RESUMEN
The surface-enhanced Raman spectroscopy (SERS) signal of a reporter on silver nanoparticles can be effectively gained by gradient electric field application. The external electric field initiates the dielectrophoresis of nanoparticles and their electrically induced dipole-dipole interaction. Owing to dielectrophoresis, the nanoparticles are concentrated in the area of high electrical field strength. The induced dipole-dipole interaction leads to additional coagulation of nanoparticles and formation of hotspots. Both dielectrophoresis and induced dipole-dipole interaction increase the number of hotspots, which leads to a SERS signal growth. These two mechanisms of SERS signal amplification are explained by the dielectrophoresis and Derjaguin-Landau-Verwey-Overbeek theories. The benefits of the surface-enhanced Raman spectroscopy in tandem with the gradient electric field are experimentally confirmed using a SERS-active reporter, 4-mercaptophenylboronic acid which has a characteristic peak at Raman shift of 1586 cm-1, conjugated to silver nanoparticles of 32, 52, 58, and 74 nm in diameter. The SERS signal gain depends on the silver nanoparticle stability, size, and electric field strength. The limit of detection for 4-mPBA in the system under study can be calculated from the concentration plot and equals to 63 nM. The enhancement factor calculated for SERS in tandem with the gradient electric field can reach 106.Graphical abstract.
RESUMEN
PURPOSE: The method of magnetic neutron capture therapy can be described as a combination of two methods: magnetic localization of drugs using magnetically targeted carriers and neutron capture therapy itself. METHODS AND MATERIALS: In this work, we produced and tested two types of particles for such therapy. Composite ultradispersed ferro-carbon (Fe-C) and iron-boron (Fe-B) particles were formed from vapors of respective materials. RESULTS: Two-component ultradispersed particles, containing Fe and C, were tested as magnetic adsorbent of L-boronophenylalanine and borax and were shown that borax sorption could be effective for creation of high concentration of boron atoms in the area of tumor. Kinetics of boron release into the physiologic solution demonstrate that ultradispersed Fe-B (10%) could be applied for an effective magnetic neutron capture therapy. CONCLUSION: Both types of the particles have high magnetization and magnetic homogeneity, allow to form stable magnetic suspensions, and have low toxicity.