Michael Blennerhassett, a non-executive director of DROPIT, said the company wanted to raise US$5 million ($6.75m).
The company recently signed a 3-year deal with the Phoenix Suns, an NBA team based in Arizona. It expects more than 180,000 fans will interact with the app during the team's home games during the 2017/18 NBA season.
"The people are important when it comes to investing in companies and the team behind DROPIT are high in energy, talented, and very focused," said Enterprise Angels founder Bill Murphy.
"Unsurprisingly, when the Phoenix Suns deal was announced, we saw a surge in investment in DROPIT," Murphy said.
DROPIT earlier this year signed a distribution deal with Daktronics, a manufacturer of electronic scoreboards and digital signage.
"Our venues and teams are hungry for interactive content, and DROPIT offers an ideal opportunity to better engage with fans, given the quick breaks in action during games," said Daktronics commercial sales engineer Josh Howardson.
"The DROPIT platform can easily be integrated across hundreds of professional and collegiate global venues, and we are excited to partner with DROPIT to bring a game-changing experience to fans," Howardson said.
DROPIT said fans are disengaged with traditional scoreboards and tend to be distracted by their phones. It aims to bring brand engagement back to the fore by combining smartphone use with stadium theatrics.
"Advertising on big screens in stadiums is failing to deliver on its potential. Fans are disengaged, distracted by their phones, and match-attendance levels are stagnating," said chief executive Peter Howell.
"Our DROPIT platform delivers fan engagement and immersion: creating pre-event anticipation and excitement followed by an 'adrenaline-pumping' reverse auction in-stadium experience multiple times during breaks in games," Howell said.
"These live, reverse auctions run simultaneously on the stadium's video board and the fans' mobile phones. Engagement continues post-game with exclusive, targeted brand offers delivered to players' mobile phones post-auction, driving fans from seats to stores, increasing brand loyalty and return on sponsorship for major consumer brands," he said.
Following in-stadium sport sponsorship, the brothers will look to shopping malls as a further area of focus.