In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Our in vitro and in vivo results suggest that incorporation of amphotericin B into lipid nanospheres of NS - 718 attenuates the nephrotoxicity of amphotericin B .
### Output Text:
Our in vitro and in vivo results suggest that incorporation of <span class="chemical">amphotericin B</span> into lipid nanospheres of NS - 718 attenuates the nephrotoxicity of <span class="chemical">amphotericin B</span> . 