Is it possible to get the equation below into closed form? I have tried using integration tables but I haven't found anything that matches. Are there any other methods to achieve a closed form expression of a bessel function with two exponentials? If so could someone please advise on how I would go about this? Kind regards.

$$\int^\infty_0 \frac{1}{2}\frac{x}{a}^\frac{b-2}{4}\exp\left(-\frac{a+x}{2}\right)\left(1-\exp\left(-\frac{x}{2}\right)\right)^{n} I_{\frac{b}{2}-1}\left(\sqrt{xa}\right) \mathrm{d}x$$

To clarify a, b and n are all integer values $\ \ge 1 $.