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Efficient and targeted delivery of impermeable exogenous material such as small molecules, proteins, and plasmids into cells in culture as well as in vivo is of great importance for drug, vaccine and gene delivery for different therapeutic strategies. Though advent of optoporation by ultrafast laser microbeam has allowed spatial targeting in cells, the requirement of high peak power to create holes on the cell membrane is not practical and also challenging in vivo. Here, we report development and use of uniquely non-reactive crystalline magnetic carbon nanoparticles (CMCNPs) for photothermal delivery (PTD) of impermeable dyes and plasmids encoding light-sensitive proteins into cells using low power continuous wave near-infrared (NIR) laser beam. Further, we utilized the magnetic nature of these CMCNPs to localize them in desired region by external magnetic field, thus minimizing the required number of nanoparticles. We discovered that irradiation of the CMCNPs near the desired cell(s) with NIR laser beam leads to temperature rise that not only stretch the cell-membrane to ease delivery, it also creates fluid flow to allow mobilization of exogenous substances to the delivery. Due to significant absorption properties of the CMCNPs in the NIR therapeutic window, PTD under in vivo condition is highly possible.

Magnetic thermal hysteresis in Co/ Gd, CoNi/ Gd, and Fe/ Gd multilayers is investigated by measurements of the total magnetic moment. A measurement of the magnetization as a function of temperature for the antiferromagnetically coupled multilayers displays a characteristic bow-tie shape indicating magnetic superheating and supercooling. The width of the thermal hysteresis can be tuned by an external magnetic field, with values of 150 K at fields near 100 Oe and values of 20 K near 400 Oe. The results are in good agreement with our theoretical calculations.

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Positron-annihilation-inducedAuger electron spectroscopy (PAES), electron-induced Auger electron spectroscopy, and low-energy electron diffraction have been used to study the composition and structure