Instrument error

hi,

i just started my PhD and I am working on an SPR 3000, somebody wanted to test and interaction between hydroxyapatite(HA) and alendronate (the HA was depose on a gold chip by laser at room temperature if i understand correctly ) . the problem is that when i wanted to test the surface with water to see the baseline and how its performing it washed off (the HA). then i ran a system check and at normalize an error occur (instrument error code 000:004 control unit or OS-9 orientation problem). Some advice please! is the IFC blocked iran unclogged and the system check is ok but wont normalize.

thank you

cristi

Hi Cristi,

SPR 3000 ? which brand is the machine?

Did you place the chip in the correct way in?
Can you try a new or old chip to try if it is the chip or the instrument?

Arnoud

it's Biacore 3000, the problem was the normalizing solution i switched the 70% (wich i needed) for 40 % that is why it didn't pass. Can you give me some advice about HA that was deposed on the gold chip because i dont know if the sensogram that i saw was correct. It started at 82000 RU and decreased in time (about 60 min and i stopped it at 79900) and i dont know if the HA was flushed away of is it normal to be that way and line is strange the red one for Flowcell 1 haw a grey background (so to speak). I'm new at this so any help is highly appreciated.
Can you give me some advice about this?
is the normalizing solution affect the HA?
If you need more information you can contact me at cristi.butnaru@gmail.com, and i can send you the sensorgrams if you wish

Thanks for such a quick response.
Cristi

Hi Cristi,

When the curves in the sensorgram are with a grey background the signal is of low quality. This can be because it is out of the dynamic range of the instrument. I think 80.000 RU is too high.

If you modify a sensorchip outside the machine you can expect some drift after docking but this should level out in time. It is hard to give a time span and what to expect, because this depends on a lot of parameters.

I'am, not sure what you did with the HA. Looked at wikipedia and HA is a small non-organic molecule. Somehow you should make a covalent bond between the sensor chip surface and the HA. Not sure how to do that with a laser. Maybe you want to rethink what you did.

What kind of sensor chip you started with?
Arnoud

Thanks a lot for the response, the chip was from SIA Au kit supplied by Biacore it is untreated just the glass and the gold surface on which HA was added (allow me to mention that is was done at another institute we just received with the HA attached to it and asked to see the interaction with the alendronate) and how they've put HA to the gold chip i told you what they told me.

I read that the attachment of HA to the chip can be done at higher temperatures (500 degrees Celsius by plasma spray or other methods electrophoretic deposition) and the bond between HA and gold should be more stable and stronger, but i dont know if it will affect the properties of HA or the binding capacity after this treatment

thanks again.

cristi

Hi Crisiti,

I have to say this is new to me. I understand what you try to do.
I have no idea what will happen to the sensor chip when you deposit HA on the surface.
The gold-HA layer must still give some SPR otherwise you cannot measure that.

Probably you have some publications regarding this. You can try to contact the authors. Maybe they can give you some valuable information for your project.

regards

Arnoud