RESUMEN
We present pulsed electron paramagnetic resonance (EPR) studies on three La(II) complexes, [K(2.2.2-cryptand)][La(Cp')3] (1), [K(2.2.2-cryptand)][La(Cpâ³)3] (2), and [K(2.2.2-cryptand)][La(Cptt)3] (3), which feature cyclopentadienyl derivatives as ligands [Cp' = C5H4SiMe3; Cpâ³ = C5H3(SiMe3)2; Cptt = C5H3(CMe3)2] and display a C3 symmetry. Long spin-lattice relaxation (T1) and phase memory (Tm) times are observed for all three compounds, but with significant variation in T1 among 1-3, with 3 being the slowest relaxing due to higher s-character of the SOMO. The dephasing times can be extended by more than an order of magnitude via dynamical decoupling experiments using a Carr-Purcell-Meiboom-Gill (CPMG) sequence, reaching 161 µs (5 K) for 3. Coherent spin manipulation is performed by the observation of Rabi quantum oscillations up to 80 K in this nuclear spin-rich environment (1H, 13C, and 29Si). The high nuclear spin of 139La (I = 7/2), and the ability to coherently manipulate all eight hyperfine transitions, makes these molecules promising candidates for application as qudits (multilevel quantum systems featuring d quantum states; d >2) for performing quantum operations within a single molecule. Application of HYSCORE techniques allows us to quantify the electron spin density at ligand nuclei and interrogate the role of functional groups to the electron spin relaxation properties.
RESUMEN
Objectives: Bisphosphonates (BFs) show clinical effectiveness in managing osteoporosis and bone metastases but pose risks of bisphosphonate-related jaw osteonecrosis (BRONJ). With no established gold standard for BRONJ treatment, our focus is on symptom severity reduction. We aimed to assess the preventive effects of bioactive glass and/or pericardial membrane in a preclinical BRONJ model, evaluating their potential to prevent osteonecrosis and bone loss post-tooth extractions in zoledronic acid (ZA)-treated animals. Methods: Rats, receiving ZA or saline biweekly for four weeks, underwent 1st and 2nd lower left molar extractions. Pericardial membrane alone or with F18 bioglass was applied post-extractions. Microarchitecture analysis and bone loss assessment utilized computerized microtomography (CT) and positron emission tomography (PET) with 18F-FDG and 18F-NaF tracers. Histological analysis evaluated bone injury. Results: Exclusive alveolar bone loss occurred post-extraction in the continuous ZA group, inducing osteonecrosis, osteolysis, osteomyelitis, and abscess formation. Concurrent pericardial membrane with F18 bioglass application prevented these outcomes. Baseline PET/CT scans showed no discernible uptake differences, but post-extraction 18F-FDG tracer imaging revealed heightened glucose metabolism at the extraction site in the ZA-treated group with membrane, contrasting the control group. Conclusion: These findings suggest pericardial membrane with F18 bioglass effectively prevents BRONJ in the preclinical model.