Highly stable luminescent europium-doped calcium phosphate nanoparticles for creatinine quantification

Nitrogen doped carbon dots and gold nanoparticles mediated FRET for the detection of creatinine in human urine samples

Serum creatinine (CR) is regarded as one of the most sought out prognostic biomarkers in medical evaluation of chronic kidney disease (CKD). In light of the diagnostic significance of CR, the utility of a fluorescence biosensor for its detection in human urine specimens has been explored based on Förster resonance energy transfer (FRET) across nitrogen-doped carbon dots (N-CDs) and gold nanoparticles (GNPs). A straightforward microwave-assisted synthesis procedure has been adopted to prepare N-CDs (λexcitation = 400 nm, λemission = 540 ± 5 nm) with bright green emissions. On addition of pre-synthesized GNPs, the radiative emanation of the N-CDs is completely suppressed on account of FRET across the N-CDs and the GNPs. About 77 % of their fluorescence intensity is recovered after adding CR to GNPs@N-CDs nanocomposite. The limit of detection for CR sensing is estimated as 0.02 µg•mL-1. This biosensor is selective enough to recognize CR in the existence of potential interfering substances (e.g., ascorbic acid, glucose, glutathione, urea, and electrolytes). Its practical utility for CR detection has been validated further on the basis of satisfactory correlation with the benchmark Jaffe method, as observed in artificial/human urine specimens. Consequently, this manuscript marks a pioneering report on employing CDs and GNPs-based FRET for identifying CR in urine specimens of CKD patients.

Tailoring the structure and self-activated photoluminescence of carbonated amorphous calcium phosphate nanoparticles for bioimaging applications

Self-activated luminescent calcium phosphate (CaP) nanoparticles, including hydroxyapatite (HA) and amorphous calcium phosphate (ACP), are promising for bioimaging and theragnostic applications in nanomedicine, eliminating the need for activator ions or fluorophores. In this study, we developed luminescent and stable citrate-functionalized carbonated ACP nanoparticles for bioimaging purposes. Our findings revealed that both the CO32- content and the posterior heating step at 400 °C significantly influenced the composition and the structural ordering of the chemically precipitated ACP nanoparticles, impacting the intensity, broadness, and position of the defect-related photoluminescence (PL) emission band. The heat-treated samples also exhibited excitation-dependent PL under excitation wavelengths typically used in bioimaging (λexc = 405, 488, 561, and 640 nm). Citrate functionalization improved the PL intensity of the nanoparticles by inhibiting non-radiative deactivation mechanisms in solution. Additionally, it resulted in an increased colloidal stability and reduced aggregation, high stability of the metastable amorphous phase and the PL emission for at least 96 h in water and supplemented culture medium. MTT assay of HepaRG cells, incubated for 24 and 48 h with the nanoparticles in concentrations ranging from 10 to 320 μg mL-1, evidenced their high biocompatibility. Internalization studies using the nanoparticles self-activated luminescence showed that cellular uptake of the nanoparticles is both time (4-24 h) and concentration (160-320 μg mL-1) dependent. Experiments using confocal laser scanning microscopy allowed the successful imaging of the nanoparticles inside cells via their intrinsic PL after 4 h of incubation. Our results highlight the potential use of citrate-functionalized carbonated ACP nanoparticles for use in internalization assays and bioimaging procedures.

Green Synthesis and the Evaluation of Osteogenic Potential of Novel Europium-Doped-Monetite Calcium Phosphate by Cissus quadrangularis

Background The quest for an ideal bone grafting material has been ongoing for decades. Calcium phosphate, alone or in combination with other materials in natural bone, has been shown to aid in bone regeneration effectively. Monetite exhibits superior solubility and resorption rates among calcium phosphates, rendering it an optimal choice for bone regeneration applications. However, the degradation rate of the Monetite is much faster than that of all the other calcium phosphates. Hence, we have added Europium onto the matrix to alter the degradation profile and enhance the osteogenic ability of the prepared matrix. Materials and methods An exclusive Europium-Monetite composite was synthesized employing eco-friendly techniques involving Cissus quadrangularis. The osteogenic potential was gauged using the MG-63 cell line through a calcium mineralization assay employing an Alizarin Red solution, collagen estimation, and an alkaline phosphatase (ALP) assay. The composite's cytocompatibility was evaluated using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay across different concentrations ranging from 12.5 µg to 100 µg. Results Scanning electron microscopy (SEM) analysis of the Europium-Monetite composite revealed a sheet-like arrangement in stacks, and the ATR-IR confirmed the presence of elements Ca, P, and Eu. The osteogenic potential, analyzed by ALP activity, calcium mineralization, and collagen staining, was 10% higher than that of the control (Monetite).  Conclusion The prepared novel Europium-Monetite calcium phosphate complex can enhance the osteogenic potential and could be a promising material for bone regeneration/tissue engineering. The newly created Europium-Monetite calcium phosphate complex holds promise for various bone grafting applications, including integration into scaffolds and as a coating for implants.

Highly cyto- and immune compatible new synthetic fluorapatite nanomaterials co-doped with rubidium(I) and europium(III) ions

In the present study, biocompatible luminescent of nanosized fluorapatite doped with rubidium(I) (Rb+ ion) and europium(III) (Eu3+ ion) ions were synthesized via hydrothermal method. It was investigated the influence of co-doped Rb+ and Eu3+ ions on the structural, and morphological characteristics of the obtained fluorapatite materials. The characterization techniques utilized included: X-ray powder diffraction (XRPD), infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). Moreover, to establish the influence of the co-doped Rb+ and Eu3+ ions on the luminescence properties of the lanthanide ion, emission excitation, emission spectrum and luminescence decays were measured. This confirmed a distinct red emission originating from Eu3+ ions and an increased emission lifetime. To determine the biocompatibility of the obtained fluorapatite compounds, in vitro studies using normal dermal human fibroblasts were performed. The results of these studies clearly demonstrate the remarkable biocompatibility of our compounds. This discovery opens exciting prospects for the use of synthetic fluorapatites doped with Eu3+ and Rb+ ions in various biomedical contexts. In particular, these materials hold great promise for potential applications in regenerative engineering, but also serve as innovative and practical solutions as bone scaffolds and dental implants containing nano-fluorapatite. Further discussion of these properties can be found in this article, along with a discussion of their importance and potential in the field of biomedical applications. However, according to our pervious study and based on our current investigations but also based on available scientific records, it was proposed potential molecular mechanism of Rb+ ions in the process of osteoclastogenesis.

A comprehensive study for the potential removal of 152+154Eu radionuclides using a promising modified strontium-based MOF

A facile modification of a strontium-based MOF using oxalic acid was carried out to prepare MTSr-OX MOF, which was used as a potential substance for eliminating 152+154Eu radioisotopes. Various analytical techniques were used to characterize MTSr-OX-MOF. The prepared MOF had a rod-like structure with a BET surface area of 101.55 m2 g-1. Batch sorption experiments were used to investigate the sorption performance of MTSr-OX-MOF towards 152+154Eu radionuclides where different parameters like pH, contact time, initial 152+154Eu concentration, ionic strength, and temperature were scrutinized to determine the optimum conditions for 152+154Eu removal. MTSr-OX-MOF showed superior effectiveness in the elimination of 152+154Eu with a maximum sorption capacity of 234.72 mg g-1 at pH 3.5. Kinetics fitted with the pseudo-second-order model and the Langmuir model correctly described the sorption mechanism. The thermodynamic variables were carefully examined, demonstrating that the 152+154Eu sorption was endothermic as well as spontaneous. The MTSr-OX-MOF has been found to be a significantly more effective sorbent towards 152+154Eu than that of many other adsorbents. When applied to real active waste, MTSr-OX-MOF demonstrated excellent removal performance for a wide range of radionuclides. As a result, the MTSr-OX-MOF can be recognized as an attractive solution for the 152+154Eu purification from active waste.

Al3+-Responsive Ratiometric Fluorescent Sensor for Creatinine Detection: Thioflavin-T and Sulfated-β-Cyclodextrin Synergy

Kidney disorders are a rising global health issue, necessitating early diagnosis for effective treatment. Creatinine, a metabolic waste product from muscles, serves as an ideal biomarker for kidney damage. The existing optical methods for creatinine detection often involve labor-intensive synthesis processes and present challenges with the aqueous solubility and sensitivity to experimental variations. In this study, we introduce a straightforward fluorescence "turn-on" ratiometric sensor system for creatinine detection in aqueous media with a limit of detection of 0.5 μM. The sensor is based on sulfated-β-cyclodextrin (SCD)-templated H-aggregate of a commercially available, ultrafast rotor dye thioflavin-T (ThT). The Al3+ ion-induced dissociation of ThT-SCD aggregates, followed by reassociation upon creatinine addition, generates a detectable signal. The modulation of monomer/aggregate equilibrium due to the disassembly/reassembly of the ThT-SCD system under Al3+/creatinine influence serves as the optimal strategy for ratiometric creatinine detection in aqueous media. Our sensor framework offers several advantages: utilization of the readily available dye ThT, which eliminates the need for a laborious synthesis of custom fluorescent probes; ratiometric sensing, which improves quantitative analysis accuracy; and compatibility with complex aqueous media. The sensor's practical utility has been successfully demonstrated in artificial urine samples. In summary, our sensor system represents a significant advancement in the rapid, selective, and sensitive detection of the clinically crucial bioanalyte creatinine, offering potential benefits for the early diagnosis and management of kidney disorders.

Plant growth promoting potential of urea doped calcium phosphate nanoparticles in finger millet (Eleusine coracana (L.) Gaertn.) under drought stress

Drought is a leading threat that impinges on plant growth and productivity. Nanotechnology is considered an adequate tool for resolving various environmental issues by offering avant-garde and pragmatic solutions. Using nutrients in the nano-scale including CaP-U NPs is a novel fertilization strategy for crops. The present study was conducted to develop and utilize environment-friendly urea nanoparticles (NPs) based nano-fertilizers as a crop nutrient. The high solubility of urea molecules was controlled by integrating them with a matrix of calcium phosphate nanoparticles (CaP NPs). CaP NPs contain high phosphorous and outstanding biocompatibility. Scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffraction analysis (XRD) were used to characterize the fabricated NPs. FE-SEM determined no areas of phase separation in urea and calcium phosphate, indicating the successful formation of an encapsulated nanocomposite between the two nano matrices. TEM examination confirmed a fiber-like structure of CaP-U NPs with 15 to 50 nm diameter and 100 to 200 nm length. The synthesized CaP-U NPs and bulk urea (0.0, 0.1% and 0.5%) were applied by foliar sprays at an interval of 15 days on pre-sowed VL-379 variety of finger millet (Eleusine coracana (L.) Gaertn.), under irrigated and drought conditions. The application of the CaP-U NPs significantly enhanced different plant growth attributes such as shoot length (29.4 & 41%), root length (46.4 & 51%), shoot fresh (33.6 & 55.8%) and dry weight (63 & 59.1%), and root fresh (57 & 61%) and dry weight (78 & 80.7%), improved pigment system (chlorophyll) and activated plant defense enzymes such as proline (35.4%), superoxide dismutase (47.7%), guaiacol peroxidase (30.2%), ascorbate peroxidase (70%) under both irrigated and drought conditions. Superimposition of five treatment combinations on drought suggested that CaP-U NPs at 0.5 followed by 0.1% provided the highest growth indices and defense-related enzymes, which were significantly different. Overall, our findings suggested that synthesized CaP-U NPs treatment of finger millet seeds improved plant growth and enzymatic regulation, particularly more in drought conditions providing insight into the strategy for not only finger millet but probably for other commercial cereals crops which suffer from fluctuating environmental conditions.

Ratiometric luminescent sensing of a biomarker for sugar consumption in an aqueous medium using a Cu(II) coordination polymer

An innovative [Cu(Hadp)₂(Bimb)]_n (KA@CP-S3) coordination polymer expands its dimensionality from a 1D chain to a 2D network. The topological analysis reveals that KA@CP-S3 has 2-connected uninodal 2D 2C1 topology. KA@CP-S3 has capable luminescent sensing for volatile organic compounds (VOCs), nitroaromatics, heavy metal ions, anions, disposed antibiotics (nitrofurantoin and tetracycline) and biomarkers. Intriguingly, KA@CP-S3 exhibits outstanding selective quenching of about 90.7% and 90.5% for the 125 mg dl^-1 and 150 mg dl^-1 strengths of sucrose, respectively, in aqueous solution along with other ranges in between. The photocatalytic degradation efficiency of KA@CP-S3 for the potentially harmful organic dye Bromophenol Blue displays 95.4%, which is the highest among the 13 dyes that were evaluated.

Lanthanides-Substituted Hydroxyapatite for Biomedical Applications

Lately, there has been an increasing demand for materials that could improve tissue regenerative therapies and provide antimicrobial effects. Similarly, there is a growing need to develop or modify biomaterials for the diagnosis and treatment of different pathologies. In this scenario, hydroxyapatite (HAp) appears as a bioceramic with extended functionalities. Nevertheless, there are certain disadvantages related to the mechanical properties and lack of antimicrobial capacity. To circumvent them, the doping of HAp with a variety of cationic ions is emerging as a good alterative due to the different biological roles of each ion. Among many elements, lanthanides are understudied despite their great potential in the biomedical field. For this reason, the present review focuses on the biological benefits of lanthanides and how their incorporation into HAp can alter its morphology and physical properties. A comprehensive section of the applications of lanthanides-substituted HAp nanoparticles (HAp NPs) is presented to unveil the potential biomedical uses of these systems. Finally, the need to study the tolerable and non-toxic percentages of substitution with these elements is highlighted.

Nanoparticles in the diagnosis and treatment of vascular aging and related diseases

Aging-induced alternations of vasculature structures, phenotypes, and functions are key in the occurrence and development of vascular aging-related diseases. Multiple molecular and cellular events, such as oxidative stress, mitochondrial dysfunction, vascular inflammation, cellular senescence, and epigenetic alterations are highly associated with vascular aging physiopathology. Advances in nanoparticles and nanotechnology, which can realize sensitive diagnostic modalities, efficient medical treatment, and better prognosis as well as less adverse effects on non-target tissues, provide an amazing window in the field of vascular aging and related diseases. Throughout this review, we presented current knowledge on classification of nanoparticles and the relationship between vascular aging and related diseases. Importantly, we comprehensively summarized the potential of nanoparticles-based diagnostic and therapeutic techniques in vascular aging and related diseases, including cardiovascular diseases, cerebrovascular diseases, as well as chronic kidney diseases, and discussed the advantages and limitations of their clinical applications.

Structural and surface studies of luminescent Ca/Eu phosphate nanomaterials: From the bulk to surface features

Three luminescent Eu-containing phosphate materials (Ca-doped europium phosphate monohydrate, Eu-doped carbonated-apatite, and europium phosphate monohydrate) were prepared and analyzed on the level of bulk structure and surface properties and compared to the biomimetic non-luminescent counterpart hydroxyapatite. Europium-containing phosphate materials exhibited nanosized dimensions but different luminescence emissions and luminescence lifetimes depending on their crystalline structures (i.e., lanthanide phosphate or apatites) and chemical composition. The introduction of Eu in the crystal lattice leads to a notable decrease in the overall Lewis acidity of the surface cationic sites detected by CO probing. Further, the mixed Eu/Ca-containing materials surfaces were found to be very similar to the reference hydroxyapatite in terms of water adsorption energy, while the pure europium phosphate resulted to have the notably higher energy values of direct interaction of water molecules with the surface cations with no detected propagation of this effect towards water overlayers.

One material, many possibilities via enrichment of luminescence in La2Zr2O7:Tb3+ nanophosphors for forensic stimuli aided applications

Engineering a single material with multidirectional applications is crucial for improving productivity, low cost, flexibility, least power consumption, etc. To achieve these requirements, novel design structures and high-performance materials are in urgent need. Lanthanide-doped nanophosphors have the greatest strengths and ability in order to tune their applications in various dimensions. However, applications of nanophosphor in latent fingerprints visualization, anti-counterfeiting, and luminescent gels/films are still in their infancy. This study demonstrated a simple strategy to enhance the luminescence of Tb³⁺ (1-11 mol %) doped La₂Zr₂O₇ nanophosphors by conjugating various fluxes via a simple solution combustion route. The photoluminescence emission spectra reveal intense peaks at ~ 491, 546, 587, and 622 nm, which arises from ⁵D₄ → ⁷F_J (J = 6, 5, 4, 3) transitions of Tb³⁺ ions, respectively. The highest emission intensity was achieved in the NH₄Cl flux assisted nanophosphor as compared to NaBr and NH₄F assisted samples. The colorimetric images of fingerprints visualized using the optimized nanophosphor on forensic related surfaces exhibit level -III ridge details, including sweat pores, the width of the ridges, bifurcation angle, and the successive distance between sweat pores, etc. These results are decisive parameters that clearly support the statement "no two persons have ever been found to have the same fingerprints". The anti-counterfeiting security ink was formulated using optimized nanophosphor and various patterns were designed by simple screen printing and dip pen technologies. The encoded information was decrypted only under ultraviolet 254 nm light. All the designed patterns are exhibit not just what it looks/feel like and how better it works. As a synergetic contribution of enhanced luminescence of the prepared nanophosphor, the green-emissive films were fabricated, which display excellent flexibility, uniformity, and transparency in the normal and ultraviolet 254 nm light illumination. The aforementioned results revealed that the prepared NH₄Cl flux-assisted La₂Zr₂O₇: Tb³⁺(7 mol %) NPs are considered to be the best candidate for multi-dimensional applications.

Synthesis, structural and luminescent properties of Mn-doped calcium pyrophosphate (Ca2P2O7) polymorphs

In the present work, three different Mn²⁺-doped calcium pyrophosphate (CPP, Ca₂P₂O₇) polymorphs were synthesized by wet co-precipitation method followed by annealing at different temperatures. The crystal structure and purity were studied by powder X-ray diffraction (XRD), Fourier-transform infrared (FTIR), solid-state nuclear magnetic resonance (SS-NMR), and electron paramagnetic resonance (EPR) spectroscopies. Scanning electron microscopy (SEM) was used to investigate the morphological features of the synthesized products. Optical properties were investigated using photoluminescence measurements. Excitation spectra, emission spectra, and photoluminescence decay curves of the samples were studied. All Mn-doped polymorphs exhibited a broadband emission ranging from approximately 500 to 730 nm. The emission maximum was host-dependent and centered at around 580, 570, and 595 nm for γ-, β-, and α-CPP, respectively.

Physicochemical Characterization of Europium-Doped Hydroxyapatite Thin Films with Antifungal Activity

Owing to its unique biological and physicochemical properties, hydroxyapatite (HAp) represents one of the most extensively studied biomaterials for biomedical applications. It is well known that Candida is currently one of the fungi frequently involved in the onset and development of post-implant infections and, owing to the appearance of antifungal resistance, it is quite difficult to treat despite all the tremendous efforts made in this regard by the scientific world. Therefore, in this context, we report for the first time in this paper, the development and characterization of europium-doped thin films (5EuHAp, xEu = 0.05) on a Si substrate by a spin-coating method. The results of ultrasound (US), zeta (ζ) potential, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR) studies are presented. The XRD studies conducted on 5EuHAp suspension revealed the nanometric dimensions of the particles and sample purity. In addition, a moderate stability of the 5EuHAp suspension was observed. XPS measurements revealed the presence of Eu 3d in the 5EuHAp thin films. In the SEM micrographs, the surface uniformity and the absence of the surface defects could be observed. Moreover, the results of the FTIR studies showed the presence of the vibrational bands specific to the HAp structure in the studied sample. The antifungal activity of the HAp and 5EuHAp suspensions and coatings was evaluated using the Candida albicans ATCC 10231 (C. albicans) fungal strain. The qualitative assays of the antifungal properties of HAp and 5EuHAp coatings were also visualized by SEM and CLSM. The antifungal studies revealed that both 5EuHAp suspensions and coatings exhibited noticeable antifungal activity against C. albicans cells.

Molecular Probes, Chemosensors, and Nanosensors for Optical Detection of Biorelevant Molecules and Ions in Aqueous Media and Biofluids

Synthetic molecular probes, chemosensors, and nanosensors used in combination with innovative assay protocols hold great potential for the development of robust, low-cost, and fast-responding sensors that are applicable in biofluids (urine, blood, and saliva). Particularly, the development of sensors for metabolites, neurotransmitters, drugs, and inorganic ions is highly desirable due to a lack of suitable biosensors. In addition, the monitoring and analysis of metabolic and signaling networks in cells and organisms by optical probes and chemosensors is becoming increasingly important in molecular biology and medicine. Thus, new perspectives for personalized diagnostics, theranostics, and biochemical/medical research will be unlocked when standing limitations of artificial binders and receptors are overcome. In this review, we survey synthetic sensing systems that have promising (future) application potential for the detection of small molecules, cations, and anions in aqueous media and biofluids. Special attention was given to sensing systems that provide a readily measurable optical signal through dynamic covalent chemistry, supramolecular host-guest interactions, or nanoparticles featuring plasmonic effects. This review shall also enable the reader to evaluate the current performance of molecular probes, chemosensors, and nanosensors in terms of sensitivity and selectivity with respect to practical requirement, and thereby inspiring new ideas for the development of further advanced systems.

Amperometric biosensors for L-arginine and creatinine assay based on recombinant deiminases and ammonium-sensitive Cu/Zn(Hg)S nanoparticles

There are limited data on amperometric biosensors (ABSs) based on deiminases that produce ammonium as a byproduct of enzymatic reaction. The most frequently proposed biosensors utilizing such a mode are based on potentiometric transducers, which contain at least two enzymes in the bioselective layer; this complicates the procedure and increases the cost of analysis. Thus, the construction of a one-enzyme ABS is a practical problem. In our manuscript ABSs for the direct measurement of creatinine (Crn) and l-arginine (Arg), based on the recombinant bacterial creatinine deiminase (CDI) and arginine deiminase (ADI), are described. To choose the best chemosensor on ammonium ions, a number of nanoparticles (NPs) were synthesized and characterized using cyclic voltammetry. Hybrid Cu/Zn(Hg)S-NPs, having a good selectivity and an extremely high sensitivities towards ammonium ions (5660 A M^-1 m^-2 at +170 mV and 1870 A M^-1 m^-2 at -300 mV, respectively), was selected for the development of deiminase-based ABSs. The novel biosensors exhibited very high sensitivities (2660 A M^-1 m^-2 to Crn for CDI-ABS; 1570 A M^-1 m^-2 to Arg for ADI-ABS), broad linear ranges, low limits of detection, satisfactory storage stabilities and good selectivities towards natural substrates. The constructed CDI-ABS and ADI-ABS were tested on real samples of biological fluids and juices for Crn and Arg assay, respectively. High correlations of the obtained results with the reference methods were demonstrated for the target analytes.

Real-Time Tracking of Highly Luminescent Mesoporous Silica Particles Modified with Europium β-Diketone Chelates in Living Cells

Highly luminescent europium complexes modified mesoporous silica particles (MSP) were synthesized as an imaging probes for both in-vitro diagnostic and in-vivo cellular tracking agents. Europium β-diketone chelates (4,4,4-trifluoro-l-(2-thienyl)-l,3-butanedione) trioctylphosphine europium (III) (Eu(TTA)₃(P(Oct)₃)₃) were incorporated inside the nanocavities that existed in hierarchical MSP (Eu@MSP). The MSP and Eu@MSP on mouse bone marrow-derived macrophages (BMDMs) did not show any toxic effect. The MSP and Eu@MSP in the BMDMs were found at cytoplasm without any degradation and immunogenicity. However, both pro- and anti-inflammatory cytokines of macrophages were significantly increased when lipopolysaccharide and a high concentration (100 μg/mL) of MSP and Eu@MSP were treated simultaneously.