You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Recent advances in carbon nanotubes as delivery systems for anticancer drugs. Problems associated with the administration of anticancer drugs, such as limited solubility, poor biodistribution,lack of selectivity, and healthy tissue damage, can be overcome by the implementation of drug delivery systems. A wide range of materials, including liposomes, microspheres, polymers and recently, carbon nanotubes (CNTs), have been investigated for delivering anticancer drugs on the purpose of reducing the number of necessary administrations, providing more localized and better use of the active agents, and increasing patient compliance. Carbon nanotubes (CNTs) have attracted particular attention as carriers of biologically relevant molecules due to their unique physical, chemical and physiological properties. The exact relationship between the physical-chemical properties of carbon nanotubes, their cell to-cell interactions, reactivity, and biological/systemic consequences are relevant issues and it is important to know suchinter-relationships beforehand to employ the benefits of these nanomaterials without the hazardous consequences. The purpose of this review is to present highlight of recent developments in the application of carbon nanotubes as cargoes for anti cancer drugs and in the diagnosis of cancer diseases.
{"Chemical": ["carbon", "Carbon"]}