You need to get rid of (or cover) the silicone to begin with. Can't you change the tip to another type?

make a thermal evaporation deposition of aluminum oxide, thin layer if possible

do you have any recommendation for other tips, usually they made by silicon or silicon nitride (hydrophobic)???

The original question has been modified changing silicone to silicon. I withdraw at this stage.

basically silicon and silicon nitride are the most common....there are metal coated tips you can purchase.....mos people coat their regular silicon tips or functionalized chemically with some organic compounds to obtain desire properties.....it is difficult to purchase a very particular tip for research needs.........

Sometimes people say "superhydrophilic" when they actually need a low, but not extreme, contact angle. If this is you, try a UV or oxygen plasma treatment.

If you really need to functionalize a tip, look into silane chemistry. Here in the US Gelest is the main supplier, and they have an extensive catalog. I'm not sure whether they sell in China, but the catalog could help you find an appropriate molecule.

I agree with Allison, use UV/ozone plasma treatment is the easiest way to modify the hydrophilicity of Si tips.

Another option is to dip-coat an AFM tip in a dispersion of graphene oxide. Not sure if it has been done before for tips but at least for silica particles it seems to work.

Check this paper: http://pubs.rsc.org/en/content/articlehtml/2011/nr/c0nr00609b

For glass surfaces (essentially the same chemistry as a silicon tip), you just need to get the surface very clean and you'll get a very low contact angle. The most straightforward way to do this get the tip as clean as possible, with UV/ozone (as Allison recommended) and/or cleaning with Piranha.

Using silane chemistry (as Allison also recommended) would also be a robust way to get a hydrophilic tip. You should look for terminal chemistry with a positive charge (such as Aptes) or preferable a zwitterion. You can also look into the literature and just see what chemical groups result in a low contact angles on glass surfaces and that should be applicable to your silicon/silicon nitride tips.