4-ArmPEG-OH is widely used in biomedical research and drug delivery systems due to its biocompatibility and ability to form hydrogels. It serves as a versatile scaffold material for tissue engineering, enabling the growth and differentiation of cells in three-dimensional environments. In drug delivery, it is utilized to create controlled-release systems, enhancing the stability and bioavailability of therapeutic agents. Additionally, its hydroxyl end groups allow for easy functionalization, making it suitable for conjugation with various bioactive molecules, such as peptides, proteins, and drugs. This adaptability also extends to its use in surface modification, where it improves the biocompatibility of medical devices and implants. Its water-soluble and non-immunogenic properties further make it a valuable component in formulations for ophthalmic, injectable, and topical applications.