Dual-Stage Propulsion Strategy for Microalgae-Based Biohybrid Microrobots.

Area of Science:

• Biomimetics and Bioengineering
• Micro-robotics and Nanotechnology
• Cellular and Molecular Biology

Background:

• Biohybrid microrobots leverage microalgae for self-propulsion and functionalization, showing potential for cargo delivery.
• Existing methods primarily focus on in vitro nanodrug transport, with limitations in capturing and directing larger microscale targets, especially biological ones.

Purpose of the Study:

• To develop a dual-stage propulsion strategy for biohybrid microrobots capable of efficiently capturing and directionally transporting large microscale targets.
• To create a versatile platform for applications in biomedical, environmental, and analytical fields.

Main Methods:

• Designed dual-actuated biohybrid microrobots using *Chlamydomonas reinhardtii* and magnetic beads, preserving algal motility.
• Engineered a dynamic 3D biomimetic capture interface through surface functionalization for enhanced target interaction.
• Implemented a two-phase propulsion: autonomous microalgal motility for initial capture and external magnetic field for directed transport.

Main Results:

• Achieved high-efficiency capture rates of up to 93% for model targets, including 20 μm polystyrene microspheres and circulating tumor cells.
• Demonstrated precise directional transport of microscale targets at speeds of 14 μm/s.
• Validated the preservation of microalgal motility and the effectiveness of magnetic actuation in the biohybrid system.

Conclusions:

• The proposed dual-stage propulsion strategy enables efficient capture and directional transport of large microscale targets using biohybrid microrobots.
• This innovative approach offers significant potential for advanced applications in targeted drug delivery, environmental monitoring, and sensitive analytical detection.