Catalytic nanomedicine: Functionalisation of nanostructured cryptomelane

Nanostructured cryptomelanes (KMn8O16) were synthesized from manganese sulphate and manganese acetate precursors by the reflux method. The respectively obtained samples, CRYSO4 and CRYAc, were functionalised with hydroxyl, ammonium, sulphate and phosphate groups in order to modify the biocompatibility and surface properties of cryptomelane. Characterization by FTIR and XRD confirmed bond formation of CRY–NH, CRYdouble bond; length as m-dashSdouble bond; length as m-dashO, CRY–NH, and CRYdouble bond; length as m-dashPO4. In both functionalise samples (CRYSO4-F and CRYAc-F), IR bands occurred at 1399 cm−1, corresponding to the sulphate species, and 1106 cm−1, related to phosphate vibrations; along with the OH and NH characteristic vibration bands in the high energy region. Biocompatibility of functionalised samples was tested by implantation of cryptomelane reservoir in the basolateral amygdala and caudal nucleus of Wistar rats using stereotactic surgery. The brains of the rats were processed in order to evaluate any damage associated with the implant. The results showed that functionalised cryptomelanes did not cause tissue damage or inflammation while not functionalised cryptomelanes caused cell death.