Sustainability-focused non-fungible token (NFT) platform OneOf has raised $8.4 million in a strategic funding round that included Amex Ventures, the venture capital arm of American Express. The credit card company will host an exclusive pop-up event that includes OneOf NFTs, according to a press release provided to CoinDesk.

Other investors included Mirabaud Lifestyle Impact and Innovation fund, Snow Hill Partners, Sangha Capital and Chain Link Crypto Fund, among others.

Miami-based OneOf built its platform on the energy-efficient Tezos and Polygon blockchains, which offer low transaction fees. Founded in 2021, OneOf has signed partnerships with the estate of late rap legend Biggie Smalls, hockey great Wayne Gretzky and the Grammy Awards, to name a few. The startup has raised more than $72 million in total funding, including a $63 million seed round in May 2021.