Effect of compound treatments on mouse lens viscoelasticity.

Previous studies have shown that pharmaceutical agents such as lipoic acid have the ability to soften the lens, presenting a promising avenue for treating presbyopia. One obstacle encountered in the preclinical stage of such agents is the need for precise measurements of lens elasticity in experimental models. This study aimed to evaluate the effects of 25-hydroxycholesterol, lipoic acid, and obeticholic acid on the viscoelastic properties of mouse lenses using a custom-built elastometer system. Data were acquired on lenses from C57BL/6J female mice from two age groups: young (age: 8-10 weeks) and old (age: 32-43 weeks). OD lenses were used as the control and OS lenses were treated. Control lenses were immersed in Dulbecco's Modified Eagle Medium (DMEM) and treatment lenses were immersed in a compound solution containing 25-hydroxycholesterol (5 young and 5 old), lipoic acid at 2.35 mM (5 young and 5 old), lipoic acid at 0.66 mM (5 old), or obeticholic acid (5 old) at 37 °C for 18 h. After treatment, the mouse lenses were placed in a DMEM-filled chamber within a custom-built elastometer system that recorded the load and lens shape as the lens was compressed by 600 µm at a speed of 50 µm/s. The load was continuously recorded during compression and during stress-relaxation. The compression phase was fit with a linear function to quantify lens stiffness. The stress-relaxation phase was fit with a 3-term exponential relaxation model providing relaxation time constants (t1, t2, t3), and equilibrium load. The lens stiffness, time constants and equilibrium load were compared for the control and treated groups. Results revealed an increase in stiffness with age for the control group (young: 1.16 ± 0.11 g/mm, old: 1.29 ± 0.14 g/mm) and relaxation time constants decreased with age (young: t1 = 221.9 ± 29.0 s, t2 = 24.7 ± 3.8 s, t3 = 3.12 ± 0.87 s, old: t1 = 183.0 ± 22.0 s, t2 = 20.6 ± 2.6 s and t3 = 2.24 ± 0.43 s). Among the compounds tested, only 25-hydroxycholesterol produced statistically significant changes in the lens stiffness, relaxation time constants, and equilibrium load. In conclusion, older mouse lenses are stiffer and less viscous than young mouse lenses. Notably, no significant change in lens stiffness was observed following treatment with lipoic acid, contrary to previous findings.

A D-π-A-type ratiometric fluorescent probe to detect polarity changes and inhibition effect during ferroptosis.

To thoroughly understand ferroptosis's biological functions in living cells, it is crucial to investigate the polarity variations that occur during this unique Fe(II)-facilitated oxidative type of cell death. In this work, we report the development of a ratiometric probe (Po-P) to visualize the polarity changes in living cells and the inhibition effect during ferroptosis. The polarity-responsive fluorophore utilized by Po-P has a D-π-A-type structure. Based on theoretical calculations, ICT was proposed as the basis for Po-P's polarity-responsive mechanism. According to cell imaging results, Po-P had a desirable capacity for monitoring polarity fluctuations and erastin-induced ferroptosis. Furthermore, inhibition imaging revealed that dihydrolipoic acid (DHLA) could potentially prevent polarity changes that occur during erastin-induced ferroptosis, just as vitamin E (VE). We anticipate that the probe Po-P could be a valuable tool to quickly monitor polarity fluctuations and inhibition effects during ferroptosis and create new medications for treating disorders related to ferroptosis.

Substrate Analogues Entering the Lipoic Acid Salvage Pathway via Lipoate-Protein Ligase 2 Interfere with Staphylococcus aureus Virulence.

Lipoic acid (LA) is an essential cofactor in prokaryotic and eukaryotic organisms, required for the function of several multienzyme complexes such as oxoacid dehydrogenases. Prokaryotes either synthesize LA or salvage it from the environment. The salvage pathway in Staphylococcus aureus includes two lipoate-protein ligases, LplA1 and LplA2, as well as the amidotransferase LipL. In this study, we intended to hijack the salvage pathway by LA analogues that are transferred via LplA2 and LipL to the E2 subunits of various dehydrogenases, thereby resulting in nonfunctional enzymes that eventually impair viability of the bacterium. Initially, a virtual screening campaign was carried out to identify potential LA analogues that bind to LplA2. Three selected compounds affected S. aureus USA300 growth in minimal medium at concentrations ranging from 2.5 to 10 µg/mL. Further analysis of the most potent compound (Lpl-004) revealed its transfer to E2 subunits of dehydrogenase complexes and a negative impact on its functionality. Growth impairment caused by Lpl-004 treatment was restored by adding products of the lipoate-dependent enzyme complexes. In addition, Caenorhabditis elegans infected with LpL-004-treated USA300 demonstrated a significantly expanded lifespan compared to worms infected with untreated bacteria. Our results provide evidence that LA analogues exploiting the LA salvage pathway represent an innovative strategy for the development of novel antimicrobial substances.

Low-Triggering-Potential and Narrow-Potential-Window Electrochemiluminescence of Silver Nanoclusters for Gene Assay.

A low-triggering potential and a narrow-potential window are anticipated to decrease the electrochemical interference and cross talk of electrochemiluminescence (ECL). Herein, by exploiting the low oxidative potential (0.82 V vs Ag/AgCl) of dihydrolipoic acid-capped sliver nanoclusters (DHLA-AgNCs), a coreactant ECL system of DHLA-AgNCs/hydrazine (N2H4) is proposed to achieve efficient and oxidative-reduction ECL with a low-triggering potential of 0.82 V (vs Ag/AgCl) and a narrow-potential window of 0.22 V. The low-triggering-potential and narrow-potential-window nature of ECL can be primarily preserved upon labeling DHLA-AgNCs to probe DNA and immobilizing DHLA-AgNCs onto the Au surface via sandwiched hybridization, which eventually enables a selective ECL strategy for the gene assay at +0.82 V. This gene assay strategy can sensitively determine the gene of human papillomavirus from 10 to 1000 pM with a low limit of detection of 5 pM (S/N = 3) and would open a way to improve the applied ECL bioassay.

Underlying mechanisms of novel cuproptosis-related dihydrolipoamide branched-chain transacylase E2 (DBT) signature in sunitinib-resistant clear-cell renal cell carcinoma.

Renal cell carcinoma (RCC) is the predominant form of malignant kidney cancer. Sunitinib, a primary treatment for advanced, inoperable, recurrent, or metastatic RCC, has shown effectiveness in some patients but is increasingly limited by drug resistance. Recently identified cuproptosis, a copper-ion-dependent form of programmed cell death, holds promise in combating cancer, particularly drug-resistant types. However, its effectiveness in treating drug resistant RCC remains to be determined. Exploring cuproptosis's regulatory mechanisms could enhance RCC treatment strategies. Our analysis of data from the GEO and TCGA databases showed that the cuproptosis-related gene DBT is markedly under expressed in RCC tissues, correlating with worse prognosis and disease progression. In our study, we investigated copper CRGs in ccRCC, noting substantial expression differences, particularly in advanced-stage tumors. We established a connection between CRG expression levels and patient survival, positioning CRGs as potential therapeutic targets for ccRCC. In drug resistant RCC cases, we found distinct expression patterns for DBT and GLS CRGs, linked to treatment resistance. Our experiments demonstrated that increasing DBT expression significantly reduces RCC cell growth and spread, underscoring its potential as a therapeutic target. This research sheds new light on the role of CRGs in ccRCC and their impact on drug resistance.

Glutathione-dependent thioredoxin reduction and lipoamide system support in-vitro mammalian ribonucleotide reductase catalysis: a possible antioxidant redundancy.

BACKGROUND: The thioredoxin system (Trx), comprising of Trx, Thioredoxin reductase (TrxR) and NADPH aids in donating hydrogen group to support Ribonucleotide reductase (RNR) catalysis during de-novo DNA biosynthesis. However, it has been observed that inhibiting TrxR does not affect the viability of cancer cells that are susceptible to pharmacological glutathione (GSH) depletion. This prompted us to study the potential antioxidant redundancies that might prolong RNR activity. METHODS: To study the RNR activity assay, the RNR complex was reconstituted by mixing purified mouse recombinant RNR subunits and the conversion of [3 H] CDP into [3 H] dCDP was monitored. In the assay system, either purified Trx and GSH or Lipoamide system was supplemented as reducing agents to support RNR catalysis. RESULTS: Herein, we have found that GSH-dependent Trx reduction supports mammalian class I RNR catalysis in absence of TrxR in the system. Our data also presents the first report that the LAM system is capable of supporting in-vitro RNR activity in the complete absence of either Trx or Grx systems. CONCLUSIONS: We conclude that GSH-mediated Trx reduction and LAM systems support basal level RNR activity in vitro; in absence of TrxR and complete redoxin systems respectively and hypothesize that potential redundancy between the various antioxidant systems might synergize in sustaining RNR activity.

Astragaloside IV exhibits anti-tumor function in gastric cancer via targeting circRNA dihydrolipoamide S-succinyltransferase (circDLST)/miR-489-3p/ eukaryotic translation initiation factor 4A1(EIF4A1) pathway.

Astragaloside IV (AS-IV) is an inartificial saponin separated from astragalus membranaceus, which has exhibited key anti-tumor regulation in some cancers. Circular RNAs (circRNAs) are important regulators in malignant development of gastric cancer (GC). Herein, we focused on the molecular mechanism of AS-IV with circRNA dihydrolipoamide S-succinyltransferase (circDLST) in GC. CircDLST, microRNA-489-3p (miR-489-3p), and eukaryotic translation initiation factor 4A1 (EIF4A1) levels were detected by quantitative real-time polymerase-chain reaction and western blot. Cell functions were assessed by cell counting kit-8 assay, ethynyl-2'-deoxyuridine assay, colony formation assay, and transwell assay. The interaction between miR-489-3p and circDLST or EIF4A1 was analyzed by dual-luciferase reporter assay. Xenograft tumor assay was adopted to check the role of circDLST and AS-IV in vivo. CircDLST and EIF4A1 were upregulated but miR-489-3p was downregulated in GC cells. AS-IV restrained cell proliferation and metastasis in GC cells by downregulating circDLST. CircDLST served as a miR-489-3p sponge, and miR-489-3p inhibition reversed anti-tumor function of AS-IV. EIF4A1 was a target for miR-489-3p and circDLST sponged miR-489-3p to regulate EIF4A1. AS-IV suppressed GC cell progression via circDLST-mediated downregulation of EIF4A1. Also, AS-IV recued tumor growth in vivo via targeting circDLST to regulate miR-489-3p/EIF4A1 axis. AS-IV inhibited the development of GC through circDLST/miR-489-3p/EIF4A1 axis.

Structure of the native pyruvate dehydrogenase complex reveals the mechanism of substrate insertion.

The pyruvate dehydrogenase complex (PDHc) links glycolysis to the citric acid cycle by converting pyruvate into acetyl-coenzyme A. PDHc encompasses three enzymatically active subunits, namely pyruvate dehydrogenase, dihydrolipoyl transacetylase, and dihydrolipoyl dehydrogenase. Dihydrolipoyl transacetylase is a multidomain protein comprising a varying number of lipoyl domains, a peripheral subunit-binding domain, and a catalytic domain. It forms the structural core of the complex, provides binding sites for the other enzymes, and shuffles reaction intermediates between the active sites through covalently bound lipoyl domains. The molecular mechanism by which this shuttling occurs has remained elusive. Here, we report a cryo-EM reconstruction of the native E. coli dihydrolipoyl transacetylase core in a resting state. This structure provides molecular details of the assembly of the core and reveals how the lipoyl domains interact with the core at the active site.

Therapy of spinal cord injury by zinc modified gold nanoclusters via immune-suppressing strategies.

BACKGROUND: Spinal cord injury (SCI) is damage to the central nervous system (CNS) that causes devastating complications from chronic pain to breathing problems. Unfortunately, few effective and safe treatments are known to relieve the damages of SCI. Nanomedicines are used for the treatment of SCI with relatively few side effects, but only depending on the delivery of additional drugs, which increase complexity to the treatment. Considering the urgent need for saving SCI patients, it is important to develop promising nanobiotechnology for relieving their pains. METHODS: The clinical survey was used to investigate SCI patients, thereafter the therapy plan was designed. The receiver-operating characteristics (ROC) curves of the prediction model were built to find symptoms after SCI. The treatment plan (i.e. immunosuppressive strategy) was designed by manufacturing therapies based on gold nanoclusters (AuNCs). The response of the immune cells (macrophages) was studied accordingly. The western blot, reactive oxygen species (ROS) activity assay, enzyme-linked immunosorbent assay (ELISA), quantitative real-time PCR (RT-qPCR), and immunochemical staining were used for evaluation of the in vivo and in vitro therapeutic effects. RESULTS: We found increased monocytes/macrophages (M/Ms) levels in 114 SCI subjects (44.7% with severe SCI complications) by the clinical survey. Additionally, the enhanced macrophage level was found to be closely related to the walking disorder after SCI. Since macrophages were central effector cells of the immune system, we assumed that the immune-suppressing strategies could be used for SCI therapy. Thereafter, AuNCs were stabilized by dihydrolipoic acid (DHLA) enantiomers (including DL-DHLA, R-DHLA; A racemic mixture (R and S) was denoted as DL; R and S refer to Rectus and Sinister), obtaining DL-DHLA-AuNCs and R-DHLA-AuNCs, respectively. In addition, zinc-modified DL-DHLA and R-DHLA stabilized AuNCs (i.e., DL-DHLA-AuNCs-Zn and R-DHLA-AuNCs-Zn) were investigated. Among these AuNCs, R-DHLA-AuNCs-Zn showed the most remarkable therapeutic effect for promoting the polarization of pro-inflammatory macrophages and reducing neuronal ROS-induced apoptosis and inflammation in vitro and in vivo; the lesion size was decreased and the survival rate of ventral neurons is higher. CONCLUSIONS: R-DHLA-AuNCs-Zn have comprehensive therapeutic capabilities, especially the immune-suppressing effects for the therapy of SCI, which is promising to relieve the pain or even recover SCI for the patients.

Lipoic acid. Kinetics and pluripotent biological properties and derivatives.

Lipoic acid (LA) is globally known and its supplements are widely used. Despite its importance for the organism it is not considered a vitamin any more. The multiple metabolic forms and the differences in kinetics (absorption, distribution and excretion), as well as the actions of its enantiomers are analysed in the present article together with its biosynthetic path. The proteins involved in the transfer, biotransformation and activity of LA are mentioned. Furthermore, the safety and the toxicological profile of the compound are commented, together with its stability issues. Mechanisms of lipoic acid intervention in the human body are analysed considering the antioxidant and non-antioxidant characteristics of the compound. The chelating properties, the regenerative ability of other antioxidants, the co-enzyme activity and the signal transduction by the implication in various pathways will be discussed in order to be elucidated the pleiotropic effects of LA. Finally, lipoic acid integrating analogues are mentioned under the scope of the multiple pharmacological actions they acquire towards degenerative conditions.

The moonlighting activities of dihydrolipoamide dehydrogenase: Biotechnological and biomedical applications.

Dihydrolipoamide dehydrogenase (DLDH) is a homodimeric flavin-dependent enzyme that catalyzes the NAD+ -dependent oxidation of dihydrolipoamide. The enzyme is part of several multi-enzyme complexes such as the Pyruvate Dehydrogenase system that transforms pyruvate into acetyl-co-A. Concomitantly with its redox activity, DLDH produces Reactive Oxygen Species (ROS), which are involved in cellular apoptotic processes. DLDH possesses several moonlighting functions. One of these is the capacity to adhere to metal-oxides surfaces. This was first exemplified by the presence of an exocellular form of the enzyme on the cell-wall surface of Rhodococcus ruber. This capability was evolutionarily conserved and identified in the human, mitochondrial, DLDH. The enzyme was modified with Arg-Gly-Asp (RGD) groups, which enabled its interaction with integrin-rich cancer cells followed by "integrin-assisted-endocytosis." This allowed harnessing the enzyme for cancer therapy. Combining the TiO2 -binding property with DLDH's ROS-production, enabled us to develop several medical applications including improving oesseointegration of TiO2 -based implants and photodynamic treatment for melanoma. The TiO2 -binding sites of both the bacterial and human DLDH's were identified on the proteins' molecules at regions that overlap with the binding site of E3-binding protein (E3BP). This protein is essential in forming the multiunit structure of PDC. Another moonlighting activity of DLDH, which is described in this Review, is its DNA-binding capacity that may affect DNA chelation and shredding leading to apoptotic processes in living cells. The typical ROS-generation by DLDH, which occurs in association with its enzymatic activity and its implications in cancer and apoptotic cell death are also discussed.

Dihydrolipoic acid-coated gold nanocluster bioactivity against senescence and inflammation through the mitochondria-mediated JNK/AP-1 pathway.

Cellular senescence is the progressive impairment of function and proliferation in response to various regulators. Dihydrolipoic acid-coated gold nanoclusters (DHLA-Au NCs), which are molecular clusters with covalently linked dihydroxyl lipoic acid, preserve cellular activities for long-term incubation. DHLA-Au NC delivery was characterized, and we determined the role of growth supplements on internalization, allowing the optimization of DHLA-Au NC bioactivity. In the optimized medium, DHLA-Au NCs attenuated the levels of the senescence-associated phenotype. Molecular mechanism analysis further indicated that during DHLA-Au NC treatment, the activation of the stress signal JNK and its downstream c-Jun were impaired under LPS induction, which led to a decline in AP-1-mediated TNF-α transactivation. Confocal microscopy and subcellular fractionation analysis suggested that DHLA-Au NCs interacted with mitochondria through their lipid moiety and attenuated mitochondria-derived reactive oxygen species. With adequate treatment, DHLA-Au NCs show protection against cellular senescence and inflammation in vitro and in vivo.

Dihydrolipoic acid enhances autophagy and alleviates neurological deficits after subarachnoid hemorrhage in rats.

Autophagy is a crucial pathological process in early brain injury (EBI) after subarachnoid hemorrhage (SAH). In this study, we investigated the role of dihydrolipoic acid (DHLA) on enhancing autophagy and alleviating neurological deficits after SAH. SAH was induced by endovascular perforation in male Sprague-Dawley rats. DHLA (30 mg/kg) was administered intraperitoneally 1 h (h) after SAH. Small interfering ribonucleic acid (siRNA) for lysosome-associated membrane protein-1 (LAMP1) was administered through intracerebroventricular (i.c.v) route 48 h before SAH induction. SAH grading score, neurological score, immunofluorescence staining, Fluoro-Jade C (FJC) staining, and Western blot were examined. DHLA treatment increased autophagy-related protein expression and downregulated the apoptosis-related protein expression 24 h after SAH. In addition, the DHLA treatment reduced neuronal cell death and alleviated neurological deficits after SAH. Furthermore, knockdown of LAMP1 abolished the neuroprotective effects of DHLA. These results indicate that LAMP1 may participate in autophagy after SAH. DHLA treatment can enhance autophagy, attenuate apoptosis, and alleviate neurofunctional deficits in EBI after SAH. It may provide an effective alternative method for the treatment of EBI after SAH.

Genome Mining, Heterologous Expression, Antibacterial and Antioxidant Activities of Lipoamides and Amicoumacins from Compost-Associated Bacillus subtilis fmb60.

Bacillus subtilis fmb60, which has broad-spectrum antimicrobial activities, was isolated from plant straw compost. A hybrid NRPS/PKS cluster was screened from the genome. Sixteen secondary metabolites produced by the gene cluster were isolated and identified using LC-HRMS and NMR. Three lipoamides D-F (1-3) and two amicoumacin derivatives, amicoumacins D, E (4, 5), were identified, and are reported here for the first time. Lipoamides D-F exhibited strong antibacterial activities against harmful foodborne bacteria, with the MIC ranging from 6.25 to 25 µg/mL. Amicoumacin E scavenged 38.8% of ABTS+ radicals at 1 mg/mL. Direct cloning and heterologous expression of the NRPS/PKS and ace gene cluster identified its importance for the biosynthesis of amicoumacins. This study demonstrated that there is a high potential for biocontrol utilization of B. subtilis fmb60, and genome mining for clusters of secondary metabolites of B. subtilis fmb60 has revealed a greater biosynthetic potential for the production of novel natural products than previously anticipated.

Amelioration of Metal-Induced Cellular Stress by α-Lipoic Acid and Dihydrolipoic Acid through Antioxidative Effects in PC12 Cells and Caco-2 Cells.

α-Lipoic acid (ALA) and its reduced form dihydrolipoic acid (DHLA) are endogenous dithiol compounds with significant antioxidant properties, both of which have the potential to detoxify cells. In this study, ALA (250 µM) and DHLA (50 µM) were applied to reduce metal (As, Cd, and Pb)-induced toxicity in PC12 and Caco-2 cells as simultaneous exposure. Both significantly decreased Cd (5 µM)-, As (5 µM)-, and Pb (5 µM)-induced cell death. Subsequently, both ALA and DHLA restored cell membrane integrity and intracellular glutathione (GSH) levels, which were affected by metal-induced toxicity. In addition, DHLA protected PC12 cells from metal-induced DNA damage upon co-exposure to metals. Furthermore, ALA and DHLA upregulated the expression of survival-related proteins mTOR (mammalian target of rapamycin), Akt (protein kinase B), and Nrf2 (nuclear factor erythroid 2-related factor 2) in PC12 cells, which were previously downregulated by metal exposure. In contrast, in Caco-2 cells, upon co-exposure to metals and ALA, Nrf2 was upregulated and cleaved PARP-1 (poly (ADP-ribose) polymerase-1) was downregulated. These findings suggest that ALA and DHLA can counterbalance the toxic effects of metals. The protection of ALA or DHLA against metal toxicity may be largely due to an enhancement of antioxidant defense along with reduced glutathione level, which ultimately reduces the cellular oxidative stress.

Network model-based screen for FDA-approved drugs affecting cardiac fibrosis.

Cardiac fibrosis is a significant component of pathological heart remodeling, yet it is not directly targeted by existing drugs. Systems pharmacology approaches have the potential to provide mechanistic frameworks with which to predict and understand how drugs modulate biological systems. Here, we combine network modeling of the fibroblast signaling network with 36 unique drug-target interactions from DrugBank to predict drugs that modulate fibroblast phenotype and fibrosis. Galunisertib was predicted to decrease collagen and α-SMA expression, which we validated in human cardiac fibroblasts. In vivo fibrosis data from the literature validated predictions for 10 drugs. Further, the model was used to identify network mechanisms by which these drugs work. Arsenic trioxide was predicted to induce fibrosis by AP1-driven TGFß expression and MMP2-driven TGFß activation. Entresto (valsartan/sacubitril) was predicted to suppress fibrosis by valsartan suppression of ERK signaling and sacubitril enhancement of PKG activity, both of which decreased Smad3 activity. Overall, this study provides a framework for integrating drug-target mechanisms with logic-based network models, which can drive further studies both in cardiac fibrosis and other conditions.

In-vitro activity of lipoic acid against Ureaplasma urealyticum and Ureaplasma parvum isolated from women with infections of the urogenital tract. A pilot study.

Several species of Ureaplasma bacteria are known to be present in the urogenital tract of humans, in both healthy individuals and symptomatic patients. These pathogens are associated with urogenital tract infections, infertility problems and spontaneous abortion in humans. The present study involved 77 strains of Ureaplasma species (Ureaplasma spp.), including 21 Ureaplasma urealyticum (U. urealyticum) strains and 56 Ureaplasma parvum (U. parvum) strains. Lipoic acid (LA) and its reduced form dihydrolipoic acid (DHLA) are synthesized in all prokaryotic and eukaryotic cells. Research of recent years increasingly points to therapeutic properties of exogenously supplemented LA. In our study, we examined for the first time the effect of LA on the bacteria multiplication and its bactericidal activity against U. urealyticum and U. parvum. The LA concentrations used were: 1200 µg/ml, 120 µg/ml, and 12 µg/ml. The titer for each strain of Ureaplasma spp. was estimated using the color changing units (CCU) assay. For CCU measurements, a series of 10-fold dilutions of each cell culture in 0.9% NaCl (titration) was prepared and 1 CCU/ml was defined as the highest dilution of cells at which color change was detected. The strongest bacteriostatic and bactericidal effect of LA was observed at a concentration of 1200 µg/ml. In contrast, at lower LA concentrations, stimulation of the bacteria multiplication was noted for 14% of the total number of strains tested. Taken together, the current data provide novel findings about potential beneficial antimicrobial effects of LA.

Surface functionalized red fluorescent dual-metallic Au/Ag nanoclusters for endoplasmic reticulum imaging.

An efficient method is reported to prepare endoplasmic reticulum-targetable dual-metallic gold-silver nanoclusters, denoted as ER-Au/Ag nanoclusters (NCs), by virtue of a rationally designed molecular ligand. The prepared ER-Au/Ag NCs possesses red-emitting fluorescence with a strong emission at 622 nm and a high fluorescence quantum yield of 5.1%, which could avoid the influence of biological auto-fluorescence. Further investigation results showed that ER-Au/Ag NCs exhibited superior photostability, minimal cytotoxicity, and ER-targeting capability. Enabled by these meritorious features, ER-Au/Ag NCs have been successfully employed for long-term bioimaging of ER in living cells.Graphical abstract A sensitive non-enzymatic fluorescent glucose probe-based ZnO nanorod decorated with Au nanoparticles.

Estimation of Lipoyllysine Content in Meat and Its Antioxidative Capacity.

During this research a simple, accurate, and environmentally friendly method to determine lipoyllysine and lipoic acid in meat was developed and validated. The presented approach was based on the hydrolysis of the proteins containing lipoic acid, reduction of disulfide bonds with tris(hydroxymethyl)phosphine, and precolumn derivatization of free thiol groups with 1-benzyl-2-chloropyridinium bromide long-term followed by HPLC separation with a diode-array detector. The method has been validated in accordance with the U.S. FDA guidelines and was linear in the range of 0.1-10 µmol/L in concentration with R2 values ≥0.9997 for both analytes. For lipoyllysine and lipoic acid, intra- and interday precision values were lower than 10%. The intraday accuracy values ranged from 91.0% to 99.4% for lipoyllysine and from 99.1% to 107.3% for lipoic acid, whereas the interday accuracy values for lipoyllysine and lipoic acid were 92.0-95.6% and 93.5-98.8%, respectively. Additionally, in this research the antioxidant activity of lipoyllysine and reduced lipoyllysine compound using spectrophotometric method with 1,1-diphenyl-2-picrylhydrazyl was examined for the first time. The data showed that dihydrolipoyllysine exhibits stronger antioxidant capacity than lipoyllysine based on a lower value of concentration required to achieve a 50% antioxidant effect in 1,1-diphenyl-2-picrylhydrazyl radical scavenging test.

From mono-PEGylation towards anti-nonspecific protein interaction: comparison of dihydrolipoic acid versus glutathione-capped fluorescent gold nanoclusters using gel electrophoresis.

Ultrafine fluorescent gold nanoclusters (AuNCs) have emerged as biocompatible nanoprobes for biomedical imaging in vivo, and the precision surface chemistry of AuNCs is the key for attaining their clinical application. Comparison of two promising candidates for future nanomedicine, i.e. dihydrolipoic acid- versus glutathione-capped AuNCs (AuNC@DHLA vs. AuNC@GSH), was conducted for the first time to clarify their polyethylene glycol-related bioconjugate chemistry (PEGylation) and protein interactions. Gel electrophoresis was performed to separate the number of AuNCs PEGylation, and the molecular weight of the PEG spacer dominated the resolution of the separation in the gel. We have engineered and isolated the mono-PEGylated AuNCs either from the indirect carbodiimide bioconjugate chemistry or the direct Au-S binding. One-pot synthesis showed great efficiency for isolating mono-PEGylated AuNC@GSH from the tailored controlled aggregation of Au(i)-thiolate complexes on in situ generated Au(0) cores. Post-PEGylation of AuNC@GSH was also feasible using monodendate thiol-terminated PEG, but bidendate ligands of AuNC@DHLA exhibited low PEGylated efficiency by Au-S binding. In addition, mono-PEGylated AuNC@GSH significantly enhanced the ability of anti-nonspecific protein adsorption, but mono-PEGylated AuNC@DHLA cannot avoid the nonspecific binding with serum albumin. In addition, specific nano-assembly involving mono-biotinylated AuNCs with streptavidin were also compared using gel electrophoresis. These results provide key insights into the selection, preparation and design of functional AuNCs as nanoprobes for versatile biomedical applications.