The aim of this study is to investigate of complex [Pd 3 (C,N-(C 6 H 4 C(Cl)=NO)-4) 6 ] in free mode and loading on nanoparticles on stabilizing a portion of telomeric DNA, called Gquadruplex DNA with the sequence of 5?-G 3 (T 2 AG 3 ) 3 -3?. By titration absorption methods, the binding constant between complex and G-q DNA was found to be (K b =4.5×10 6 M ?1 ) and showed that this interaction is more selective than ligand (K b =3.5×10 5 M ?1 ) or duplex DNA (K b =1.5×10 5 M ?1 ). Type of interaction using titration absorption, thermal denaturation, and fluorescence competitive experiments was investigated and all three represented the groove binding.The thermodynamic parameters were measured by thermal denaturation experiment and the negative value of ?G°=-8.24 kcal mol ?1 indicated spontaneously interaction and represented, with increasing in the concentration of the complex from 1 to 120 ?M, melting denaturation was shifted and increased, therefore, interactions was bimolecular and also confirmed complex as an stabilizer on G-q DNA structure. In order to make more effective use of the drug and remove undesirable side effects, drug delivery system with nanoparticles was chosen. The reason of synthesis BSA nanoparticles and cellulose as drug delivery system is biodegradable/biocompatible properties. The complex was loaded on them and then the release of drug from was investigated in vitro and were compared with each other and with complex free form. The results showed BSA were better candidates as carriers because of smaller size and lower release. Interaction of complex adsorbed on BSA nanoparticles and G-q DNA was also studied and its comparison with the free mode showed the most effective interaction. The number of binding sites was calculated by Job plot technique and was found to be 2:1 that represented 2 of complexes connected to each G-q DNA. In the end, in biological studies, value of IC 50 =50 ?M showed that the complex has significant antitumor activities against MCF-7 (breast cancer) cells then this complex can inhibit telomerase by establish of G-q DNA structure.
