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: A biodegradable polymer dextran has been utilized as a carrier for synthesis of etodolac - dextran conjugates ( ED ) to improve its aqueous solubility and reduce gastrointestinal side effects .
### Output Text:
A biodegradable polymer <span class="chemical">dextran</span> has been utilized as a carrier for synthesis of <span class="chemical">etodolac</span> - <span class="chemical">dextran</span> conjugates ( ED ) to improve its aqueous solubility and reduce gastrointestinal side effects . 