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Self-assembly of diphenylalanine peptide with controlled polarization for power generation

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ABSTRACT

Peptides have attracted considerable attention due to their biocompatibility, functional molecular recognition and unique biological and electronic properties. The strong piezoelectricity in diphenylalanine peptide expands its technological potential as a smart material. However, its random and unswitchable polarization has been the roadblock to fulfilling its potential and hence the demonstration of a piezoelectric device remains lacking. Here we show the control of polarization with an electric field applied during the peptide self-assembly process. Uniform polarization is obtained in two opposite directions with an effective piezoelectric constant d33 reaching 17.9 pm V−1. We demonstrate the power generation with a peptide-based power generator that produces an open-circuit voltage of 1.4 V and a power density of 3.3 nW cm−2. Devices enabled by peptides with controlled piezoelectricity provide a renewable and biocompatible energy source for biomedical applications and open up a portal to the next generation of multi-functional electronics compatible with human tissue.

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Related in: MedlinePlus

PFM and SKPM characterization of the microrod arrays.(a,b) PFM phase image and corresponding SKPM surface potential map of a microrod from the positive-EF growth (a) and a microrod from the negative-EF growth (b). The phase and surface potential distributions are shown by the colour overlaid on the topography of the top of the microrod. (c) Statistics of the piezoelectric phase for the arrays from the positive-EF growth, negative-EF growth and no-EF growth. Detailed data for this chart is provided in Supplemental Table 1. (d) Linear dependence of the PFM amplitude on the applied voltage for FF peptide microrods from growth with different electric fields. The slopes of the lines provide effective piezoelectric coefficients d33, which are 17.9, 11.7 and 9.3 pm V−1 for microrods from the negative-EF growth, positive-EF growth and no-EF growth, respectively. Error bar: s.d.
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f2: PFM and SKPM characterization of the microrod arrays.(a,b) PFM phase image and corresponding SKPM surface potential map of a microrod from the positive-EF growth (a) and a microrod from the negative-EF growth (b). The phase and surface potential distributions are shown by the colour overlaid on the topography of the top of the microrod. (c) Statistics of the piezoelectric phase for the arrays from the positive-EF growth, negative-EF growth and no-EF growth. Detailed data for this chart is provided in Supplemental Table 1. (d) Linear dependence of the PFM amplitude on the applied voltage for FF peptide microrods from growth with different electric fields. The slopes of the lines provide effective piezoelectric coefficients d33, which are 17.9, 11.7 and 9.3 pm V−1 for microrods from the negative-EF growth, positive-EF growth and no-EF growth, respectively. Error bar: s.d.

Mentions: Piezoresponse force microscopy (PFM) was employed to investigate both the orientation of electrical polarization and the piezoelectric strength of FF peptide microrods. As we applied an alternating voltage on the FF peptide microrods, an FF peptide microrod with either upward or downward polarization deformed either out of phase (180°) or in phase (0°), respectively, (Supplementary Fig. 3). The phase distributions of vertical microrods from a positive-EF growth and from a negative-EF growth in Fig. 2a,b, respectively, show that applying opposite electric fields during growth results in FF peptides with phases of polarization 180° apart. Scanning Kelvin Probe Microscopy (SKPM) was also employed and confirmed that the surface charge on the microrod tip was consistent with the polarization, verifying the mechanism shown in Fig. 1a,b. The polarization was very stable and could not be switched with a high electric field once the growth was completed (Supplementary Fig. 4). Randomly selected 20 microrods from each growth process were tested (Fig. 2c and Supplementary Table 1). The results indicated that 95–100% of microrods had polarization in the direction of the applied electric field. In the absence of an electric field during growth, the polarization became much less uniform (Fig. 2c). A preferential polarization was often observed in such no-EF growth, which might have been due to native charges on the substrate or even small electric fields from surrounding equipment283031. The inherent polarization of FF peptides originates from the ordered arrangement of positively charged amino termini (NH3+) and negatively charged carboxyl termini (COO−)30. Therefore, microrod arrays with opposite polarizations have either NH3+ groups or COO− groups predominantly exposed at the top surface. Hence, the biofunctionality of the FF peptide microrod array can be tuned by simply switching the electric field during growth.


Self-assembly of diphenylalanine peptide with controlled polarization for power generation
PFM and SKPM characterization of the microrod arrays.(a,b) PFM phase image and corresponding SKPM surface potential map of a microrod from the positive-EF growth (a) and a microrod from the negative-EF growth (b). The phase and surface potential distributions are shown by the colour overlaid on the topography of the top of the microrod. (c) Statistics of the piezoelectric phase for the arrays from the positive-EF growth, negative-EF growth and no-EF growth. Detailed data for this chart is provided in Supplemental Table 1. (d) Linear dependence of the PFM amplitude on the applied voltage for FF peptide microrods from growth with different electric fields. The slopes of the lines provide effective piezoelectric coefficients d33, which are 17.9, 11.7 and 9.3 pm V−1 for microrods from the negative-EF growth, positive-EF growth and no-EF growth, respectively. Error bar: s.d.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5120215&req=5

f2: PFM and SKPM characterization of the microrod arrays.(a,b) PFM phase image and corresponding SKPM surface potential map of a microrod from the positive-EF growth (a) and a microrod from the negative-EF growth (b). The phase and surface potential distributions are shown by the colour overlaid on the topography of the top of the microrod. (c) Statistics of the piezoelectric phase for the arrays from the positive-EF growth, negative-EF growth and no-EF growth. Detailed data for this chart is provided in Supplemental Table 1. (d) Linear dependence of the PFM amplitude on the applied voltage for FF peptide microrods from growth with different electric fields. The slopes of the lines provide effective piezoelectric coefficients d33, which are 17.9, 11.7 and 9.3 pm V−1 for microrods from the negative-EF growth, positive-EF growth and no-EF growth, respectively. Error bar: s.d.
Mentions: Piezoresponse force microscopy (PFM) was employed to investigate both the orientation of electrical polarization and the piezoelectric strength of FF peptide microrods. As we applied an alternating voltage on the FF peptide microrods, an FF peptide microrod with either upward or downward polarization deformed either out of phase (180°) or in phase (0°), respectively, (Supplementary Fig. 3). The phase distributions of vertical microrods from a positive-EF growth and from a negative-EF growth in Fig. 2a,b, respectively, show that applying opposite electric fields during growth results in FF peptides with phases of polarization 180° apart. Scanning Kelvin Probe Microscopy (SKPM) was also employed and confirmed that the surface charge on the microrod tip was consistent with the polarization, verifying the mechanism shown in Fig. 1a,b. The polarization was very stable and could not be switched with a high electric field once the growth was completed (Supplementary Fig. 4). Randomly selected 20 microrods from each growth process were tested (Fig. 2c and Supplementary Table 1). The results indicated that 95–100% of microrods had polarization in the direction of the applied electric field. In the absence of an electric field during growth, the polarization became much less uniform (Fig. 2c). A preferential polarization was often observed in such no-EF growth, which might have been due to native charges on the substrate or even small electric fields from surrounding equipment283031. The inherent polarization of FF peptides originates from the ordered arrangement of positively charged amino termini (NH3+) and negatively charged carboxyl termini (COO−)30. Therefore, microrod arrays with opposite polarizations have either NH3+ groups or COO− groups predominantly exposed at the top surface. Hence, the biofunctionality of the FF peptide microrod array can be tuned by simply switching the electric field during growth.

View Article: PubMed Central - PubMed

ABSTRACT

Peptides have attracted considerable attention due to their biocompatibility, functional molecular recognition and unique biological and electronic properties. The strong piezoelectricity in diphenylalanine peptide expands its technological potential as a smart material. However, its random and unswitchable polarization has been the roadblock to fulfilling its potential and hence the demonstration of a piezoelectric device remains lacking. Here we show the control of polarization with an electric field applied during the peptide self-assembly process. Uniform polarization is obtained in two opposite directions with an effective piezoelectric constant d33 reaching 17.9 pm V−1. We demonstrate the power generation with a peptide-based power generator that produces an open-circuit voltage of 1.4 V and a power density of 3.3 nW cm−2. Devices enabled by peptides with controlled piezoelectricity provide a renewable and biocompatible energy source for biomedical applications and open up a portal to the next generation of multi-functional electronics compatible with human tissue.

No MeSH data available.


Related in: MedlinePlus