Research ArticleBIOCHEMISTRY

Off-on switching of enzyme activity by near-infrared light-induced photothermal phase transition of nanohybrids

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Science Advances  21 Aug 2019:
Vol. 5, no. 8, eaaw4252
DOI: 10.1126/sciadv.aaw4252
  • Fig. 1 Synthesis and characterization of PE-E/Pt.

    (A) Illustration depicts the synthesis of PE-E/Pt and the mechanism for off-on switching of enzyme activity by NIR light or heating. Ammonium persulfate (APS) and tetramethylethylenediamine (TEMED) were used as catalyst. (B) Negatively stained HRTEM image of GA/Pt. Inset is a representative GA/Pt nanoparticle, and the red line outlines the enzyme shape. (C) Turbidity curves of PE-GA/Pt 1, PE-GA/Pt 2, and PE-GA/Pt 3 with different phase transition temperatures. The nanohybrid concentration is 1.0 weight % (wt %). (D and E) TEM images of PE-GA/Pt 2 dropped on the grids at 25°C (D) or 45°C (E). Insets are the optical images of corresponding bulk solutions. (F) Hydrodynamic diameters of PE-GA/Pt 2 at 25 and 45°C. The size of GA at 25°C is used as a control. d, diameter. (G) Relative enzyme stability of PE-GA/Pt 2 and GA in the presence of papain. The enzyme activities of PE-GA/Pt 2 and GA were detected after incubation with papain (0.1 mg/ml) for 48 hours. ***P < 0.001 analyzed by Student’s t test (n = 3). (Photo credit: Song Zhang, East China Normal University.)

  • Fig. 2 Enzyme activity of PE-GA/Pt tuned by changing temperature or NIR light.

    (A) Illustration shows NIR light turns on the activity of PE-GA/Pt. PE-GA/Pt aggregates are disassembled upon NIR irradiation and recover the enzyme activity of digesting starch (the polysaccharide shown in black). Iodine (I3, shown in orange) was added into the wells to stain the remaining starch, yielding blue-colored products. (B) Glucose production of PE-GA/Pt incubated at different temperatures for 30 min and the corresponding fold increase of enzyme activity. ***P < 0.001 analyzed by Student’s t test (n = 3). (C) Temperature changes of PE-GA and PE-GA/Pt solutions upon NIR irradiation (3.8 W cm−2, 30 min, n = 3). (D) Amount of glucose produced by PE-GA and PE-GA/Pt with or without NIR irradiation (3.8 W cm−2, 30 min). ***P < 0.001 analyzed by Student’s t test (n = 3). (E) Cycled off-on switching of the enzyme activity of PE-GA/Pt 2 by NIR light (3.8 W cm−2, 30 min for each cycle, n = 3). (F) Relative fold increase of enzyme activity of PE-GA/Pt 2 at different concentrations when heated at 25 and 45°C.

  • Fig. 3 PE-GA/Pt 2-associated enzymatic hydrogel photopatterning.

    (A) Scheme of the three-enzyme cascade reaction. PE-GA/Pt 2 catalyzes the degradation of starch into glucose. GOx catalyzes the oxidation of glucose to H2O2, and HRP catalyzes the conversion of TMB into colored products in the presence of H2O2. The colors are changed in response to different pH values. (B) Illustration of the photolithographic process. PE-GA/Pt and starch are embedded in an alginate-Ca2+ hydrogel. The hydrolysis reaction of starch was triggered upon NIR irradiation (3.8 W cm−2, 20 min). (C and D) Abbreviation of East China Normal University (ECNU) (C) and different geometrical patterns by photolithography.

  • Fig. 4 Enzyme activity of PE-ProK/Pt tuned by changing temperature or NIR light.

    (A) Schematic illustrates PE-ProK/Pt catalyzes proteolysis upon NIR irradiation. (B and C) Relative fold increase of PE-ProK (B) and PE-ProK/Pt (C) activities by heating in water bath (45°C) or exposure to NIR light (3.8 W cm−2, 20 min). ***P < 0.001 analyzed by Student’s t test (n = 3). (D) SDS-PAGE of casein after different treatments (bottom). Casein is incubated with PE-ProK/Pt or ProK, and NIR irradiation (3.8 W cm−2, 20 min) is applied to turn on the activity of PE-ProK/Pt. The remaining casein is stained by Coomassie Brilliant Blue G250 (top). M means protein marker (from top to bottom: 250, 150, 100, 70, 50, 35, and 25 kDa). (E) PE-ProK/Pt catalyzes the digestion of phycocyanin, a red fluorescent protein. The alginate-Ca2+ hydrogel containing PE-ProK/Pt and phycocyanin is exposed to NIR light (2.5 W cm−2) for 30 min. The dashed line represents the border of laser irradiation region. (Photo credit: Song Zhang, East China Normal University.)

  • Fig. 5 Enzyme activity of PE-DNase I/Pt tuned by changing temperature or NIR light.

    (A) Illustration shows that PE-DNase I/Pt catalyzes the degradation of plasmid DNA. (B) Agarose gel electrophoresis of plasmid PX330 after different treatments. M means DNA marker. (C and D) Relative fold increase of PE-DNase I and PE-DNase I/Pt activities by heating in water bath (45°C) or exposure to NIR light (3.8 W cm−2, 20 min). ***P < 0.001 analyzed by Student’s t test (n = 3).

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/8/eaaw4252/DC1

    Fig. S1. Circular dichroism spectra of GA and GA/Pt, infrared spectra of poly(AAm-co-AN) and PE-GA/Pt 2, and enzyme activity of GA before and after modifications.

    Fig. S2. Calibration curves for GA, ProK, casein, and DNase I.

    Fig. S3. Negatively stained HRTEM image of ProK/Pt, turbidity curve of PE-ProK/Pt, and enzyme activity of ProK before and after modifications.

    Fig. S4. Negatively stained HRTEM image of DNase I/Pt, turbidity curve of PE-DNase I/Pt, and enzyme activity and stability of DNase I before and after modifications.

    Fig. S5. Enzyme activities of PE-GA at different temperatures, time-dependent glucose production by PE-GA/Pt 2 upon NIR irradiation, cycled off-on switching of the enzyme activity of PE-GA/Pt 2 by changing temperature, and turbidity curves of PE-GA/Pt 2 at different concentrations.

    Fig. S6. Turbidity curve and enzyme activity of PE-GA/Pt 4.

    Fig. S7. Color changes of the oxidative product of TMB at different pH values.

    Fig. S8. Temperature changes of alginate-Ca2+ hydrogel embedded with PE-ProK/Pt during NIR irradiation and fluorescence images of phycocyanin-embedded hydrogel without and with NIR irradiation.

    Table S1. The compositions of PE-GA/Pt.

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Circular dichroism spectra of GA and GA/Pt, infrared spectra of poly(AAm-co-AN) and PE-GA/Pt 2, and enzyme activity of GA before and after modifications.
    • Fig. S2. Calibration curves for GA, ProK, casein, and DNase I.
    • Fig. S3. Negatively stained HRTEM image of ProK/Pt, turbidity curve of PE-ProK/Pt, and enzyme activity of ProK before and after modifications.
    • Fig. S4. Negatively stained HRTEM image of DNase I/Pt, turbidity curve of PE-DNase I/Pt, and enzyme activity and stability of DNase I before and after modifications.
    • Fig. S5. Enzyme activities of PE-GA at different temperatures, time-dependent glucose production by PE-GA/Pt 2 upon NIR irradiation, cycled off-on switching of the enzyme activity of PE-GA/Pt 2 by changing temperature, and turbidity curves of PE-GA/Pt 2 at different concentrations.
    • Fig. S6. Turbidity curve and enzyme activity of PE-GA/Pt 4.
    • Fig. S7. Color changes of the oxidative product of TMB at different pH values.
    • Fig. S8. Temperature changes of alginate-Ca2+ hydrogel embedded with PE-ProK/Pt during NIR irradiation and fluorescence images of phycocyanin-embedded hydrogel without and with NIR irradiation.
    • Table S1. The compositions of PE-GA/Pt.

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