This manuscript fails to meet the standard for publication in Nanomaterials subject to the following points. The experimental design, style of presentation, the data interpretation are problematic. I recommend the authors to thoroughly redesign the experiments, improve the quality of work and have a complete proofreading before submission to elsewhere. In the Methods section, drug or NPs should remain incubated with cells during the ROS measurement. Annexin V-FITC apotosis assay is a totally different assay as TUNEL. In the Results section, The IR spectrum of Fe3O4 has not been normalized. The so-called Fe3O4/HAp nanocomposite looks like the physical mixture of these two components. There is no evidence to show the success of nanocomposite formation. The BET specific surface area of the nanocomposite is not high at all for drug loading. The composite has lower magnetization than Fe3O4 NPs. Why are the authors still claiming that it has better magnetic property? More cancer cell lines and normal cell lines should be tested on the nanocomposite for their cytoxicity. The drug loading efficiency and capacity should be measured and presented. The drug release profile should be checked as well at lease in buffers. We have not seen the low pH controlled drug release as claimed by the authors. There is an inconsistency between the description of Figure 7 and the legend. I have no idea whether the images in Figure 7 are obtained from drug-loaded nanocomposite or bare nanocomposite. There is a confusion whether DCFH signal is determined by fluorescence imaging or flow cytometry. In Annexin V-PI flow cytometry study, the percentage of PI positive cell population is recommended to be presented.