Fans raised concerns about the well-being of online inventor Julian Brown after his mysterious disappearance from social media.The 21-year-old, who went viral for claiming to develop usable fuels from plastic waste, has 1.7 million followers on social media.Brown is widely known for developing ‘Plastoline,’ a usable fuel such as gasoline, diesel, and jet fuel from plastic waste.After his invention went viral, Julian Brown started multiple GoFundMes to help finance the project, including one titled “Plastic to Fuel – Together we Will Heal Earth!” in 2023.“I have been self taught in turning plastic into fuel for 5 years, and now I will need YOUR help to raise money for the most important upgrade yet. This will be my first official invention,” as per the description for Brown’s GoFundMe.However, fans suspect that he has gone missing since his last post on Instagram on July 9.The online inventor shared a video on the social media platform, in which he claimed that he was “under attack”.Read more: Missing woman’s body found after 30 years in Karachi, Police register murder case“I’m still working. I’m still building. Nothing is going to stop that,” Julian Brown said in the video. View this post on Instagram A post shared by Julian Brown (@naturejab_)The missing inventor wrote in the caption, “Something is happening keep me in your prayers please SCREEN RECORD THIS. I don’t know e.”With no word from him or his family, fans have been speculating that Brown might have gone missing.Meanwhile, his disappearance has not been officially confirmed or denied by his family or the local authorities in Atlanta.