title: Optofluidic platform for real-time monitoring of live cell secretory activities using Fano resonance in gold nanoslits.
abstract: An optofluidic platform for real-time monitoring of live cell secretory activities is constructed via Fano resonance in a gold nanoslit array. Large-area and highly sensitive gold nanoslits with a period of 500 nm are fabricated on polycarbonate films using the thermal-annealed template-stripping method. The coupling between gap plasmon resonance in the slits and surface plasmon polariton Bloch waves forms a sharp Fano resonance with intensity sensitivity greater than 11 000% per refractive index unit. The nanoslit array is integrated with a cell-trapping microfluidic device to monitor dynamic secretion of matrix metalloproteinase 9 (MMP-9) from human acute monocytic leukemia cells in situ. Upon continuous lipopolysaccharide (LPS) stimulation, MMP-9 secretion is detected within 2 h due to ultrahigh surface sensitivity and close proximity of the sensor to the target cells. In addition to the advantage of detecting early cell responses, the sensor also allows interrogation of cell secretion dynamics. Furthermore, the average secretion per cell measured using our system well matches previous reports while it requires orders of magnitude less cells. The optofluidic platform may find applications in fundamental studies of cell functions and diagnostics based on secretion signals.
authors.affiliation: Institute of Biophotonics, National Yang-Ming University, No.155, Sec. 2, Linong Street, Taipei, Taiwan 11221 (ROC), Taiwan.
authors.forename: Shu-Han
authors.initials: SH
authors.lastname: Wu
authors.forename: Kuang-Li
authors.initials: KL
authors.lastname: Lee
authors.forename: Arthur
authors.initials: A
authors.lastname: Chiou
authors.forename: Xuanhong
authors.initials: X
authors.lastname: Cheng
authors.forename: Pei-Kuen
authors.initials: PK
authors.lastname: Wei
mesh_terms: D002460:Cell Line; D002470:Cell Survival; D002477:Cells / Q000378:metabolism*; D003199:Computer Systems; D004797:Enzyme-Linked Immunosorbent Assay; D006046:Gold / Q000737:chemistry*; D006801:Humans; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D044085:Microfluidics / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry*; D055095:Optics and Photonics / Q000379:methods*; D020349:Surface Plasmon Resonance; D013696:Temperature
chemical_list: D006046:Gold; D020780:Matrix Metalloproteinase 9
keywords: Fano resonance; cell secretions; gold nanoslits; localized surface plasmon resonance; microfluidics