@saicharan - do we have any cell culture medium available with this HEPES buffer?
@ Chandrashekaram Kans- Hyclone make DMEM media is available with HEPES Buffer
Any one here can have comment on new designed incubator with Tri gases; nitrogen, CO2 and Oxygen plus controlled %RH? As far as I know, N2 gas used to control oxygen level in incubator, by doing this one can set his incubator to hypoxic condition reducing oxygen level to less than 5%.
I wonder if old fashion incubator having only CO2 monitor will be good enough for cell growth comparing with new designed which have %RH and oxygen level monitored?
In order to culture cells under optimum conditions the media they grow in needs to be buffered so it stays at neutral pH (around pH 7). It is possible to add a buffering compound to the media, like sodium phosphates or Tris or Hepes, but often these compounds affect the cells' growth. A carbonate buffer system, of HCO3- and H2CO3 has been found to affect the growth of cells the least. H2CO3 in water is in equilibrium with H2O+CO2. To keep the CO2 in the buffer solution at the right level you have to supply CO2 in the atmosphere above the buffer, otherwise all the CO2 would dissipate and the H2CO3 would disappear and there would be no more buffering effect (and the medium would become alkaline). So when you use a CO2 cell culture incubator, make sure the media contains bicarbonate buffer (usually from NaHCO3).
Of all the buffer system available to us and that can be safely used in tissue/cell culture system, CO2 -HCO3 have the extra advantage.... one of the component is gaseous(CO2). So just by adjusting the diffusion of this volatile component, the pH can be effectively regulated, without the need to re-dissolve any solute component. So CO2 finds its use is cell culture system (inspite of the fact that the buffer range of the CO2-HCO3 system is rather sleek and removed far away (9.2-10.8)from the physiological range(7.2-7.4) . Interestingly even the human body adopts bicarbonate buffer system as primary over other buffers, Respiration by lungs and alveolar exchange of CO2 can be adjusted to counter acidemia/alkalemia(in addition to the renal compensation). Imidazole buffer (buffer range of 6.2-7.8) is the next important one with His residue of the aa providing the necessary imidazole groups.
Khalid Omer Alfarouk
Indian Institute of Technology Bombay
National Institute of Oceanography
University of Leipzig
Chandrasekaram Kans 430-2100
Fundação Universidade Federal do Rio Grande (FURG)
Mahdi Habibpour Fatideh
Amirkabir University of Technology