We confirmed that gold nanoparticles have absorbance in ultraviolet region by measuring the absorbance spectrum of gold nanoparticles aqueous solution (4.5 × 1010 [particle counts / ml]) and demonstrated that they function as a parasol. Fig. 1 reveals that this spectrum has a peak around 280nm.
Fig. 1 . Absorbance spectrum of gold nanoparticles aqueous solution (4.5 × 1010 [particle counts / ml])
Ultraviolet light can be divided into three types: UVA, UVB and UVC. These three lights have different wavelength ranges. Approximately, UVA has wavelength range in 400-315nm, UVB has in 315-280nm, and UVC has under 280nm.Among these lights, UVA and UVB are related to sunburn. UVB reaches the surface of skin and damages skin and eye. This is the major cause of sunburn. Not as much as UVB, but UVA can be also the cause of sunburn by being exposed to for long time.
Looking back to Fig. 1 , you can see that there’s a peak around the wavelength of UVB, which is the major cause of sunburn, so we’ve decided to use gold nanoparticles as a parasol.
Sequence of gold nanoparticle’s “handle DNA”
After conjugating gold nanoparticles(GNPs) and gold nanoparticles’ “handle DNA” by Au-S connection, we confirmed this by attaching FAM-modified DNA partially complementary to gold nanoparticle’s “handle DNA” and taking fluorescence spectrum with excitation wavelength of 480nm(Fig. 1. (a) , (b) , (c)).
Fluorescence spectrum in Fig. 1. (a) shows a peak at the wavelength around 520nm, which is the wavelength emitted from FAM. However, spectra described in Fig. 1. (b) and (c), taken as control experiments, do not show a peak like this.
From these results, we confirmed that gold nanoparticles’ “handle DNA” conjugated to gold nanoparticles.
Fig. 1. (a)(b)(c) Scheme of the experiment (left) and its spectrum data (right).