Evaluation of biomolecular interactions and cytotoxic activity of organometallic binuclear Ru(II) complexes of ferrocenyl thiosemicarbazones
JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS
Authors: Khanvilkar, Priyanka; Dash, Soumya R.; Vohra, Alisagar; Devkar, Ranjitsinh; Chakraborty, Debjani
Abstract
Four new ferrocenyl substituted thiosemicarbazone ligands (L1-L4) and their corresponding binuclear ruthenium(II) arene complexes of the general type [(eta(6)-pcym)(L)Ru(mu-im)Ru(L)(eta(6)-p-cym)]Cl (C1-C4) and [(eta(6)-pcym)(L)Ru(mu-azpy)Ru(L)(eta(6)-p-cym)]Cl-2(C5-C8) (cym = cymene, im = imidazole, azpy = 4,4 '-azopyridine) have been synthesized and characterized. The structures of the complexes were established through DFT calculations and geometry optimization. The interactions of the binuclear complexes with DNA were investigated by absorption, emission and viscosity studies which indicated that the complexes bind to DNAviaintercalation. Meanwhile, the interaction of complexes with the protein, bovine serum albumin (BSA), has also been studied using fluorescence emission spectroscopy. The experimental results show that the binuclear complexes exhibit good binding propensities to BSA. The complexes can quench the intrinsic fluorescence of BSA remarkably through a static or dynamic quenching process. In addition, thein vitrocytotoxicity of complexesC1-C8against HeLa cell line was assayed which showed lower IC(50)values indicating their higher cytotoxicity and potency in killing the cancer cells at low concentrations. Communicated by Ramaswamy H. Sarma
Biomechanical Comparison of Posterior Fixation Combinations with an Allograft Spacer between the Lateral Mass and Pedicle Screws
APPLIED SCIENCES-BASEL
Authors: Lee, Soo-Bin; Lee, Hwan-Mo; Park, Tae-Hyun; Lee, Sung Jae; Kwon, Young-Woo; Moon, Seong-Hwan; Lee, Byung Ho
Abstract
Background: There are a few biomechanical studies that describe posterior fixation methods with pedicle screws (PS) and lateral mass screws (LMS); the combination of both screw types and their effect on an allograft spacer in a surgically treated cervical segment is unknown. Methods: Finite element model (FEM) analyses were used to investigate the effects of a hybrid technique using posterior PS and LMS. Stress distribution and subsidence risk from a combination of screws under hybrid motion control conditions, including flexion, extension, axial rotation, and lateral bending, were investigated to evaluate the biomechanical characteristics of different six-screw combinations. Findings: The load sharing on the allograft spacer in flexion mode was highest in the LMS model (74.6%) and lowest in the PS model (35.1%). The likelihood of subsidence of allograft spacer on C6 was highest in the screws from the distal LMS (type 5) model during flexion and extension (4.902 MPa, 30.1% and 2.189 MPa, 13.4%). In lateral bending, the left unilateral LMS (type 4) model screws on C5 (3.726 MPa, 22.9%) and C6 (2.994 MPa, 18.4%) yielded the greatest subsidence risks, because the lateral bending forces were supported by the LMS. In counterclockwise axial rotation, the left unilateral LMS (type 4) model screws on C5 (3.092 MPa, 19.0%) and C6 (3.076 MPa, 18.9%) demonstrated the highest subsidence risks. Conclusion: The asymmetrical ipsilateral use of LMS and posterior PS in lateral bending and axial rotation demonstrated the lowest stability and greatest subsidence risk. We recommend bilateral symmetrical insertion of LMS or posterior PS and posterior PS on distal vertebrae for increased stability and reduced risk of allograft spacer subsidence.