Nanoscale zinc oxide (n-ZnO) is widely used in personal care products and textiles, thus, it would likely be released into human sweat. To better evaluate the potential human health risks of n-ZnO, it is essential to understand its chemical transformations in physiological solutions, such as human sweat, and the resulting changes in the n-ZnO bioavailability. Here, two types of n-ZnO, ZnO nanoparticles (ZnO-NPs) and nanorod-based ZnO nanospheres (ZnO-NSs) were synthesized and incubated in 3 types of simulated sweat with different pH values and phosphate concentrations. The content of Zn₃(PO₄)₂ in the transformed n-ZnO was quantified by selective dissolution of Zn₃(PO₄)₂ in 0.35 M ammonia solution where 100% and 5.5% of Zn₃(PO₄)₂ and ZnO were dissolved, respectively. The kinetics analysis indicated that by 24-48 h the content of Zn₃(PO₄)₂ reached the maximum, being 15-21% at pH 8.0 and 45-70% at pH 5.5 or 4.3. Interestingly, no correlation was observed between the rate constants of Zn₃(PO₄)₂ formation and the specific surface areas of n-ZnO, implying that chemical transformations from n-ZnO to Zn₃(PO₄)₂ in the simulated sweat might not be simply attributed to dissolution and precipitation. Using a variety of characterization techniques, we demonstrated the formation of a ZnO-Zn₃(PO₄)₂ core-shell structure with the shell consisting of amorphous Zn₃(PO₄)₂ at pH 8.0 and additionally of crystalline Zn₃(PO₄)₂ and Zn₃(PO₄)₂•4H₂O at pH 5.5 or 4.3. The phosphate-induced transformation of n-ZnO in the simulated sweat at pH 5.5 and 4.3 greatly reduced the antibacterial efficacy of n-ZnO through moderating the nanoparticle dissolution, indicating limited bioavailability of the NPs upon transformation. The results improve the understanding of the fate and hazards of n-ZnO.

纳米级氧化锌（n-ZnO）广泛用于个人护理产品和纺织品中，因此很可能会释放到人的汗液中。为了更好地评估n-ZnO的潜在人类健康风险，必须了解其在生理溶液（例如人的汗液）中的化学转化以及n-ZnO生物利用度的变化。在此，合成了两种类型的n-ZnO，ZnO纳米颗粒（ZnO-NPs）和基于纳米棒的ZnO纳米球（ZnO-NSs），并在3种类型的具有不同pH值和磷酸盐浓度的模拟汗液中进行了培养。通过选择性溶解Zn ₃（PO ₄）_2来量化转化的n-ZnO中Zn ₃（PO ₄）₂的含量。在0.35 M的氨溶液中溶解100％和5.5％的Zn ₃（PO ₄）₂和ZnO。动力学分析表明，到24-48小时，Zn ₃（PO ₄）₂的含量达到最大值，在pH 8.0时为15-21％，在pH 5.5或4.3时为45-70％。有趣的是，没有观察到Zn ₃（PO ₄）₂形成的速率常数与n-ZnO的比表面积之间的相关性，这意味着从n-ZnO到Zn ₃（PO ₄）_2的化学转化。模拟汗水中的碳可能不能简单地归因于溶解和沉淀。使用各种表征技术，我们证明了ZnO-Zn ₃（PO ₄）₂核-壳结构的形成，该壳由pH 8.0的无定形Zn ₃（PO ₄）₂和结晶的Zn ₃（PO）组成₄）₂和Zn ₃（PO ₄）₂ •4H ₂pH为5.5或4.3的O。在pH 5.5和4.3的模拟汗液中磷酸盐诱导的n-ZnO转化通过减缓纳米颗粒的溶解而大大降低了n-ZnO的抗菌功效，表明转化后NP的生物利用度有限。结果提高了对n-ZnO的命运和危害的认识。