Since then, numerous small molecule drugs, e.g., methotrexate [21] and cisplatin [22] for the treatment of cerebral cancer or tacrine [23, 24], rivastigmine [25] or rosmarinic acid [26] for treatment of Alzheimer’s disease, and peptide/protein drugs such as the nerve growth factor [27, 28] also for the treatment of Alzheimer’s disease or arylsulfatase A [29] for metachromatic leukodystrophy have been successfully delivered into the brain using PS-coated PBCA NPs. Here, ARSA is linked to Alzheimer disease.