Figure 4.

Synchrotron Infrared Microspectroscopy and X-ray Photoelectron Spectroscopy of a Single Green Fluorescent Biofiber

(A) Image of a UV illuminated biofiber and IMS image at 1655cm⁻¹ showing the distribution of amide I bond from protein. For interpretation of the amide I bond signal intensity, a pseudocolor scale bar is introduced, where blue represents the highest intensity and red the lowest. Scale bar, 20 μm.

(B) The red box is the mesh used for IR mapping, the blue box is the control region, and the orange box is the biofiber region where IR spectra were extracted. Scale bar, 20 μm.

(C) Averaged second derivative IR spectra of the control and fiber regions.

(D–F) (D) N 1s, (E) S 2p, and (F) P 2p XPS spectra of Ar⁺ sputtered Au (triangles), DTTO on Au (squares), and biofibers (circles). S 2p presents two doublets associated to S=O bond (red) and S-C bond (blue). In all peaks the background was subtracted and a constant value added to order the samples. S 2p and P 2p were fitted by doublets in fixed energy shift (2p_3/2 and 2p_1/2). Signal of S 2p of biofibers was multiplied by a factor 10. See also Table S2.