Matthews and Johnson, each of whom started one game earlier this season, were listed as out for the Bruins' game against Purdue. The report also ruled out reserve offensive tackle Mack Indestad, reserve wide receiver Jonah Smith, backup center Sam Yoon, and reserve defensive backs Joshua Dixon and Jamier Johnson.
Wide receiver Aidan Mizell, linebacker Ryan McCulloch and defensive back Jhase McMillan were listed as questionable for UCLA.
Matthews, who has made four catches for 88 yards, went down against San Diego State last weekend with an apparent left leg injury. Mizell also was hurt while making his season debut against the Aztecs.
Johnson was hurt in the season opener against Cal, giving way to backup Ta'Shawn James, who went on to make two interceptions and move into the starting lineup against San Diego State.
Indestad was hurt against San Diego State. Yoon, a former starter who lost his spot to Riley Robell, has been out for a while with a foot injury that has forced him to get around on a scooter.
Purdue will be without defensive backs Mister Clark and Raderrion Daniels as well as tight end Kylan Fox. Clark had five tackles, one sack and a pass broken up during the Boilermakers' season-opening victory over Indiana State before missing their double-overtime loss to Wake Forest last week.
The availability report was the first of four that will be issued each week during Big Ten play under new conference guidelines. Teams must submit reports three days, two days and one day before every Big Ten game, plus a final gameday submission two hours before kickoff.
For the first three reports of each week, players are designated as either probable, questionable, doubtful, out or out for the first half. The gameday reports require players to be listed as either a game-time decision, out or out for the first half. Anyone not listed is considered available.
Visiting teams are required to indicate the availability of players who are part of the travel squad or have been included in the two-deep on offense, defense or special teams, or otherwise regularly play in games.