In this work, hydrogel photonic crystal beads with inverse opal structure are generated on a well-controlled microfluidic chip device. An online droplet drying method and templating technique are integrated into the producing process. This process results in the silica nanoparticles in the droplets self-assembled into spherical photonic crystals with narrow stop bands and identical structural colours, which is the ideal template for fabricating inverse opal hydrogel beads. The effects of acrylic acid (AA) concentration, water dosage and buffer pH on the equilibrium swelling of inverse opal hydrogel are discussed. In the concentration of AA (3%) and water (31%), the inverse opal hydrogel beads show wide sensing range and rapid response (less than 30 s) to pH variation. Overall, the inverse opal hydrogels as pH sensors show homogeneous structural colour changes due to the spherical 3D structure. The present characterization of quite mechanically robust and good reproducibility for the spherical pH sensor may have promise application in advanced optical devices.
Lijun Ji,Mindong Gong,Tong Xu,Jun Gu,Xu Jiang,Taotao Liang,Yu Chen,Qingren Liu
The interactions of ions and molecules with material surface are highly dependent on the surface properties of the material. Therefore, the distribution of ions or molecules near the material surface may be affected by the surface properties. This phenomenon can be significant enough for controlling the structure of a material synthesized in the sub-micrometer scale confinement space of a template. This work confirms that inverse opals are perfect templates for offering confinement space, while their different surface properties can strongly affect ion and block copolymer distribution in the confinement space. This surface effect principle can be used for the controlled synthesis of colloids with complex composition. As an example, four kinds of mesoporous magnetic bioactive glass colloids with ordered mesopores, core–shell structure, open surface pores, or disordered mesopores are prepared by using polystyrene and carbon inverse opal templates. This work reveals that inverse opal templates possess great advantage in controlled synthesizing colloidal structures due to their surface effect on ions and molecules and confinement space.
Lu Li,Xugang Dong,Zhanfang Liu,Juan Wei,Jingru Li,Hong Zhou,Jun Zhu,Xinwei Shi
In this study, a visual and ultrasensitive method for the determination of trace mercury ions in water was developed based on the high efficiency of urease catalysis and pH-sensitive inverse opal polymeric photonic crystals (IOPPCs). Mercury ions can inhibit urea hydrolysis and suppress the production of ammonium and bicarbonate ions in the solution, resulting in the redshift of IOPPCs. Therefore, the redshift of IOPPCs Bragg diffraction is directly related to the concentration of mercury ions. Meanwhile, the color of IOPPCs varied significantly with the shift of the Bragg diffraction wavelength, thus achieving the visual semi-quantitative detection of mercury ions by the naked eye. The minimum detection concentration of this method is 5 × 10 −16 g/L, which is much lower than the maximum contaminant level for the safe drinking of water (2 × 10 −6 g/L) recommended by the environmental protection agency (EPA), USA. In addition, this is a simple and quick method for effective on-site detection of mercury ions, which shows a great promise in emergency leakage monitoring and control.
危险品化学品经营许可证（带存储）