Currently, the treatment for acute disease encompasses the use of various biological drugs (BDs). However, the utilisation of BDs is limited due to its rapid clearance and non-specific accumulation in unwanted sites which results in a lack of therapeutic efficacy accompanied with adverse effects. While nanoparticles were considered a good candidate to resolve this problem, some available polymeric carriers for these BDs are mainly designed for long-term sustained release. Thus, there is a need to explore new polymeric carriers for diseases' acute phase that requires sustained release of BDs in a short period such as thrombolysis and infec-tion. Poly(succinimide)-oleylamine (PSI-OA), a biocompatible polymer with tuneable dissolu-tion profile, represents a promising strategy to load BD for sustained release within a 48-hour period. In this work, we developed a two-step nanoprecipitation method to load the model protein (e.g. bovine serum albumin (BSA) and lipase) with PSI-OA. The characteristics of the nanoparticles were assessed based on various loading parameters, such as concentration, stir-ring rate, flow rate, volume ratios, dissolution, and the release of the protein. The optimised NPs displayed a size within 200 nm that is suitable for vasculature delivery to the target sites. These findings suggest that PSI-OA can be employed as a carrier for BDs for applications that require sustained release in a short period.