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Recent research has increasingly focused on synthesizing nanoparticles (NPs) through various methods to determine how these processes influence their characteristics, and consequently, their biological activity. Calcium zinc hydroxide dihydrate (CaZn2(OH)6·2H2O) nanoparticles, designates as CZ, were obtained via sol–gel (CZ-SG), hydrothermal (CZ-HT), and microwave (CZ-MW) methods, and their properties were characterized using XRD, SEM, TEM, and BET analyses. The different synthesis revealed distinct CZ nanoparticle attributes, including variations in crystallite sizes (72 nm for CZ-SG, 65 nm for CZ-HT and CZ-MW) and morphologies (fibrous for CZ-HT and spherical agglomerates for CZ-SG and CZ-MW). Surface area analysis showed low values across all synthesis methods, with CZ-HT exhibiting the best surface area (8.154 m2/g). The investigation also explored how these synthesis routes influence antifungal efficacy against fourteen fungal strains associated with the biodeterioration of limestone cultural heritage structures. Our results highlight the notable antifungal activity of CZ-NPs, particularly those synthesized via the CZ-HT method, which demonstrated the most effective antifungal action as evidenced by the lowest minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC). This effectiveness is attributed to the unique fibrous morphology, which proves to be highly inhibitory to fungal cell proliferation. These findings not only advance our understanding of CZ NPs-mediated antifungal mechanisms but also open a new effort for the development of effective preservation strategies for cultural heritage conservation. [ABSTRACT FROM AUTHOR]

Fungal growth on construction materials in tropical climates can degrade aesthetics and manifestations on modern and historical sick buildings, affecting the health of their inhabitants. This study synthesized ZnO nanoparticles with enhanced antifungal properties using a precipitation method. Different concentrations (25%, 50%, and 100%) of Eichhornia crassipes aqueous extract were used with Zn(NO3)2·6H2O as the precursor to evaluate their spectroscopic, morphological, textural, and antifungal properties. X-ray diffraction confirmed the hexagonal wurtzite phase of ZnO with crystallite sizes up to 20 nm. Fourier-transform infrared spectroscopy identified absorption bands at 426, 503, and 567 cm−1 for ZnO-100, ZnO-50, and ZnO-25, respectively. Nitrogen physisorption indicated a type II isotherm with macropores and a fractal dimension coefficient near 2 across all concentrations. Polydispersity index analysis showed that ZnO-50 had a higher PDI, indicating a broader size distribution, while ZnO-25 and ZnO-100 exhibited lower PDI values, reflecting uniform and monodisperse particle sizes. FESEM observations revealed semi-spherical ZnO morphologies prone to agglomeration, particularly in ZnO-25. Antifungal tests highlighted ZnO-25 as the most effective, especially against Phoma sp. with an MFC/MIC ratio of 78 µg/mL. Poisoned plate assays demonstrated over 50% inhibition at 312 µg/mL for all tested fungi, outperforming commercial antifungals. The results indicate that ZnO NPs synthesized using E. crassipes extract effectively inhibit fungal growth on construction materials. This procedure offers a practical approach to improving the durability of building aesthetics and may contribute to reducing the health risks associated with exposure to fungal compounds. [ABSTRACT FROM AUTHOR]

A series of poly[2-(dimethylamino)ethyl methacrylate]s (PDMAEMAs) of different molar mass were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymers were subsequently treated with two different alkyl halides (1-iodobutane (BuI) and iodomethane (MeI)) to obtain a library of 21 PDMAEMAs with different degree of quaternization (DQ). This is the first report where the antifungal activity of these polymers is assessed for different fungi relevant in biomineralization and aesthetic biodeterioration of stone surfaces. The antifungal activity was assessed with the minimum inhibitory concentration (MIC), the minimum fungicidal concentration (MFC) and the mycelia growth inhibition in plate for the most promising materials. The obtained results demonstrated that all evaluated polymers possess certain level of antifungal activity against the evaluated fungi (even unquaternized PDMAEMAs). However, polymers of low molar mass (series III) revealed predominantly fungicidal activity at low values of MFC (from 2500 to 9.7 μg mL−1). Unexpectedly, the performed mycelia growth inhibition tests showed that the DQ has a less significant effect on the antifungal properties of the polymers than the polymer molar mass. Hence, the antifungal activity of these polymers may depend to a great extent on the physiological and morphological characteristics of the fungi, wherein the best antifungal activity was observed in III-M2, III-B1 and III-B2. It is worth mentioning that this detailed screening contributes to a better understanding of PDMAEMA-based composites that can be utilized in the development and optimization of low-cost and accessible antimicrobial protective coatings for petrous surfaces in cultural heritage monuments or modern buildings. [Display omitted] • Antifungal activity of PDMAEMA derivatives against relevant biodeterioration fungi. • Most of PDMAEMAs were fungicide and some fungistatic as well. • A better fungicide performance was observed for PDMAEMAs of low molar mass. • PDMAEMAs could be applied as coatings for conservation of petrous surfaces. [ABSTRACT FROM AUTHOR]

• The photocatalytic activity improves as the concentration of Ca(OH) 2 increases in mixtures with CZ. • The addition of low concentration of Ca(OH) 2 to CaZn 2 (OH) 6 •2H 2 O improves the fungicidal action. • The synergy of CZ and Ca(OH) 2 can consolidate the rock and inhibit antifungal growth. • Stability of CZ in solution improves with low proportions of Ca(OH) 2. The antifungal and photocatalytic activity of mixed compounds of double hydroxide [CaZn 2 (OH) 6 •2H 2 O] with portlandite [Ca(OH) 2 ] synthesized via sol-gel were evaluated. The compound was tested by in vitro assay to determine its antifungal activity using the agar diffusion and broth microdilution assays, applied to the fungal models: Aspergillus niger and Penicillium oxalicum. Also, these compounds were characterized by X-ray diffraction, infrared spectroscopy, dynamic light scattering, and its morphological structure was identified by HR-SEM and TEM-SAED which shows agglomerated particles formed by nanoparticle sizes between 100−500 nm, which are correlated whit hydrodynamic radio around 155 nm. Additionally, in the relation of microbiological assays, the outstanding minimum inhibitory concentration of unmixed calcium zincate hydroxide dihydrate (CZ) correspond to 156 μg/mL, however, when is mixed with 10 % of Ca(OH) 2 diminishes up to 78 μg/mL, indistinctively of the evaluated fungus. Likewise, a photocatalytic degradation test was carried out with methylene blue dye as a model organic pollutant, reaching an efficiency of ∼92 %. Our results suggest that low concentrations of Ca(OH) 2 improve the antifungal activity of CZ, without altering the solution stability, the photocatalytic and chemical properties of the compounds. Therefore, the compatibility with the limestone of both materials can be proposed as an excellent product to avoid fungal biodeterioration. [ABSTRACT FROM AUTHOR]