Basaran Selim, Dey Sourik, Bhusari Shardul, Sankaran Shrikrishnan, Kraus Tobias
INM - Leibniz Institute for New Materials, Saarbrücken, Germany.
INM - Leibniz Institute for New Materials, Saarbrücken, Germany; Chemistry Department, Saarland University, 66123 Saarbrücken, Germany.
Biomater Adv. 2023 Apr;147:213332. doi: 10.1016/j.bioadv.2023.213332. Epub 2023 Feb 14.
Engineered living materials (ELMs) encapsulate microorganisms within polymeric matrices for biosensing, drug delivery, capturing viruses, and bioremediation. It is often desirable to control their function remotely and in real time and so the microorganisms are often genetically engineered to respond to external stimuli. Here, we combine thermogenetically engineered microorganisms with inorganic nanostructures to sensitize an ELM to near infrared light. For this, we use plasmonic gold nanorods (AuNR) that have a strong absorption maximum at 808 nm, a wavelength where human tissue is relatively transparent. These are combined with Pluronic-based hydrogel to generate a nanocomposite gel that can convert incident near infrared light into heat locally. We perform transient temperature measurements and find a photothermal conversion efficiency of 47 %. Steady-state temperature profiles from local photothermal heating are quantified using infrared photothermal imaging and correlated with measurements inside the gel to reconstruct spatial temperature profiles. Bilayer geometries are used to combine AuNR and bacteria-containing gel layers to mimic core-shell ELMs. The thermoplasmonic heating of an AuNR-containing hydrogel layer that is exposed to infrared light diffuses to the separate but connected hydrogel layer with bacteria and stimulates them to produce a fluorescent protein. By tuning the intensity of the incident light, it is possible to activate either the entire bacterial population or only a localized region.
工程化活材料（ELMs）将微生物封装在聚合物基质中，用于生物传感、药物递送、捕获病毒和生物修复。通常希望能够远程实时控制它们的功能，因此微生物通常经过基因工程改造以响应外部刺激。在这里，我们将热基因工程改造的微生物与无机纳米结构相结合，使一种工程化活材料对近红外光敏感。为此，我们使用在808nm处具有强吸收峰的等离子体金纳米棒（AuNR），该波长下人体组织相对透明。将这些与基于普朗尼克的水凝胶相结合，生成一种纳米复合凝胶，该凝胶可以将入射的近红外光局部转化为热量。我们进行了瞬态温度测量，发现光热转换效率为47%。使用红外光热成像对局部光热加热产生的稳态温度分布进行量化，并与凝胶内部的测量结果相关联，以重建空间温度分布。采用双层几何结构将金纳米棒层和含细菌的凝胶层结合起来，模拟核壳型工程化活材料。暴露于红外光的含金纳米棒水凝胶层的热等离子体加热扩散到与细菌分离但相连的水凝胶层，并刺激它们产生荧光蛋白。通过调节入射光的强度，可以激活整个细菌群体或仅激活局部区域。
