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Like citrate, the molecule hydroxycitrate is shown to inhibit growth of the crystal that is the principal component of kidney stones, suggesting that hydroxycitrate could be another treatment for kidney stone disease. Novel inhibitor action on 'kidney stone' crystal growth This paper reports that both citrate and hydroxycitrate molecules are able to inhibit growth of crystals of calcium oxalate monohydrate — the principal component of kidney stones — even in a supersaturated solution where the inhibitor concentration is far smaller than the concentration of the solutes. The mechanism for crystal growth inhibition diverges from the classical picture of such processes: atomic force microscopy images and other data point to a mechanism in which inhibitor–crystal interactions impart localized strain to the crystal lattice that are alleviated by oxalate and calcium ions. Potassium citrate is an established treatment for kidney stone disease and the authors suggest that the clinical potential of hydroxycitrate might also be worth exploring and report preliminary in vitro investigations to support this suggestion. Crystalline materials are crucial to the function of living organisms, in the shells of molluscs 1 , 2 , 3 , the matrix of bone 4 , the teeth of sea urchins 5 , and the exoskeletons of coccoliths 6 . However, pathological biomineralization can be an undesirable crystallization process associated with human diseases 7 , 8 , 9 . The crystal growth of biogenic, natural and synthetic materials may be regulated by the action of modifiers, most commonly inhibitors, which range from small ions and molecules 10 , 11 to large macromolecules 12 . Inhibitors adsorb on crystal surfaces and impede the addition of solute, thereby reducing the rate of growth 13 , 14 . Complex inhibitor–crystal interactions in biomineralization are often not well elucidated 15 . Here we show that two molecular inhibitors of calcium oxalate monohydrate crystallization—citrate and hydroxycitrate—exhibit a mechanism that differs from classical theory in that inhibitor adsorption on crystal surfaces induces dissolution of the crystal under specific conditions rather than a reduced rate of crystal growth. This phenomenon occurs even in supersaturated solutions where inhibitor concentration is three orders of magnitude less than that of the solute. The results of bulk crystallization, in situ atomic force microscopy, and density functional theory studies are qualitatively consistent with a hypothesis that inhibitor–crystal interactions impart localized strain to the crystal lattice and that oxalate and calcium ions are released into solution to alleviate this strain. Calcium oxalate monohydrate is the principal component of human kidney stones 16 , 17 , 18 , 19 and citrate is an often-used therapy 20 , but hydroxycitrate is not. For hydroxycitrate to function as a kidney stone treatment, it must be excreted in urine. We report that hydroxycitrate ingested by non-stone-forming humans at an often-recommended dose leads to substantial urinary excretion. In vitro assays using human urine reveal that the molecular modifier hydroxycitrate is as effective an inhibitor of nucleation of calcium oxalate monohydrate nucleation as is citrate. Our findings support exploration of the clinical potential of hydroxycitrate as an alternative treatment to citrate for kidney stones.

Efforts to recreate a prebiotically plausible protocell, in which RNA replication occurs within a fatty acid vesicle, have been stalled by the destabilizing effect of Mg²⁺ on fatty acid membranes. Here we report that the presence of citrate protects fatty acid membranes from the disruptive effects of high Mg²⁺ ion concentrations while allowing RNA copying to proceed, while also protecting single-stranded RNA from Mg²⁺-catalyzed degradation. This combination of properties has allowed us to demonstrate the chemical copying of RNA templates inside fatty acid vesicles, which in turn allows for an increase in copying efficiency by bathing the vesicles in a continuously refreshed solution of activated nucleotides.

Nanocrystals of apatitic calcium phosphate impart the organic-inorganic nanocomposite in bone with favorable mechanical properties. So far, the factors preventing crystal growth beyond the favorable thickness of ca. 3 nm have not been identified. Here we show that the apatite surfaces are studded with strongly bound citrate molecules, whose signals have been identified unambiguously by multinuclear magnetic resonance (NMR) analysis. NMR reveals that bound citrate accounts for 5.5 wt% of the organic matter in bone and covers apatite at a density of about 1 molecule per (2 nm)², with its three carboxylate groups at distances of 0.3 to 0.45 nm from the apatite surface. Bound citrate is highly conserved, being found in fish, avian, and mammalian bone, which indicates its critical role in interfering with crystal thickening and stabilizing the apatite nanocrystals in bone.

Silver nanoparticles (AgNPs) have tremendous potentials in medical devices due to their excellent antimicrobial properties. Blood compatibility should be investigated for AgNPs due to the potential blood contact. However, so far, most studies are not systematic and have not provided insights into the mechanisms for blood compatibility of AgNPs. In this study, we have investigated the blood biological effects, including hemolysis, lymphocyte proliferation, platelet aggregation, coagulation and complement activation, of 20 nm AgNPs with two different surface coatings (polyvinyl pyrrolidone and citrate). Our results have revealed AgNPs could elicit hemolysis and severely impact the proliferation and viability of lymphocytes at all investigated concentrations (10, 20, 40 μg/mL). Nevertheless, AgNPs didn’t show any effect on platelet aggregation, coagulation process, or complement activation at up to ~40 μg/mL. Proteomic analysis on AgNPs plasma proteins corona has revealed that acidic and small molecular weight blood plasma proteins were preferentially adsorbed onto AgNPs, and these include some important proteins relevant to hemostasis, coagulation, platelet, complement activation and immune responses. The predicted biological effects of AgNPs by proteomic analysis are mostly consistent with our experimental data since there were few C3 components on AgNPs and more negative than positive factors involving platelet aggregation and thrombosis.

Antifreeze proteins (AFPs) are specific proteins that are able to lower the freezing point of aqueous solutions relative to the melting point. Hyperactive AFPs, identified in insects, have an especially high ability to depress the freezing point by far exceeding the abilities of other AFPs. In previous studies, we postulated that the activity of AFPs can be attributed to two distinct molecular mechanisms: (i) short-range direct interaction of the protein surface with the growing ice face and (ii) long-range interaction by protein-induced water dynamics extending up to 20 Å from the protein surface. In the present paper, we combine terahertz spectroscopy and molecular simulations to prove that long-range protein–water interactions make essential contributions to the high antifreeze activity of insect AFPs from the beetle Dendroides canadensis . We also support our hypothesis by studying the effect of the addition of the osmolyte sodium citrate.

The growing demand for sustainable food packaging has driven the development of active packaging systems using biopolymers like poly(lactic acid) (PLA) and natural antimicrobials. This study focuses on creating novel nanohybrids by loading carvacrol (CV) and -cinnamaldehyde ( CN) onto ZnO nanorods for incorporation into PLA/triethyl citrate (TEC) films. The CV@ZnO and CN@ZnO nanohybrids were synthesized and characterized using XRD, FTIR, desorption kinetics, and by assessing their antioxidant and antibacterial properties. These nanohybrids were then integrated into PLA/TEC films via extrusion. The resulting active films were evaluated for their physicochemical, mechanical, barrier, antioxidant, and antibacterial properties. The CN@ZnO nanohybrid exhibited a stronger interaction with the ZnO surface and a slower release rate compared to CV@ZnO. While this strong interaction limited its direct antioxidant activity, it proved highly beneficial for the final film's performance. Films containing 10% CN@ZnO demonstrated the strongest antibacterial efficacy in vitro against and and functioned as potent mechanical reinforcement fillers. Crucially, in a practical application, the PLA/TEC/10 CN@ZnO film significantly extended the shelf-life of fresh minced pork during 6 days of refrigerated storage. It effectively suppressed microbial growth (TVC), delayed lipid oxidation (lower TBARS values), and preserved the meat's colour and nutritional quality (higher heme iron content) compared to control packaging. The developed CN@ZnO nanohybrid is confirmed to be a highly effective active agent for creating PLA/TEC-based packaging that can enhance the preservation of perishable foods.

Biodegradable poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL) composite films were prepared with a compatibilizer (tributyl citrate, TBC) using a solvent casting method. Incorporation of 5% TBC (w/v, of PCL weight) improved tensile strength and elongation at break (21.93 ± 2.33 MPa and 21.02 ± 1.54%, respectively) and reduced water vapor permeability (from 0.12 ± 0.01 to 0.098 ± 0.01 g·mm·m2·h·kPa), indicating improved compatibility between PLA and PCL. Staphylococcus aureus phage PBSA08 demonstrated rapid and persistent bacteriolytic activity for up to 24 h, suggesting its potential as a promising antibacterial biological agent. To impart antibacterial properties to the developed PLA/PCL/TBC film, PBSA08 was loaded into sodium alginate (SA) and coated on the film surface. The optimal composition was 3% (w/v) SA and 3% (w/v) glycerol, which exhibited suitable dynamic behavior as a coating solution and excellent adhesion to the film surface. The phage-coated antibacterial films demonstrated progressive and significant inhibition against S. aureus starting from 10 to 24 h, with controlled phage-release properties. Overall, the developed active film might exert sustained and remarkable antibacterial effects through controlled release of biological agents (phage) under realistic packaging conditions.

Due to their potent antibacterial properties, silver nanoparticles (AgNPs) are widely used in industry and medicine. However, they can cross the brain–blood barrier, posing a risk to the brain and its functions. In our previous study, we demonstrated that oral administration of bovine serum albumin (BSA)-coated AgNPs caused an impairment in spatial memory in a dose-independent manner. In this study, we evaluated the effects of AgNPs coating material on cognition, spatial memory functioning, and neurotransmitter levels in rat hippocampus. AgNPs coated with BSA (AgNPs(BSA)), polyethylene glycol (AgNPs(PEG)), or citrate (AgNPs(Cit)) or silver ions (Ag+) were orally administered at a dose of 0.5 mg/kg b.w. to male Wistar rats for a period of 28 days, while the control (Ctrl) rats received 0.2 mL of water. The acquisition and maintenance of spatial memory related to place avoidance were assessed using the active allothetic place avoidance task, in which rats from AgNPs(BSA), AgNPs(PEG), and Ag+ groups performed worse than the Ctrl rats. In the retrieval test assessing long-term memory, only rats from AgNPs(Cit) and Ctrl groups showed memory maintenance. The analysis of neurotransmitter levels indicated that the ratio between serotonin and dopamine concentration was disturbed in the AgNPs(BSA) rats. Furthermore, treatment with AgNPs or Ag+ resulted in the induction of peripheral inflammation, which was reflected by the alterations in the levels of serum inflammatory mediators. In conclusion, depending on the coating material used for their stabilization, AgNPs induced changes in memory functioning and concentration of neurotransmitters.

In this study, the protein and salts distribution (Ca, P, Na and Mg) in processed cheese (PC) samples prepared with 180 or 360 mEq/kg of the calcium sequestering salts (CSS) disodium phosphate (DSP), disodium pyrophosphate (DSPP), sodium hexametaphosphate (SHMP) and trisodium citrate (TSC) was studied. For this purpose, a water-soluble extract (WSE) of PC samples was prepared. All PC samples contained 45–46% moisture, 26–27% fat and 20–21% protein and had a pH of 5.2 or 5.7. Ultracentrifugation slightly reduced the protein content of the WSE of PC, indicating that most protein in the WSE was non-sedimentable. At equal concentration of CSS, the protein content of the WSE was higher for PC at pH 5.7 compared to PC at pH 5.2. Approximately 55–85% of the Ca and P in the WSE of samples was 10 kDa-permeable for PC prepared with DSPP and SHMP. This suggests that the formation of non-permeable Ca–polyphosphate–casein complexes. For PC prepared with TSC, >90% of Ca in the WSE was 10 kDa-permeable, indicating that micellar disruption arises from sequestration of micellar Ca. These results indicate that the WSE method is an appropriate method to understand how salts present in PC are distributed. However, the WSE and ultracentrifugal supernatant of the WSE can include both soluble and protein-associated salts. Therefore, determining levels of salts in 10 kDa permeate of ultracentrifugal supernatant of the WSE is most appropriate.