Efficient lepidolite flotation at neutral pH and low temperatures without depressants remains challenging. This study introduces a novel amide–diamine surfactant, N-(2-((2-aminoethyl)amino)ethyl)dodecanamide (N-123), combined with sodium oleate (NaOL), for efficiently separating lepidolite from albite and quartz. Flotation experiments on ternary mixed minerals (mass ratio 1:1:1) demonstrated that at pH 7.0, N-123/NaOL (1:4) achieved Li2O recoveries of 84.25% at 25 °C and 73.17% at 5 °C, outperforming conventional dodecylamine (DDA)/NaOL at 54.93% at 25 °C and 32.77% at 5 °C. An amide–diamine structure provides good water solubility and a low Krafft point, enabling low-temperature flotation. Surface tension results showed that N-123 and N-123/NaOL exhibited higher surface activity than DDA and DDA/NaOL, respectively, and that both maintained relatively high surface activity at 5 °C. Wettability and froth stability tests confirmed synergistic co-assembly of N-123/NaOL at the interface, enhancing lepidolite hydrophobicity while reducing froth height and half-life to minimize gangue entrainment. ζ-potential, Fourier transform infrared (FT-IR) spectroscopy, in situ atomic force microscopy (AFM), and force measurements revealed that N-123/NaOL carried a net negative charge and co-adsorbed on lepidolite mainly via hydrophobic forces, while adsorption on albite and quartz was suppressed by electrostatic repulsion. Thus, the synergistic N-123/NaOL collector enables efficient, depressant-free lepidolite flotation.
Glyceride crystals stabilize water-in-oil (W/O) emulsions through two complementary mechanisms: formation of a crystalline layer around water droplets (Pickering stabilization) and development of a crystal network within the continuous oil phase. To better understand how glyceride crystallization influences emulsion stability during storage, this study examined the crystallization behavior of monoglycerides (MGs) and triglycerides (TGs) with defined acyl chain lengths in W/O emulsions formulated with medium-chain triglyceride (MCT) oil. During cooling after emulsification, MGs crystallized both at the droplet interface and in the bulk oil, providing direct evidence of combined Pickering and network stabilization, whereas TGs crystallized mainly as spherulites in the oil phase, leading to rapid phase separation. Among the MGs investigated, glycerol monostearate (GMS) provided substantially greater long-term stability than monopalmitin (MP), whose crystals underwent significant morphological changes during storage. Synchrotron small-angle and wide-angle X-ray scattering revealed that both MP-MCT and GMS-MCT systems initially formed metastable crystalline phases that transformed into the thermodynamically stable β phase upon ageing. However, MP β crystals continued to grow through Ostwald ripening, causing progressive emulsion destabilization, while GMS crystals remained structurally stable and maintained emulsion integrity. These findings establish clear links between glyceride crystallization, polymorphic transformations, and emulsion stability, providing valuable guidance for selecting effective Pickering stabilizers and designing crystallization pathways to enhance the long-term stability of W/O emulsions.
Marine stromal proteins represent a promising but underexplored source of natural emulsifiers for developing functional emulsions. This study investigated the effects of high-intensity ultrasound (HIU) on the physicochemical characteristics, interfacial properties, and antioxidant performance of emulsions formulated with stromal protein extracted from Dosidicus gigas mantle and cinnamon essential oil. Sonication time (0, 3, 5, and 10 min) and amplitude (40, 70, and 100%) were evaluated. The physicochemical and colloidal properties of the emulsions were evaluated through oil-holding capacity (OHC), particle size, polydispersity index (PDI), zeta potential, and rheological behavior. At the same time, antioxidant performance was determined using DPPH, ABTS, FRAP, and erythrocyte hemolysis inhibition assays. HIU markedly improved the physicochemical properties of the emulsions. The Z-average droplet diameter of the emulsions ranged from 195.3 ± 1.5 to 368.7 ± 4.0 nm. The treatment at 5 min and 70% amplitude produced the smallest droplets (195.3 ± 1.5 nm), corresponding to an approximately 27% reduction compared with the untreated emulsion (268.7 ± 4.6 nm), as well as the lowest PDI (0.215 ± 0.026) and a zeta potential of −15.8 ± 0.4 mV. Ultrasound also improved oil retention and enhanced antioxidant performance, although the magnitude of the response depended on the assay employed. The emulsions inhibited AAPH-induced erythrocyte hemolysis by approximately 77–95%, with the highest inhibition observed after treatment for 10 min at 40% amplitude. Overall, HIU enhanced the interfacial functionality of squid stromal proteins, supporting their potential application as natural emulsifiers in protein-based antioxidant delivery systems.
The development of an effective recognition interface is a critical step in biosensor design. In this study, aptamer- and antibody-functionalized gold surfaces were compared as capture interfaces for Bacillus cereus spores. Two aptamer sequences and different antibody immobilization approaches, including random and oriented immobilization, were investigated. Spore capture was evaluated by fluorescence imaging using either an aptamer–antibody sandwich assay or direct SYTO®9 staining, with Raman spectroscopy employed as a complementary characterization method. At the fixed spore concentration investigated, the aptamer-functionalized surfaces produced higher fluorescence responses than the antibody-functionalized surfaces under the tested experimental conditions. Raman bands associated with calcium dipicolinate provide additional evidence consistent with the presence of captured endospores. An opal/gold hybrid structure was also examined as a preliminary optical transduction platform. The immobilization of two distinct molecular recognition elements (MREs) was performed via spotter deposition, thus enhancing the signal-to-noise ratio. Our findings suggest that, in this configuration, aptamers outperform antibodies in capturing B. cereus spores and, therefore, are identified as the most useful MRE to be implemented in future biosensors. Furthermore, an easy method for the fluorescence labeling of spores, i.e., via SYTO®9, is proposed as an effective way to directly detect spore presence.
Doxorubicin hydrochloride (DX) is a widely used chemotherapeutic agent whose severe side effects can be attenuated by suitably designing drug delivery systems. The complexation between DX and the biocompatible and biodegradable sodium alginate (ALG) results in the formation of DX@ALG nanoparticles under conditions where neither the drug nor the polymer tends to form nanoscopic structures. DX@ALG complex formation leads to the quenching of DX intrinsic fluorescence, and the drug shows chiroptical properties characteristic of supramolecular gels of DX. The association of DX and ALG into supramolecular nanoparticles takes place at low DX concentration and without salt addition. More than 99% of the moles of DX complexed with ALG form a gel-like phase, and DX@ALG nanoparticles show a high DX loading efficiency. Nanoparticle formation is revealed by Dynamic Light Scattering (DLS) and Atomic Force Microscopy (AFM). Quantum Mechanics (QM) calculations support the formation of supramolecular DX-ALG aggregates by π–π stacking and hydrogen bonds. DX@ALG nanoparticles have been fully characterized by several spectroscopic techniques. Preliminary in vitro evaluation of DX@ALG toxicity revealed an antiproliferative activity against selected cancer cell lines.
