Carbon nanodots (C-Dots) as a new form of carbonaceous nanomaterials have aroused much interest and intensive research due to their inspiring properties. Compared to traditional semiconductor quantum dots, these newly emergent nanodots possess a number of advantageous characteristics, among which low-toxicity is particularly fascinating. More and more research into C-Dots have focused on synthesis methods and biology-related applications. Microwave-assisted approaches have attracted attention because microwave treatment can provide intensive and efficient energy, and as a consequence shorten the reaction time. In this article, we designed a “green”, rapid, eco-friendly and waste-reused approach to synthesize fluorescent and water-soluble C-Dots from eggshell membrane (ESM) ashes according to a microwave-assisted process. ESM selected as the carbon source was a common protein-rich waste in daily life and can be obtained easily and cheaply. The C-Dots from our method showed the maximal fluorescence emission peak at 450 nm and the fluorescence quantum yield was about 14%. We further designed a sensitive probe for glutathione based on the fluorescence turn off and on of the C-Dots–Cu²⁺ system, which showed a linear range of 0.5–80 μmol L⁻¹ and detection limit of 0.48 μmol L⁻¹. In general, the C-Dots prepared briefly and inexpensively from ESM revealed excellent fluorescent property with promising potential for applications such as sample detection and biotechnology.

A series of nitrogen-rich nitronyl nitroxide radical PPNIT (1)-based (PPNIT = 2-(1-(pyrazin-2-yl)-1H-pyrazole)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) 3d–4f ring-shaped tetranuclear clusters [Ln₂Cu₂(hfac)₁₀(PPNIT)₂(H₂O)₂]·CHCl₃ (Ln^III = Gd 2, Tb 3, Dy 4; hfac = hexafiuoroacetylacetonate) with multifunctional properties were isolated. The magnetic behavior, luminescence and heat capacity of the 3d–4f complexes were investigated, displaying interesting multiple properties of the molecular materials. The Gd derivative shows a magnetocaloric effect with the maximum entropy change (−ΔS_m) of 15.3 J kg⁻¹ K⁻¹ at 2 K for ΔH = 70 kOe. The Tb cluster exhibits spin glass behavior and the characteristic fluorescence emission of the Tb^III ion, while the Dy cluster exhibits SMM behaviour, and the heat capacity has been investigated. Notably, in nitronyl nitroxide radical–metal systems, the investigation of diverse properties is still scarce so far. This work can pave the way towards the synthesis of multifunctional materials that combine SMM behavior, and optical or/and thermodynamic properties.

Flexible piezoresistive pressure sensors have promising applications in wearable devices, artificial intelligence, and other fields. However, developing low-cost and high-performance pressure sensors still poses a great challenge. Herein, we utilize low-cost carbon black (CB) and multi-walled carbon nanotubes (MWCNTs) mixed in porous polydimethylsiloxane to assemble a flexible piezoresistive pressure sensor combined with interdigitated electrodes. Simultaneously, the COMSOL Multiphysics simulation analysis was performed to predict the sensing behavior of the pressure sensor, which was verified by experiments; the preparation of the pressure sensor was guided according to the prediction. Additionally, we studied the effects of the mixed conductive filler's weight ratio, the shape of the interdigital electrode, and the line width and spacing of the interdigital electrode on the performance of the sensor. Based on the interaction of the 3D porous structure and the synergistic conductive network of CB/MWCNTs, the prepared pressure sensor exhibits a high sensitivity of 3.57 kPa^-1 (∼21 kPa), a wide detection range of 0-275 kPa, fast response time (96 ms), fast recovery time (198 ms), good durability (about 3000 cycles), and good flexibility. Moreover, the fabricated sensor can monitor and recognize human activities (such as finger bending and mouse clicking), indicating that it has great potential in flexible wearable devices and other fields. It is worth noting that the preparation process of the entire pressure sensor was simple, low cost, and environmentally friendly, which provides a certain basis for industrial and commercial applications.

Scheme of the MnO₂NP-mediated fluorescence turn-off-on process of CDs with MnO₂NPs and GSH.

Taking advantage of a nitronyl nitroxide radical ligand 8-QNNIT (1) (8-quinolyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) and Ln(hfac)₃·2H₂O (Ln^III = Tb 2 and Dy 3; hfac = hexafluoroacetylacetonate), two Ln–radical one-dimensional chains [Ln(hfac)₃(8-QNNIT)]_n were constructed. The magnetic properties, thermodynamics and optical behavior of both compounds were observed, exhibiting polyfunctionality of the 2p–4f system. Complexes 2 and 3 show typical single-chain magnet (SCM) properties with temperature-dependent relaxation peaks giving an effective energy barrier (U_eff/k_B) of 47.4 K (2) and 64.6 K (3). Luminescence spectra and ultravioletvisible (UV-vis) absorption spectra of the Tb compound, and UV-vis absorption spectra and thermodynamics properties of the Dy complex were investigated. As far as we know, the Dy complex is the first SCM with thermodynamics behavior and optical properties comparable to those of multifunctional magnetic materials. This study aims to provide a new way and field of vision for the construction of 2p–4f heterospin multi-functional materials.

A scheme of the construction of a CPs@MnO₂–AgNP nanocomposite for GSH sensing and cancer theranostics.