There are provided methods for producing a hydrogel that is capable of adhesion of cells and which comprises enzymatically cross-linked conjugates of a hydrogel forming agent and a flavonoid, formed from a reaction using peroxide and peroxidase. Strain gauge sensors preferably provide signals having a magnitude that is indicative of the weight of the seat occupant. These particles have the capacity to bind cholesterol and are administered to a patient to enhance cellular cholesterol efflux and reduce cholesterol levels in cells, tissues, organs, and blood vessels.