Within proton-lead collisions collected by the LHCb detector at nucleon-nucleon center-of-mass energy of 5 and 8.16 TeV, a rich set of open charm hadrons is observed with abundant statistics. Thanks to the LHCb forward acceptance that is complementary to general purpose detectors and excellent performance in particle reconstruction and identification, these charm states are studied down to zero $p_T$ with overwhelming precision in heavy ion data. Presented in this talk is the measurements of production of charm mesons and baryons reconstructed in exclusive hadronic final states. Nuclear effects are studied, quantified by the nuclear modification factors, forward-to-backward production ratios and baryon-to-meson ratios. The impact of the results, in particularly, on the improvement of nuclear PDF and parton saturation are discussed.