Development of Analytical Quality by Design RP-HPLC Method and Its Validation for Estimation of Gefitinib from Bulk, Tablet Dosage Form and Complex Nanoformulation.

BACKGROUND: Estimation of the drug and development of the method is a critical aspect of formulation development and a critical factor for analytical scientists. Gefitinib is a poorly soluble anticancer drug. OBJECTIVE: The present research enlightens the topic of the development of innovative quality by design methods for the estimation of Gefitinib (GF) from bulk, pharmaceutical tablet formulation and complex nanoformulations. METHODS: To simplify the estimation of poorly soluble drugs like GF, Response Surface Methodology (RSM) was adopted with effective leverages to obtain precise computation design space using the Box-Behnken Design (BBD) model. The major 3 mixed effect independent factors (Percentage of Buffer, pH of buffer and flow rate) were screened with 3 prominent dependent responses (viz., Theoretical Plate, Retention Time, and Tailing Factor) selected for optimal analysis. Furthermore, co-processed steps were employed for the estimation of the analyte from the complex formulation. RESULTS: The RP-HPLC method utilizes the quality by design (QbD) approach can effectively estimate the analyte concentration of less than 4.5 min. The developed method was economically robust, and sensitive and shows a % relative standard deviation (%RSD) of less than 2% for all the selected validation parameters. The estimated design space suggests the highest desirability (R2-0.998) at 60% of buffer in the mobile phase, pH 4.25, and flow rate of 0.7 mL/min. CONCLUSION: The QbD approach was used to design and develop the method by understanding the interaction between dependent and independent variables to get the optimum values. The developed method was validated successfully and can be useful for formulation scientists to estimate drug concentration and drug release profiles from complex nanoformulations. HIGHLIGHTS: The analytical approach was designed and quantified using a quality-by-design approach to make the RP-HPLC method more robust and efficient for the estimation of analytes from complex nanoformulations. The method is also useful to eliminate the interfering molecule during estimation by employing co-processing steps. The developed method saves time, and cost of solvent and employs QbD as a requirement of recent regulatory concern.

Structural and biochemical insights into purine-based drug molecules in hBRD2 delineate a unique binding mode opening new vistas in the design of inhibitors of the BET family.

The bromodomain and extra-terminal (BET) family proteins, which are involved in chromatin function, have been shown to be promising drug targets in several pathological conditions, including cancer and inflammation. There is considerable interest in the development of BET inhibitors with novel scaffolds to modulate the epigenesis of such diseases. Here, high-resolution crystal structures of the purine class of FDA-approved drugs (theophylline, doxophylline and acyclovir) and non-FDA-approved compounds (3-methyl-7-propylxanthine and theobromine) complexed with hBRD2 bromodomains BD1 and BD2 are reported. Remarkably, a new binding site is exhibited by stacking the compounds against the WPF shelf of BD1 and BD2. This serendipitous binding, in addition to the known acetyl-lysine binding site, sufficiently anchors the ligands in the solvent-exposed region. In addition, slight variations in the lipophilicity of these molecules significantly affected the in vitro binding affinity and selectivity towards BD1 compared with BD2. This idiosyncratic binding provides a new structural framework to link these sites for the development of next-generation inhibitors of the BET family.

Chlorhexidine as a Keap1-Nrf2 inhibitor: a new target for an old drug for Parkinson's disease therapy.

Oxidative stress plays a vital role in the pathophysiology of most neurodegenerative diseases such as Parkinson's disease (PD). The Keap1-Nrf2-ARE pathway, one of the internal defense mechanisms, curbs the reactive oxygen species (ROS) generated in the cellular environment. The pathway leads to the expression of antioxidant genes such as HO-1, GCLC, and NQO1, which act as cellular redox switches and protect the cellular environment. Keap1, the negative regulator of Nrf2, is a potential therapeutic target for treating age-related neurodegenerative diseases. Tecfidera (Dimethyl fumarate), used in the intervention for relapsing multiple sclerosis, is the only commercial drug known to regulate the Nrf2 function. Here, we have identified a repurposing drug, chlorhexidine (LBP125), through ligand-based pharmacophore development and screening against the DrugBank, as a potential inhibitor of the ß-propeller domain of Keap1 (Keap1-DC). Chlorhexidine, an antimicrobial agent, is widely used as a mouthwash, skin cleanser, and intervening bacterial infection during childbirth. The biochemical assay confirmed a significant binding affinity of 30 µM and competitively inhibited the Nrf2 peptide interaction. Moreover, chlorhexidine also exerts cytoprotection in a neurotoxic cell model of PD through Keap1-Nrf2 disruption leading to nuclear translocation of Nrf2 and expression of downstream genes, HO-1, and NQO1. Hence, the chemical scaffold of chlorhexidine is a potential lead to develop new chemical libraries with drug-like properties for treating PD.Communicated by Ramaswamy H. Sarma.

Molecular Insights into Coumarin Analogues as Antimicrobial Agents: Recent Developments in Drug Discovery.

A major global health risk has been witnessed with the development of drug-resistant bacteria and multidrug-resistant pathogens linked to significant mortality. Coumarins are heterocyclic compounds belonging to the benzophenone class enriched in different plants. Coumarins and their derivatives have a wide range of biological activity, including antibacterial, anticoagulant, antioxidant, anti-inflammatory, antiviral, antitumour, and enzyme inhibitory effects. In the past few years, attempts have been reported towards the optimization, synthesis, and evaluation of novel coumarin analogues as antimicrobial agents. Several coumarin-based antibiotic hybrids have been developed, and the majority of them were reported to exhibit potential antibacterial effects. In the present work, studies reported from 2016 to 2020 about antimicrobial coumarin analogues are the focus. The diverse biological spectrum of coumarins can be attributed to their free radical scavenging abilities. In addition to various synthetic strategies developed, some of the structural features include a heterocyclic ring with electron-withdrawing/donating groups conjugated with the coumarin nucleus. The suggested structure-activity relationship (SAR) can provide insight into how coumarin hybrids can be rationally improved against multidrug-resistant bacteria. The present work demonstrates molecular insights for coumarin derivatives having antimicrobial properties from the recent past. The detailed SAR outcomes will benefit towards leading optimization during the discovery and development of novel antimicrobial therapeutics.

Insights into the role of F26 residue in the FMN: ATP adenylyltransferase activity of Staphylococcus aureus FAD synthetase.

The bifunctional flavin adenine dinucleotide synthetase (FADS) synthesizes the flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) co-factors essential for the function of flavoproteins. The Staphylococcus aureus FADS (SaFADS) produces FMN from riboflavin (RF) by ATP:riboflavin kinase (RFK) activity at its C-terminal domain. The N-terminal domain converts FMN to FAD under a reducing environment by FMN:ATP adenylyltransferase (FMNAT) activity which is reversible (FAD pyrophosphorylase activity). Herein, we investigated the role of F26 residue of the 24-GFFD-28 motif of SaFADS FMNAT domain, mostly conserved in the reducing agent-dependent FADSs. The steady-state kinetics studies showed changes in the KmATP values for mutants, indicating that the F26 residue is crucial for the FMNAT activity. Further, the FMNAT activity of the F26S mutant was observed to be higher than that of the wild-type SaFADS and its other variants at lower reducing agent concentration. In addition, the FADpp activity was inhibited by an excess of FAD substrate, which was more potent in the mutants. The altered orientation of the F26 side-chain observed in the molecular dynamics analysis suggested its plausible involvement in stabilizing FMN and ATP substrates in their respective binding pockets. Also, the SaFADS ternary complex formed with reduced FMN exhibited significant structural changes in the ß4n-ß5n and L3n regions compared to the oxidised FMN bound and apo forms of SaFADS. Overall, our data suggests the functional role of F26 residue in the FMNAT domain of SaFADS.

Structural investigation of a pyrano-1,3-oxazine derivative and the phenanthridinone core moiety against BRD2 bromodomains.

The BET (bromodomain and extra-terminal) family of proteins recognize the acetylated histone code on chromatin and play important roles in transcriptional co-regulation. BRD2 and BRD4, which belong to the BET family, are promising drug targets for the management of chronic diseases. The discovery of new scaffold molecules, a pyrano-1,3-oxazine derivative (NSC 328111; NS5) and phenanthridinone-based derivatives (L10 and its core moiety L10a), as inhibitors of BRD2 bromodomains BD1 and BD2, respectively, has recently been reported. The compound NS5 has a significant inhibitory effect on BRD2 in glioblastoma. Here, the crystal structure of BRD2 BD2 in complex with NS5, refined to 2.0 Šresolution, is reported. Moreover, as the previously reported crystal structures of the BD1-NS5 complex and the BD2-L10a complex possess moderate electron density corresponding to the respective ligands, the crystal structures of these complexes were re-evaluated using new X-ray data. Together with biochemical studies using wild-type BRD2 BD1 and BD2 and various mutants, it is confirmed that the pyrano-1,3-oxazine and phenanthridinone derivatives are indeed potent inhibitors of BRD2 bromodomains.

In silico screening of small molecule modulators and their binding studies against human sirtuin-6 protein.

Sirtuin-6 (SIRT6), class III family of deacetylase regulates several biological functions, including transcriptional repression, telomere maintenance, and DNA repair. It is unique among sirtuin family members with diverse enzymatic functions: mono-ADP-ribosylase, deacetylase and defatty-acylase. The studies so far implicated SIRT6 role in lifespan extension, tumor suppression, and is considered as an attractive drug target for aging-related disease. In this study, we have carried out in silico screening for human SIRT6 modulators using NCI Diversity Set III library, molecular dynamic (MD) simulations to analyze the protein-ligand interaction, and validated their binding-affinity (Kd) using MicroScale Thermophoresis. This study yielded two novel compounds, ((3Z)-3-((4-(dimethylamino)phenyl)methylidene)-5-(5,6,7,8-tetrahydronaphthalen-2-yl)furan-2-one and 5-phenyl-2-(5-phenyl-2,3-dihydro-1,3-benzoxazol-2-yl)-2,3-dihydro-1,3-benzoxazole showing high-affinity interaction for SIRT6. The structural analysis from MD simulation suggests both compounds might act as substrate-analogs or mimic the nicotinamide binding. On considering the uniqueness of SIRT6 substrate binding acyl channel among sirtuin family member, binding of both compounds to the above site suggesting their specificity for SIRT6 isoform. Therefore, it may form the basis for the development of potential modulators for human SIRT6.Communicated by Ramaswamy H. Sarma.

Electrostatic deposition assisted preparation, characterization and evaluation of chrysin liposomes for breast cancer treatment.

Chrysin (CHR), a flavone found in multiple vegetables, fruits and mushrooms has been explored so far as a neurotropic, anti-inflammatory and anti-cancer biomolecule. Despite the stated therapeutic potential, low solubility and bioavailability limit its therapeutic benefit. To circumvent these drawbacks, development of chrysin liposomes (CLPs) is reported in the present investigation. The CLPs were developed by electrostatic deposition assisted film hydration method using chitosan/lecithin to protect chrysin in the nano-lipoidal shell. Developed CLPs were extensively characterized by DSC, XPRD, FE-SEM, TEM, particle size, polydispersity index, zeta potential, percent drug loading and encapsulation efficiency. These CLPs were further characterized by in vitro dissolution, in vivo bioavailability, in vitro anticancer and stability study. Suitable particle size, PDI and ZP implying stabilization of developed CLPs. The % DL and % EE was found to be 3.56 ± 0.13 and 90.5 ± 1.49 respectively. DSC and PXRD study revealed amorphous transition of CHR, which may help to increase its solubility and dissolution profile. In vivo pharmacokinetic study demonstrated more than 5-fold increase in relative bioavailability of CLPs. The in silico molecular docking study results demonstrated the electrostatic interaction between two polymers. The present study suggests that chitosan could protect and encapsulate chrysin which eventually enhances its cytotoxicity as well as bioavailability.

A key role by polymers in microneedle technology: a new era.

The skin serves as the major organ in the targeted transdermal drug delivery system for many compounds. The microneedle acts as a novel technique to deliver drugs across the different layers of the skin, including the major barrier stratum corneum, in an effective manner. A microneedle array patch comprises dozens to hundreds of micron-sized needles with numerous structures and advantages resulting from their special and smart designs. The microneedle approach is much more advanced than conventional transdermal delivery pathways due to several benefits like minimally invasive, painless, self-administrable, and enhanced patient compliance. The microneedles are classified into hollow, solid, coated, dissolving, and hydrogel. Several polymers are used to fabricate microneedle, such as natural, semi-synthetic, synthetic, biodegradable, and swellable polymers. Researchers in the preparation of microneedles also explored the combinations of polymers. The safety of the polymer used in microneedle is a crucial aspect to prevent toxicity in vivo. Thus, this review aims to provide a detailed review of microneedles and mainly focus on the various polymers used in the fabrication of microneedles.

Structural insights into the multiple binding modes of Dimethyl Fumarate (DMF) and its analogs to the Kelch domain of Keap1.

The activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) transcription function has been implicated in the protection of neurodegenerative diseases. The cytoplasmic protein, Kelch-like ECH-associated protein 1 (Keap1), negatively regulates Nrf2. The Keap1-Nrf2 pathway is a potential therapeutic target for tackling free-radical damage. Dimethyl fumarate (DMF) is currently an approved drug for the treatment of relapsing multiple sclerosis. Recent studies showed that DMF modifies the reactive cysteines in the BTB domain of Keap1 and thus activates Nrf2 transcription function. Intriguingly, our crystal structure studies revealed that DMF also binds to the ß-propeller domain (Keap1-DC) of Keap1. The crystal structure of the complex, refined to 1.54 Å resolution, revealed unexpected features: DMF binds (a) to the Nrf2-binding site (bottom region of Keap1-DC, site 1) with moderate interaction, and (b) to the top region of Keap1-DC, near to the blade II (site 2). The specificity of the binding 'site 2' was found to be unique to blade II of the ß-propeller domain. The newly identified 'site 2' region in Keap1-DC may have a different functional role to regulate Nrf2. Moreover, the crystal structures of Keap1-DC in complex with the DMF analogs, including monoethyl fumarate, fumarate, and itaconate, also exhibited similar binding modes with Keap1-DC. Binding studies confirmed that DMF binds, in a nanomolar range, to the Keap1-DC region as well as the BTB domain of Keap1. Furthermore, the competitive binding assay in the presence of the Nrf2 peptide affirmed the direct binding of DMF at the Nrf2-binding region of Keap1-DC. Overall, our studies suggest that the drug molecule, DMF, binds at multiple sites of Keap1 and thus potentially activates Nrf2 function through covalent as well as the noncovalent mode of action, to combat oxidative stress. DATABASE: Structural data are available in RCSB-protein data bank database(s) under the accession numbers 6LRZ, 7C60, and 7C5E.

Black Phosphorus as Multifaceted Advanced Material Nanoplatforms for Potential Biomedical Applications.

Black phosphorus is one of the emerging members of two-dimensional (2D) materials which has recently entered the biomedical field. Its anisotropic properties and infrared bandgap have enabled researchers to discover its applicability in several fields including optoelectronics, 3D printing, bioimaging, and others. Characterization techniques such as Raman spectroscopy have revealed the structural information of Black phosphorus (BP) along with its fundamental properties, such as the behavior of its photons and electrons. The present review provides an overview of synthetic approaches and properties of BP, in addition to a detailed discussion about various types of surface modifications available for overcoming the stability-related drawbacks and for imparting targeting ability to synthesized nanoplatforms. The review further gives an overview of multiple characterization techniques such as spectroscopic, thermal, optical, and electron microscopic techniques for providing an insight into its fundamental properties. These characterization techniques are not only important for the analysis of the synthesized BP but also play a vital role in assessing the doping as well as the structural integrity of BP-based nanocomposites. The potential role of BP and BP-based nanocomposites for biomedical applications specifically, in the fields of drug delivery, 3D printing, and wound dressing, have been discussed in detail to provide an insight into the multifunctional role of BP-based nanoplatforms for the management of various diseases, including cancer therapy. The review further sheds light on the role of BP-based 2D platforms such as BP nanosheets along with BP-based 0D platforms-i.e., BP quantum dots in the field of therapy and bioimaging of cancer using techniques such as photoacoustic imaging and fluorescence imaging. Although the review inculcates the multimodal therapeutic as well as imaging role of BP, there is still research going on in this field which will help in the development of BP-based theranostic platforms not only for cancer therapy, but various other diseases.

Computational studies and biosensory applications of graphene-based nanomaterials: a state-of-the-art review.

Graphene, graphene oxide (GO) and graphene quantum dots (GQDs) are expected to play a vital role in the diagnosis of severe ailments. Computer-based simulation approaches are helpful for understanding theoretical tools prior to experimental investigation. These theoretical tools still have a high computational requirement. Thus, more efficient algorithms are required to perform studies on even larger systems. The present review highlights the recent advancement in structural confinement using computer simulation approaches along with biosensory applications of graphene-based materials. The computer simulation approaches help to identify the interaction between interacting molecules and sensing elements like graphene sheets. The simulation approach reduces the wet-lab experiment time and helps to predict the interaction and interacting environment. The experimental investigation can be tuned at a molecular level easily to predict small changes in structural configuration. Here, the molecular simulation study could be useful as an alternative to actual wet experimental approaches. The sensing ability of graphene-based materials is a result of interactions like hydrogen bonding, base-base interaction, and base-to-pi interaction to name a few. These interactions help in designing and engineering a substrate for sensing of various biomolecules.

Novel pyrano 1,3 oxazine based ligand inhibits the epigenetic reader hBRD2 in glioblastoma.

Glioblastoma (GBM) is the most common primary brain malignancy, rarely amenable to treatment with a high recurrence rate. GBM are prone to develop resistance to the current repertoire of drugs, including the first-line chemotherapeutic agents with frequent recurrence, limiting therapeutic success. Recent clinical data has evidenced the BRD2 and BRD4 of the BET family proteins as the new druggable targets against GBM. In this relevance, we have discovered a compound (pyrano 1,3 oxazine derivative; NSC 328111; NS5) as an inhibitor of hBRD2 by the rational structure-based approach. The crystal structure of the complex, refined to 1.5 Šresolution, revealed that the NS5 ligand significantly binds to the N-terminal bromodomain (BD1) of BRD2 at the acetylated (Kac) histone binding site. The quantitative binding studies, by SPR and MST assay, indicate that NS5 binds to BD1 of BRD2 with a KD value of ∼1.3 µM. The cell-based assay, in the U87MG glioma cells, confirmed that the discovered compound NS5 significantly attenuated proliferation and migration. Furthermore, evaluation at the translational level established significant inhibition of BRD2 upon treatment with NS5. Hence, we propose that the novel lead compound NS5 has an inhibitory effect on BRD2 in glioblastoma.

Overcoming Wnt-ß-catenin dependent anticancer therapy resistance in leukaemia stem cells.

Leukaemia stem cells (LSCs) underlie cancer therapy resistance but targeting these cells remains difficult. The Wnt-ß-catenin and PI3K-Akt pathways cooperate to promote tumorigenesis and resistance to therapy. In a mouse model in which both pathways are activated in stem and progenitor cells, LSCs expanded under chemotherapy-induced stress. Since Akt can activate ß-catenin, inhibiting this interaction might target therapy-resistant LSCs. High-throughput screening identified doxorubicin (DXR) as an inhibitor of the Akt-ß-catenin interaction at low doses. Here we repurposed DXR as a targeted inhibitor rather than a broadly cytotoxic chemotherapy. Targeted DXR reduced Akt-activated ß-catenin levels in chemoresistant LSCs and reduced LSC tumorigenic activity. Mechanistically, ß-catenin binds multiple immune-checkpoint gene loci, and targeted DXR treatment inhibited expression of multiple immune checkpoints specifically in LSCs, including PD-L1, TIM3 and CD24. Overall, LSCs exhibit distinct properties of immune resistance that are reduced by inhibiting Akt-activated ß-catenin. These findings suggest a strategy for overcoming cancer therapy resistance and immune escape.

Discovery of N-Cyano-sulfoximineurea Derivatives as Potent and Orally Bioavailable NLRP3 Inflammasome Inhibitors.

NLRP3 inflammasome mediated release of interleukin-1ß (IL-1ß) has been implicated in various diseases. In this study, rationally designed mimics of sulfonylurea moiety were investigated as NLRP3 inhibitors. Our results culminated into discovery of series of unprecedented N-cyano sulfoximineurea derivatives as potent NLRP3 inflammasome inhibitors. Compound 15 (IC50 = 7 nM) and analogues were found to be highly potent and selective NLRP3 inflammasome inhibitor with good pharmacokinetic profile. These effects translate in vivo, as 15, 29, and 34 significantly inhibit NLRP3 dependent IL-1ß secretion in mice.

Recent Advancement in Bio-precursor derived graphene quantum dots: Synthesis, Characterization and Toxicological Perspective.

Graphene quantum dots (GQDs), impressive materials with enormous future potential, are reviewed from their inception, including different precursors. Considering the increasing burden of industrial and ecological bio-waste, there is an urgency to develop techniques which will convert biowaste into active moieties of interest. Amongst the various materials explored, we selectively highlight the use of potential carbon containing bioprecursors (e.g. plant-based, amino acids, carbohydrates), and industrial waste and its conversion into GQDs with negligible use of chemicals. This review focuses on the effects of different processing parameters that affect the properties of GQDs, including the surface functionalization, paradigmatic characterization, toxicity and biocompatibility issues of bioprecursor derived GQDs. This review also examines current challenges and s the ongoing exploration of potential bioprecursors for ecofriendly GQD synthesis for future applications. This review sheds further light on the electronic and optical properties of GQDs along with the effects of doping on the same. This review may aid in future design approaches and applications of GQDs in the biomedical and materials design fields.

Development of amine-functionalized superparamagnetic iron oxide nanoparticles anchored graphene nanosheets as a possible theranostic agent in cancer metastasis.

The major objective of the present investigation was to assess the targeting potential of a designed system for breast cancer at metastatic phases with imaging ability. In a nutshell, we have developed surface-engineered graphene oxide (GO) nanosheets by covalent linking with amine-functionalized iron oxide nanoparticles (IONPs) (GOIOIs). Gefitinib (Gf) was selected as a model drug and entrapped in between exfoliated GO sheets (GOIGF) via π-π* stacking before functionalization with IONPs. Preliminary characterization of GO, IONPs, GOIOI, and GOIGF was performed using UV-visible and Fourier transform infrared spectroscopy. Scanning and transmission electron microscopy studies confirmed successful surface engineering of GO with IONPs. The in vitro drug release study demonstrated sustained release of Gf. The magnetic behavior of IONPs and GOIOI demonstrated a sigmoidal-shaped hysteresis loop with superparamagnetic properties. The in vitro cell cytotoxicity assay was carried out on MDA-MB-231 breast cancer adenocarcinoma cell lines. The cell cytotoxicity assay showed 61.18% inhibition of cell growth with 30 ppm concentration containing 64% of the drug, whereas 100% of the pure drug revealed only 56% of inhibition. In the near future, GOIOI could be tailored further for theranostic research, especially for metastatic cancers. Graphical abstract.

Design, synthesis, in-vitro evaluation and molecular docking studies of novel indole derivatives as inhibitors of SIRT1 and SIRT2.

Sirtuins (SIRTs), class III HDAC (Histone deacetylase) family proteins, are associated with cancer, diabetes, and other age-related disorders. SIRT1 and SIRT2 are established therapeutic drug targets by regulating its function either by activators or inhibitors. Compounds containing indole moiety are potential lead molecules inhibiting SIRT1 and SIRT2 activity. In the current study, we have successfully synthesized 22 indole derivatives in association with an additional triazole moiety that provide better anchoring of the ligands in the binding cavity of SIRT1 and SIRT2. In-vitro binding and deacetylation assays were carried out to characterize their inhibitory effects against SIRT1 and SIRT2. We found four derivatives, 6l, 6m, 6n, and 6o to be specific for SIRT1 inhibition; three derivatives, 6a, 6d and 6k, specific for SIRT2 inhibition; and two derivatives, 6s and 6t, which inhibit both SIRT1 and SIRT2. In-silico validation for the selected compounds was carried out to study the nature of binding of the ligands with the neighboring residues in the binding site of SIRT1. These derivatives open up newer avenues to explore specific inhibitors of SIRT1 and SIRT2 with therapeutic implications for human diseases.

Biochemical insight into pseudouridine synthase 7 (PUS7) as a novel interactor of sirtuin, SIRT1.

Sirtuin1 (SIRT1) forms a dynamic regulatory network with multiple proteins. The SIRT1 protein interactome comprises histone, non-histone substrates, and modulators of SIRT1 deacetylase. Proteomic studies have enlisted several proteins in SIRT1 network, but the structural and functional details of their interactions remain largely unexplored. In this study, we establish Pseudouridine synthase 7 (PUS7), a nuclear protein involved in stem cell development and intellectual disabilities, as a novel interactor of SIRT1. The binding regions are predicted and analyzed based on molecular docking studies. The direct interaction occurs between SIRT1 and PUS7, as evidenced by pull-down studies and surface plasmon resonance (SPR) assay. Furthermore, the truncation studies unambiguously suggested that the N-terminal region of PUS7 is essential for forming a stable complex with SIRT1. Overall, our results suggest that PUS7 may regulate the SIRT1 function when it directly interacts with SIRT1.

Graphene-based nanocomposites for sensitivity enhancement of surface plasmon resonance sensor for biological and chemical sensing: A review.

Surface plasmon resonance (SPR) offers exceptional advantages such as label-free, in-situ and real-time measurement ability that facilitates the study of molecular or chemical binding events. Besides, SPR lacks in the detection of various binding events, particularly involving low molecular weight molecules. This drawback ultimately resulted in the development of several sensitivity enhancement methodologies and their application in the various area. Among graphene materials, graphene-based nanocomposites stands out owing to its significant properties such as strong adsorption of molecules, signal amplification by optical, high carrier mobility, electronic bridging, ease of fabrication and therefore, have established as an important sensitivity enhancement substrate for SPR. Also, graphene-based nanocomposites could amplify the signal generated by plasmon material and increase the sensitivity of molecular detection up to femto to atto molar level. This review focuses on the current important developments made in the potential research avenue of SPR and fiber optics based SPR for chemical and biological sensing. Latest trends and challenges in engineering and applications of graphene-based nanocomposites enhanced sensors for detecting minute and low concentration biological and chemical analytes are reviewed comprehensively. This review may aid in futuristic designing approaches and application of grapheneous sensor platforms for sensitive plasmonic nano-sensors.