Fig. 3.

(a) Baseline-corrected SERS spectra of glutaric acid internal standard, pure DPA, and DPA extracted from B. cereus and B. subtilis spores. The DPA ring breathing vibration at 1006 cm⁻¹ and the glutaric acid C–H stretch at 2934 cm⁻¹ used for quantification are highlighted. Chemical structures of DPA and glutaric acid are shown on the right hand side. Reproduced with permission (Cowcher et al., 2013).

(b) Particle size distribution obtained via DLS. Reproduced with permission (Jarzebski et al., 2019).