Sounds like Bios by Robert Charles Wilson (haven't read it myself, just going by the reviews), which was also one of the proposed answers (none was accepted) to this question. Maybe one of these covers will ring a bell. There is a limited preview at Google Books.
From a review by "Nick Gifford" (Keith Brooke) at Infinity Plus:
In a future where instantaneous interstellar travel is possible, but hugely expensive and tightly controlled by the ruling families of Earth, the planet Isis is singled out for special investigation, hosting an orbital scientific station and a number of research posts on its surface.
The reason for the planet's importance is the diversity of life it supports: no native intelligence, but a wild array of life-forms with tremendous medical and biological potential: a planetary pharmacopoeia, much of the exploration and research funded by medical trusts on Earth. It's also a good testing ground for novel technologies.
Perhaps 'diversity' is not the best word to describe the life of Isis: ferocity might be more apt, a biochemical ferocity evolved through billions of years where there have been no mass extinctions to wipe the evolutionary slate clean, allowing an ever-more sophisticated biological arms race to take place.
For the humans investigating Isis, a lungful of air, the briefest of touches, an encounter with a single example from the vast array of native micro-organisms, would be fatal, inducing within a matter of hours intense haemorrhagic illness and a painful and gruesome death. With scientists' dark humour, the researchers call two of their outposts on the planetary surface, Yambuku and Marburg, after the first two strains of haemorrhagic fever that went on to devastate 21st Century Earth.
Zoe Fisher, cloned by one of the Trusts, abandoned in an Iranian orphanage only to be rescued again, is more adapted than any human to survive in the wilds of Isis. Where others need bulky bioarmoured suits for any excursion, Zoe can leave the secure dome in only a membranous body-suit - both suit and genetically-modified Zoe are among the novel technologies being tested on Isis.
Bios presents an enthralling tale of planetary investigation, scientific endeavour at the mercy of both the political machinations of the power-plays back in the Solar System, as Family-led Trusts vie for power, and individual whim. For, right at the start, we witness a surgeon making a final rebellious gesture against the establishment before she retires: during a routine surgical tweak to Zoe's configuration, she removes a vital augmentation, a gland that controls extremes of mood and emotion. The effects will be slow to kick in, but they will mean that Zoe will learn to fear and care and, even, to love, when she arrives on Isis.
The disappointment in Bios comes in the closing stages, as an increasingly gripping plot converges inevitably on disaster. There's nothing wrong with well-handled tragedy, but too often the tragic ending can be the easy option, a solution where there is no solution, no gathering together of threads.
And no: in describing the ending of Bios as tragic, a true disaster story, I don't think it gives away too much of the ending, as there is also an element of hope and triumph in the conclusion, albeit one that appears more as an afterthought.