Carbon nanowalls, vertically aligned graphene nanosheets, attract attention owing to their tunable band gap, high conductivity, high mechanical robustness, high optical absorbance and other remarkable properties. In this paper, we report for the first time the use of hydrophobic boron-doped carbon nanowalls (CNWs) for laser desorption/ionization of small compounds and their subsequent detection by mass spectrometry (LDI-MS). The proposed method offers sensitive detection of various small molecules in the absence of an organic matrix. The CNWs were grown by microwave plasma enhanced chemical vapor deposition (MW-PECVD), using a boron–carbon gas flow ratio of 1200 in H₂/CH₄ plasma, on silicon wafer. The hydrophobicity of the surface offers a straightforward MS sample deposition, consisting of drop casting solutions of analytes and drying in air. Limits of detection in the picomolar and femtomolar ranges (25 fmol μL⁻¹ for neurotensin) were achieved for different types of compounds (fatty acids, lipids, metabolites, saccharides and peptides) having clinical or food industry applications. This rapid and sensitive procedure can also be used for quantitative measurements without internal standards with RSDs <19%, as in the case of glucose in aqueous solutions (LOD = 0.32 ± 0.02 pmol), blood serum or soft drinks. Moreover, melamine (63 ± 8.19 ng μL⁻¹), a toxic compound, together with creatinine and paracetamol, was detected in urine samples, while lecithin was detected in food supplements.

The brain capitalizes on the complexity of both its biochemistry for neurons to encode diverse pieces of information with various neurotransmitters and its morphology at multiple scales to route different pathways for neural interconnectivity. Conducting polymer dendrites can show similar features by differentiating between cations and anions thanks to their charge accumulation profile and the asymmetry in their dendriticity that allows projecting spike signals differently. Here, we exploit such mimicry for in materio classification of bursting activity and investigate, in phosphate buffered saline, the capability of such object to sense bursts of voltage pulses of 100 mV amplitude, emitted by a local gate in the vicinity of the dendrite. The dendrite integrates the different activities with a fading memory time window that is characteristic of both the polarity of the spikes and the temporality of the burst. By this first demonstration, the ‘material-object’ definitely shows great potential to be a node halfway between the two realms of brain and electronic communication.

In this paper, we report an original method to immobilize a model peptide on silicon nanowires (SiNWs) via a photolinker attached to the SiNWs’ surface. The silicon nanowires were fabricated by a metal assisted chemical etching (MACE) method. Then, direct characterization of the peptide immobilization on SiNWs was performed either by X-ray photoelectron spectroscopy (XPS) or by laser-desorption/ionization mass spectrometry (LDI-MS). XPS allowed us to follow the peptide immobilization and its photorelease by recording the variation of the signal intensities of the different elements present on the SiNW surface. Mass spectrometry was performed without the use of an organic matrix and peptide ions were produced via a photocleavage mechanism. Indeed, thanks to direct photorelease achieved upon laser irradiation, a recorded predictable peak related to the molecular peptide ion has been detected, allowing the identification of the model peptide. Additional MS/MS experiments confirmed the photodissociation site and confirmed the N-terminal immobilization of the peptide on SiNWs.