4) at 1650 cm − cm −1 were assigned to C=O stretching and N-H stretching. To further probe the chemical composition and properties of both materials we applied the non-destructive method of FT-IR spectroscopy and compared the absorption bands of key constituent molecules of the both artificial and natural horn material 8.
4(b) on the other hand, shows that both real and artificial horns started to decompose approximately at 200 ☌ with final residues of 1.5 wt% and 1.3 wt%, respectively. 4(a) the DSC analysis demonstrated that both materials were surprisingly similar with that peaks at 100 ☌ indicating the insipient moisture of the samples while the broad endothermic peak from about 200 ☌ to 400 ☌ indicates the degradation of the protein. This data allows us to probe not only physical phenomena such as phase transitions between the solid, liquid and gaseous states of the various components of the material studied but also chemical phenomena such as thermal decomposition and reactions between surfaces.Īs shown in Fig. Thermal Gravimetric Analysis (TGA), on the other hand, measures the mass of a single sample as it changes with temperature over time. To this effect we used DSC and TGA to investigate the similarity of the thermal properties between samples of our artificial horns and the real horn.ĭifferential Scanning Calorimetry (DSC) is a thermo-analytical technique comparing the heat required to increase the temperature of a sample and a reference allowing us to study physical transformations such as phase transitions and determine whether the process is exothermic or endothermic as well as indicating a glass transition. Importantly for our more fundamental interests in the novel material, rather than the more superficial copying of structures, was the analysis of its material qualities.
On the microscopic level our Light and Scanning-Electron Microscopy confirmed that not only the gross morphology and anatomy of the faux horn but also the more detailed fine structure was similar to those of real rhino horn. If carefully polished a faux horn could thus be easily modified to resemble the outside of a rhino horn.
The smaller ones, which were our focus for analysis, filed and polished very nicely into surfaces rather similar, indeed confusingly similar, to surfaces of native rhino horn naturally polished by rubbing.
The smaller horn (around 4 cm diameter and 10 cm length) cured within a few days while the largest one (around 12 cm diameter and 35 cm length) took weeks in the vacuum oven to dry. Importantly, the RSF material we used can also easily be moulded and cured into a tough matrix to fill-in between the horse-tail hairs.īy bundling the LiBr washed hairs as tightly as possible while infusing them with the RSF solution we were able to create solid composite cylinders of hair-horn.
Assuming such a highly proteinaceous and sticky horn matrix we used for this function in our faux horns the RSF silk fibroin, which we know how to prepare and deploy 12. Thus the matrix of the native rhino horn would in essence be a largely proteinaceous glue with inclusions of soil and plant sap where the animal has rubbed the growing horn. Such cells would contain high levels of intra-cellular proteins as well as carrying along the rather adhesive extra-cellular fibronectin glycoprotein.
As there is no detailed information on the composition of the rhino’s nose-tip exudate and horn matrix material other than that it seems to be a sebatious gland exudate full of deceased highly melanised cells 10.