Water samples from two naturally hypersaline lakes, renowned for their balneotherapeutic properties, were investigated through a pilot SERS monitoring program. Nanotechnology-based techniques were employed to periodically measure the ultra-sensitive SERS molecular characteristics of the raw water-bearing microbial community and the inorganic content. Employing the Pearson correlation coefficient revealed a robust linear relationship between electrical conductivity and pH and Raman and SERS spectral data of water samples, highlighting the interplay complexity of Raman/SERS signals and physicochemical parameters within each lake. The SERS data obtained from raw waters with AgNPs exhibited a dominant, reproducible SERS feature resembling adsorbed β-carotene at submicromole concentration, which could be related to the cyanobacteria-AgNPs interface and supported by TEM analyses. Notably, spurious SERS sampling cases showed molecular traces attributed to additional metabolites, suggesting multiplexed SERS signatures. The conducted PCA demonstrated observable differences in the β-carotene SERS band intensities between the two lakes, signifying potential variations in picoplankton abundance and composition or environmental influences. Moreover, the study examined variations in the SERS intensity ratio I₂₄₅/I₁₅₁₂, related to the balance between inorganic (Cl⁻-induced AgNPs aggregation) and organic (cyanobacteria population) balance, in correlation with the electrical conductivity. These findings signify the potential of SERS data for monitoring variations in microorganism concentration, clearly dependent on ion concentration and nutrient dynamics in raw, hypersaline water bodies.

The sustainable conversion of biogenic waste into high-value materials presents a promising approach for addressing environmental and industrial challenges. This work reports an advancement into antioxidant-enriched phosphate minerals derived from green conversion of biogenic calcium carbonates of crustaceans. We demonstrate the effectiveness of Raman technology in controlling conversion using phosphoric acid treatment. The effects of reaction parameters—including acid stoichiometry, granular size distribution, and thermal treatment at 700 °C and 1200 °C—were systematically evaluated. Raman spectroscopy results validated by X-ray diffraction (XRD) and SEM-EDX analyses revealed mixed-phase minerals monetite, brushite, whitlockite or hydroxylapatite resepectively. Notably, reducing particle size enhanced conversion efficiency by increasing the reactive surface area, while the use of excess phosphoric acid facilitated conversion to monocalcium phosphate and promoted the degradation of the organic matrix. Thermal treatment further altered the product composition: heating at 700 °C produced a whitlockite-rich phase, whereas treatment at 1200 °C shifted the balance toward hydroxylapatite. The synthesized calcium phosphate compounds, including hydroxylapatite, monocalcium phosphate, whitlockite, and brushite hold significant practical utility in biomedical applications (such as bone grafts and dental implants), agriculture, and industrial processing. Moreover, we have proven that by controlling the reaction parameters the final product composition can be tailored according to the specific needs, a greener approach yields brushite, monetite, or monocalcium phosphate while a more energy demanding process including heating to 1200 0C yields a high purity hydroxylapatite. This research offers a sustainable analytical route for producing high-purity calcium phosphate materials from wasted biomaterials, contributing to both bioeconomy as well as scientific innovation.

The sustainable conversion of biogenic waste into high-value materials presents a promising approach for addressing environmental and industrial challenges. This work reports an advancement into antioxidant-enriched phosphate minerals derived from green conversion of biogenic calcium carbonates of crustaceans. We demonstrate the effectiveness of Raman technology in controlling conversion using phosphoric acid treatment. The effects of reaction parameters—including acid stoichiometry, granular size distribution, and thermal treatment at 700 °C and 1200 °C—were systematically evaluated. Raman spectroscopy results validated by X-ray diffraction (XRD) and SEM-EDX analyses revealed mixed-phase minerals monetite, brushite, whitlockite or hydroxylapatite, respectively. Notably, reducing particle size enhanced conversion efficiency by increasing the reactive surface area, while the use of excess phosphoric acid facilitated conversion to monocalcium phosphate and promoted the degradation of the organic matrix. Thermal treatment further altered the product composition: heating at 700 °C produced a whitlockite-rich phase, whereas treatment at 1200 °C shifted the balance toward hydroxylapatite. The synthesized calcium phosphate compounds, including hydroxylapatite, monocalcium phosphate, whitlockite, and brushite, hold significant practical utility in biomedical applications (such as bone grafts and dental implants), agriculture, and industrial processing. Moreover, we have proven that by controlling the reaction parameters the final product composition can be tailored according to the specific needs. A greener approach yields brushite, monetite, or monocalcium phosphate, while a more energy-demanding process, including heating to 1200 °C, yields a high-purity hydroxylapatite. This research offers a sustainable analytical route for producing high-purity calcium phosphate materials from wasted biomaterials, contributing to both the bioeconomy as well as scientific innovation.

This pilot study uses Raman spectroscopy and SERS to monitor monthly water composition changes in two adjacent hypersaline lakes (L1 and L2) at a balneary resort, during the peak tourist season (May–October 2023). In situ pH and electrical conductivity (EC) measurements, along with evaporite analyses, complemented the spectroscopic data. Although traditionally considered similar, the lakes frequently raise public questions about their relative bathing benefits. While not directly addressing the therapeutic effects, the study reveals distinct physicochemical profiles between the lakes. Raman data showed consistently higher sulfate levels in L2, a trend also observed in winter monitoring. pH levels were higher in L1 (8–9.8) than in L2 (7.2–8), except for one October depth reading. This trend held during winter, except in April. Surface waters showed more variability and slightly higher values than those at 1 m depth. SERS spectra featured β-carotene peaks, linked to cyanobacteria, and Ag–Cl bands, indicating nanoparticle aggregation from inorganic ions. SERS intensity strongly correlated with pH and EC, especially in L2 (r = 0.96), suggesting stable surface–depth chemistry. L1 exhibited more monthly variability, likely due to differing biological activity. Although salinity and EC were not linearly correlated at high salt levels, both reflected seasonal trends. The integration of Raman, SERS, and physicochemical data proves effective for monitoring hypersaline lake dynamics, offering a valuable tool for environmental surveillance and therapeutic water quality assessment, in support of evidence-based water management and therapeutic use of salt lakes, aligning with goals for sustainable medical tourism and environmental stewardship.

Seafood-derived carbonate waste, primarily calcium carbonate (CaCO₃), has attracted growing interest for sustainable reuse, yet the unique potential of aged biogenic sources remains underexplored. Blue crab (Callinectes sapidus) shells are particularly distinctive: they consist of Mg-calcite with an intrinsic 3D-porous structure and naturally embedded astaxanthin, a potent antioxidant not found in other calcite- or aragonite-based residues. While organic degradation over time is often assumed to compromise functionality, this study demonstrates that five-years-aged crustacean shell waste retains both its crystallinity and bioactive carotenoids after calibrated ball milling. Across four powder batches produced under distinct milling conditions by varying frequencies and durations, dynamic light scattering confirmed only subtle particle size variation, while Raman spectroscopy, XRD, FT-IR, and SEM-EDX confirmed structural and chemical integrity and highlighted the subtle amorphization induced by slightly different milling parameters, which, in turn, driven to slightly different conversion efficiency into phosphate mineral. Strikingly, all powders underwent rapid transformation into dicalcium phosphate dihydrate (brushite) enriched with carotenoids upon reaction with phosphoric acid. This work reveals, for the first time, that years-aged biogenic Mg-calcite waste not only preserves its naturally embedded carotenoids but also offers a direct route to functional phosphate composites, establishing its untapped value in environmental and biomedical applications.

Biogenic carbonate waste from seafood exploitation, primarily composed of calcium carbonate (CaCO₃), occurs in various polymorphic forms, making it valuable for envi-ronmental and biomedical applications. Mg-calcite from blue crab (Callinectes sapidus) shells is especially promising due to its 3D-ordered porosity and naturally embedded astaxanthin antioxidant, offering advantages over other calcite- or aragonite-based waste. These properties enable its use in pharmaceutical formulations and biostimulants for ac-tive compound loading and controlled release. However, long-term aged biogenic waste may experience organic degradation, potentially altering its physical, chemical, and functional performance. In this study, calibrated ball milling conditions were applied to years-aged biogenic waste to assess structural integrity, crystallinity, and functionality of the resulting powders. Notably, the antioxidant carotenoid remained preserved across all fine powders. Dynamic light scattering revealed that particle size distribution varied subtly between two milling durations (12 and 15 min) and frequencies (25 and 27 Hz). Pigmentation, crystallinity, and repurposing potential of the powders were investigated using Raman spectroscopy, X-ray diffraction (XRD), FT-IR, and SEM-EDX. Ultimately, all four powder batches showed successful conversion into phosphate minerals enriched with antioxidants when treated with phosphoric acid, highlighting the potential of aged shell waste in high-value applications under optimized mechanical and chemical condi-tions.