Photoacoustic Imaging-Trackable Magnetic Microswimmers for Pathogenic Bacterial Infection Treatment

Abstract

Micro/nanorobots have been extensively explored as a tetherless small-scale robotic biodevice to perform minimally invasive interventions in hard-to-reach regions. Despite the emergence of versatile micro/nanorobots in recent years, matched in vivo development remains challenging, limited by unsatisfactory integration of core functions. Herein, we report a polydopamine (PDA)-coated magnetic microswimmer consisting of a magnetized Spirulina (MSP) matrix and PDA surface. Apart from the properties of the existing MSP (e.g., robust propulsion, natural fluorescence, tailored biodegradation, and selective cytotoxicity), the introduced PDA coating enhances the photoacoustic (PA) signal and photothermal effect of the MSP, thus making PA image tracking and photothermal therapy possible. Meanwhile, the PDA’s innate fluorescence quenching and diverse surface reactivity allows an off–on fluorescence diagnosis with fluorescence probes (e.g., coumarin 7). As a proof of concept, real-time image tracking (by PA imaging) and desired theranostic capabilities of PDA-MSP microswimmer swarms are demonstrated for the treatment of pathogenic bacterial infection. Our study suggests a feasible antibacterial microrobot for in vivo development and a facile yet versatile functionalization strategy of micro/nanorobots.

Medical Micro/Nanorobots in Precision Medicine

“…[244] Later studies reported photothermal therapy against a mouse subcutaneous drug-resistant Klebsiella pneumonia infection model. [245] Despite considerable progress in reducing hunger in the world, more than one-third of the worldwide population still suf- Reproduced with permission. [232] Copyright 2019, Wiley.…”

Magnetic Micromotors for Multiple Motile Sperm Cells Capture, Transport, and Enzymatic Release

“…1cm deep). [63][64][65] Another hurdle that needs to be considered is the complex environment inside the reproductive system in vivo, from which there is very little known from the literature,for example the oviduct hydrodynamics in the presence of oocytesa nd micromotors or the exact fertilization timing. Fortunately,v ersatile micromotors not only enable various bio-applications but can also be used as non-invasive microtools to study cell/tissue biophysics [66] or perform local sensing.…”

“…Fortunately,v ersatile micromotors not only enable various bio-applications but can also be used as non-invasive microtools to study cell/tissue biophysics [66] or perform local sensing. [63]…”

Engineering Intelligent Nanosystems for Enhanced Medical Imaging

“…More recently, Xie et al demonstrated magnetic actuation with photoacoustic tracking of magnetized Spirulina and off/on fluorescent detection of a bacterial infection in mice. [ 155 ] Photoacoustic computed tomography (PACT) has been used for the in vivo monitoring of a microrobotic system by Wu et al [ 154 ] The authors designed a gastrointestinal tract‐targeted system consisting of gold–magnesium micromotors, which were encapsulated into a hydrogel to protect them from the harsh conditions of the stomach. Upon oral administration, their distribution through the bowels was monitored by PACT.…”