Biowaste-derived carbon dots/hydroxyapatite nanocomposite as drug delivery vehicle for acetaminophen

In this work, carbon dots/hydroxyapatite (CD-HAP) nanocomposite has been synthesized and used as drug carrier for acetaminophen. Carbon dots are synthesized from a biowaste precursor, which is sugarcane bagasse char using hydrothermal method. The synthesis of carbon dots is studied under four different temperatures of 150, 170, 190, and 210 °C. The fluorescence behaviour of carbon dots is greatest at an optimum temperature of 190 °C. Carbon dots with the best fluorescence properties are merged with the hydroxyapatite. The transmission electron microscopy (TEM) analysis confirms the formation of spherical nanodots with average diameter of 7.5 nm. The field emission scanning electron microscopy (FESEM) analysis confirms the formation of rod-shaped hydroxyapatite with an average diameter of 142 nm. Elemental analysis shows a Ca/P ratio of 1.71, which is close to Ca/P ratio of 1.67 found in natural bone, indicating the biocompatibility of the nanocomposite. Elemental analysis also shows an increase in carbon weight percentage in CD-HAP when compared with blank HAP, proving the formation of carbon dots in the nanocomposite. The pairing of carbon dots and hydroxyapatite improved the fluorescence of composite greatly, as well as the surface area from 41.631 to 78.752 m 2 /g. The drug loading and release performance is evaluated by loading acetaminophen into the nanocomposite. CD-HAP-40 gives the highest loading capacity of 48.5%. Acetaminophen release is slower in CD-HAP-20, and the release kinetics fits the Higuchi model. This finding shows that the acetaminophen is released via a diffusion mechanism. Highlights The composite of CD-HAP was synthesis via sol–gel method to improve the fluorescence property of hydroxyapatite and prolong the fluorescence behaviour. The carbon dots were synthesized from sugarcane bagasse using hydrothermal method, with the optimum temperature of 190 °C showing the highest fluorescence intensity. The presence of carbon dots in hydroxyapatite composite was found to improve the surface area from 41.631 to 78.752 m 2 /g as well as the fluorescence intensity. The highest loading of acetaminophen using CD-HAP was found at 48.5%.