**3.2 Hemeproteins**

Hemeproteins such as hemoglobin (Hb), myoglobin (Mb), horseradish peroxidase (HRP), catalase, and cytochrome *c* (cyt *c*) have the prosthetic group, ferrous or

**153**

(O2 −•

**Figure 7.**

*nanorods in O2*

*−•*

*Technological Applications of Porphyrins and Related Compounds: Spintronics and Micro…*

ferric protoporphyrin IX (heme group), as the redox center. The heme group makes hemeproteins useful for a medical and technological application that involves redox reactions. The use of hemeproteins in nanodevices can be impaired by denaturation or the orientation of the redox site [92]. However, literature has several examples of the use of hemeproteins in nanodevices [93–95]. Hemeproteins can also be used in the self-propelling of MNRs. Hemeproteins can act in MNMs by the bubble recoil mechanism. Catalase is the best hemeprotein for use in MNMs due to the capacity to convert hydrogen peroxide to oxygen generating propulsion bubbles [96]. Pavel et al. [97] fabricated nanorods with self-electrophoresis taking advantage of the

*to the ferric form by transferring electrons through the PPy-Au nanorod to HRP compound I (Por•+Fe(IV) = O) and compound II (PorFe(IV) = O) that recycles to native HRP. The structures of HRP and cytochrome c were obtained from protein data Bank (1HCH and 1HRC, respectively). Mechanism from Pavel el al. [97].*

*Proposed bio-electrochemical mechanism behind the enhanced diffusive motion of (HRP)PPy-Au(cyt c)* 

*· and H2O2 solutions. Native HRP (PorFe(III)) reduces H2O2 to water and is converted to* 

*−•*

*. Ferrous cyt c (PorFe(II)) recycles* 

One half of the nanorod was made of polypyrrole (PPy) modified with HRP, and the other half was made of gold and decorated with cyt *c*. [97]. The charge separation was promoted by the reaction of cytochrome *c* with superoxide ion

oxidized form by transferring one electron through the nanorod to the high valence forms of HRP generated by the reaction with hydrogen peroxide (**Figure 7**) [97]. The study published by Pavel et al. demonstrated that the hemeproteins are robust

Porphyrins and hemeproteins have been widely studied because of their biological roles in energy metabolism and light harvesting in photosynthesis. More recently, with the advancement of bioelectronics and micro-/nanorobotics, porphyrins and hemoproteins have gained interest because of their specific properties. Porphyrins have desirable properties for single-molecule spintronic such as current switching, long-range electron tunneling, current rectifying, and others.

−•

to O2 and is recycled to the

combined catalysis of HRP and cytochrome *c* as illustrated in **Figure 7**.

enough to maintain the activity even immobilized on solid substrates [97].

) and HRP with H2O2. Ferric cyt *c* oxidizes O2

*compound I (Por•+Fe(IV) = O), while ferric cyt c (PorFe(III)) is reduced by O2*

**4. Conclusions and perspectives**

*DOI: http://dx.doi.org/10.5772/intechopen.86206*

*Technological Applications of Porphyrins and Related Compounds: Spintronics and Micro… DOI: http://dx.doi.org/10.5772/intechopen.86206*

#### **Figure 7.**

*Solid State Physics - Metastable, Spintronics Materials and Mechanics of Deformable...*

metal–organic frameworks (MOFs) were fabricated with hydrophobic meso-tetra (4-carboxyphenyl)-porphyrin (H4-TCPP-H2, L) ligands bound to Zr-oxo clusters. The H4-TCPP-H2, L responds for the hydrophobic character of the framework [90]. Similar MOFs were described in the literature before, once they are efficient in the controlled release of surface-active substances proportionating a controlled motion. However, usually, the MOFs use high-cost surface-active substances [90]. The MOFs fabricated with meso-tetra(4-carboxyphenyl)-porphyrin ligands bound to Zr-oxo clusters use much less expensive fuels. The particles have the advantage to be refu-

*Supramolecular aggregates of meso-5,10,15,20-sulfonate-phenyl porphyrin (TPPS4). (a) The free-base monomer of TPPS4, (b) the head-to-tail linear self-assembly of TPPS4, and (c) the J-aggregate of TPPS4.*

fuel, the microstructure, and surface wettability of the MOF surface determine the efficiency of motion. In another study, Serrà et al. [91] reported the fabrication of a multifunctional nanorobotic platform with magnetic properties to promote the death of cancer cells by magnetic and mechanical destruction. A multi-segmented nanowire composed by nickel and gold alternating segments was produced by electrodeposition of metals inside the nanochannels of a polycarbonate membrane. In sequence, the nickel segments were transformed in core-shell Ni/NiO segments by the treatment of the nanowire with NaOH 0.5 M for 6 h. The nanowires were treated sequentially with zinc protoporphyrin IX and 1,9-nonanedithiol that displaces the porphyrin from the gold segments. The nanotubes exhibited ferromagnetism and could be manipulated by a magnet. When the bi-functionalized nanotubes attain cells, magnet or photostimulation can induce cell death that is useful for cancer treatments since the effect of some medical procedures, like hyperthermia and photodynamic therapy, could be

Hemeproteins such as hemoglobin (Hb), myoglobin (Mb), horseradish peroxidase (HRP), catalase, and cytochrome *c* (cyt *c*) have the prosthetic group, ferrous or

. Interestingly, the type of

eled multiple times and attained speeds of ca. 200 mm·s<sup>−</sup><sup>1</sup>

improved by application of a rotary magnetic field [91].

**152**

**Figure 6.**

**3.2 Hemeproteins**

*Proposed bio-electrochemical mechanism behind the enhanced diffusive motion of (HRP)PPy-Au(cyt c) nanorods in O2 −• · and H2O2 solutions. Native HRP (PorFe(III)) reduces H2O2 to water and is converted to compound I (Por•+Fe(IV) = O), while ferric cyt c (PorFe(III)) is reduced by O2 −• . Ferrous cyt c (PorFe(II)) recycles to the ferric form by transferring electrons through the PPy-Au nanorod to HRP compound I (Por•+Fe(IV) = O) and compound II (PorFe(IV) = O) that recycles to native HRP. The structures of HRP and cytochrome c were obtained from protein data Bank (1HCH and 1HRC, respectively). Mechanism from Pavel el al. [97].*

ferric protoporphyrin IX (heme group), as the redox center. The heme group makes hemeproteins useful for a medical and technological application that involves redox reactions. The use of hemeproteins in nanodevices can be impaired by denaturation or the orientation of the redox site [92]. However, literature has several examples of the use of hemeproteins in nanodevices [93–95]. Hemeproteins can also be used in the self-propelling of MNRs. Hemeproteins can act in MNMs by the bubble recoil mechanism. Catalase is the best hemeprotein for use in MNMs due to the capacity to convert hydrogen peroxide to oxygen generating propulsion bubbles [96]. Pavel et al. [97] fabricated nanorods with self-electrophoresis taking advantage of the combined catalysis of HRP and cytochrome *c* as illustrated in **Figure 7**.

One half of the nanorod was made of polypyrrole (PPy) modified with HRP, and the other half was made of gold and decorated with cyt *c*. [97]. The charge separation was promoted by the reaction of cytochrome *c* with superoxide ion (O2 −• ) and HRP with H2O2. Ferric cyt *c* oxidizes O2 −• to O2 and is recycled to the oxidized form by transferring one electron through the nanorod to the high valence forms of HRP generated by the reaction with hydrogen peroxide (**Figure 7**) [97]. The study published by Pavel et al. demonstrated that the hemeproteins are robust enough to maintain the activity even immobilized on solid substrates [97].

## **4. Conclusions and perspectives**

Porphyrins and hemeproteins have been widely studied because of their biological roles in energy metabolism and light harvesting in photosynthesis. More recently, with the advancement of bioelectronics and micro-/nanorobotics, porphyrins and hemoproteins have gained interest because of their specific properties. Porphyrins have desirable properties for single-molecule spintronic such as current switching, long-range electron tunneling, current rectifying, and others.

Regarding the hemoproteins, they combine the presence of a porphyrin (iron protoporphyrin IX) as the redox center with the chiral protein structure that acts as a spin filter. To date, cytochrome *c* stands out as the hemoprotein for which the capacity to produce CISS effect has already been demonstrated experimentally. Porphyrins and hemoproteins also have proven potential for nanorobotic application. Porphyrins are particularly useful for nanorobotics applied to medicine because of their photochemical properties. Porphyrins also can self-assemble in structures such as J-aggregates to form nanotubes. On the other hand, the catalytic properties of hemoproteins are the most relevant factor that makes them applicable to self-propulsion in micro-/nanorobotics. The studies and applications of porphyrins and hemoproteins in spintronic and nanorobotic are still in their early stages, and a wide field of study of these compounds is open to the area of bioelectronics. Among the numerous advances that are possible for the field of spintronic, special attention has been given to spinterface, that is, the interface between a ferromagnetic (FM) metal and an organic semiconductor, in which unique hybrid states are formed. The FM metal/molecular interfaces constitute an important building block for the future of spintronics. The unique hybrid states of spinterfaces influence magnetic properties such as magnetic anisotropy, magnetic exchange coupling, interfacial spin polarization, and others. Further, the interactions between the FM metal and organic molecules are tunable in such a way that the spinterfaces are applicable to multifunctional devices meeting the industry tendency of miniaturization using single-molecule devices. The external control of spinterface by external signals, especially light because the ultra-fast optical transmission, is a promising area for future investigations. An important challenge for the design of spintronic devices is the changeable control and switch of single molecules adsorbed on the surface of FM materials. Particularly, for the metalloporphyrins, an interesting example is the use of axial ligands of the porphyrin transition metal center to change the magnetism of the molecular component [98]. NO• was able to reversibly switch the spin state of the Co and Fe of porphyrins adsorbed on Ni(001) Co substrates, respectively. Similarly, NH3 was able to induce the transition of Ni porphyrin on Co substrate from low to high spin states [99, 100]. Another emerging field of spintronics is the use of antiferromagnets that are affected by spin-polarized currents. Antiferromagnetic materials have several advantages for spintronics such as they do not create external magnetic fields and only weak interactions occur with each other and the antiferromagnets have the characteristic frequencies of switching between their states significantly higher than the values obtained for ferromagnets. Further, the occurrence of ordering in antiferromagnets it is more frequent and occurs at soft conditions than in ferromagnets. Also, these materials can behave as a conductor for a spin polarization and as an insulator for other spin polarization. The antiferromagnets can provide desirable characteristics for spintronics that are high speed of operation in terahertz range, performance, easy manipulation, high sensitivity, and low energy cost [101].

The field of micro/nanorobotics that also can take advantage of the properties of porphyrins and hemeproteins has as the principal challenge for advances as the control and powering of the movement. The crescent interest in the application of MNR in theranostic poses the additional challenge for the use of biocompatible and high-performance materials and fuels. An interesting alternative regarding the elimination of toxic fuels is the use of systems having the propulsion powered by external field that are fuel-free and allow the remote control of the movement. The MNRs with a real potential to operate in vivo are rare now and constitute an important area for future investigations that requires multi- and interdisciplinary studies [102].

**155**

**Author details**

and Iseli L. Nantes-Cardoso\*

Santo André, SP, Brazil

provided the original work is properly cited.

\*Address all correspondence to: ilnantes@gmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

David M. Lopes, Juliana C. Araujo-Chaves, Lucivaldo R. Menezes

Laboratory of Nanostructures for Biology and Advanced Materials, Center of Natural Sciences and Humanities, Federal University of ABC,

*Technological Applications of Porphyrins and Related Compounds: Spintronics and Micro…*

The author thanks FAPESP 2015/017688-0, 2017/02317-2, SisNano

the financial support and CEM/UFABC for the access to facilities.

(402289/2013-7), NBB/UFABC, CAPES grant 001, and CNPq (309247/2017-9) for

*DOI: http://dx.doi.org/10.5772/intechopen.86206*

The authors declare no conflict of interest.

**Acknowledgements**

**Conflict of interest**

*Technological Applications of Porphyrins and Related Compounds: Spintronics and Micro… DOI: http://dx.doi.org/10.5772/intechopen.86206*
