Pengaruh Konsentrasi Asam Klorida (HCl) terhadap Dispersibilitas, Solubilitas, dan Toksisitas Carbon nanotube Terfungsionalisasi sebagai Penghantar Obat Kanker = The Effect of Hydrochloric acid (HCl) Addition on Dispersibility, Solubility, and Toxicity of Functionalized Carbon nanotube as Drug Delivery Material for Cancer