Selecting the correct scaffold model for assessing of the dielectric response of collagen-based biomaterials

Fish collagen (Col) was cross-linked using two methods: dehydrothermal treatment (DHT) and 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) in the presence of N-hydroxy-succinimide (NHS). For the samples marked Col, Col-DHT and Col-EDC/NHS, dielectric properties were measured in the frequency range from 100 Hz to 100 kHz and temperatures from 25 to 145 °C. In the full temperature range, the average values of relative permittivity and dielectric losses for Col samples are lower than those recorded for Col-DHT and Col-EDC/NHS samples. The peak temperature of the dielectric parameters attributed to the denaturation temperature for Col, Col-DHT and Col-EDC/NHS, respectively, is about 75 °C, 83 °C and 89 °C. In addition, the values of these parameters are much higher in Col-EDC/NHS than in Col-DHT at the same temperature and frequency. The permittivity decrement and conductivity increment, respectively, for Col-EDC/NHS are about 62 and 32 times greater than those given by Col-DHT, which is a consequence of the EDC/NHS crosslinking action. Our electrical and dielectric studies of fish Col cross-linked by EDC/NHS or DHT provide deeper insight into the structure of collagen materials and help improve the synthesis of Col-based scaffolds for tissue engineering.