Matt Donlan and Jordan Andrew added 18 points each for the Penguins (9-13, 4-5 Horizon). Youngstown State had a 49-25 lead in the first half that the Flames (2-18, 0-9) nearly erased when Michael Kolawole's free throws made it 78-76 with 23 seconds left.
Santiago put the Penguins back up by four at the foul line and Najeal Young's tip-in with five seconds left was too late for UIC to get another shot.
Dikembe Dixson set a career high with 32 points and tied another with 15 rebounds. Young added 12 points and a personal-best 16 rebounds, Kolawole scored 15 and Tai Odiase had 13 points and 13 boards for the Flames.