Quantum mechanics

Magnetic field

Nanoparticle

Magnetization

Biology

Fabrication

Biomedical engineering

Materials science

Biocompatible material

Cell culture

Ferromagnetism

Transfection

Neodymium magnet

Remanence

Alternative medicine

Genetics

Physics

Nanotechnology

Medicine

Magnet

Magnetic nanoparticles

Pathology

Advanced Materials

The application of nanoparticles for drug or gene delivery promises benefits in the form of single‐cell‐specific therapeutic and diagnostic capabilities. Many methods of cell transfection rely on unspecific means to increase the transport of genetic material into cells. Targeted transport is in principle possible with magnetically propelled micromotors, which allow responsive nanoscale actuation and delivery. However, many commonly used magnetic materials (e.g., Ni and Co) are not biocompatible, possess weak magnetic remanence (Fe 3 O 4 ), or cannot be implemented in nanofabrication schemes (NdFeB). Here, it is demonstrated that co‐depositing iron (Fe) and platinum (Pt) followed by one single annealing step, without the need for solution processing, yields ferromagnetic FePt nanomotors that are noncytotoxic, biocompatible, and possess a remanence and magnetization that rival those of permanent NdFeB micromagnets. Active cell targeting and magnetic transfection of lung carcinoma cells are demonstrated using gradient‐free rotating millitesla fields to drive the FePt nanopropellers. The carcinoma cells express enhanced green fluorescent protein after internalization and cell viability is unaffected by the presence of the FePt nanopropellers. The results establish FePt, prepared in the L1 0 phase, as a promising magnetic material for biomedical applications with superior magnetic performance, especially for micro‐ and nanodevices.

Biocompatible Magnetic Micro‐ and Nanodevices: Fabrication of FePt Nanopropellers and Cell Transfection