ABSTRACT
This article presents a high-voltage (HV) pulse driver based on silicon-on-insulator (SOI) technology for biomedical ultrasound actuators and multi-channel portable imaging systems specifically. The pulse driver, which receives an external low-voltage drive signal and produces high-voltage pulses with a balanced rising and falling edge, is designed by synthesizing high-speed, capacitor-coupled level-shifters with a high-voltage H-bridge output stage. In addition, an on-chip floating power supply has also been developed to simplify powering the entire system and reduce static power consumption. The electrical and acoustic performance of the integrated eight-channel pulse driver has been verified by using medical-grade ultrasound probes to acquire the transmit/echo signals. The driver can produce pulse signals >100 Vpp with rise and fall times within 18.6 and 18.5 ns, respectively. The static power required to support the overall system is less than 3.6 mW, and the power consumption of the system during excitation is less than 50 mW per channel. The second harmonic distortion of the output pulse signal is as low as -40 dBc, indicating that the integrated multi-channel pulse driver can be used in advanced portable ultrasonic imaging systems.
ABSTRACT
Organometallic Ru(II)-arene complexes have emerged as potential alternatives to platinum appended agents due to their wide range of interesting features such as stability in solution and solid, significant activity, less toxicity and hydrophobic property of arene moiety, etc. Hence, a series of Ru(II)-p-cymene complexes, [(η6-p-cymene)Ru(η2-N,N-L1)Cl]Cl (1), [(η6-p-cymene)Ru(η1-N-L2)Cl2] (2) and [(η6-p-cymene)Ru(η1-N-L3)Cl2] (3) were prepared from pyrazole based ligands [2-(1H-pyrazol-3-yl)pyridine (L1), 3-(furan-2-yl)-1H-pyrazole (L2) and 3-(thiophen-2-yl)-1H-pyrazole (L3)], and [RuCl2-(η6-p-cymene)] dimer. The new Ru(II)-p-cymene complexes were well characterized by elemental analysis, and spectroscopic (FT-IR, UV-Visible, 1H NMR, 13C NMR and mass) and crystallographic methods. The Ru(II)-p-cymene complexes (1-3) were found to adopt their characteristic piano stool geometry around Ru(II) ion. The calf thymus DNA (CT-DNA) binding ability of the new complexes was investigated by electronic absorption spectroscopic titration and viscosity methods. The molecular docking study results showed that complex 1 strongly bound with targeted biomolecules than 2 and 3. Docked poses of bidentate pyrazole based Ru(II)-p-cymene complex 1 revealed that the complex formed a crucial guanine N7 position hydrogen bond with DNA receptor. Complexes 1-3 might hydrolyze under physiological conditions and form aqua complexes 4-8, and docking calculations showed that the aqua complexes bound strongly with the receptors than original complexes. The in vitro cytotoxicity of the Ru(II)-p-cymene complexes and cisplatin was evaluated against triple negative breast cancer (TNBC) MDA-MB-231 cells. Our results showed that the inhibitory effect of bidentate pyrazole based Ru(II)-p-cymene complex 1 on the growth of breast cancer cells was superior to other tested complexes.
