Aptamer-　or　antibody-based　sensing　protocols　have　been　reported　for　detecting　carcinoembryonic　antigen　(CEA),　but　most　exhibit　complicated　procedures　or　multiple　reactions.　In　this　work,　we　developed　a　one-step　aptasensing　protocol　for　the　spectrometric　determination　of　CEA　based　on　4-nitrophenol　(4-NP)-loaded　magnetic　mesoporous　silica　nanohybrids　(MMSNs)　for　bioresponsive　controlled-release　applications.　To　fabricate　such　a　responsive-controlled　sensing　system,　single-stranded　complementary　oligonucleotides　relative　to　the　CEA-specific　aptamer　were　first　modified　on　the　aminated　MMSN.　Thereafter,　4-NP　molecules　blocked　the　pores　with　the　assistance　of　the　aptamers　via　a　hybridization　reaction.　The　introduced　target　CEA　specifically　reacted　with　the　hybridized　aptamer,　thus　detaching　from　the　MMSN　to　open　the　gate.　The　loaded　4-NP　molecules　were　released　from　the　pores,　as　determined　using　ultraviolet-visible　(UV-vis)　absorption　spectroscopy　after　magnetic　separation.　Under　optimum　conditions,　the　absorbance　increased　with　an　increase　in　the　target　CEA　in　the　sample　and　exhibited　a　good　linear　relationship　within　the　dynamic　range　of　0.1-100　ng　mL(-1),　with　a　detection　limit　of　46　pg　mL(-1).　Moreover,　this　system　also　displayed　high　specificity,　good　reproducibility,　and　acceptable　accuracy　for　analyzing　human　serum　specimens,　in　comparison　with　a　commercialized　human　CEA-enzyme-linked　immunosorbent　assay　(ELISA)　kit.