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:

Effect of guanidinylation on the properties of poly(2-aminoethylmethacrylate)-based antibacterial materials. The effect of converting ammonium into guanidine moieties, compared to other factors such as molecular weight or hydrophobicity, on the antibacterial activity is investigated for homo- and copolymers of 2-aminoethylmethacrylate in solution or coatings. Polymers are obtained by free radical polymerization, polymer-analogous guanidinylation is conducted with cyanamide; non-leaching immobilization is achieved by LBL assembly of homopolymers or crosslinking of functional sidegroups in copolymers. Antibacterial activity to Escherichia coli or Bacillus subtilis is determined by different standard methods. Guanidinylation improves antibacterial activity and speed as well as cytotoxicity of hydrophilic homo- and copolymers in solution or coatings.
{"Chemical": ["2-aminoethylmethacrylate", "cyanamide", "poly(2-aminoethylmethacrylate)", "ammonium", "guanidine"]}