First of all, unlike consumer product companies or even a software company developing a new platform, proof of concept and prototyping costs are extremely high in biotechnology. Even the initial R&D requires access to laboratories, industrial machinery, chemical components etc. Furthermore, costs for highly experienced and trained team members come at a premium. In general, start-up capital comprises a large percentage of the overall investment.
Another requirement for funding is extensive due diligence. The specifics of biotechnology start-ups lie in the fact that much of the value of your company will be in intangible assets (intellectual property), which are difficult to value and prove initially.