The 27-year-old has attracted interest from a number of Serie A clubs after helping Livorno secure promotion back to the top flight.
The Brazilian has also caught the eye of Black Cats boss Paulo Di Canio, who is looking to bolster his squad to avoid a repeat of the club's relegation battle last season.
"Sampdoria's offer is the most concrete, they have followed Paulinho for two-three months and we have already had some contact with them," Paulinho's agent Eugenio Ascari told tuttomercatoweb.com.
"Abroad, I think that Di Canio's Sunderland are planning to make an offer soon, and then every day I always read new teams are interested in the press."