Sericin is a water-soluble silk protein, which is currently discarded in silk processing and manufacturing as industrial waste during degumming raw silk. This review critically examines the molecular characteristics of sericin that may contribute to its reducing activity, its proposed roles in nanoparticle formation and stabilization, and the extent to which current mechanistic interpretations are supported by experimental evidence. The performance of sericin is further compared with other classes of bio-reductants, including plant polyphenols, microbial systems, free amino acids, and polysaccharides, with particular emphasis on reduction kinetics, stabilization, reproducibility, and practical applicability. Available evidence indicates that sericin can contribute to both metal-ion reduction and nanoparticle stabilization under appropriate aqueous conditions; however, the relative contributions of individual functional groups and the molecular basis of nanoparticle formation remain incompletely established. Reproducibility is also influenced by variation in sericin composition, molecular characteristics, and preparation conditions. In addition, challenges associated with mechanistic validation, scale-up, formulation stability, and long-term biomedical safety limit assessment of its broader technological applications. Sericin therefore represents a potentially useful biomaterial for sustainable nanofabrication, but further standardized characterization, quantitative mechanistic studies, and scalable process development are required to define its practical advantages more reliably.
Controlling the morphology of metal oxide nanostructures through simple and scalable synthetic strategies remains challenging because crystal growth is strongly governed by interfacial surface chemistry. Herein, we present a polymer-mediated strategy for directing the growth of RuO 2 nanorods on electrospun V 2 O 5 nanofibers by tuning the polyvinylpyrrolidone (PVP)/polyacrylonitrile (PAN) ratio in the precursor solution. PAN incorporation preserves the one-dimensional V 2 O 5 framework while progressively promoting the formation of vertically aligned RuO 2 nanorods. Structural and spectroscopic analyses reveal that PAN-induced thermal evolution modifies the surface chemistry of V 2 O 5 by increasing pyridinic nitrogen functionalities and oxygen-deficient surface sites. These surface characteristics are proposed to facilitate preferential Ru precursor nucleation, leading to anisotropic crystal growth without altering the crystal structures of either V 2 O 5 or RuO 2 . The optimized composition containing 50 wt % PAN exhibits the most homogeneous and vertically aligned RuO 2 nanorod arrays.
A three-position thermodynamic model of grain-boundary segregations in binary and ternary alloys is proposed that accounts for the finite grain size and the energetic inequivalence of sites at the boundary. The classical McLean and Fowler isotherms are generalized to the case of three types of sites (i.e., with negative, near-zero, and positive segregation energy). The model parameters are matched to the first moments of the skew-normal spectra of segregation energies E s obtained from atomistic and machine-learning calculations. For concentrated systems and ternary alloys, the equilibrium concentrations are obtained by minimization of the free energy of a system consisting of the bulk and grain boundaries, and the critical grain sizes are determined. The critical size L cr (1) is the grain size at which the grain interior is practically purified, the bulk concentration falling to nearly zero, while the boundary concentration undergoes a sharp break; L cr (2) is the grain size at which the integral degree of demixing is maximal. Both depend on temperature and on the average composition. In the dilute weak-segregation approximation, analytical expressions are also given for two characteristic sizes, L c (1) (half-depletion radius) and L c (2) , which locate a smooth crossover in this case. It is shown that, in the presence of sites with a tendency to antisegregation, the average boundary concentration in the low-temperature limit tends to a value lower than unity; with decreasing grain size, the impurity is exhausted first in the bulk and then in the sites with segregation energies of smaller absolute value. In ternary systems with competition for the same sites, “locking” effects of the components appear and the concentration–grain-size dependences can become non-monotonic. Size-effect analysis is performed for Ni–Cu and Ni–(Pd, Pt) alloys. A generalized phase diagram of the nanocrystalline Ni–Cu alloy is constructed that demonstrates the suppression of decomposition and the stabilization of the solid solution upon grain-size reduction. The model reveals qualitative features of segregation size effects that are inaccessible within the single-site approximation and can serve as a basis for the analysis of thermodynamic stability of nanocrystalline alloys.
In this study, a CuO/ZnFe2O4 heterostructure in the form of a flower, consisting of rod-like surface features associated with CuO on ZnFe2O4 microspheres, was successfully synthesized and evaluated for its catalytic reduction of chloramphenicol (CAP) in the presence of NaBH4. Structural and morphological analysis confirmed the successful formation of the heterostructure with enhanced contact between ZnFe2O4 and CuO. Compared to pure ZnFe2O4, the CuO/ZnFe2O4 catalyst exhibited significantly improved catalytic activity for CAP reduction. Reaction conditions strongly influenced reduction efficiency, with optimal performance at pH 6, a catalyst dosage of 2.5 g·L−1, and a short reaction time of 20 min. The enhanced catalytic performance under mild, environmentally friendly conditions highlights CuO’s crucial role in promoting surface electron transfer and facilitating reduction. Kinetic analysis at room temperature indicated a change in apparent kinetic behavior during the reaction, with pseudo-first-order behavior in the initial stage and a tendency toward zeroth-order behavior at later times. This evolution is consistent with the involvement of surface-mediated catalytic processes. Overall, the CuO/ZnFe2O4 heterostructure shows significant potential as an efficient catalyst for rapid CAP reduction under near-neutral conditions, offering a promising strategy for wastewater treatment.
Conventional contrast agents for magnetic resonance imaging (MRI) and computed tomography (CT) have long served as the backbone of diagnostic imaging. Yet, their well-recognized limitations, including nephrogenic systemic fibrosis and progressive gadolinium deposition with Gd-based chelates, contrast-induced nephropathy with iodinated agents, and serious hypersensitivity reactions with approved iron oxide formulations, continue to drive the search for safer alternatives. Nanoparticle-based contrast agents (NCAs) have emerged as a compelling next generation of imaging tools, offering a degree of rational design simply not achievable with small-molecule agents. By independently tuning core composition, hydrodynamic size, surface chemistry, and morphology, NCAs can be engineered to enhance relaxivity or X-ray attenuation, extend vascular residence time, direct clearance toward renal or hepatobiliary pathways, and carry targeting ligands for site-specific delivery. This review covers the principal NCA classes, iron oxide nanoparticles, gadolinium- and manganese-based nanomaterials, gold and copper nanostructures, carbon dots, lanthanide-doped upconversion nanocrystals, and quantum dots, examining their physicochemical design, pharmacokinetics, biocompatibility, and diagnostic performance across oncological and vascular applications. A recurring theme is the central role of size: Particles below the ≈6 nm glomerular filtration threshold undergo renal excretion and exhibit lower bioaccumulation risk, while larger formulations follow hepatobiliary routes with implications for long-term tissue retention. Surface coating, protein corona formation, and mononuclear phagocyte system recognition are discussed as equally decisive determinants of in vivo behavior, often outweighing core composition in their influence on clearance and tolerability. Across material classes, preclinical evidence consistently shows favorable safety profiles for well-engineered NCAs, with minimal hemolysis, low immunogenicity, and absence of histological organ injury at imaging-relevant doses, a meaningful contrast to the adverse effect profiles of conventional agents. On the efficacy side, targeted NCA formulations have demonstrated promising results across multiple tumor types, including breast, brain, liver, lung, and renal cancers, with receptor-specific designs enabling molecular-level lesion characterization that conventional agents cannot provide. Multimodal and theranostic constructs, combining MRI or CT contrast with concurrent therapeutic function, further illustrate the flexibility that nanoparticulate platforms offer. Blood–brain barrier penetration for neurooncological applications and the emerging potential of magnetic particle imaging as a future translational direction for platforms based on superparamagnetic iron oxide nanoparticles are also discussed. The translational gap between preclinical promise and clinical reality remains the field’s most honest challenge, rooted in the scarcity of long-term human safety data, the lack of standardized preclinical evaluation frameworks, and the demanding requirements of good-manufacturing-practice production at scale. Addressing these gaps, through unified safety pipelines, harmonized reporting standards, and early-phase trials that connect imaging performance to clinical outcomes, is what will ultimately determine whether NCAs fulfill their considerable potential in diagnostic medicine.
