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Supramolecular short-peptide assemblies have been widely used for the development of biomaterials with potential biomedical applications. These peptides can self-assemble in multitude of chiral hierarchical structures triggered by the application of different stimuli, such as changes in temperature, pH, solvent, etc. The self-assembly process is very susceptible to the chemical composition of the peptides, being affected by specific amino acid sequence, type and chirality. The resulting supramolecular chirality of these materials has been explored to modulate protein and cell interactions. Recently, significant attention has been focused on the development of chiral materials with potential spintronic applications as it has been shown that transport of charge carriers through a chiral environment polarizes the carrier spins. This effect, named Chirality Induced Spin Selectivity or CISS, has been studied in different chiral organic molecules and materials, as well as carbon nanotubes functionalized with chiral molecules. Nevertheless, this effect has been only explored in homochiral systems in which the chirality of the medium, and hence the resulting spin polarization, is defined by the chirality of the molecule, with limited options for tunability. Herein, we have developed heterochiral carbon nanotube-short-peptide materials made by the combination of two different chiral sources, that is, homochiral peptides (L/D) + glucono-δ-lactone. We show that the presence of a small amount of glucono-δ-lactone with fixed chirality can alter the supramolecular chirality of the medium, thereby modulating the sign of the spin signal from “up” to “down” and vice versa. In addition, small amounts of glucono-δ-lactone can even induce non-zero spin polarization in an otherwise achiral and spin-inactive peptide-nanotube composite. Such “chiral doping” strategies could allow development of complimentary spintronic devices on a single material platform, opening novel design directions for CISS-based spintronic devices and circuits., This study was supported by project PID2020-118498GB-I00 funded by MCIN/AEI/10.13039/501100011033 and project P18-FR-3533 by FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades (Spain). MCMT acknowledge grant PRE2018-083773 funded by MCIN/AEI/10.13039/501100011033 and FSE “El FSE invierte en tu futuro”, Spain.

Molecular functionalization of CNTs is a routine procedure in the field of nanotechnology. However, whether and how these molecules affect the spin polarization of the charge carriers in CNTs are largely unknown. In this work we demonstrate that spin polarization can indeed be induced in twodimensional (2D) CNT networks by “certain” molecules and the spin signal routinely survives length scales significantly exceeding 1 μm. This result effectively connects the area of molecular spintronics with that of carbon-based 2D nanoelectronics. By using the versatility of peptide chemistry, we further demonstrate how spin polarization depends on molecular structural features such as chirality as well as molecule−nanotube interactions. A chiralityindependent effect was detected in addition to the more common chiralitydependent effect, and the overall spin signal was found to be a combination of both. Finally, the magnetic field dependence of the spin signals has been explored, and the “chirality-dependent” signal has been found to exist only in certain field angles., Project FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades (Spain) project P18-FR- 3533, Grant PRE 2018-083773, funded by MCIN/AEI/10.13039/501100011033