We proposed a method to fabricate label-free protein sensor with sub-wavelength nanograting structures to be used for diagnosing acute myocardial infarction. A nickel stamp for the injection molding of nanograting integrated protein sensor was fabricated by electroforming process with high fidelity. By using metallic stamp, we replicated label-free protein sensor via injection molding, which is an outstanding method for low-cost and mass production of polymer products. Finally, we performed a feasibility test, examining cardiac troponin T (cTnT) and anti-cTnT interactions. From the results, we demonstrated that the fabricated protein sensor can provide information for the early and accurate detection of cardiac diseases such as acute myocardial infarction.