Synthesis and characterization of amlodipine-conjugated Gd3+-Citric acid PEG dendrimers for enhanced cardiac MRI contrast

•Novel contrast Agent: Amlodipine-conjugated Gd³⁺-PEG dendrimer for improved cardiac MRI.•Targeted & Safe: Targets cardiovascular tissues, reducing free gadolinium toxicity.•Superior Contrast: Higher R1 relaxation rate than magnevist for better imaging.•Effective Imaging: Enhanced cardiac tissue visualization in vivo.•Biocompatibility: Non-toxic in cells, efficiently excreted via kidneys and liver. The incorporation of nanotechnology in medicine has led to the development of advanced imaging agents, particularly at the nanoscale. Magnetic Resonance Imaging (MRI) stands out in medical imaging due to its non-invasive nature and superior soft tissue contrast. However, the low sensitivity of current MRI contrast agents necessitates the development of improved alternatives. Gadolinium-based contrast agents (GBCAs) enhance diagnostic capabilities but pose toxicity risks, particularly in patients with severe chronic kidney diseases. This study aims to design and synthesize a novel gadolinium-loaded, citric acid-based polyethylene glycol (PEG) dendrimer (dendrimer-G2) conjugated with amlodipine for enhanced cardiac MR imaging. The final product was characterized using LC-Mass, TEM, and EDX. Cytotoxicity was assessed using the MTT assay on HEK-293 cells. The MR imaging potential and biodistribution were evaluated in vivo, with mice receiving injections of the Gd3+-dendrimer-amlodipine complex followed by MRI and plasma mass spectrometry analysis. Our result showed that the Gd3+-dendrimer-amlodipine complex demonstrated no cytotoxic effects across all tested concentrations. The complex exhibited superior in vitro relaxivity (r1) compared to Magnevist, indicating enhanced contrast properties. In vivo studies showed significant cardiac uptake and efficient excretion through renal and hepatobiliary systems, confirming its potential for targeted cardiac imaging. In conclusion, the synthesized Gd3+-dendrimer-amlodipine complex demonstrates promising biocompatibility, favorable contrast properties, and efficient excretion patterns in preliminary studies. Further in vivo investigations are warranted to confirm its efficacy and safety profile as a novel MR contrast agent. [Display omitted]