Peptide-drug conjugate designated for targeted delivery to HER2-expressing cancer cells.

Targeted therapy of the highest globally incident breast cancer shall resolve the issue of off-target toxicity concurring with augmented killing of specific diseased cells. Thus, the goal of this study was to prepare a peptide-drug conjugate targeting elevated expression of HER2 receptors in breast cancer. Towards this, the rL-A9 peptide was conjugated with the chemotherapeutic drug doxorubicin (DOX) through a N-succinimidyl-4-(N-maleimidomethyl) cyclohexane-1-carboxylate (SMCC) linker. The synthesized peptide-drug conjugate, rL-A9-DOX, was characterized by mass spectrometry. Molecular docking studies, based on binding energy data, suggested a stronger interaction of rL-A9-DOX with the HER2 receptor in comparison to the unconjugated peptide, rL-A9. The cytotoxic effect of the rL-A9-DOX conjugate was observed to be higher in HER2-positive SKOV3 cells compared to HER2-negative MDA-MB-231 cells, indicating selective cell killing. Cellular internalization of the rL-A9-DOX conjugate was evident from the flow cytometry analysis, where a noticeable shift in mean fluorescent intensity (MFI) was observed for the conjugate compared to the control group. This data was further validated by confocal microscopy, where the fluorescent signal ascertained nuclear accumulation of rL-A9-DOX. The present studies highlight the promising potential of rL-A9-DOX for targeted delivery of the drug into a defined group of cancer cells.

Tuneable quantised conductance memory states in TiO2 based resistive switching devices in crossbar geometry for high density memory applications.

The tunability and controllability of conductance quantization mediated multilevel resistive switching (RS) memory devices, fabricated in crossbar geometry can be a promising alternative for boosting storage density. Here, we report fabrication of Cu/TiO2/Pt based RS devices in 8×8 crossbar geometry, which showed reliable bipolar RS operations. The crossbar devices showed excellent spatial and temporal variability, time retention and low switching voltage (<1 V) and current (~100 µA). Furthermore, during the reset switching, highly repeatable and reliable integral and half-integral quantized conductance (QC) was observed. The observed QC phenomenon was attributed to the two dimensional confinement of electrons as lateral width of the conducting filament (CF) matches the fermi wavelength. The magnitude and number of the QC steps were found to increase from ~2.5- 12.5 and from 5- 18, respectively by increasing the compliance current (IC) from 50 to 800µA which also increased the diameter of the CF from 1.2 to 3.3 nm. The enhancement in both number and magnitude of QC states was explained using electrochemical dissolution mechanism of CF of varying diameter. A thicker CF, formed at higher IC,undergoes a gradual rupture during reset process yielding a greater number of QC steps compared to a thinner CF. The realisation of QC states in the crossbar Cu/TiO2/Pt device as well as IC mediated tunability of their magnitude and number may find applications in high-density resistive memory storage devices and neuromorphic computing. .

Effect of non-linear strain stiffening in eDAH and unjamming.

In cell clusters, the prominent factors at play encompass contractility-based enhanced tissue surface tension and cell unjamming transition. The former effect pertains to the boundary effect, while the latter constitutes a bulk effect. Both effects share outcomes of inducing significant elongation in cells. This elongation is so substantial that it surpasses the limits of linear elasticity, thereby giving rise to additional effects. To investigate these effects, we employ atomic force microscopy (AFM) to analyze how the mechanical properties of individual cells change under such considerable elongation. Our selection of cell lines includes MCF-10A, chosen for its pronounced demonstration of the extended differential adhesion hypothesis (eDAH), and MDA-MB-436, selected due to its manifestation of cell unjamming behavior. In the AFM analyses, we observe a common trend in both cases: as elongation increases, both cell lines exhibit strain stiffening. Notably, this effect is more prominent in MCF-10A compared to MDA-MB-436. Subsequently, we employ AFM on a dynamic range of 1-200 Hz to probe the mechanical characteristics of cell spheroids, focusing on both surface and bulk mechanics. Our findings align with the results from single cell investigations. Specifically, MCF-10A cells, characterized by strong contractile tissue tension, exhibit the greatest stiffness on their surface. Conversely, MDA-MB-436 cells, which experience significant elongation, showcase their highest stiffness within the bulk region. Consequently, the concept of single cell strain stiffening emerges as a crucial element in understanding the mechanics of multicellular spheroids (MCSs), even in the case of MDA-MB-436 cells, which are comparatively softer in nature.

Effectiveness of Immune Checkpoint Inhibitors in Various Tumor Types Treated by Low, Per-Weight, and Conventional Doses at a Tertiary Care Center in Mumbai.

PURPOSE: The cost of immune checkpoint inhibitors (ICIs) limits their accessibility to a small number of patients with cancer in low- and middle-income countries. Early-phase clinical trials have shown target inhibition and high activity at doses lower than those registered and evaluated in clinical trials. Here, we report everyday experience of using ICIs in 100 Indian patients, many of whom received lower doses of ICIs. METHODS: Consecutive patients who received at least one dose of an ICI irrespective of tumor type at a tertiary care hospital in Mumbai, India, that was able to access ICIs for its patients were enrolled. The objectives were to study the doses used over a 3-year time period, and the effectiveness of therapy, assessed primarily by the overall response rate (ORR), overall survival (OS), and progression-free survival were secondary end points. RESULTS: Twenty-five patients were treated with conventional doses of ICIs, 29 patients received lower doses per body weight, and 46 patients received low-dose treatment. The median number of cycles received was 5 (range, 1-28). Seventy-eight patients received ICIs in a palliative setting. The median follow-up time was 10.2, 9.8, and 3.9 months for those receiving fixed approved dosing, per body weight dosing, and low-dose treatment, respectively. There was a trend with time to prescribe lower doses. Response evaluation was available for 92 patients. Twenty-one (five-adjuvant and 16-palliative) patients received ICIs only. The ORR did not differ statistically among different dosing groups, but comparisons are confounded by inclusion of different ICIs, different tumor sites, and concurrent treatments. The median OS was 6.8 (range, 4.6-9.0) months. CONCLUSION: Adoption of per-body weight and lower dosing of ICIs appears to give acceptable outcomes. Lower dosing can improve access and timely delivery of ICIs in low- and middle-income countries.

Putative staphylococcal enterotoxin possesses two common structural motifs for MHC-II binding.

Staphylococcus aureus has become a significant cause of health risks in humankind. Staphylococcal superantigens (SAgs) or enterotoxins are the key virulent factors that can exhibit acute diseases to severe life-threatening conditions. Recent literature reports S. aureus has steadily gained new enterotoxin genes over the past few decades. In spite of current knowledge of the established SAgs, several questions on putative enterotoxins are still remaining unanswered. Keeping that in mind, this study sheds light on a putative enterotoxin SEl26 to characterize its structural and functional properties. In-silico analyses indicate its close relation with the conventional SAgs, especially the zinc-binding SAgs. Additionally, important residues that are vital for the T-cell receptor (TcR) and major histocompatibility complex class II (MHC-II) interaction were predicted and compared with established SAgs. Besides, our biochemical analyses exhibited the binding of this putative enterotoxin with MHC-II, followed by regulating pro-inflammatory and anti-inflammatory cytokines.

Crystal structure of a thiolase from Archaeal Pyrococcus furiosus and its in silico functional annotation.

In most of the eukaryotes and archaea, isopentenyl pyrophosphate (IPP) and dimethyl allyl pyrophosphate (DMAPP) essential building blocks of all isoprenoids synthesized in the mevalonate pathway. Here, the first enzyme of this pathway, acetoacetyl CoA thiolase (PFC_04095) from an archaea Pyrococcus furiosus is structurally characterized. The crystal structure of PFC_04095 is determined at 2.7 Å resolution, and the crystal structure reveals the absence of catalytic acid/base cysteine in its active site, which is uncommon in thiolases. In place of cysteine, His285 of HDAF motif performs both protonation and abstraction of proton during the reaction. The crystal structure shows that the distance between Cys83 and His335 is 5.4 Å. So, His335 could not abstract a proton from nucleophilic cysteine (Cys83), resulting in the loss of enzymatic activity of PFC_04095. MD simulations of the docked PFC_04095-acetyl CoA complex show substrate binding instability to the active site pocket. Here, we have reported that the stable binding of acetyl CoA to the PFC_04095 pocket requires the involvement of three protein complexes, i.e., thiolase (PFC_04095), DUF35 (PFC_04100), and HMGCS (PFC_04090).

Staphylococcal superantigen-like protein 10 enhances the amyloidogenic biofilm formation in Staphylococcus aureus.

Staphylococcus aureus is a highly infectious pathogen that represents a significant burden on the current healthcare system. Bacterial attachment to medical implants and host tissue, and the establishment of a mature biofilm, play an important role in chronic diseases such as endocarditis, osteomyelitis and wound infections. These biofilms decrease bacterial susceptibility to antibiotics and immune defences, making the infections challenging to treatment. S. aureus produces numerous exotoxins that contribute to the pathogenesis of the bacteria. In this study, we have identified a novel function of staphylococcal superantigen-like protein 10 (SSL10) in enhancing the formation of staphylococcal biofilms. Biofilm biomass is significantly increased when SSL10 is added exogenously to bacterial cultures, whereas SSL2 and SSL12 are found to be less active. Exogenously added SSL10 mask the surface charge of the bacterial cells and lowers their zeta potential, leading to the aggregation of the cells. Moreover, the biofilm formation by SSL10 is governed by amyloid aggregation, as evident from spectroscopic and microscopic studies. These findings thereby give the first overview of the SSL-mediated amyloid-based biofilm formation and further drive the future research in identifying potential molecules for developing new antibacterial therapies against Staphylococcus aureus.

Deciphering the mannose transfer mechanism of mycobacterial PimE by molecular dynamics simulations.

Phosphatidyl-myo-inositol mannosides (PIMs), Lipomannan (LM), and Lipoarabinomannan (LAM) are essential components of the cell envelopes of mycobacteria. At the beginning of the biosynthesis of these compounds, phosphatidylinositol (PI) is mannosylated and acylated by various enzymes to produce Ac 1/2PIM4, which is used to synthesize either Ac1/2PIM6 or LM/LAM. The protein PimE, a membrane-bound glycosyltransferase (GT-C), catalyzes the addition of a mannose group to Ac1PIM4 to produce Ac1PIM5, using polyprenolphosphate mannose (PPM) as the mannose donor. PimE-deleted Mycobacterium smegmatis (Msmeg) showed structural deformity and increased antibiotic and copper sensitivity. Despite knowing that the mutation D58A caused inactivity in Msmeg, how PimE catalyzes the transfer of mannose from PPM to Ac1/2PIM4 remains unknown. In this study, analyzing the AlphaFold structure of PimE revealed the presence of a tunnel through the D58 residue with two differently charged gates. Molecular docking suggested PPM binds to the hydrophobic tunnel gate, whereas Ac1PIM4 binds to the positively charged tunnel gate. Molecular dynamics (MD) simulations further demonstrated the critical roles of the residues N55, F87, L89, Y163, Q165, K197, L198, R251, F277, W324, H326, and I375 in binding PPM and Ac1PIM4. The mutation D58A caused a faster release of PPM from the catalytic tunnel, explaining the loss of PimE activity. Along with a hypothetical mechanism of mannose transfer by PimE, we also observe the presence of tunnels through a negatively charged aspartate or glutamate with two differently-charged gates among most GT-C enzymes. Common hydrophobic gates of GT-C enzymes probably harbour sugar donors, whereas, differently-charged tunnel gates accommodate various sugar-acceptors.

Rationally Designed Novel Phenyloxazoline Synthase Inhibitors: Chemical Synthesis and Biological Evaluation to Accelerate the Discovery of New Antimycobacterial Antibiotics.

The uncontrolled spread of drug-resistant tuberculosis (DR-TB) clinical cases necessitates the urgent discovery of newer chemotypes with novel mechanisms of action. Here, we report the chemical synthesis of rationally designed novel transition-state analogues (TSAs) by targeting the cyclization (Cy) domain of phenyloxazoline synthase (MbtB), a key enzyme of the conditionally essential siderophore biosynthesis pathway. Following bio-assay-guided evaluation of TSA analogues preferentially in iron-deprived and iron-rich media to understand target preferentiality against a panel of pathogenic and non-pathogenic mycobacteria strains, we identified a hit, i.e., TSA-5. Molecular docking, dynamics, and MMPBSA calculations enabled us to comprehend TSA-5's stable binding at the active site pocket of MbtB_Cy and the results imply that the MbtB_Cy binding pocket has a strong affinity for electron-withdrawing functional groups and contributes to stable polar interactions between enzyme and ligand. Furthermore, enhanced intracellular killing efficacy (8 µg/mL) of TSA-5 against Mycobacterium aurum in infected macrophages is noted in comparison to moderate in vitro antimycobacterial efficacy (64 µg/mL) against M. aurum. TSA-5 also demonstrates whole-cell efflux pump inhibitory activity against Mycobacterium smegmatis. Identification of TSA-5 by focusing on the modular MbtB_Cy domain paves the way for accelerating novel anti-TB antibiotic discoveries.

Isolation and spectral characterisation of bioactives from sea weed Hydrocharis laevigata (Humb. & Bonpl. ex Willd.) Byng & Christenh. - using in silico & high throughput analytical techniques.

This work is the first report dealing with the identification and characterisation of the secondary metabolites of the ethanolic extract of Hydrocharis Laevigata (Humb. & Bonpl. Ex Willd.) Byng & Christenh. The ethanolic extract of H. laevigata was analysed by LCMS& Direct mass spectral analysis which is allowed to identify and Interpreted 6 & 15 compounds. The main constituents were caffeic acid, rosemary acid, Perilic acid, strychnine, hydroxy stearic acid, respectively. The extract further purified by column chromatography 15 fractions was isolated, out of which Perilic acid and strychnine are in high quantities. The structure determination of Perilic acid and strychnine was analysed by FTIR and NMR, respectively. By the molecular docking studies of Perilic acid and strychnine shows active binding energies for antidiabetic activity, respectively. The binding energy was compared with Metformin.

Deciphering the conformational stability of MazE7 antitoxin in Mycobacterium tuberculosis from molecular dynamics simulation study.

MazEF Toxin-antitoxin (TA) systems are associated with the persistent phenotype of the pathogen, Mycobacterium tuberculosis (Mtb), aiding their survival. Though extensively studied, the mode of action between the antitoxin-toxin and DNA of this family remains largely unclear. Here, the important interactions between MazF7 toxin and MazE7 antitoxin, and how MazE7 binds its promoter/operator region have been studied. To elucidate this, molecular dynamics (MD) simulation has been performed on MazE7, MazF7, MazEF7, MazEF7-DNA, and MazE7-DNA complexes to investigate how MazF7 and DNA affect the conformational change and dynamics of MazE7 antitoxin. This study demonstrated that the MazE7 dimer is disordered and one monomer (Chain C) attains stability after binding to the MazF7 toxin. Both the monomers (Chain C and Chain D) however are stabilized when MazE7 binds to DNA. MazE7 is also observed to sterically inhibit tRNA from binding to MazF7, thus suppressing its toxic activity. Comparative structural analysis performed on all the available antitoxins/antitoxin-toxin-DNA structures revealed MazEF7-DNA mechanism was similar to another TA system, AtaRT_E.coli. Simulation performed on the crystal structures of AtaR, AtaT, AtaRT, AtaRT-DNA, and AtaR-DNA showed that the disordered AtaR antitoxin attains stability by AtaT and DNA binding similar to MazE7. Based on these analyses it can thus be hypothesized that the disordered antitoxins enable tighter toxin and DNA binding thus preventing accidental toxin activation. Overall, this study provides crucial structural and dynamic insights into the MazEF7 toxin-antitoxin system and should provide a basis for targeting this TA system in combating Mycobacterium tuberculosis.Communicated by Ramaswamy H. Sarma.

Comparison of Contact Electrification Mechanisms of Selected Polymers and Surface-Functionalized Molecules.

Among the possible alternatives for the improvement of contact electrification for triboelectric energy harvesting purposes, the functionalization of contact surfaces has attracted wide attention due to its versatility and cost-efficiency. Similarly, low-stiffness polymeric materials such as poly(dimethylsiloxane) (PDMS) are regarded as a promising choice of contact material for the same purpose. However, for defining the most efficient combinations of materials of the aforementioned types, a number of theoretical questions still frequently pose difficulties for practical implementation-related tasks. In this regard, the presented study theoretically assesses the possibilities of consistently selecting optimum performance combinations of contact materials. Here, the optimum is defined as the minimum energy of the charge transfer reaction and, consequently, the maximum density of the predicted triboelectric surface charge. With this aim, the most promising combinations in terms of electron-transfer energies were identified among the candidates of functionalized molecules and polymers. Based on the ordering of materials according to the basic characteristics of charge-transfer reactions─electron and hole affinities─certain differences were observed. These findings indicate that for the materials under consideration, it is not possible to establish a single triboelectric series solely based on a single characteristic. Furthermore, to evaluate the potential compatibility of charge-transfer reaction mechanisms based on electron and material transfer, molecular dynamics simulations were conducted using structures that depict pairs of polymers and self-assembled monolayers of functionalized molecules in contact and separated types of operations. The obtained results indicate that the formation of equally charged free fragments of polymer chains is likely taking place in the contact electrification for N-(2-aminoethyl)-3-aminopropyl trimethoxysilane/PDMS interfaces. At variance, a contact electrification mechanism by charge-dependent material transfer may occur for 1H, 1H, 2H, 2H-perfluorooctyl trimethoxysilane/PDMS interfaces.

In vitro Quality Assessments of Perfluorocarbon Nanoemulsions for Near-infrared Fluorescence Imaging of Inflammation in Preclinical Models.

Tracking macrophages by non-invasive molecular imaging can provide useful insights into the immunobiology of inflammatory disorders in preclinical disease models. Perfluorocarbon nanoemulsions (PFC-NEs) have been well documented in their ability to be taken up by macrophages through phagocytosis and serve as 19F magnetic resonance imaging (MRI) tracers of inflammation in vivo and ex vivo. Incorporation of near-infrared fluorescent (NIRF) dyes in PFC-NEs can help monitor the spatiotemporal distribution of macrophages in vivo during inflammatory processes, using NIRF imaging as a complementary methodology to MRI. Here, we discuss in depth how both colloidal and fluorescence stabilities of the PFC-NEs are essential for successful and reliable macrophage tracking in vivo and for their detection in excised tissues ex vivo by NIRF imaging. Furthermore, PFC-NE quality assures NIRF imaging reproducibility and reliability across preclinical studies, providing insights into inflammation progression and therapeutic response. Previous studies focused on assessments of colloidal property changes in response to stress and during storage as a means of quality control. We recently focused on the joint evaluation of both colloidal and fluorescence properties and their relationship to NIRF imaging outcomes. In this protocol, we summarize the key assessments of the fluorescent dye-labeled nanoemulsions, which include long-term particle size distribution monitoring as the measure of colloidal stability and monitoring of the fluorescence signal. Due to its simplicity and reproducibility, our protocols are easy to adopt for researchers to assess the quality of PFC-NEs for in vivo NIRF imaging applications.

A Reversibly Thermoresponsive, Theranostic Nanoemulgel for Tacrolimus Delivery to Activated Macrophages: Formulation and In Vitro Validation.

Despite long-term immunosuppression, organ transplant recipients face the risk of immune rejection and graft loss. Tacrolimus (TAC, FK506, Prograf®) is an FDA-approved keystone immunosuppressant for preventing transplant rejection. However, it undergoes extensive first-pass metabolism and has a narrow therapeutic window, which leads to erratic bioavailability and toxicity. Local delivery of TAC directly into the graft, instead of systemic delivery, can improve safety, efficacy, and tolerability. Macrophages have emerged as promising therapeutic targets as their increased levels correlate with an increased risk of organ rejection and a poor prognosis post-transplantation. Here, we present a locally injectable drug delivery platform for macrophages, where TAC is incorporated into a colloidally stable nanoemulsion and then formulated as a reversibly thermoresponsive, pluronic-based nanoemulgel (NEG). This novel formulation is designed to undergo a sol-to-gel transition at physiological temperature to sustain TAC release in situ at the site of local application. We also show that TAC-NEG mitigates the release of proinflammatory cytokines and nitric oxide from lipopolysaccharide (LPS)-activated macrophages. To the best of our knowledge, this is the first TAC-loaded nanoemulgel with demonstrated anti-inflammatory effects on macrophages in vitro.

Targeting Staphylococcal Cell-Wall Biosynthesis Protein FemX Through Steered Molecular Dynamics and Drug-Repurposing Approach.

Staphylococcus aureus-mediated infection is a serious threat in this antimicrobial-resistant world. S. aureus has become a "superbug" by challenging conventional as well as modern treatment strategies. Nowadays, drug repurposing has become a new trend for the discovery of new drug molecules. This study focuses on evaluating FDA-approved drugs that can be repurposed against S. aureus infection. Steered molecular dynamics (SMD) has been performed for Lumacaftor and Olaparib against staphylococcal FemX to understand their binding to the active site. A time-dependent external force or rupture force has been applied to the ligands to calculate the force required to dislocate the ligand from the binding pocket. SMD analysis indicates that Lumacaftor has a high affinity for the substrate binding pocket in comparison to Olaparib. Umbrella sampling exhibits that Lumacaftor possesses a higher free energy barrier to displace it from the ligand-binding site. The bactericidal activity of Lumacaftor and Olaparib has been tested, and it shows that Lumacaftor has moderate activity along with biofilm inhibition potential (MIC value with conc. 128 µg/mL). Pharmacokinetic and toxicology evaluations indicate that Lumacaftor has higher pharmacokinetic potential with lower toxicity. This is the first experimental report where staphylococcal FemX has been targeted for the discovery of new drugs. It is suggested that Lumacaftor may be a potential lead molecule against S. aureus.

Design, synthesis and development of a dual inhibitor of Topoisomerase 1 and poly (ADP-ribose) polymerase 1 for efficient killing of cancer cells.

Combinatorial inhibition of Topoisomerase 1 (TOP1) and Poly (ADP-ribose) polymerase 1 (PARP1) is an attractive therapeutic strategy which is under active investigation to address chemoresistance to TOP1 inhibitors. However, this combinatorial regimen suffers from severe dose limiting toxicities. Dual inhibitors often offer significant advantages over combinatorial therapies involving individual agents by minimizing toxicity and providing conducive pharmacokinetic profiles. In this study, we have designed, synthesized and evaluated a library of 11 candidate conjugated dual inhibitors for PARP1 and TOP1, named as DiPT-1 to DiPT-11. Our extensive screening showed that one of the hits i.e.DiPT-4 has promising cytotoxicity profile against multiple cancers with limited toxicities towards normal cells. DiPT-4 induces extensive DNA double stand breaks (DSBs), cell cycle arrest and apoptosis in cancer cells. Mechanistically, DiPT-4 has the propensity to bind catalytic pockets of TOP1 and PARP1, leading to significant inhibition of both TOP1 and PARP1 at in vitro and cellular level. Interestingly, DiPT-4 causes extensive stabilization of TOP1-DNA covalent complex (TOP1cc), a key lethal intermediate associated with induction of DSBs and cell death. Moreover, DiPT-4 inhibited poly (ADP-ribosylation) i.e. PARylation of TOP1cc, leading to long lived TOP1cc with a slower kinetics of degradation. This is one of the important molecular processes which helps in overcoming resistance in cancer in response to TOP1 inhibitors. Together, our investigation showed DiPT-4 as a promising dual inhibitor of TOP1 and PARP1, which may have the potential to offer significant advantages over combinatorial therapy in clinical settings.

Epithelial layer fluidization by curvature-induced unjamming.

The transition of an epithelial layer from a stationary, quiescent state to a highly migratory, dynamic state is required for wound healing, development, and regeneration. This transition, known as the unjamming transition (UJT), is responsible for epithelial fluidization and collective migration. Previous theoretical models have primarily focused on the UJT in flat epithelial layers, neglecting the effects of strong surface curvature that is characteristic of epithelial tissues in vivo. In this study, we investigate the role of surface curvature on tissue plasticity and cellular migration using a vertex model embedded on a spherical surface. Our findings reveal that increasing curvature promotes epithelial unjamming by reducing the energy barriers to cellular rearrangements. Higher curvature favors cell intercalation, mobility, and self-diffusivity, resulting in epithelial structures that are malleable and migratory when small, but become more rigid and stationary as they grow. As such, curvature-induced unjamming emerges as a novel mechanism for epithelial layer fluidization. Our quantitative model proposes the existence of a new, extended, phase diagram wherein local cell shape, cell propulsion, and tissue geometry combine to determine the epithelial migratory phenotype.

Synthesis and 177Lu Labeling of the First Retro Analog of the HER2-Targeting A9 Peptide: A Superior Variant.

The retro analog of the HER2-targeting A9 peptide was synthesized by coupling amino acids in a reverse fashion and switching the N-terminal in the original sequence of the L-A9 peptide (QDVNTAVAW) to the C-terminal in rL-A9 (WAVATNVDQ). Modification in the backbone resulted in higher conformational stability of the retro peptide as evident from CD spectra. Molecular docking analysis revealed a higher HER2 binding affinity of [177Lu]Lu-DOTA-rL-A9 than the original radiopeptide [177Lu]Lu-DOTA-L-A9. Enormously enhanced metabolic stability of the retro analog led to significant elevation in tumor uptake and retention. SPECT imaging studies corroborated biodistribution results demonstrating a remarkably higher tumor signal for [177Lu]Lu-DOTA-rL-A9. The presently studied retro probe has promising efficiency for clinical screening.

Crystal structure of a mycobacterial secretory protein Rv0398c and in silico prediction of its export pathway.

Secretory proteins are used by pathogenic bacteria to manipulate the host systems and compete with other microorganisms, thereby enabling their survival in their host. Similar to other bacteria, secretory proteins of Mycobacterium tuberculosis also play a pivotal role in evading immune response within hosts, thereby leading to acute and latent tuberculosis infection. Prokaryotes have several classes of bacterial secretory systems out of which the Sec and Tat pathways are the most conserved in Mtb to transport proteins across the cytoplasmic membrane. Here, we report the crystal structure of a secretory protein, Rv0398c determined to 1.9 Å resolution. The protein comprises a core of antiparallel ß sheets surrounded by α helices adopting a unique ß sandwich fold. Structural comparison with other secretory proteins in Mtb and other pathogenic bacteria reveals that Rv0398c may be secreted via the Sec pathway. Our structural and in silico analyses thus provide mechanistic insights into the pathway adopted by Mtb to transport out secretory protein, Rv0398c which will facilitate the invasion to the host immune system.

Tunable, reversible resistive switching behavior of PVA-zirconia nanocomposite films and validation of the trap-assisted switching mechanism by the selective application of external bias voltages.

Flexible, free-standing polyvinyl alcohol (PVA)-zirconia (mean particle size ∼24 nm) nanocomposite films have been synthesized and their performance as a potential next-generation resistive switching device material has been assessed in this report. The nanocomposite films switch from a high resistive state (HRS) to a low resistive state (LRS) at the SET potential and from LRS to HRS at the RESET potential within the voltage window of 5 V. The origination of trap-assisted SET/RESET potentials has been experimentally validated by analyzing the experimental data and invoking various theoretical models. The impregnation of zirconium dioxide (ZrO2) nanoparticles considerably enhances the interfacial charges facilitated by the formation of dangling bonds. The current (I)-voltage (V) characteristics elucidate how the alteration of free volumetric space in the nanocomposites can modify the SET-RESET potential. This leads to tunable SET/RESET potential, good resistance ratio (∼80), and extensive cycling ability of these PVA-ZrO2 organic flexible nanocomposite films. Herein, we have also investigated the effect of applying external bias voltage (equal to the RESET potential) for possible energy bandgap modification and polymer chain orientation. The impedance spectra differ considerably when the sample is subjected to SET, RESET, and zero voltage bias. The observations have been correlated with the UV-vis absorption spectra and electrical studies. The adopted analysis method and obtained results can open up new avenues for designing and analyzing resistive switching-based random-access memory devices.