Synthesis, characterization, kinetic drug release and anticancer activity of bisphosphonates multi-walled carbon nanotube conjugates.

The statistical proof that most forms of cancer metastasize to bone tissue has redirected research focus to the development of efficient secondary bone cancer treatment regimens. Bisphosphonates (BPs) have been earmarked as a drug of choice for bone metastasis. However, they have a shortcoming of being released before reaching targeted sites due to their low molecular weight. In haste to attain increased efficacy, there is a tendency for drug overdose to occur, resulting in systemic toxicity. One way to curb this is by employing drug delivery systems for targeted and controlled release of the drugs. Having been explored as versatile and innovative drug carriers, multi-walled carbon nanotubes (MWCNTs) have emerged as potential drug delivery systems. Hence, in the present study, alendronate, neridronate and pamidronate are three classes of bisphosphonates that were conjugated onto multi-walled carbon nanotubes. Conjugation was confirmed by characterization techniques including SEM, TEM, EDX, FTIR, Raman and TGA. Drug release studies were also conducted at pH 1.2, 5.5 and 7.4 to study the mechanism of release for neridronate. Results obtained were fitted into Zero order (42.6%), Higuchi (26%) and Korsmeyer-Peppas (22%). The best models describing the release of neridronate from MWCNTs were Zero order, Higuchi and Korsmeyer-Peppas at pH 1.2, 5.5 and 7.4, respectively. A tetrazolium cell viability assay was performed to assess the anticancer activity of the MWCNTs conjugated BPs.

Carbon nanospheres conjugated bisphosphonates: synthesis, characterization and in vitro antimalarial activity.

About 40% of the world's population lives in malaria zones where it presents a challenging health problem. Malaria treatment and prevention have been hindered by drug resistance. Bisphosphonates have been found to be active against Trypanosoma cruzi and Plasmodium falciparum that cause Chaga's disease and malaria respectively. However, bisphosphonates have a shortcoming of being rapidly removed from the bloodstream through the kidneys before reaching the target sites due to their low molecular weight. In the current study, increased bisphosphonates' efficacy for malaria treatment was attempted by conjugating bisphosphonates onto carbon nanospheres (CNSs). The synthesis of the target compounds was confirmed by SEM, TEM, EDX, FTIR, Raman and TGA. The target CNSs containing bisphosphonates were evaluated for antimalarial activity against a chloroquine-resistant strain of P. falciparum. From the free bisphosphonates to the conjugates, the results obtained revealed that there were improvements in percentage parasite kill (from -10.71% to 18%, -18.93% to 28.09% and 10.47% to 28.33% for alendronate, pamidronate and neridronate, respectively). The haemolysis assays revealed that the synthesized compound did not have a toxic impact on healthy red blood cells. The results indicate that bisphosphonates conjugated CNSs are said to be promising P. falciparum blood stage inhibitors.