Photoacoustic computed tomography guided microrobots for targeted navigation in intestines in vivo

Li, Lei; Wu, Zhiguang; Yang, Yiran; Hu, Peng; Gao, Wei; Wang, Lihong V.

doi:10.1117/12.2547559

Cited by 1 publication

(1 citation statement)

References 34 publications

(40 reference statements)

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“…In order to not only actuate, but also localize and track the motion of the microrobot in an in vivo setting, the magnetic actuation needs to be combined with an imaging modality [23][24][25]. For the localization of microrobots, existing medical imaging modalities such as photoacoustic computed tomography [26], positron emission tomography [27], magnetic resonance imaging [28], photoacoustic imaging [29], and ultrasound [30] have been explored. Each of these medical imaging modalities has different requirements, such as sufficient contrast agents, echogenicity or the presence of radioactive agents.…”

Section: Introductionmentioning

confidence: 99%

Drug-Loaded IRONSperm clusters: modeling, wireless actuation, and ultrasound imaging

et al. 2022

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Individual biohybrid microrobots have the potential to perform biomedical in vivo tasks such as remote-controlled drug and cell delivery and minimally invasive surgery. This work demonstrates the formation of biohybrid sperm-templated clusters under the inﬂuence of an external magnetic ﬁeld and essential functionalities for wireless actuation and drug delivery. Ferromagnetic nanoparticles are electrostatically assembled around dead sperm cells, and the resulting nanoparticle-coated cells are magnetically assembled into threedimensional biohybrid clusters. The aim of this clustering is threefold: First, to enable rolling locomotion on a nearby solid boundary using a rotating magnetic ﬁeld; second, to allow for noninvasive localization; third, to load the cells inside the cluster with drugs for targeted delivery. A magneto-hydrodynamic model captures the rotational response of the clusters in a viscous ﬂuid, and predicts an upper bound for their step-out frequency, which is independent of their volume or aspect ratio. Below the step-out frequency, the rolling velocity of the clusters increases nonlinearly with their perimeter and actuation frequency. During rolling locomotion, the clusters are localized using ultrasound at a relatively large distance, which makes these biohybrid clusters promising for deep-tissue applications. Finally, we show that the estimated drug load scales with the number of cells in the cluster and can be retained for more than 10 hours. The aggregation of microrobots enables them to collectively roll in a predictable way in response to an external rotating magnetic ﬁeld, and enhances ultrasound detectability and drug loading capacity compared to the individual microrobots. The favorable features of biohybrid microrobot clusters place emphasis on the importance of the investigation and development of collective microrobots and their potential for in vivo applications.

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