Bioengineered bacterial vesicles as biological nano-heaters for optoacoustic imaging

Abstract

Advances in genetic engineering have enabled the use of bacterial outer membrane vesicles (OMVs) to deliver vaccines, drugs and immunotherapy agents, as a strategy to circumvent biocompatibility and large-scale production issues associated with synthetic nanomaterials. We investigate bioengineered OMVs for contrast enhancement in optoacoustic (photoacoustic) imaging. We produce OMVs encapsulating biopolymer-melanin (OMV Mel ) using a bacterial strain expressing a tyrosinase transgene. Our results show that upon near-infrared light irradiation, OMV Mel generates strong optoacoustic signals appropriate for imaging applications. In addition, we show that OMV Mel builds up intense heat from the absorbed laser energy and mediates photothermal effects both in vitro and in vivo. Using multispectral optoacoustic tomography, we noninvasively monitor the spatio-temporal, tumour-associated OMV Mel distribution in vivo. This work points to the use of bioengineered vesicles as potent alternatives to synthetic particles more commonly employed for optoacoustic imaging, with the potential to enable both image enhancement and photothermal applications.

Optically responsive delivery platforms: from the design considerations to biomedical applications

“…The obtained results indicated that upon NIR light irradiation bacteria vesicles with melanin generated strong optoacoustic signals appropriate for bioimaging applications. In addition, the developed bacteria vesicles released heat upon NIR-laser irradiation, which resulted in photothermal effects both in vitro and in vivo [252].…”

Promoting Oxygen Evolution Reaction of Co‐Based Catalysts (Co3O4, CoS, CoP, and CoN) through Photothermal Effect

“…Photothermal conversion is one of the main commercialized applications for solar energy harvesting . Photothermal materials directly convert solar light into heat immediately, which have been widely used in water evaporation and cancer therapy . There are two definitive advantages related to the introduction of photothermal effect (PE) into catalytic processes.…”

Radiolabelled Bacterial Metallophores as Targeted PET Imaging Contrast Agents for Accurate Identification of Bacteria and Outer Membrane Vesiclesin vivo

“…We have also validated how 64 Cu-YbT can potentially be used to advance bacterial therapies using engineered bacteria. Advances in genetic engineering have enabled us to explore the potential of using bacteria, particularly for cancer therapy in the last two decades 31,[48][49][50][51] . One of the most notable initial studies tested genetically engineered Salmonella for its anticancer activity in mouse models of subcutaneously implanted B16F10 melanoma tumors 51 .…”

“…Optical imaging techniques based on bioluminescence and fluorescence have the inherent drawback of limited light penetration, unlike PET imaging which is depth independent. Recently, tumour localization of OMVs from E. coli was confirmed via photoacoustic imaging 48 . While the study described a novel strategy to specifically image the presence of OMVs in the body, it involved an additional step of vesicle design to make it amenable for optoacoustic imaging.…”