An extremely simple and efficiency way to kill Gram-positive, -negative and multidrug resistant bacteria was provided. The selling point of this invention was that gold (Au) nanoparticles were grown self-assembling to yield Au nanoshells on the surface of bacteria (bacteria coated with Au nanoshells or bacterial nanomaterials) by the Au growing solution but no adding reductant. Due to Au with the high efficiently to convert absorbed radiation into heat for serving as photothermal therapeutic agents, enabled the bacteria coated with Au nanoshells acted as photothermal agents to kill bacteria efficiently. As a result, these bacterial nanomaterials showed impressive photothermolytic efficacy to reduce the viability of bacteria with linear or nonlinear laser irradiation and an excellent ability to emit photoluminescence after nonlinear laser irradiation which was generated from the dead bacteria coated with bacterial nanomaterials. The stronger photoluminescence was emitted, the more bacteria were killed. Moreover, the photoluminescence which was able to sustain femtosecond laser exposure, keep luminescence emitted and prevent from photobleaching was still generated after even 15 min exposure being very qualified to nonlinear optical contrast agents. As a result, these nanomaterials were definitely able to serve as brand-new contrast agents or indicators to determine viability, track and localize bacteria.本發明係提供一非常簡易且有效率之方式來殺死不論是革蘭式陽性、陰性與抗藥性細菌。主要發明發現在於不用加任何還原劑即可在細菌表面自行組裝產生一層金奈米殼層,由於金有非常好的光熱轉換效率,故可利用線性連續式與非線性飛秒式雷射照射此細菌金奈米材料來產生熱並有效率的殺死細菌,亦即光熱分解效應;另一大發現為利用非線性飛秒式雷射照射時,此細菌金奈米材料不僅會產生熱能,同時具有產生冷光之光學特質,殺死的細菌越多,產生的冷光越強,且可持續放光不會產生光漂白。藉此冷光可當作一指示劑,來追蹤與確認細菌的存活,動向與座落之位置。
