Adenosine Triphosphate Molecules Research Articles

Nanopore single molecule ATP detection based on the dual effects of specific capturing and signal amplification

Adenosine triphosphate (ATP) plays a crucial role in energy metabolism. Some serious diseases such as Alzheimer’s disease are related to abnormal ATP concentrations. Fast, sensitive, and specific ATP detection is important and challenging in disease diagnosis and biomedical research. In present study, conical nanopore was designed and employed to detect ATP at single molecule level. For overcoming the inherent defects such as non-selectivity and low sensitivity of nanopore in sensing small target molecule, two collaborative improvements of specific identification and signal amplification were proposed. We first used split aptamer capture probes (H1 and S1) to anchor ATP molecule, and then used auxiliary probes (H2 and H3) to form a long-nicked duplex ATP-DNA concatemer by hybridization chain reaction (HCR). Referring ATP-DNA concatemer rather than native ATP to nanopore sensor, characteristic current signals with high signal-to-noise ratio were obtained. By such indirect way, specific and sensitive ATP detection was realized with a linear range from 20 pM to 5 nM and a detection limit of 3.9 pM (S/N = 3). Additionally, the sensor exhibited many merits such as simplify, anti-interference, and especially allowing ATP detection in real sample. So, we believe that the nanopore sensor has good application prospects in screening and management of ATP-related diseases.

Engineering smart thioflavin T binders with switchable DNA topologies for constructing multiple label-free biosensors

Thioflavin T (ThT) has been used as a sensitive fluorescence probe for lighting up nucleic acids. The binding of ThT is dependent on the structural topologies of DNA sequences. To date, most oligonucleotides interact with ThT through only a single topology, and this limits the applications of ThT as a sensing agent. Here, we modulated an HIV-1 integrase aptamer, 93del, to have switchable topologies by optimizing its 3′ flanking residues to enhance its ThT-binding capacity. Our data revealed that the sequences formed stem-loop hairpins and I-motif/G-quadruplex (G4) hybrids in Na+ buffer under alkaline and acidic conditions, respectively. Both topologies could bind ThT with high affinity (Kd ∼ 0.5 μM) and dramatically enhance the fluorescent signal of ThT. However, in the presence of K+, the sequences could be assembled into interlocked G4s, which had a low affinity for ThT but a high affinity for N-methyl mesoporphyrin IX (NMM). This allowed us to build highly sensitive fluorescent K+ sensors that were insusceptible to interference from Na+. Additionally, we found that the stacking of homologous base pairs in the hairpin loops was essential for ThT recognition and could be used as an indicator in the construction of label-free molecular beacons, allowing monitoring of microRNAs effectively in human serum spiked test. By employing external stimuli to induce the transformation of these topologies, we were able to sensitively detect adenosine triphosphate (ATP) molecules or Hg2+in vitro under specific acidic conditions. Our study provides a strategy for exploiting undiscovered functions of existing aptamers.

Inhibition of microtubule function prevents hypoxia-induced glycolysis

In normoxic conditions where oxygen supply exceeds demand, mammalian cells produce 38 molecules of adenosine triphosphate (ATP) per molecule of glucose through cellular respiration which is primarily oxygen-dependent. In hypoxia where oxygen demand exceeds supply, the cell enters a bioenergetic crisis due to the decrease in oxygen-dependent ATP synthesis. The cell relies on overcoming this deficiency in ATP through upregulation of glycolytic gene expression via the hypoxia inducible factor 1-a (HIF-1a). However, it is highly unlikely, if not impossible, that the bioenergetic requirements of the hypoxic cell depend solely on the increased expression of glycolytic enzymes distributed randomly in the cytoplasm. We have recently shown that in response to hypoxia, glycolytic enzymes coalesce to form a glycolytic metabolon to effciently increase ATP production in response to this metabolic challenge (Kierans SJ, et al., 2023). While the function of this metabolon has been characterised, the mechanisms underpinning formation, scaffolding, and intracellular distribution remains poorly understood. Here we investigate the possible role of the cytoskeleton as a scaffold or transport system. Microtubules are a primary method of intracellular transport and may alter the energy distribution strategies of cells in bioenergetic crisis. It is hypothesized that the microtubular network transports glycolytic enzymes and/or facilitates increased glycolytic ATP production by promoting metabolon formation to induce glycolysis in hypoxia. Through western blots, it was successfully shown that upon exposure to 1% oxygen, caco2 intestinal epithelial cells induce a robust hypoxic response by stabilising HIF-1a. To investigate the role of the microtubules, two microtubule inhibitors were used: nocodazole, a microtubule assembly and disassembly inhibitor and dynarrestin, a dynein-1 motor transport protein inhibitor. Non-toxic concentrations of nocodazole and dynarrestin were determined using cell viability assays (trypan blue and resazurin assays). Upon exposure to 24 hours of hypoxia, caco2 cells elicit a statistically significant increase in intracellular lactate (185.9% ± 7.5% SEM, n = 3), which was then supressed when treated with nocodazole or dynarrestin (20.6% ± 10.2% SEM and 74.9% ± 8.87 SEM respectively, n = 3). These results thus implicate a role for the transport and structural capabilities of the microtubules in hypoxia-induced glycolysis. Kierans, S. J., Fagundes, R. R., Malkov, M. I., Sparkes, R., Dillon, E. T., Smolenski, A.,... & Taylor, C. T. (2023). Hypoxia induces a glycolytic complex in intestinal epithelial cells independent of HIF-1-driven glycolytic gene expression. Proceedings of the National Academy of Sciences, 120(35), e2208117120. University College Dublin, School of Medicine. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Probing actin-activated ATP turnover kinetics of human cardiac myosin II by single molecule fluorescence.

Mechanistic insights into myosin II energy transduction in striated muscle in health and disease would benefit fromfunctional studies of a wide range of point-mutants. This approach is, however, hampered by the slow turnaround of myosin II expression that usually relies on adenoviruses for gene transfer. A recently developed virus-free method is more time effective but would yield too small amounts of myosin for standard biochemical analyses. However, if the fluorescent adenosine triphosphate (ATP) and single molecule (sm) total internal reflection fluorescence microscopy previously used to analyze basal ATP turnover by myosin alone, can be expanded to actin-activated ATP turnover, it would appreciably reduce the required amount of myosin. To that end, we here describe zero-length cross-linking of human cardiac myosin II motor fragments (sub-fragment 1 long [S1L]) to surface-immobilized actin filaments in a configuration with maintained actin-activated ATP turnover. After optimizing the analysis of sm fluorescence events, we show that the amount of myosin produced from C2C12 cells in one 60 mm cell culture plate is sufficient to obtain both the basal myosin ATP turnover rate and the maximum actin-activated rate constant (kcat). Our analysis of many single binding events of fluorescent ATP to many S1L motor fragments revealed processes reflecting basal and actin-activated ATPase, but also a third exponential process consistent with non-specific ATP-binding outside the active site.

Modulation by Co (II) Ion of Optical Activities of L/D-glutathione (GSH)-modified Chiral Copper Nanoclusters for Sensitive Adenosine Triphosphate Detection.

Chiral nanoscale enantiomers exhibit different biological effects in living systems. However, their chirality effect on the detection sensitivity for chiral biological targets still needs to be explored. Here, we discovered that Co2+ can modulate the luminescence performance of L/D-glutathione (GSH)-modified copper nanoclusters (L/D-Cu NCs) and induce strong chiroptical activities as the asymmetric factor was enhanced 223-fold with their distribution regulating from the ultraviolet to visible region. One Co2+ coordinated with two GSH molecules that modified on the surface of Cu NCs in the way of CoN2O2. On this basis, dual-modal chiral and luminescent signals of Co2+ coordinated L/D-Cu NCs (L/D-Co-Cu NCs) were used to detect the chiral adenosine triphosphate (ATP) based on the competitive interaction between surficial GSH and ATP molecules with Co2+. The limits of detection of ATP obtained with fluorescence and circular dichroism intensity were 9.15 μM and 15.75 nM for L-Co-Cu NCs, and 5.35 μM and 4.69 nM for D-Co-Cu NCs. This demonstrated that selecting suitable chiral configurations of nanoprobes effectively enhances detection sensitivity. This study presents not only a novel method to modulate and enhance the chiroptical activity of nanomaterials but also a unique perspective of chirality effects on the detection performances for bio-targets.

Modulation by Co (II) Ion of Optical Activities of L/D‐glutathione (GSH)‐modified Chiral Copper Nanoclusters for Sensitive Adenosine Triphosphate Detection

AbstractChiral nanoscale enantiomers exhibit different biological effects in living systems. However, their chirality effect on the detection sensitivity for chiral biological targets still needs to be explored. Here, we discovered that Co2+ can modulate the luminescence performance of L/D‐glutathione (GSH)‐modified copper nanoclusters (L/D−Cu NCs) and induce strong chiroptical activities as the asymmetric factor was enhanced 223‐fold with their distribution regulating from the ultraviolet to visible region. One Co2+ coordinated with two GSH molecules that modified on the surface of Cu NCs in the way of CoN2O2. On this basis, dual‐modal chiral and luminescent signals of Co2+ coordinated L/D−Cu NCs (L/D−Co−Cu NCs) were used to detect the chiral adenosine triphosphate (ATP) based on the competitive interaction between surficial GSH and ATP molecules with Co2+. The limits of detection of ATP obtained with fluorescence and circular dichroism intensity were 9.15 μM and 15.75 nM for L−Co−Cu NCs, and 5.35 μM and 4.69 nM for D−Co−Cu NCs. This demonstrated that selecting suitable chiral configurations of nanoprobes effectively enhances detection sensitivity. This study presents not only a novel method to modulate and enhance the chiroptical activity of nanomaterials but also a unique perspective of chirality effects on the detection performances for bio‐targets.

Peculiarities of the Fluorescence Quenching in the ATP – Calix[4]arene C-107 Aqueous Solutions

The nature of fluorescence (FL) quenching for the aqueous solutions of adenosine triphosphate (ATP) with calix[4]arenes C-107 in the presence of silver nitrate AgNO3 is studied. It is shown that, for the water solutions of ATP and calix[4]arenes C-107 at a constant concentration of ATP molecules with an increase in the content of C-107, a complex nature of the PL quenching is observed, while maintaining the position of the PL band near 395 nm (λex = 285 nm). Its complexity is based, on the one hand, in the wide range of concentrations of C-107, at which it occurs, and, on the other hand, there are gaps in the quenching values for individual concentrations of calix[4]arene, near which it changes slightly. The indicated nature of the PL quenching significantly depends on the wavelength of excitation and the temperature. Similar quenching behavior is preserved, when AgNO3s alts are added to the ATP–C-107 mixtures, (CATP = CC-107 = 1 × 10−4M) in the concentration range from 1 × 10−4M to 1 × 10−3M. The computer modeling shows that the system ATP–C-107 can form energetically stable complexes, when ATP is located on the top of the calix[4]arene and along the wall of it due to π-π-stacking interaction, and the complexes are characterized by a shrinking of the energy bands.

Femtomolar endogenous adenosine triphosphate-responded photoelectrochemical biosensor based on Au@Cu2O core-shell nanocubes for the ultrasensitive determination of Escherichia coli O157:H7 in foods

Sensitive and precise determination of virulent foodborne pathogens is significant for food safety. Herein, an ultrasensitive photoelectrochemical (PEC) bioanalysis was developed using the endogenous adenosine triphosphate (ATP)-responded Au@Cu2O core-shell nanocubes (Au@Cu2O NCs) to measure Escherichia coli O157: H7 (E. coli O157:H7) in food. Briefly, the phage-functionalized gold wire was used to specifically recognize the target pathogen. With the bacteriolysis of lysozyme, the endogenous ATP molecules were emitted from the captured target bacteria and enriched by another ATP aptamer-modified gold wire. Following the exchange with complementary DNA (cDNA) chains, the bonded ATP would be released. It could simultaneously etch the Au@Cu2O NCs and compete with external circuit electrons to combine photogenerated holes on the Au@Cu2O NCs-modified screen-printed electrode. With the synergy of the two signal amplification mechanisms, a significant attenuation of photocurrent signal appeared even with femtomolar ATP. Therefore, the purpose of ultrasensitive determination of E. coli O157:H7 was realized, which depended on the endogenous ATP rather than exogenous signal probes. The proposed biosensor presented a good analysis performance within 10–106 CFU/mL with a detection limit of 5 CFU/mL. Besides, its specificity, repeatability, and stability were also investigated and acceptable. The detection results for food samples matched well with the results detected by the plate counting method. This work gives an innovative and sensitive signal amplification strategy for PEC bioassays in foodborne pathogens detection.

Black Phosphorus/MnO2 Nanocomposite Disrupting Bacterial Thermotolerance for Efficient Mild-Temperature Photothermal Therapy.

The emergence of multi-drug resistant (MDR) pathogens is a major public health concern, posing a substantial global economic burden. Photothermal therapy (PTT) at mild temperature presents a promising alternative to traditional antibiotics due to its biological safety and ability to circumvent drug resistance. However, the efficacy of mild PTT is limited by bacterial thermotolerance. Herein, a nanocomposite, BP@Mn-NC, comprising black phosphorus nanosheets and a manganese-based nanozyme (Mn-NZ) is developed, which possesses both photothermal and catalytic properties. Mn-NZ imparts glucose oxidase- and peroxidase-like properties to BP@Mn-NC, generating reactive oxygen species (ROS) that induce lipid peroxidation and malondialdehyde accumulation across the bacterial cell membrane. This process disrupts unprotected respiratory chain complexes exposed on the bacterial cell membrane, leading to a reduction in the intracellular adenosine triphosphate (ATP) content. Consequently, mild PTT mediated by BP@Mn-NC effectively eliminates MDR infections by specifically impairing bacterial thermotolerance because of the dependence of bacterial heat shock proteins (HSPs) on ATP molecules for their proper functioning. This study paves the way for the development of a novel photothermal strategy to eradicate MDR pathogens, which targets bacterial HSPs through ROS-mediated inhibition of bacterial respiratory chain activity.

ATP and ssDNA aptamer-mediated peroxidase-like activity of rGO@PDA@CeO2 nanozyme: Exosomal proteins profiling and detection at physiological pH for colorimetric sensor

Exosomes are extracellular vesicles that inherit molecular markers from their parent cells for the transfer and delivery of membrane and cytosolic molecules between cells. Exosome detection and protein profiling provide noninvasive access to disease diagnosis and treatment. The nanozyme designed in this paper contains polydopamine-functionalization of graphene oxide (rGO@PDA) units that can adsorb ssDNA aptamers and CeO2 metal oxide nanosheet units with peroxidase activity. As auxiliary regulator, adenosine triphosphate (ATP) enhances peroxidase activity of rGO@PDA@CeO2 under a wide range of pH (4–7.4), which breaks through the limitation that traditional nanozymes can only exhibit peroxidase activity under acidic conditions. The ssDNA aptamers, which are recognition probes of exosome, can be adsorbed on the surface of rGO@PDA by aromatic stacking, competing with ATP molecules. Thus, the ssDNA aptamer acts as the switch for colorimetric sensor to flexibly regulate the peroxidase activity of the rGO@PDA@CeO2 under physiological conditions, and realizes sensitive detection of exosomes. This assay achieves a detection linear range of 0.46 × 107–108 particle/mL and a limit down to 3.81 × 105 particles/mL. In addition, this aptasensor sensitively profiles six exosomal protein across five cell types and clinical samples, suggesting their potential in clinic diagnosis.

Mitochondrial epigenetics in aging and cardiovascular diseases.

Mitochondria are cellular organelles which generate adenosine triphosphate (ATP) molecules for the maintenance of cellular energy through the oxidative phosphorylation. They also regulate a variety of cellular processes including apoptosis and metabolism. Of interest, the inner part of mitochondria-the mitochondrial matrix-contains a circular molecule of DNA (mtDNA) characterised by its own transcriptional machinery. As with genomic DNA, mtDNA may also undergo nucleotide mutations that have been shown to be responsible for mitochondrial dysfunction. During physiological aging, the mitochondrial membrane potential declines and associates with enhanced mitophagy to avoid the accumulation of damaged organelles. Moreover, if the dysfunctional mitochondria are not properly cleared, this could lead to cellular dysfunction and subsequent development of several comorbidities such as cardiovascular diseases (CVDs), diabetes, respiratory and cardiovascular diseases as well as inflammatory disorders and psychiatric diseases. As reported for genomic DNA, mtDNA is also amenable to chemical modifications, namely DNA methylation. Changes in mtDNA methylation have shown to be associated with altered transcriptional programs and mitochondrial dysfunction during aging. In addition, other epigenetic signals have been observed in mitochondria, in particular the interaction between mtDNA methylation and non-coding RNAs. Mitoepigenetic modifications are also involved in the pathogenesis of CVDs where oxygen chain disruption, mitochondrial fission, and ROS formation alter cardiac energy metabolism leading to hypertrophy, hypertension, heart failure and ischemia/reperfusion injury. In the present review, we summarize current evidence on the growing importance of epigenetic changes as modulator of mitochondrial function in aging. A better understanding of the mitochondrial epigenetic landscape may pave the way for personalized therapies to prevent age-related diseases.

Fluorescence Imaging of Nanoparticle Uptake into Liquid-Liquid Phase-Separated Droplets.

Liquid-liquid phase separation (LLPS) in living cells has received considerable attention in the biomedical research field. This study is the first to report nanoparticle (NP) uptake into LLPS droplets. Fluorescent dye, Nile red loaded polystyrene NPs (NR-PSt NPs) uptake into model LLPS droplets consisting of adenosine triphosphate (ATP) and poly-L-lysine (PLL) was visualized using fluorescence imaging. Fluorescence imaging showed that the LLPS droplets had a quick NP uptake behavior. Furthermore, temperature changes (4-37 °C) significantly affected the NP uptake behavior of the LLPS droplets. Moreover, the NP-incorporated droplets displayed high stability under strong ionic strength conditions (1 M NaCl). ATP measurements displayed that ATP was released from the NP-incorporated droplets, indicating that the weakly negatively charged ATP molecules and strongly negatively charged NPs were exchanged, which resulted in the high stability of the LLPS droplets. These fundamental findings will contribute to the LLPS studies using various NPs.

Molecular Insights on the Conformational Transitions and Activity Regulation of the c-Met Kinase Induced by Ligand Binding.

The tyrosine-protein kinase Met (c-Met) is an important signaling molecule involved in cellular growth and division. The dysregulation of c-Met may induce many fatal diseases, including non-small cell lung cancer, gastrointestinal cancers, hepatocellular carcinoma, etc. The activation of the c-Met kinase is dominant by the structure and dynamics of many important functional motifs, which are regulated by adenosine triphosphate (ATP) binding. c-Met inhibitors bind to the ATP-binding site or the allosteric pocket to compete with ATP molecules or alter the conformation of the function-related domains. Nevertheless, the mechanisms of ligand binding to c-Met are still unclear, especially the regulation of the functional motifs by different inhibitors. These greatly impede the development of novel drugs to overcome the drug tolerance to the currently marketed c-Met inhibitors. In this study, we used enhanced sampling technology to study the binding and regulation of two specific c-Met inhibitors. The results show that the two ligands adopt different binding processes even though with similar binding affinity. More importantly, our results uncovered different protein conformational features and the correlated motions of functional motifs regulated by the inhibitors, providing the structural basis for the functional suppression of the protein kinases.

Enantioselective catalysts based on metal-organic framework-supported nucleotides

Adenosine triphosphate (ATP) and other nucleotides can be irreversibly bound to the metal-organic framework (MOF) MIL-101(Cr). Analysis of X-ray diffraction data suggests that the location of the adsorbed ATP molecule is in proximity of the Cr3 clusters. Solid-state NMR and DFT calculations indicate that ATP is bound to MIL-101(Cr) through linkages of the terminal phosphate group with Cr(III) of the framework. In the presence of Cu(II) ions, the MOF-supported nucleotides can function as stable and reusable enantioselective heterogeneous catalysts for reactions like Diels-Alder and Michael addition. Compared to the corresponding homogeneous nucleotide-based artificial metalloenzymes (ArMs), the MOF-supported nucleotide-based ArMs exhibit significantly enhanced activity and selectivity in certain cases, demonstrating their potential as a new class of enantioselective heterogeneous catalysts.

Application of phytoaccumulation perspective of Monochoria hastate L. on fluoride contaminated water in hydroponic treatment: its statistical design and characterization studies

The present research work approaches the accumulation of fluoride ions from contaminated water using an aquatic plant Monochoria hastate L. in hydroponic culture. A design of experiment (DOE) has been adopted and an analysis of variance has been conducted to establish the statistical significance of various process parameters. The different experimental factors are root and shoot (Factor A), fluoride concentration (Factor B), and experimental days (Factor C) largely influence the output response. Plants treated with 5 mg/L of fluoride solutions accumulated the highest concentration in root biomass 1.23 mg/gm, and shoot biomass 0.820 mg/gm, dry weight after 21 days’ experimentation. The accumulation mechanism and potentiality of treated plants depend on root cells of the plasma membrane and energy-capturing molecules of adenosine triphosphate. Monochoria hastate L. root biomass was characterized to confirm the accumulation of fluoride ions in the experimented plants using scanning electron micrographs-energy dispersive spectrum (SEM-EDS), and Fourier transforms infrared analysis (FTIR) analysis.

Thioflavin-T-Incorporated Cerium-ATP Coordination Polymer Nanoparticles: A Promising System for Detection of Uranyl Ion (UO22+) in Aqueous Medium.

Lanthanide-based coordination polymer nanoparticles (Ln-CPNs) are studied for analytical and biomedical sensing, mainly utilizing the luminescent properties of lanthanides. However, the inclusion of fluorescent guest molecules within the nanoparticles can lead to a stimuli-responsive system with modulated photo-physical properties that can be useful for detecting analytes. In this work, we have synthesized cerium(III) coordination polymer nanoparticles using adenosine triphosphate (ATP) molecules as the ligands. The porous polymeric structure enables CPNs for reversible inclusion and release of thioflavin-T (ThT), which is a weakly emissive dye in the free state but becomes highly emissive when incorporated into the Ce-ATP CPNs. Modulation of the photo-physical properties of ThT-incorporated CPNs in response to the radiotoxic and environmentally alarming uranyl ion (UO22+) has been used for its detection in aqueous medium in the range of 0-20 μM by fluorimetry with an LOD of 80 ng mL-1 (0.34 μM) in deionized water without interference from the most commonly occurring metal ions. Furthermore, the sensing platform has been successfully utilized for UO22+ determination in seawater sample without any pre-treatment and adjustment of pH.

Ketone Bodies and Brain Metabolism: New Insights and Perspectives for Neurological Diseases.

Ketone Bodies and Brain Metabolism: New Insights and Perspectives for Neurological Diseases.

Evaluation of the Effectiveness of Overheated Dry-Saturated Steam Disinfection in the Control of the Dental Chair Contamination by Bioluminescence Analysis: A Pilot In Vitro Study

This study aimed to evaluate, through Adenosine triphosphate (ATP) bioluminescence analysis, the effectiveness of an overheated dry-saturated steam device (Polti Sani System) in decreasing the superficial microbial contamination on dental chairs’ surfaces after 30 s steam disinfection (T1) in comparison to baseline (T0), i.e., at the end of an aerosol-generating procedure (AGDP), and to investigate any differences in the tested surfaces’ contamination at T0 in relation to the surface’s type. Three dental chair surfaces (scialytic lamp, control button panel, spit bowl), sized 10 × 10 cm each, were swabbed and analyzed before and after steam application. The procedure was repeated 20 times for a total of 60 before–after evaluations. Non-parametric tests were used to analyze Relative Light Unit (RLU) values and categorical data on the ATP molecules’ amount detected on the tested surfaces. Statistically significant differences were found for both RLU and categorical data for all surfaces, and each type of surface evaluated at T0 and T1 (p < 0.05). Differences in RLU among the tested surfaces at T0 were not significant. By reducing the microbial contamination on the evaluated surfaces, the overheated dry-saturated steam system was an effective measure for the disinfection of the dental chair’s surfaces after AGDPs, potentially reducing the risk of cross-infections.

Water-Soluble Conjugated Polyelectrolytes for Adenosine Triphosphate (ATP) Detection

Facile detection of adenosine triphosphate (ATP) at different concentration levels is important for applications such as assessing physiological status and monitoring bacterial and microbial contamination of food. A series of cationic conjugated polymers, PFPE-TEGx-NMe3+, with poly[fluorenyl-alt-p-phenyleneethynylene] (PFPE) as the backbone and different ratios of side chains consisting of a hexyl quaternary ammonium group and triethylene glycol, were synthesized for ATP sensing. Careful calculations based on the integrals of several specific proton peaks in the NMR spectra suggest that the ratios of different side chains of obtained polymers were consistent with the feeding ratios and the quaternization was close to 100%. Sensing application found that the fluorescence of polymers in aqueous solution was quenched upon adding ATP. The limit of detection (LOD) decreased with the increase in cation density on the polymer, which could be as low as 0.25 μM, and the higher the density of the quaternary ammonium group, the higher the sensitivity of polymer to ATP. The sensing system was selective to ATP over other possible interferents. Dynamic light scattering and zeta potential measurements show that ATP molecules were bound to polymer chains mainly through electrostatic interaction, while other interactions also existed, resulting in the formation of aggregates and the consequent fluorescence quenching. Relating the sensing performance to the chemical structures of analytes and fluorescent polymers revealed that the four negative charges combined with the organic part with a π-structure and some other interaction sites, which makes ATP unique compared with those possible interferents. At relatively low densities, the density of cationic groups had a significant effect on LOD and sensitivity, but at high densities, its effect became smaller; this observation is consistent with a sensing mechanism based on multiple interaction synergies dominated by electrostatic interactions. This study provides a general strategy for the design of sensing systems for biomolecules with relatively complex structures.

Renal and Cardiovascular Metabolic Impact Caused by Ketogenesis of the SGLT2 Inhibitors

Sodium-glucose cotransporter type 2 inhibitors (SGLT2i) are glycosuric drugs that were originally developed for the treatment of type 2 diabetes mellitus (T2DM). There is a hypothesis that SGLT2i are drugs that are capable of increasing ketone bodies and free fatty acids. The idea is that they could serve as the necessary fuel, instead of glucose, for the purposes of cardiac muscle requirements and could explain antihypertensive effects, which are independent of renal function. The adult heart, under normal conditions, consumes around 60% to 90% of the cardiac energy that is derived from the oxidation of free fatty acids. In addition, a small proportion also comes from other available substrates. In order to meet energy demands with respect to achieving adequate cardiac function, the heart is known to possess metabolic flexibility. This allows it to switch between different available substrates in order to obtain the energy molecule adenosine triphosphate (ATP), thereby rendering it highly adaptive. It must be noted that oxidative phosphorylation in aerobic organisms is the main source of ATP, which is a result of reduced cofactors. These cofactors include nicotine adenine dinucleotide (NADH) and flavin adenine dinucleotide (FADH2), which are the result of electron transfer and are used as the enzymatic cofactors that are involved in the respiratory chain. When there is an excessive increase in energy nutrients-such as glucose and fatty acids-which occur in the absence of a parallel increase in demand, a state of nutrient surplus (which is better known as an excess in supply) is created. The use of SGLT2i at the renal level has also been shown to generate beneficial metabolic alterations, which are obtained by reducing the glucotoxicity that is induced by glycosuria. Together with the reduction in perivisceral fat in various organs, such alterations also lead to the use of free fatty acids in the initial stages of the affected heart. Subsequently, this results in an increase in production with respect to ketoacids, which are a more available energy fuel at the cellular level. In addition, even though their mechanism is not fully understood, their vast benefits render them of incredible importance for the purposes of further research.