Effect of Additives on the Crystal Morphology of Amino Acids: A Theoretical and Experimental Study

Abstract

The crystal morphology of amino acids can be altered in a controlled manner through inclusion of tailor-made additives in their structure, in order to widen their scope for applications in drug design and targeted delivery. In this study, the effect of multiadditive combinations of hydrophobic and hydrophilic amino acids on the growth and morphology of l-alanine was investigated. Theoretical calculations were performed using two crystal growth models in Materials Studio software: (1) build-in model; (2) surface docking model. Crystallization experiments were carried out using the metal-assisted and microwave accelerated evaporative crystallization (MA-MAEC) technique with multiple hydrophobic and hydrophilic amino acids added in stoichiometric amounts to l-alanine solution. The crystal morphology was established and compared with predicted crystal morphology. The use of hydrophilic and hydrophobic additives was predicted to have significant changes in the morphology of l-alanine crystals. Multiadditive combinations with hydrophobic amino acids resulted in elongation of l-alanine crystals through the (120) face. Experimental data corroborates with the theoretical predictions in relation to the morphological changes due to additives, indicating the accuracy of theoretical models in predicting the impact of additives in crystal growth.

Effect of Microwave Heating on the Crystallization of Glutathione Tripeptide on Silver Nanoparticle Films

“…These calculations were based on the Forcite module using the consistent valence force field method and the growth morphology method, which assumes that the growth rate of a crystal surface is directly proportional to its attachment energy. 12 The most significant crystal faces were found to be {002}, {012} and {201} as shown in Figure 8. Calculated attachment energies for the {201} and {002} crystal faces have the lowest and highest attachment energy of −85.8 kcal/mol and −17.7 kcal/mol, respectively.The attachment energy values imply that GSH crystal is predicted to grow significantly faster on the (201) face and slower on the {012} and the slowest on the {002}.…”

“…The SH group of the molecule is involved in hydrogen bonding and other short intermolecular contacts hold the unit cell together. Unit cell dimensions were obtained from the Cambridge Structural Database (CSD) and are given as follows: a = 5.62 Å, b = 8.78 Å, c = 27.99 Å, α = β = γ = 90° The crystal morphology was calculated (per the procedure published previously 12 ) and the morphologically similar surfaces, based on the observed experimental images for GSH crystal, were highlighted. These calculations were based on the Forcite module using the consistent valence force field method and the growth morphology method, which assumes that the growth rate of a crystal surface is directly proportional to its attachment energy.…”

“…Metal nanostructures of silver, gold, copper, nickel, and indium tin oxide are deposited onto poly(methyl methacrylate) (PMMA) platforms combined with silicon isolators (i.e., the iCrystal plates). 12–16 The unique design of the iCrystal plates ensures that microwave radiation is distributed homogeneously across the wells formed by the silicon isolator. 17,18 In studies based on the MA-MAEC technique by our research group to date, two different microwave systems operating at 2.45 GHz was employed: a multimode conventional microwave system (fixed power, 7001000 W) 10,11 and the iCrystal system (monomode, variable power up to 100 W).…”

Ultra-Rapid Crystallization of L-Alanine Using Monomode Microwaves, Indium Tin Oxide and Metal-Assisted and Microwave-Accelerated Evaporative Crystallization

“…The unit cell dimensions (a = 6.032, b = 12.343, c = 5.784; α = β = γ = 90°) were obtained from the Cambridge Structural Database (CSD) and the calculations were carried out using Biovia Materials Studio 8. The details of these calculations were provided in a previous publication [ 22 ].…”

Crystallization of Ammonium Persulfate in the Presence of an Additive: Experimental and Molecular Dynamics Simulation Studies

“…A molecular simulation was also used to explain the change of morphology in the presence of additives via a build‐in approach and a surface‐docking approach . The binding energy between additives and the crystal surface was calculated as a means of predicting the morphology . Though there have been a large number of studies examining the growth inhibition effects of interactions between additives and the crystal surface, the effects of the diffusion coefficient have not been taken into consideration.…”