晶格參數調控拓印光子晶體感測雙酚A之靈敏度

Abstract

本研究中開發可對BPA分子具有快速偵測與高靈敏度之ZrO2拓印光子晶體感測器，藉由感測器與標的物BPA結合時所引起的折射率與光子能隙變化產生的繞射波長位移量，對BPA進行定量分析。光子晶體是以乳化與無乳化聚合法製備粒徑為235-385 nm聚苯乙烯球作為晶體模板，分子拓印是添加標的物雙酚A(BPA)模板與功能性單體苯基三甲氧基矽氧烷(PTMOS)以-作用力鍵結並與交聯劑正丙醇鋯(ZPO)聚合形成無機高分子。拓印光子晶體是在50°C下以重力沉降方式將聚苯乙烯球自組裝形成晶體結構，以BPA/PTMOS/ZPO/EtOH莫耳比為1/1/30/80合成拓印溶膠溶液，取2 µL拓印溶膠溶液待完全滲透入晶體後，拓印溶膠溶液水解縮合反應控制在高溫度(60°C)與高濕度(RH: 100%)環境下可製得最佳微結構之拓印拓印光子晶體(IPC)感測器。XPS鑑定中表面Si/Zr元素比例比整體Si/Zr元素相比較高，顯示BPA拓印孔洞分布在表面，屬於表面拓印(Surface imprinting)形式。IPC感測器偵測實驗中吸附平衡時間僅需20 min內，另外，不同尺寸IPC對於50 mg/L BPA偵測實驗中，IPC-235至IPC-305關係，波長位移量(4.5 nm-6.3 nm)提升1.4 倍，達到以晶格參數調控拓印光子晶體靈敏度之目的。IPC感測器具有良好重複使用性與兩階段線性範圍(0.5-1.0mg/L與 1.0 mg/L-90 mg/L)，而方法偵測極限為0.50 mg/L。另外，對於類BPA分子結構近乎零波長位移，可證明IPC感測器對於標的物BPA具有高選擇性，綜合上述實驗結果，證明本研究製備之拓印光子晶體感測器兼具高選擇性及反應快速的特性，為未來極具發展潛力感測器。

In this study, a high sensitive and quick responsive ZrO2 imprinted photonic crystal (IPC) for detection of BPA was developed. The diffraction wavelength shift, resulting from the changes in the refractive index(n) of the IPC after rebinding of BPA, is used for the quantification of the target compound. Polystyrene(PS) microspheres with the sizes in the range of 235-285 nm as the template for inverse opal photonic crystals were prepared using emulsion free and emulsion polymerization method. They self-assembled into opal structure through a heat-assisted method at 50C. Imprinted precursor solution, containing phenyltrimethoxysilane (PTMOS) as the functional monomer and zirconium propoxide (ZPO) as cross-linker in the molar ratio of PTMOS/BPA/ZPO/EtOH molar ratio of 1/1/30/80, was infilitraed into the void of the colloidal crystals in N2. Hydrolysis of the precursor solution at a high temperature (60C) and high hymidity (relative humidity: 100 %) leads the imprinted cavities generating at the surface more than in the bulk. The IPC reached an adsorbtion equilibrium within 20 min in 50 mg/L BPA solution, and wavelength shifted from 4.5 to 6.3 nm when the pore diameters increased from 160 to 200 nm (correspondingly the PS size increased from 235 to 305 nm). The optimal IPC exhited two linear rages in 0.5-1.0 mg/L and 1.0-90.0 mg/L, and the detection limit was 0.50 mg/L. Insignificant response for BPA analogues indicates its high selectivity. These results clearly demonstrated that the IPC has high sensitivity and quick response which is promising for in-situ and on-site analysis in the future.