I think we dont need 222.
I found that:
Appl Biochem Biotechnol. 2012 Oct;168(4):936-46. doi: 10.1007/s12010-012-9832-3. Epub 2012 Sep 6.
Extraction and purification of purple membrane for photochromic thin film development: application in photoelectrochemical investigation.
Pandey PC, Pandey D, Singh R.
Source
Department of Applied Chemistry, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005, India.
pcpandey.apc@itbhu.ac.in
Abstract
Purple membrane (PM) has been extracted and purified from archaebacteria for thin film development. The
purified purple membrane is isolated in 1 % polyvinyl alcohol solution for making thin film within gelatin and
organically modified silicate matrices. For thin film within gelatin matrix, homogenized
purple membrane suspension is mixed with 8 % gelatin and
poured into a specially designed
block with desired thickness of spacer having hydrophobicity
followed by gelatinization of the same over home-made thermostatic control unit
at 38 °C. The
gelatinized matrix is then allowed to dry under controlled conditions of humidity and temperature. The films of varying thicknesses ranging between 40, 50, and 60 μ are used for photo-electrochemical measurements. The results on photo-electrochemistry of non-oriented purple membrane film provides valuable information on the generation of forward (light on) and backward (light off) photocurrent as a function of: (a) applied potential and (b) film thickness. An increase in applied negative potential increases the amplitude of photocurrent whereas decrease in film thickness facilitates the reversibility of photocurrent response.
PMID: 22956275 [PubMed - indexed for MEDLINE]