One of the most successful medical crowdfunding communities is the SENS / longevity community.

You should look at what they're doing.

Typically they are using IndieGoGo, or Lifespan.io, which was created specifically for this goal, or FightAging.org, or longecity.org, or sens.org, and ad-hoc methods with mailing lists and donate pages, but which have raised hundreds of thousands over the past few years. This has emerged organically from the community.

The question you have to answer is why should groups like this use your site given what they're doing now? If you can answer that, you might get somewhere.