Structure, molecular simulation, and release of a spirin from intercalated Zn–Al-layered double hydroxides

• Aspirin was firstly intercalated into Zn–Al-layered double hydroxides by two methods and released in two buffered solutions: phosphate and borate buffered saline.
• By molecular simulation, the firstly illuminate the different arrangement of molecules in LDH interlayers influenced by different preparation.
• In the release process, the first time explain the anion exchange process by bonding energy calculated by Material Studio.
• Experimental phenomenon that the structure of LDH was destroyed after release in phosphate buffered saline is first reported and analyzed.

Aspirin or acetylsalicylic acid (AA), a non-steroidal anti-inflammatory drug, is intercalated into Zn–Al-layered double hydroxides (ZnAl-LDHs) by co-precipitation and reconstruction methods. The composition, structure, and morphology of the intercalated products as well as their release behavior are determined experimentally and theoretically by Material Studio 5.5. Experimental results disclose the strong interaction between the LDHs sheets and AA in the intercalated ZnAl-LDHs produced by co-precipitation and slow release of AA from the intercalated ZnAl-LDHs in both phosphate buffered saline (PBS) and borate buffered saline (BBS) solutions. The percentage of AA released from the ZnAl-LDHs prepared by both methods in PBS (96.87% and 98.12%) are much more than those in BBS (68.59% and 81.22%) implying that both H4BO4− and H2PO4− can exchange with AA in the ZnAl-LDHs. After AA is released to PBS, ZnAl-LDHs break into small pieces. The experimental results are explained theoretically based on the calculation of the bonding energy between the anions and LDHs sheets as well as the AlO bond length change in the LDHs sheets.

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