Nocito Giuseppe, Sciuto Emanuele Luigi, Franco Domenico, Nastasi Francesco, Pulvirenti Luca, Petralia Salvatore, Spinella Corrado, Calabrese Giovanna, Guglielmino Salvatore, Conoci Sabrina
Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres, 31, 98168 Messina, Italy.
Department of Chemical Science, University of Catania, Viale A. Doria, 6, 95125 Catania, Italy.
Nanomaterials (Basel). 2022 Mar 7;12(5):885. doi: 10.3390/nano12050885.
Carbon nanomaterials have shown great potential in several fields, including biosensing, bioimaging, drug delivery, energy, catalysis, diagnostics, and nanomedicine. Recently, a new class of carbon nanomaterials, carbon dots (CDs), have attracted much attention due to their easy and inexpensive synthesis from a wide range of precursors and fascinating physical, chemical, and biological properties. In this work we have developed CDs derived from olive solid wastes of two Mediterranean regions, Puglia (CDs_P) and Calabria (CDs_C) and evaluated them in terms of their physicochemical properties and antibacterial activity against () and (. Results show the nanosystems have a quasi-spherical shape of 12-18 nm in size for CDs_P and 15-20 nm in size for CDs_C. UV-Vis characterization indicates a broad absorption band with two main peaks at about 270 nm and 300 nm, respectively, attributed to the π-π* and n-π* transitions of the CDs, respectively. Both samples show photoluminescence (PL) spectra excitation-dependent with a maximum at λ = 420 nm (λ = 300 nm) for CDs_P and a red-shifted at λ = 445 nm (λ = 300 nm) for CDs_C. Band gaps values of ≈ 1.48 eV for CDs_P and ≈ 1.53 eV for CDs_C are in agreement with semiconductor behaviour. ζ potential measures show very negative values for CDs_C compared to CDs_P (three times higher, -38 mV vs. -18 mV at pH = 7). The evaluation of the antibacterial properties highlights that both CDs have higher antibacterial activity towards Gram-positive than to Gram-negative bacteria. In addition, CDs_C exhibit bactericidal behaviour at concentrations of 360, 240, and 120 µg/mL, while lesser activity was found for CDs_P (bacterial cell reduction of only 30% at the highest concentration of 360 µg/mL). This finding was correlated to the higher surface charge of CDs_C compared to CDs_P. Further investigations are in progress to confirm this hypothesis and to gain insight on the antibacterial mechanism of both cultivars.
碳纳米材料在包括生物传感、生物成像、药物递送、能源、催化、诊断和纳米医学在内的多个领域展现出了巨大潜力。近来，一类新型碳纳米材料——碳点（CDs），因其能通过多种前驱体简便且低成本地合成，以及具有迷人的物理、化学和生物学特性而备受关注。在本研究中，我们制备了源自两个地中海地区普利亚（CDs_P）和卡拉布里亚（CDs_C）橄榄固体废弃物的碳点，并对其物理化学性质以及针对（）和（）的抗菌活性进行了评估。结果表明，纳米系统呈准球形，CDs_P的尺寸为12 - 18纳米，CDs_C的尺寸为15 - 20纳米。紫外可见光谱表征显示出一个宽吸收带，分别在约270纳米和300纳米处有两个主峰，分别归因于碳点的π - π和n - π跃迁。两个样品的光致发光（PL）光谱均依赖于激发，CDs_P在λ = 420纳米（λ = 300纳米激发）处有最大值，CDs_C在λ = 445纳米（λ = 300纳米激发）处发生红移。CDs_P的带隙值约为1.48电子伏特，CDs_C的带隙值约为1.53电子伏特，这与半导体行为相符。ζ电位测量显示，与CDs_P相比，CDs_C的值非常负（高3倍，pH = 7时为 - 38毫伏对 - 18毫伏）。抗菌性能评估突出表明，两种碳点对革兰氏阳性菌的抗菌活性均高于革兰氏阴性菌。此外，CDs_C在浓度为360、240和120微克/毫升时表现出杀菌行为，而CDs_P的活性较低（在最高浓度360微克/毫升时细菌细胞减少仅30%）。这一发现与CDs_C相比CDs_P具有更高的表面电荷有关。进一步的研究正在进行中，以证实这一假设并深入了解这两个品种的抗菌机制。
