Steering microtubule shuttle transport with dynamically controlled magnetic fields

Abstract

Nanoscale control of matter is critical to the design of integrated nanosystems. Here, we describe a method to dynamically control directionality of microtubule (MT) motion using programmable magnetic fields. MTs are combined with magnetic quantum dots (i.e., MagDots) that are manipulated by external magnetic fields provided by magnetic nanowires. MT shuttles thus undergo both ATP-driven and externally-directed motion with a fluorescence component that permits simultaneous visualization of shuttle motion. This technology is used to alter the trajectory of MTs in motion and to pin MT motion. Such an approach could be used to evaluate the MT-kinesin transport system and could serve as the basis for improved lab-on-a-chip technologies based on MT transport.

Magnetic Quantum Dots Steer and Detach Microtubules From Kinesin‐Coated Surfaces

“…For example, magnetic fields can be used to align or direct the movement of MTs labeled with CoFe 2 O 4 NPs. Building upon this work, we have shown that magnetic quantum dots (i.e., MagDots) in combination with patterned nanowires and microdisks can be used to control the trajectory of MTs in motion …”

“…MagDots were synthesized and conjugated to biotin as described previously . Briefly, MagDots were synthesized using carboxyl‐terminated poly(styrene)‐b‐poly(ethylene oxide) (PS‐PEO) amphiphiles (Cat No.…”

“…Alternatively, active steering strategies exert force on unsupported MT tips as they are passed from one kinesin motor to the next using electrostatic or magnetic fields . These strategies offer the freedom to control MT motion dynamically, provided fields can be dynamically altered and the forces applied are sufficient to overcome Brownian motion thermal fluctuations.…”

“…These strategies offer the freedom to control MT motion dynamically, provided fields can be dynamically altered and the forces applied are sufficient to overcome Brownian motion thermal fluctuations. Recently, we and others showed that MTs in the inverted motility configuration can be driven by magnetic forces applied to attached micro/nanoparticles (NPs). For example, magnetic fields can be used to align or direct the movement of MTs labeled with CoFe 2 O 4 NPs.…”

Micelle-templated, poly(lactic-<em>co</em>-glycolic acid) nanoparticles for hydrophobic drug delivery

“…This approach is an extension of our previous work using poly(styrene-b-ethylene oxide) (PS-b-PEO) BCPs (molecular weight 9500-b-18000 Da) to encapsulate hydrophobic NPs. [26][27][28][29] PS has been previously used for hydrophobic drug delivery 30 and may promote cellular uptake compared to hydroxyacid-based systems (ie, PLGA, poly(caprolactone)), 31 whereas the PEO block (a long chain form of PEG) creates a corona with the potential to repel opsonin proteins, reducing immunogenicity and increasing circulation times. 32 This approach is distinct from methods that encapsulate chemically similar polymers in micelles, such as those incorporating homopolymers or BCPs with common block(s), 33,34 as PLGA is chemically distinct from both PS and PEO blocks.…”