Methylmercury (CH3Hg+) is the most toxic form of mercury found in fish, shellfish, and other aquatic organisms and poses significant risks to human health through the food chain. The present study reports the development of a fluorescence aptasensor for the quantification of CH3Hg+ using aptamer-functionalized gold nanostars (AuNSs) and complementary DNA-functionalized alendronic acid-modified upconversion nanoparticles (ADA-UCNPs). The ADA-UCNPs-AuNSs fluorescence aptasensor employed an on-off detection mode and completed the detection within 60 min. The developed fluorescence aptasensor exhibited a good linear response to CH3Hg+ over the concentration range of 0.5 to 20.0 µM, with a limit of detection of 0.37 µM. The aptasensor exhibited satisfactory accuracy and precision, with relative standard deviations within the evaluated CH3Hg+ concentration range and recoveries of 91.00% to 99.20% in aquatic products. The newly constructed aptasensor also showed satisfactory selectivity and resistance to interference and maintained good stability, supporting its potential for practical application in food monitoring.

The synthesis and characterization of six new phosphonate linkers and their coordination networks are reported in this paper. All have the s-triazine heterocyclic core as a common structural feature and display mono- or di-substitution by aminoalkyl-phosphonate grafts. The phosphonate-bearing, amine-containing nucleophiles used for the substitution were amino-bis(methylenephosphonate) (ABMP), (3-amino-1-hydroxypropane-1,1-diyl)bis(phosphonic acid) (pamidronate, PAM), (4-amino-1-hydroxy-1-phosphonobutyl)phosphonic acid (alendronate, ALE), and (6-amino-1-hydroxyhexane-1,1-diyl)bis(phosphonic acid) (neridronate, NER). ABMP features a secondary amine, and PAM, ALE, and NER feature primary amines. The products isolated were Tr-1ABMP, Tr-1PAM, Tr-2PAM, Tr-1ALE, Tr-2ALE, and Tr-2NER (Tr = triazine; the numbers 1 and 2 indicate mono- and di-substitution). These ligands were used to synthesise coordination networks with alkaline earth metal ions. The crystal structures of three derivatives, namely Sr-Tr-1ABMP (2D), Ca-Tr-1PAM (1D), and Sr-Tr-2NER (1D), reveal the rich coordination chemistry and potential of these ligands. Tr-1PAM and Tr-2NER use only their phosphonate moieties for coordination, whereas Tr-1ABMP employs also the N and O atoms from the triazine ring. None of the structures display π-π stacking interactions. The structures of the metal derivatives are analysed and compared to several triazine-containing literature examples to determine the electronic and protonation state of the triazine ring. The triazine ring and external N atoms in the compounds Ca-Tr-1PAM, Sr-Tr-1ABMP, and Sr-Tr-2NER are planar, in agreement with the extended planarity concept. The protonation state of the triazine ring depends on the synthesis pH. The triazine ring is neutral (non-protonated) in Sr-Tr-1ABMP, but one of the N atoms is protonated in Ca-Tr-1PAM and Sr-Tr-2NER. This research establishes a promising entry to the coordination chemistry of phosphonate-substituted triazine rings. Such ligands can enrich the phosphorus synthetic chemist's "toolbox" for the creation of new coordination networks with diverse structure types.

Bone tissue engineering has made significant advances in recent years; however, the development of scaffolds that not only support tissue regeneration but also effectively deliver therapeutic agents remains a major challenge. The present study investigates the fabrication and evaluation of 3D-printed polycaprolactone (PCL)/layered double hydroxide (LDH) hybrid scaffolds incorporating alendronate (ALN) for bone tissue engineering applications. First, LDH particles were synthesized via a co-precipitation method and loaded with ALN. Subsequently, scaffolds with varying PCL-to-LDH ratios (2 : 1, 3 : 1, 4 : 1, and 5 : 1) were fabricated and characterized. Field emission scanning electron microscopy (FE-SEM) revealed the characteristic hexagonal morphology of the LDH particles, while X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) analyses confirmed the successful intercalation of ALN into the LDH structure. Among the different formulations, the scaffold with a PCL-to-LDH ratio of 2 : 1 exhibited the best overall performance. The incorporation of LDH into this scaffold improved hydrophilicity, reducing the water contact angle from ∼90° to 60°, increasing the ultimate tensile strength from ∼30 to 90 MPa, enhancing the elastic modulus from ∼350 to 750 MPa, and reducing the elongation at break from ∼170% to 50%. Furthermore, ALN was uniformly dispersed within the polymer matrix, resulting in a highly similar biphasic drug release profile consisting of a slight initial burst release during the first 7 days, followed by a sustained release phase extending up to 28 days. Biological evaluations, including MTT assays, cell adhesion studies, and alkaline phosphatase (ALP) activity measurements, further demonstrated that this scaffold promoted superior cell viability, attachment, and osteogenic differentiation. These findings indicate that the 3D-printed scaffold with a PCL-to-LDH ratio of 2 : 1 is a promising platform for localized ALN delivery and bone tissue engineering applications.

Levothyroxine (LT4), a synthetic thyroid hormone used in the treatment of hypothyroidism, may interact with co-administered drugs and metal ions, potentially influencing its distribution and bioavailability. In this study, steady-state fluorescence spectroscopy was used to examine the interactions of bovine serum albumin (BSA) with LT4, ciprofloxacin, sodium alendronate, and selected metal ions (Fe[3+], Al[3+], and Ca[2+]), both individually and in LT4-containing systems. Fluorescence-quenching and apparent binding parameters were evaluated using Stern-Volmer and reciprocal binding analyses. LT4 and ciprofloxacin exhibited moderate-to-strong apparent interactions with BSA, with Ka,app values of 2.73 × 10[5] and 2.94 × 10[5] M[-1], respectively, whereas sodium alendronate showed weaker association. Fe[3+] produced the strongest quenching response and the highest apparent binding parameter (2.92 × 10[8] M[-1]); this value was interpreted cautiously because strong quenching, hydrolysis, phosphate coordination, and ion-speciation effects may contribute to the observed response. LT4 markedly attenuated the apparent Fe[3+]- and Al[3+]-associated interactions, moderately reduced the ciprofloxacin response, modestly affected Ca[2+], and produced little change in sodium alendronate association. Temperature-controlled fluorescence measurements at 298.15, 303.15, and 308.15 K were used for three-point Van't Hoff analysis, yielding apparent ΔG, ΔH, and ΔS values with unaltered fit statistics and regression-only uncertainty estimates. Overall, the results reveal ligand-dependent differences in BSA interaction and identify Fe[3+] and Al[3+] as the systems most strongly modulated by LT4 while supporting cautious physiological interpretation.

Osteoporosis in men is under-recognized and under-treated despite a substantial disease burden and poorer fracture-related outcomes than in women. Secondary osteoporosis is highly prevalent in men, making the identification and management of underlying causes essential. Bone mineral density (BMD) and fracture risk are influenced by sex-specific patterns of skeletal growth and age-related bone loss, with men typically exhibiting greater cortical thickness, larger bone size, and trabecular thinning rather than loss of trabecular number. Although randomized controlled trials in men are fewer than in postmenopausal women, bisphosphonates, denosumab, teriparatide, abaloparatide, and romosozumab have all been shown to significantly increase BMD. Fracture outcome data remain limited; however, reductions in vertebral fracture risk have been demonstrated for zoledronate, alendronate, risedronate, denosumab, and teriparatide. Treatment should be individualized according to fracture risk, comorbidities, and patient preferences. In men at very high fracture risk, osteoanabolic therapy should be considered as first-line treatment, followed by antiresorptive therapy to consolidate and maintain BMD gains. Goal-directed (treat-to-target) management, including long-term maintenance therapy, and careful discontinuation strategies, particularly following denosumab, is essential for optimizing long-term skeletal health. This narrative review and position statement by The ECTS Clinical Action Group provides an updated overview of current and emerging treatment options and offers practical, evidence-based recommendations for the long-term management of osteoporosis in men.

Medication-related osteonecrosis of the external auditory canal (MROEAC) is a rare complication of antiresorptive therapy, and guidance for diagnosis and management remains limited. We describe 2 patients with prolonged antiresorptive exposure who developed MROEAC and were treated with teriparatide. An 81-year-old woman developed bilateral external auditory canal erosions after 10 years of denosumab therapy. An 8-week course of teriparatide was associated with clinical improvement and a transient rise in bone formation markers, but computed tomography findings remained unchanged. Denosumab withdrawal led to delayed rebound bone resorption, prompting denosumab reintroduction. A 67-year-old woman developed left-sided MROEAC after 15 years of alendronate followed by a short course of denosumab. Four months of teriparatide was associated with symptomatic and biochemical improvement, but radiologic abnormalities persisted, and definitive surgery was required. These cases highlight the difficulty of differentiating MROEAC from more common otologic disorders, the discordance between clinical, biochemical, and radiologic response, the importance of multidisciplinary management, and therapeutic challenges created by denosumab discontinuation. Teriparatide was well tolerated and was associated with increased bone turnover markers, but radiologic resolution was incomplete. Surgical management may still be necessary.

Prolonged unloading of the shoulder, most seen after stroke related hemiparesis, accelerates degeneration of the supraspinatus enthesis in part through localized bone loss at the tendon to bone interface. Because bisphosphonates are often used in populations experiencing disuse, it remains unclear whether they can mitigate bone deterioration at the supraspinatus enthesis. In this study, we examined how unloading and alendronate treatment influence bone architecture, mineral composition, cellular activity, and mechanical behavior at the supraspinatus enthesis using a 24-day murine model of botulinum toxin induced supraspinatus paralysis. Unloading produced significant trabecular deterioration, including reduced bone volume fraction and trabecular thickness, while fibrocartilage morphology and tendon area remained unchanged. Alendronate did not prevent structural bone loss, though it produced clear compositional changes such as increased carbonate substitution. Mineral to matrix ratio, crystallinity, and phosphate peak position did not differ significantly across any of the four treatment groups: under disuse- conditions, bisphosphonate treatment, or combined condition with bisphosphonate. Histomorphometry showed no differences in osteoblast or osteoclast number or surface, suggesting that bone loss occurs primarily through suppressed formation rather than elevated resorption. Because osteoclast number and surface were unchanged, elevated resorption is unlikely to account for observed bone loss. Osteoblast number and surface were similarly unaffected, indicating that any deficit in formation is more likely attributable to reduced activity per cell rather than to a reduction in osteoblast recruitment or abundance. Mechanical testing demonstrated that unloading reduced supraspinatus humerus complex strength and modulus. Although alendronate did not preserve trabecular structure, it produced a non-significant trend toward higher complex level strength, raising the possibility that material-level changes can influence failure independently of architecture. However, combined unloading and turnover suppression reduced post yield properties, highlighting tradeoffs for enthesis quality under low load conditions. These findings show that disuse induced bone loss at the supraspinatus enthesis is driven by formation and that bisphosphonates, while modifying mineral composition, do not prevent structural degeneration.