Search for: All records

We recently applied carbonic anhydrase (CA) for the rapid catalytic conversion of carbon dioxide to enable the self-healing properties of concrete and in the development of a carbon-negative concrete replacement named Enzymatic Construction Material (ECM). Here, we explore the stability and carbonate generation ability of model molecular mimics of carbonic anhydrase under high pH and elevated temperatures relevant to long-term durability in cementitious and concrete-like materials. Molecular mimics include Zn2+-based organometallic complexes with an aromatic ligand tris(2-pyridylmethyl)amine, TPA, and with an aliphatic ligand cyclen, 1,4,7,10-tetraazacyclododecane. The Zn(TPA) and Zn(cyclen) complexes are stable in aqueous environments at standard pressures ranging from neutral to pH 13 and temperatures up to 120 °C, where CA is inactive. Under the temperature and pH conditions studied, organometallic degradation pathways do not involve the decomposition of either organic ligand but rather the dissociation of the complex that is reversible upon neutralization in the case of Zn(TPA). Zn(cyclen) is stable at high temperatures at pH 12 and above, resembling cementitious conditions for over 365 days with no signs of degradation. Separately, alkaline calcium-containing solutions with either 25 nM CA or 5 mM Zn(cyclen) catalyst demonstrated accelerated pH decreases compared to catalyst-free controls upon sparging with carbon dioxide because of the conversion of CO2 and H2O to HCO3– and H+. Notably, the inclusion of sub-molar concentrations of detergents, such as sodium dodecyl sulfate, in carbonate production reactions demonstrated no change in the reactivity of control solutions or those with the Zn(cyclen) catalyst but severely attenuated the conversion in CA-containing solutions concomitant with CA denaturation and loss of enzymatic activity. 

Current solutions to global challenges place tension between global benefits and local impacts. The result is increasing opposition to implementation of beneficial climate policies. Prioritizing investment in projects with tangible local benefits that also contribute to global climate change can resolve this tension and make local communities’ partners instead of antagonists to change; the approach advocated is a new take on “thinking globally, acting locally”. This approach is a departure from the usual strategy of focusing resources on solutions perceived to have the largest potential global impact, without regards to local concerns. Reclamation of polluted mine sites by using fast growing bamboo to remove heavy metals provides a case study to show what is possible. Effective implementation of thinking globally while acting locally will require increased coordination between different types of researchers, new educational models, and greater stakeholder participation in problem identification and solution development. 

We present the first experimental evidence that supports that low stresses are experienced by central cells and is driving the biological response of aggregates. Our model improves upon previous models, however, it can still become more robust. We plan to obtain higher resolution biophysical data with validation to further alter cell contractility distributions and iterate our model’s parameters. It is necessary to incorporate heterogeneous mechanical properties to accurately estimate the distribution of the emergent stress fields in our aggregates.