Host–guest interactions in biocompatible anion-intercalated Mg-Al layered double hydroxides and their influence on L-lactate uptake

The mass production of human induced pluripotent stem cells (hiPSCs) is important in the area of regenerative medicine. During proliferation, stem cells metabolize D-glucose into L-lactate, the accumulation of which in a cell culture medium impairs the mass production of cells. It is therefore important to supply D-glucose and remove L-lactate from the cell culture medium to ensure that the stem cell mass culture can be achieved. In the present study, L-lactate-selective Mg-Al layered double hydroxide (LDH) adsorbents containing celL-culture-compatible exchangeable anions were designed. More specifically, different stem cell nutrients (i.e., L-alanyL-L-glutamine, L-glutamine, L-serine, L-methionine, L-cysteine, L-glutamate and α-ketoglutarate) and the cell culture buffer component (i.e., 4-(2-hydroxyethyl)-1-piperazineethanesulfonate (HEPES)) were incorporated into the Mg-Al LDHs via a rehydration method. The orientations of the organic guests and the host–guest interactions were characterized using a range of analytical and computational techniques. It was deduced that the L-lactate adsorption ability of the LDHs and the selectivity over D-glucose depended on a number of factors, including the charge density of the LDH guest relative to L-lactate, the guest orientation and the hydrogen bonds formed in the host–guest, guest–guest and guest–host–glucose complexes. Overall, this study provides insights into the design of effective and potentially biocompatible adsorbents for cell culture media regeneration to promote the cost-effective mass production of stem cells.