Intracellular bio-synthesizing Gold Nanoparticles using bacterial systems and their applications in photothermal therapy (A green approach)

EcN engineered to biosynthesize intracellular gold nanoparticles produces EcN::AuNPs that reach a 75.4 C peak within 5 minutes under continuous-wave NIR laser irradiation.

• Why it matters: Conventional gold nanoparticle photothermal therapy is limited by systemic toxicity, inconsistent accumulation, and poor deep-tissue penetration in heterogeneous tumor microenvironments.
• What they did: Cultured probiotic Escherichia coli Nissle 1917 were exposed to 1 mM HAuCl4 and green-synthesized intracellular AuNPs using ascorbic acid, then characterized by UV-Vis and tested in vitro under continuous-wave NIR laser.
• The result: Au3+ to Au0 reduction was indicated by an irreversible pale-yellow to deep dark-brownish color shift and a broadened SPR band centered at 560 nm; despite viability dropping from 10^8 CFU/mL to 10^3 CFU/mL, surviving cells retained chemotaxis and the platform showed concentration-dependent hyperthermia exceeding pure EcN, bare HAuCl4, and standalone ascorbic acid controls.

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