Volbots: Volvox Microalgae‐Based Robots for Multimode Precision Imaging and Therapy

Abstract

Biohybrid microrobotics are exploited as a delivery approach to actively transport therapeutic payload to tumors. However, the therapeutic utility of this approach can be diminished by tumor hypoxia. Moreover, current biohybrid microrobotics design is mainly focused on the living organisms’ motility and biocompatibility, yet the unique biological function of the natural organism is often overlooked. Here, an all‐in‐one self‐propelled volvox‐based multifunctional robot, that is, Volbot, with built‐in capabilities of fluid mixing, multimode imaging, and photosynthesis‐mediated in situ oxygen generation that can potentially relieve hypoxia is developed. Volbots can follow a pre‐specified route and directionality under the control of a magnetic field. Red‐light irradiation (λ = 650 nm) can enhance the Volbot's locomotive behavior, enhance the mixing of biofluids, and modulate the oxygen production to improve the efficacy of photodynamic therapy. Moreover, Volbots can absorb near‐infrared irradiation and produce localized hyperthermia to treat tumors. Subcutaneous tumor suppression can be achieved by this high‐yield oxygen‐producing biohybrid “microfactory” in a photodynamic/photothermal‐synergistic therapy strategy. Furthermore, Volbots also offer imaging capabilities and exhibit considerable promise as a multifunctional microrobotics‐based theranostic approach for a precision tumor therapy strategy.

Advanced medical micro-robotics for early diagnosis and therapeutic interventions

“…Bacteria-driven biohybrid robots have demonstrated their capabilities for active drug delivery to tumors or other target areas. More recently, Volbot ( Wang et al., 2022 ), a type of biohybrid volvox-based micro-robot, has been developed with self-propelled capability. The biohybrid Volbot can be known as an all-in-one multifunctional micro-robot, since it has autonomous phototaxis navigation and multimode imaging capabilities.…”

Microbial Cells as a Microrobots: From Drug Delivery to Advanced Biosensors

“…Volvox aureus green multicellular alga was used to create biohybrid microrobots that were capable of transporting anticancer drugs as cargo and produced oxygen for hypoxia prevention [ 56 ]. The cargo system was based on the functionalization of the target drug or nanoparticles by chitosan.…”

“…The basic idea is to use cell motility to bring drugs as the cargo with high accuracy to the target—a place with pathology needs to be cured (e.g., its advanced drug delivery). In the case of microalgae or algae, an additional opportunity exists because of photosynthesis, which means that they can produce oxygen to fight against hypoxia [ 56 ]. Microrobots demonstrate a long-time operation and produce treatments as a reaction on the sensed molecule related to dysfunction [ 102 ].…”

Oxygen switches: Refueling for cancer radiotherapy

“…Single-cell sequencing helped us understand how hypoxia is shaped and the evolutionary landscapes of tumor genomics ( 70 ). Nano-robots can follow a specified route and directionality under control, thus leading to a more precise oxygen delivery ( 71 ). Genome editing may improve the safety and oxygen-generating capability of microorganisms-mediated photosynthesis ( 72 ).…”