Revealing the Interlayer Interaction Forces in 2D Graphene Materials by Graphene-Wrapped Nanoprobe.

Understanding the interlayer interaction between 2D layered structures is critical for the construction of various micro- and nanoscale functional devices. However, both the normal and the tangential interlayer interactions between 2D layered materials have rarely been studied simultaneously. In this work, an immersion and lift-up method is proposed to wrap a layer of graphene flakes onto a plasma-pretreated atomic force microscopy (AFM) nanoprobe for the measurements of interaction forces by AFM. The normal interactions (adhesion force and adhesion energy) and tangential interactions (friction force) between two different probes (Pt-coated probe and graphene-wrapped probe) and two different 2D graphene materials [graphene and graphene oxide (GO)] were systematically measured, respectively. The adhesion energies of Pt-GO, Pt-graphene, graphene-GO, and graphene-graphene were measured to be 0.72 ± 0.05, 0.41 ± 0.03, 0.19 ± 0.02, and 0.10 ± 0.02 J m-2, respectively. The graphene-graphene contact pair showed the lowest adhesion force (5.57 ± 1.03 nN) and adhesion energy (0.10 ± 0.02 J m-2), which was attributed to the strong covalent bonds and charge density distribution. The friction coefficients of Pt-GO, graphene-GO, Pt-graphene, and graphene-graphene were determined to be 0.38, 0.14, 0.054, and 0.013. The graphene-graphene tribo-pair exhibited a superlow friction state for a long time, which was attributed to incommensurate contact and weak van der Waals interactions. These findings provide a technical route to reveal the interlayer interactions of various 2D layered materials, which can be widely applied in microelectromechanical systems.

Correction: Zaman et al. Synthesis and Evaluation of Thiol-Conjugated Poloxamer and Its Pharmaceutical Applications. Pharmaceutics 2021, 13, 693.

In the original publication, there was a mistake in one author name, Mohammed Alasmari should be Mohammed S [...].

Discovery of novel 1,2,4-triazole tethered ß-hydroxy sulfides as bacterial tyrosinase inhibitors: synthesis and biophysical evaluation through in vitro and in silico approaches.

In this study, a series of 1,2,4-triazole-tethered ß-hydroxy sulfide scaffolds 11a-h was synthesized in good to remarkable yields (69-90%) through the thiolysis of oxiranes by the thiols in aqueous basic catalytic conditions. The synthesized 1,2,4-triazole-tethered ß-hydroxy sulfides were screened against bacterial tyrosinase enzyme, and Gram-positive and Gram-negative bacterial cultures i.e., (S. aureus) Staphylococcus aureus & (E. coli) Escherichia coli. Among the synthesized derivatives, the molecules 11a (IC50 = 7.67 ± 1.00 µM), 11c (IC50 = 4.52 ± 0.09 µM), 11d (IC50 = 6.60 ± 1.25 µM), and 11f (IC50 = 5.93 ± 0.50 µM) displayed the better tyrosinase inhibitory activity in comparison to reference drugs ascorbic acid (IC50 = 11.5 ± 1.00 µM) and kojic acid (IC50 = 30.34 ± 0.75 µM). The molecule benzofuran-triazol-propan-2-ol 11c proved to be the most potent bacterial tyrosinase inhibitory agent with a minimum IC50 of 4.52 ± 0.09 µM, as compared to other synthesized counterparts and both standards (kojic acid and ascorbic acid). The compound diphenyl-triazol-propan-2-ol 11a and benzofuran-triazole-propan-2-ol 11c showed comparable anti-bacterial chemotherapeutic efficacy with minimum inhibitory concentrations (MIC = 2.0 ± 2.25 mg mL-1 and 2.5 ± 0.00 mg mL-1, respectively) against S. aureus bacterial strain in comparison with standard antibiotic penicillin (MIC = 2.2 ± 1.15 mg mL-1). Furthermore, among the synthesized derivatives, only compound 11c demonstrated better anti-bacterial activity (MIC = 10 ± 0.40 mg mL-1) against E. coli, which was slightly less than the standard antibiotic i.e., penicillin (MIC = 2.4 ± 1.00 mg mL-1). The compound 11c demonstrated a better binding score (-7.08 kcal mol-1) than ascorbic acid (-5.59 kcal mol-1) and kojic acid (-5.78 kcal mol-1). Molecular docking studies also validate the in vitro anti-tyrosinase assay results; therefore, the molecule 11c can be the lead bacterial tyrosinase inhibitor as well as the antibacterial agent against both types of bacterial strains after suitable structural modifications.

Exploring theophylline-1,2,4-triazole tethered N-phenylacetamide derivatives as antimicrobial agents: unraveling mechanisms via structure-activity relationship, in vitro validation, and in silico insights.

Theophylline, a nitrogen-containing heterocycle, serves as a promising focal point for medicinal researchers aiming to create derivatives with diverse pharmacological applications. In this work, we present an improved synthetic method for a range of theophylline-1,2,4-triazole-S-linked N-phenyl acetamides (4a‒g) utilizing ultrasound-assisted synthetic approach. The objective was to assess the effectiveness of synthesized theophylline-1,2,4-triazoles (4a‒g) as inhibitors of HCV serine protease and as antibacterial agents against B. subtilis QB-928 and E. coli AB-274. Theophylline-1,2,4-triazoles were obtained in good to excellent yields (69%-95%) in a shorter time than conventional approach. 4-Chlorophenyl moiety containing theophylline-1,2,4-triazole 4c displayed significantly higher inhibitory activity against HCV serine protease enzyme (IC50 = 0.015 ± 0.25 mg) in comparison to ribavirin (IC50 = 0.165 ± 0.053 mg), but showed excellent binding affinity (-7.55 kcal/mol) with the active site of serine protease, better than compound 4c (-6.90 kcal/mol) as well as indole-based control compound 5 (-7.42 kcal/mol). In terms of percentage inhibition of serine protease, 2-chlorophenyl compound 4b showed the maximum percentage inhibition (86%), more than that of the 3,4-dichlorophenyl compound 4c (76%) and ribavirin (81%). 3,4-Dimethylphenyl-based theophylline-1,2,4-triazole 4g showed the lowest minimum inhibitory concentration (MIC = 0.28 ± 0.50 µg/mL) against the B. subtilis bacterial strain as compared to the standard drug penicillin (MIC = 1 ± 1.50 µg/mL). The other 4-methylphenyl theophylline-1,2,4-triazole 4e (MIC = 0.20 ± 0.08 µg/mL) displayed the most potent antibacterial potential against E. coli in comparison to the standard drug penicillin (MIC = 2.4 ± 1.00 µg/mL). Molecular docking studies further helped in an extensive understanding of all of the interactions between compounds and the enzyme active site, and DFT studies were also employed to gain insights into the molecular structure of the synthesized compounds. The results indicated that theophylline-linked triazole derivatives 4b and 4c showed promise as leading contenders in the fight against the HCV virus. Moreover, compounds 4e and 4g demonstrated potential as effective chemotherapeutic agents against E. coli and B. subtilis, respectively. To substantiate these findings, additional in vivo studies and clinical trials are imperative, laying the groundwork for their integration into future drug design and development.

Optimizing broadband antireflection with Au micropatterns: a combined FDTD simulation and two-beam LIL approach.

Broadband antireflection (AR) is highly significant in a wide range of optical applications, and using a gold (Au) micropattern presents a viable method for controlling the behavior of light propagation. This study investigates a novel, to the best of our knowledge, methodology to achieve broadband AR properties in Au micropatterns. It employed the three-dimensional finite-difference time-domain (FDTD) method to simulate and optimize the design of micropatterns. In contrast, the fabrication of Au micropatterns was carried out using two-beam laser interference lithography (LIL). The fabricated Au micropatterns were characterized by a scanning electron microscope (SEM) and spectroscope to validate their antireflection and transmission properties and evaluate their performance at various wavelengths. The optimized Au micropatterns had a high transmittance rating of 96.2%. In addition, the device exhibits a broad-spectrum antireflective property, covering wavelengths ranging from 400 to 1100 nm. The simulation data and experimentally derived results show comparable patterns. These structures can potentially be employed in many optical devices, such as solar cells and photodetectors, whereby achieving optimal device performance reduced reflection and enhanced light absorption.

Superhydrophobic Antifrosting 7075 Aluminum Alloy Surface with Stable Cassie-Baxter State Fabricated through Direct Laser Interference Lithography and Hydrothermal Treatment.

Frost formation and accumulation can have catastrophic effects on a wide range of industrial activities. Hence, a dual-scale surface with a stable Cassie-Baxter state is developed to mitigate the frosting problem by utilizing direct laser interference lithography assisted with hydrothermal treatment. The high Laplace pressure tolerance under the evaporation stimulus and prolonged Cassie-Baxter state maintenance under the condensation stimulus demonstrate the stable Cassie-Baxter state. The dual-scale surface exhibits a lengthy frost-delaying time of up to 5277 s at -7 °C due to the stable Cassie-Baxter state. The self-removal of frost is achieved by promoting the mobility of frost melts driven by the released interfacial energy. In addition, the dense flocculent frost layer is observed on the single-scale micro surface, whereas the sparse pearl-shaped frost layer with many voids is obtained on the dual-scale surface. This work will aid in understanding the frosting process on various-scale superhydrophobic surfaces and in the design of antifrosting surfaces.

Recent Trends in the Petasis Reaction: A Review of Novel Catalytic Synthetic Approaches with Applications of the Petasis Reaction.

The Petasis reaction, also called the Petasis Borono-Mannich reaction, is a multicomponent reaction that couples a carbonyl derivative, an amine and boronic acids to yield substituted amines. The reaction proceeds efficiently in the presence or absence of a specific catalyst and solvent. By employing this reaction, a diverse range of chiral derivatives can easily be obtained, including α-amino acids. A broad substrate scope, high yields, distinct functional group tolerance and the availability of diverse catalytic systems constitute key features of this reaction. In this review article, attention has been drawn toward the recently reported methodologies for executing the Petasis reaction to produce structurally simple to complex aryl/allyl amino scaffolds.

Synthesis, Cytotoxic, and Computational Screening of Some Novel Indole-1,2,4-Triazole-Based S-Alkylated N-Aryl Acetamides.

Molecular hybridization has emerged as the prime and most significant approach for the development of novel anticancer chemotherapeutic agents for combating cancer. In this pursuit, a novel series of indole-1,2,4-triazol-based N-phenyl acetamide structural motifs 8a-f were synthesized and screened against the in vitro hepatocellular cancer Hep-G2 cell line. The MTT assay was applied to determine the anti-proliferative potential of novel indole-triazole compounds 8a-f, which displayed cytotoxicity potential as cell viabilities at 100 µg/mL concentration, by using ellipticine and doxorubicin as standard reference drugs. The remarkable prominent bioactive structural hybrids 8a, 8c, and 8f demonstrated good-to-excellent anti-Hep-G2 cancer chemotherapeutic potential, with a cell viability of (11.72 ± 0.53), (18.92 ± 1.48), and (12.93 ± 0.55), respectively. The excellent cytotoxicity efficacy against the liver cancer cell line Hep-G2 was displayed by the 3,4-dichloro moiety containing indole-triazole scaffold 8b, which had the lowest cell viability (10.99 ± 0.59) compared with the standard drug ellipticine (cell viability = 11.5 ± 0.55) but displayed comparable potency in comparison with the standard drug doxorubicin (cell viability = 10.8 ± 0.41). The structure-activity relationship (SAR) of indole-triazoles 8a-f revealed that the 3,4-dichlorophenyl-based indole-triazole structural hybrid 8b displayed excellent anti-Hep-G2 cancer chemotherapeutic efficacy. The in silico approaches such as molecular docking scores, molecular dynamic simulation stability data, DFT, ADMET studies, and in vitro pharmacological profile clearly indicated that indole-triazole scaffold 8b could be the lead anti-Hep-G2 liver cancer therapeutic agent and a promising anti-Hep-G2 drug candidate for further clinical evaluations.

Unfolding the Antibacterial Activity and Acetylcholinesterase Inhibition Potential of Benzofuran-Triazole Hybrids: Synthesis, Antibacterial, Acetylcholinesterase Inhibition, and Molecular Docking Studies.

In this study, a series of novel benzofuran-based 1,2,4-triazole derivatives (10a-e) were synthesized and evaluated for their inhibitory potential against acetylcholinesterase (AChE) and bacterial strains (E. coli and B. subtilis). Preliminary results revealed that almost all assayed compounds displayed promising efficacy against AChE, while compound 10d was found to be a highly potent inhibitor of AChE. Similarly, these 5-bromobenzofuran-triazoles 10a-e were screened against B. subtilis QB-928 and E. coli AB-274 to evaluate their antibacterial potential in comparison to the standard antibacterial drug penicillin. Compound 10b was found to be the most active among all screened scaffolds, with an MIC value of 1.25 ± 0.60 µg/mL against B. subtilis, having comparable therapeutic efficacy to the standard drug penicillin (1 ± 1.50 µg/mL). Compound 10a displayed excellent antibacterial therapeutic efficacy against the E. coli strain with comparable MIC of 1.80 ± 0.25 µg/mL to that of the commercial drug penicillin (2.4 ± 1.00 µg/mL). Both the benzofuran-triazole molecules 10a and 10b showed a larger zone of inhibition. Moreover, IFD simulation highlighted compound 10d as a novel lead anticholinesterase scaffold conforming to block entrance, limiting the swinging gate, and disrupting the catalytic triad of AChE, and further supported its significant AChE inhibition with an IC50 value of 0.55 ± 1.00 µM. Therefore, compound 10d might be a promising candidate for further development in Alzheimer's disease treatment, and compounds 10a and 10b may be lead antibacterial agents.

Laser Interference Lithography-A Method for the Fabrication of Controlled Periodic Structures.

A microstructure determines macro functionality. A controlled periodic structure gives the surface specific functions such as controlled structural color, wettability, anti-icing/frosting, friction reduction, and hardness enhancement. Currently, there are a variety of controllable periodic structures that can be produced. Laser interference lithography (LIL) is a technique that allows for the simple, flexible, and rapid fabrication of high-resolution periodic structures over large areas without the use of masks. Different interference conditions can produce a wide range of light fields. When an LIL system is used to expose the substrate, a variety of periodic textured structures, such as periodic nanoparticles, dot arrays, hole arrays, and stripes, can be produced. The LIL technique can be used not only on flat substrates, but also on curved or partially curved substrates, taking advantage of the large depth of focus. This paper reviews the principles of LIL and discusses how the parameters, such as spatial angle, angle of incidence, wavelength, and polarization state, affect the interference light field. Applications of LIL for functional surface fabrication, such as anti-reflection, controlled structural color, surface-enhanced Raman scattering (SERS), friction reduction, superhydrophobicity, and biocellular modulation, are also presented. Finally, we present some of the challenges and problems in LIL and its applications.

Synthesis of Thiol-Modified Hemicellulose, Its Biocompatibility, Studies, and Appraisal as a Sustained Release Carrier of Ticagrelor.

Background: Nature has always been considered as the primary source of pharmaceutical ingredients. A variety of hemicelluloses, as well as their modified forms, have been under investigation. Herein, a study was designed to explore the biocompatibility of hemicellulose and its modified form (thiolated hemicellulose) as well as its potential as a pharmaceutical excipient. Method: For thiol modification thiourea was used as the thiol donor, HCl as the catalytic reagent, and methanol was used for washing purposes. Modified polymers were characterized for physicochemical characteristics, including surface morphology, the amorphous or crystalline nature of the particles, modification of polymer by FTIR, and biocompatibilities. For acute oral toxicity study, a single dose of 2 g/kg was administered to albino rats of 200 g average weight (n = 3). Polymers were evaluated as pharmaceutical excipients by preparing compressed tablets of antiplatelet drug (Ticagrelor), followed by various quality control tests, such as swelling index, thickness and diameter, disintegration, and in-vitro drug release. Results: From the results, it was observed that thiol modification has been successfully accomplished as characteristic peaks belonging to -SH group appeared at 2667.7691 cm-1 in FTIR scan. The modified polymer was found safe in the use concentration range, confirming their safe use for in vivo analysis. No significant effect has been observed in the behavior, biological fluid (blood), or on vital organs. Thiolated hemicellulose was found to be an excellent drug retarding polymer as 8 h of dissolution studies showed that 67.08% of the drug has been released. Conclusion: Conclusively, incorporation of thiol moiety made the polymer more mucoadhesive with, and a worthy carrier of, the drug with good biocompatibilities.

Self-Assembly of DNA molecules in magnetic Fields.

In this work, a rich variety of self-assembled DNA patterns were obtained in the magnetic field. Herein, atomic force microscopy (AFM) was utilized to investigate the effects of the concentration of DNA solution, intensity and direction of magnetic field and modification of mica surface by different cations on the self-assembly of DNA molecules. It was found that owning to the change of the DNA concentration, even under the same magnetic field, the DNA self-assembly results were different. Thein situtest results showed that the DNA self-assembly in an magnetic field was more likely to occur in liquid phase than in gas phase. In addition, whether in a horizontal or vertical magnetic field, a single stretched dsDNA was obtained in a certain DNA concentration and magnetic field intensity. Besides, the modification of cations on the mica surface significantly increased the force between the DNA molecules and mica surface, and further changed the self-assembly of DNA molecules under the action of magnetic field.

Synthesis and Evaluation of Thiol-Conjugated Poloxamer and Its Pharmaceutical Applications.

The current study was designed to convert the poloxamer (PLX) into thiolated poloxamer (TPLX), followed by its physicochemical, biocompatibilities studies, and applications as a pharmaceutical excipient in the development of tacrolimus (TCM)-containing compressed tablets. Thiolation was accomplished by using thiourea as a thiol donor and hydrochloric acid (HCl) as a catalyst in the reaction. Both PLX and TPLX were evaluated for surface morphology based on SEM, the crystalline or amorphous nature of the particles, thiol contents, micromeritics, FTIR, and biocompatibility studies in albino rats. Furthermore, the polymers were used in the development of compressed tablets. Later, they were also characterized for thickness, diameter, hardness, weight variation, swelling index, disintegration time, mucoadhesion, and in vitro drug release. The outcomes of the study showed that the thiolation process was accomplished successfully, which was confirmed by FTIR, where a characteristic peak was noticed at 2695.9968 cm-1 in the FTIR scan of TPLX. Furthermore, the considerable concentration of the thiol constituents (20.625 µg/g of the polymer), which was present on the polymeric backbone, also strengthened the claim of successful thiolation. A mucoadhesion test illustrated the comparatively better mucoadhesion strength of TPLX compared to PLX. The in vitro drug release study exhibited that the TPLX-based formulation showed a more rapid (p < 0.05) release of the drug in 1 h compared to the PLX-based formulation. The in vivo toxicity studies confirmed that both PLX and TPLX were safe when they were administered to the albino rats. Conclusively, the thiolation of PLX made not only the polymer more mucoadhesive but also capable of improving the dissolution profile of TCM.

Synthesis and characterization of thiol modified beta cyclodextrin, its biocompatible analysis and application as a modified release carrier of ticagrelor.

Thiol modification of beta cyclodextrin (ß-CD) was carried out using thiourea, which served as a thiol donor. The chemical reaction was mediated using HCl. Polymer prepared via thiolation was further subjected to physicochemical and biocompatible analysis. Acute oral toxicity and compatibility was determined in albino rats. Furthermore, compressed tablets of ticagrelor (TCG) were prepared using modified and unmodified polymers and evaluated via various quality control tests. Thiolation was successfully achieved and confirmed by the FTIR scan, as a significant corresponding peak was observed at 2692 cm-1 wavenumber, demonstrating the attachment of -SH group. In vivo analysis has confirmed the safe use of ß-CD, as none of the vital organs showed any kind of toxic effects. Dissolution studies revealed that Tß-CD was able to release 96.62% of the drug within 1 h of the study, hence providing an immediate release. Conclusively, a thiol moiety was successfully attached to the polymeric backbone and was found safe to be used as a pharmaceutical excipient.

The pulley suture: A reliable option for closure of selected soft tissue defects under tension- three years experience of a tertiary care hospital.

OBJECTIVE: To assess the outcome of closure of soft tissue defects through pulley suture in different clinical situations. METHODS: The descriptive chart review was conducted at The Indus Hospital, Karachi, and comprised data from May 2008 to November 2011. A detailed questionnaire was developed to address variables of interest. All patients with less than three months of follow-up or inadequate information were excluded. The data was collected through Health Management Information System. Data was entered and analysed by SPSS 16. RESULTS: There were 259 patients with 289 wounds in the study. The mean age was 29.2±11.9 years. At follow-up of two weeks, there was wound dehiscence in 2.07%, infection in 0.69% and partial flap necrosis in 1.03% patients. At 12 weeks, hypertrophic scar was reported in 2.07% and stretched scar in 0.3% patients. Acute pain was not reported in the first week of surgery. Type of wound was found to have significant association with complications (p value<0.005). Age and gender were not found have any significant association with complications (p value 0.372 and 0.238 respectively). None of the patients reported scar tenderness at 12-week follow-up. Cosmetic outcome was acceptable to all patients. CONCLUSIONS: Judicious use of pulley suture can lead to primary closure of selected soft tissue defects under moderate tension. The technique, however, needs to be utilised by surgeons experienced in soft tissue reconstruction.

A comparative review of three techniques of syndactyly release.

OBJECTIVE: To compare the outcome of three techniques of congenital syndactyly release; to identify factors leading to difference in outcome, and to identify the incidence of neurovascular abnormalities in various types of syndactyly. METHODS: The chart review was conducted at The Indus Hospital, Karachi, and comprised data of all patients who had undergone syndactyly release between August 2008 and December 2014. Three techniques of release were included as described in literature by Bauer, Skoog and Niranjan. The data was collected through Health Management Information System. A detailed questionnaire was designed to address variables of interest. RESULTS: The age of the 29 patients with 50 webs in the study ranged from 2.2 to 17.1 years. The male to female ratio was 21:8. The complications encountered were web creep, skin flap necrosis, flexion deformity and contracture of joint. Single neurovascular bundle was found in 04(8%)webs and 45(90%) required skin graft for resurfacing of the digits. CONCLUSIONS: Bauer technique was found to be to be superior for web formation and there was low incidence of web creep compared to Skoog technique. Inclusion of syndromic cases may lead to increased complication and dissatisfaction rate. Tight closure of flaps should be avoided and generous use of skin grafts is advocated for success.

Protection of heel flaps with Ilizarov fixator as an elevation frame: A case series and review of literature.

OBJECTIVE: To compare outcome of Ilizarov fixator for protection of heel and foot flaps with that of plaster of Paris boot technique. METHODS: The retrospective chart review was conducted at The Indus Hospital, Karachi, and comprised data of patients who underwent flap reconstruction of the heel from January 2011 to December 2014. All patients had a minimum follow-up of 3 months. The patients using Ilizarov fixator were placed in group A and those with modified plaster of Paris boot as the elevation device were placed in group B. A detailed questionnaire was developed to note down the relevant variables. RESULTS: Of the 31 patients, 21(70%) were in group A and 10(30%) in group B. The modified boot was considered heavy (70%) compared to none in the Ilizarov group. The mean time of removal was 5.9 wks in group A and 4.8 weeks in group B. The mean time for use of Foley\'s catheter was 16.8 hours in group A and 14.8 hours in group B. There was significant number of associated bony injuries (33%) in group A and none in group B. Both groups were satisfied with the outcome. CONCLUSIONS: While Ilizarov technique is recommended for patients with extensive wounds along the heel and foot, obese patients and those non-compliant to the positioning protocol, careful use of modified plaster of Paris boot technique in relatively simpler situations of heel reconstruction with flaps is also very rewarding.

Methyl 2-(2-hydroxy-acetamido)benzoate.

The title compound, C(10)H(11)NO(4), was formed from 4,1-benzoxazepine-2,5(1H,3H)-dione and ammonia gas. Intra-molecular hydrogen bonding is present between the amide N-H group and the carbonyl O atom of the ester group. The crystal structure features inter-molecular O-H⋯O hydrogen bonds.

cis-(9S,10S)-Methyl 1-propyl-1,2,3,4-tetra-hydro-ß-carboline-3-carboxyl-ate.

The title compound, C(16)H(20)N(2)O(2), was synthesized from (S)-tryptophan methyl ester hydro-chloride and butyraldehyde. The absolute configuration 9S,10S was assigned on the basis of the unchanging chirality of the C9 centre. The NH group of the indole ring is involved in inter-molecular N-H⋯O hydrogen bonding, while the NH group of the six-membered ring is not. This latter ring has a half-chair conformation.