I was given three groups of chips to SEM. The first group had undergone the Diazerine and PEG1000 treatment followed by incubation with either PBS, IgG, or BSA. The second ‘group’ was a chip that had been treated with diazerine and PEG1000 but had not been incubated. The last group was a chip which had…

In my recent tenting posts, the membrane has shown that it can deform and wrap around edges. I wanted to follow up on this phenomenon and see if we could get a contiguous sheet of membrane around a PDMS edge (not completely sharp). If we can get some membranes around a ~90 sidewall, we could have…

In Josh’s forthcoming paper about clogging in forward and reverse configurations using 20 nm and 100 nm sepcons, we thought there was reason to discuss how the data agrees with the already existing models of membrane fouling. In this post, Josh discusses some of his efforts to model the data without accounting for the fact…

This is a followup to my previous post, which can be found here. Previously I reported that fluorescein diphosphate (FDP) incubated on the surface of an NPN chip would adhere well enough to be visible on the membrane after gentle washing and treatment with a fluorescence-activating enzyme (alkaline phosphatase, AP.) I also reported that pre-incubation…

It is of interest to investigate the properties of CO2 transfer into a cell culture media using nanomembrane technologies. Maintaining the pH of the cell culture medium is critical to cell viability. Most cell lines grow well at pH 7.4 and are inhibited by growth at pH 6.8. Glucose is usually the sugar included in…

After the disaster with the fridge freezing our gold nanoparticles and causing them to irreversibly aggregate, I figured that it would be a shame to waste the ruined gold solutions and so I took some conductivity and pH measurements with them. I found that conductivity could vary by a factor of 1.5 between the solutions (from…

This is a summary I wrote ~3 weeks ago of the work Josh Miller and I are doing under the CEIS grant for NPN Lift-off. Summary: Josh and I have been working for about four weeks so far on this program. During that time we have done preliminary lift-off (LO) tests on two wafers: one…

You may recall that last year I spent some time working on a proof-of-concept experiment for a high-throughput, non-specific drug discovery assay. The experiment involved binding up a FLAG-peptide sequence-tagged alkaline phosphatase (AP) enzyme with a biotinylated anti-FLAG antibody, in turn bound to a large avidin bead. This very large complex was unable to move…

  The NPN tenting mechanism I’ve described in a few different posts has relied solely on mechanical technique. I poke the substrate with tweezers, or delaminate it with high electrical forces, or heat it up and let it contract while in contact with each other.  It would scale very poorly if we tried to make this…

I have been using ITO electrodes deposited on PTFE sheets for my TEER measurements. A 100 nm thin ITO is deposited on ~300 micron PTFE sheets, and have a sheet resistivity of 60 ohms/sq. This sheet is commercially available from Sigma; so the electrode properties are consistent within the experiments. Although ITO has a huge…