Conical Hollow Microhelices with Superior Swimming Capabilities for Targeted Cargo Delivery

Abstract

Inspired by flagellate microorganisms in nature, the microhelix is considered as an ideal model for transportation in fluid environment with low Reynolds number. However, how to promote the swimming and loading capabilities of microhelices with controllable geometries remains challenging. In this study, a novel kind of conical hollow microhelices is proposed and a method is developed to rapidly fabricate these microhelices with controllable parameters by femtosecond vortex beams generated from spatial light modulation along helical scanning. Conical hollow microhelices with designable heights (H = 45–75 µm), diameters (D = 6–18 µm), pitch numbers (Pi = 2–4), taper angles (T = 0.1–0.6 rad), and pitch periods (ΔP = 10–30 µm) are efficiently fabricated. In addition, compared with straight microhelices, the forward swimming capability of conical microhelices increases by 50% and the lateral drift of the conical hollow microhelices is reduced by 70%. Finally, the capabilities of these conical hollow microhelices for nanocargo loading and release by the inner hollow core, as well as transportation of neural stem cells by the outer surface are demonstrated. This work provides new insights into faster and simultaneous transportation of multicargoes for hybrid drug delivery, targeted therapy, and noninvasive surgery in vivo.

Nano-and Micromotors Designed for Cancer Therapy

“…The use of rotating fields in combination with mostly helical shapes is a sophisticated approach allowing for propulsion with high precision even in complex, often highly viscous, biological fluids. Xin et al analyzed the shape optimization for both, swimming and transport capabilities [111]. Also liquid metals have been used as guidable objects [112] and motility control was implemented using a magnetic trap [113].…”

Femtosecond laser programmed artificial musculoskeletal systems

“…Zhang et al successfully fabricated magnetic microswimmer robots by coating magnetic materials on both artificial helical microstructures and natural biological matrix, enabling targeted gene delivery and in vivo imaging-guided therapy 2 , 41 . Wu et al successfully fabricated conical hollow microhelices robots via femtosecond vortex beams generated by spatial light modulation 8 . The aforementioned successful examples have proven the importance of nanofabrication technologies for 3D soft microbots.…”

“…ecent years have witnessed the ground-breaking advances of microbots, which have revealed great potential for cutting-edge applications in microsurgery [1][2][3] , cell manipulation [4][5][6] , drug delivery [7][8][9][10] , and biosensing 1,[11][12][13] . Conventional microbots are mostly mechatronics systems that are composed of rigid materials (e.g., metals, silicon, and silica), and therefore suffer from poor biocompatibility, softness, flexibility, and biodegradability, which limits their applications in biomedical fields.…”

“…The advancement of soft microbots has been boosted by the rapid progress of material science 36,37 and micro/nanofabrication technologies 8,30,38,39 . A general approach to soft microbots is directly prototyping 3D micro/nanostructures based on smart materials.…”

Magnetic Nanomotor-Based Maneuverable SERS Probe

“…Up to now, compared with other propulsion mechanisms, magnetically powered motors have apparent advantages regarding the accuracy and adaptability of the motion control on the movement of MNMs [61][62][63]. In addition to the other merits of biocompatibility and tissue penetration of the magnetic field, magnetic MNMs thus hold a promising potential to be applied in a biosensing field [64][65][66][67].…”