Only in a very loose (and incorrect) sense of the word "dilution."
Yes, it would increase the number of shares outstanding.
No, it would not decrease the book value per share if the sale was at around current price levels.
In SEC-speak, "dilution" refers strictly to the latter. In fact, a sale of shares by the company at current prices would be anti-dilutive.
I have no objection to biotechs selling shares or converts at decent prices (for example what INCY did earlier this year). A strong balance sheet is a great asset. But of course I am very wary of the Rodman-type pump-'n-dump offerings below market with high warrant coverage.