerobic photosensitization occurred at pH 8.5 for solutions containing 200 mm Arg. These results suggest potential approaches to optimizing RB_M²⁻-photosensitized protein crosslinking in tissues.

中文翻译：

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玫瑰红二聚化对光敏化的影响

玫瑰红（RB ^2-）光敏化的蛋白质交联具有多种医学应用，了解光敏化机制可以提高治疗效果。为此，我们研究了单体 RB ^2- (RB _M ^2- ) 和二聚体 RB ^2- (RB _D ^2- ) 的光化学效率以及角膜中厌氧 RB ^2-光敏化的最佳 pH 值。吸收光谱和动态光散射 (DLS) 测量用于估计 RB _M ^2-和 RB _D ^2-的分数。RB ²⁻自光敏化漂白用于评估RB _M ^2-和RB _D ^2-的光活性。在离体兔角膜中评估了厌氧 RB ^{2-光敏化的 pH 依赖性。}549 nm/515 nm 吸收比表明浓度 > 0.10 m m RB 含有 RB _D ^2-。_{DLS 的结果给出了 RB M} ^2-和 RB _D ^2-的估计平均直径分别为 0.70 ± 0.02 nm 和 1.75 ± 0.13 nm，并表明 1 m m RB ^2-包含相等比例的 RB _M ^2-和 RB _D ²⁻. ^{RB 2-}漂白的量子产率不受RB ^{2-溶液中的 RB} _D ^2-影响，尽管考虑到 RB ^2-浓度对反应动力学的影响表明 RB _D ^2-不是光敏剂。对于含有 200 mm Arg 的溶液，最佳厌氧光敏化发生在 pH 8.5。这些结果表明了优化组织中 RB _M ^2-光敏蛋白交联的潜在方法。