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The optimization of an undergraduate experiment for Organic Chemistry students is described to explore the concept of click chemistry. The preparation of a terminal fluorescent alkyne and an organic azide is reported consisting of simple steps. These are employed in the Cu(I)-catalized azide-alkyne cycloaddition to obtain a novel molecule containing a triazole ring whose characterization allows the students to practice a variety of techniques: NMR (1H, 13C, COSY and HSQC), melting point, thin layer chromatography, IR, fluorescence spectroscopy and mass spectrometry to confirm the structure of their obtained product. An alternative methodology in a one-pot reaction is also explored and a full laboratory manual provided., FQM-208. GlycoChemBio: Glycochemistry and Bioconjugation

The use of edible coatings has surged as a response to the ever-increasing demand for ecologically-friendly methods for maintaining fruit quality during storage. This study analyses the application of different polysaccharide-based coatings, carboxymethylcellulose, chitosan, dextrin and starch, and the use of a plasticizer agent, glycerol, with dextrin shown to be the most effective in maintaining the postharvest quality of zucchini fruit during cold storage. Subsequently, to improve these results, the nutraceutical additives oleuropein and olive oil, were tested in combination with dextrin. Results showed that dextrin coatings reduced weight loss, chilling injury, and oxidative stress in zucchini fruit at low temperature, maintaining fruit quality. The natural additives obtained from the olive tree showed a higher induction of antioxidant enzymes as well as a greater accumulation of ascorbate and total phenolics, with the dextrin coating with olive oil being even more effective in maintaining the chilling injury low until the end of storage, associated to phenolic metabolism. This type of preservation could be implemented for extending postharvest life and enhancing the overall quality of zucchini fruit., Programa Operativo FEDER Andalucía 2014-2020 (Project BAGR-296-UGR20), FPI grants (MEC) (Project AGL2017-82885-C2-2-R), Universidad de Granada / CBUA

The work was financially supported by the Spanish institutions Ministerio de Ciencia, Innovacion y Universidades (PGC2018-098770-B-I00 and CTQ2017-86125-P) and Junta de Andalucia (ProgramaOperativo FEDER 2014-2020, grants B-FQM-141-UGR18, A1-FQM-341-UGR-18, C-FQM-497-UGR18)., Water-insoluble carbon dots are recognized as promising materials, although their applications in nanomedicine are rarely explored, despite their lipophilic character and foreseen compatibility with biological membranes. In this article, we exploit the anhydride functionalization of carbon dots obtained by thermolysis of citric acid to synthesize amphiphilic-like carbon dots (LCDs) by reaction with alkyl amines. A differential feature of this approach is that the hydrophobicity of LCDs is a balance between the ionization of the carboxylic groups resulting from the reaction and the hydrophobicity from the grafted amines. The alkyl chains allow LCDs to entrap hydrophobic molecules and the ionization of the carboxylic groups increases the hydrosolubility, permitting the transfer between organic and aqueous phases. The biomedical interest of these features is illustrated by analyzing the application of LCDs as carriers of the drug campothecin and their evaluation on a battery of cancer cell lines, as well as the transformation of LCDs into a phototherapeutic agent by the formation of a complex with IR780 dye. Results demonstrate that LCDs behave as nanocarriers in a manner that resembles other supramolecular hosts with two differential features: (i) the length of the alkyl chains determines the size of the hosted guest, and (ii) the hydrosolubility of the complex can be modulated by pH., Ministerio de Ciencia, Innovacion y Universidades PGC2018-098770-B-I00 CTQ2017-86125-P, Junta de Andalucia B-FQM-141-UGR18 A1-FQM-341-UGR-18 C-FQM-497-UGR18

Bisphosphonates (BPs) are bone-binding molecules that provide targeting capabilities to bone cancer cells when conjugated with drug-carrying polymers. This work reports the design, synthesis, and biological evaluation of polyethyleneimine− BP−cyclodextrin (PEI-BP-CD) ternary conjugates with supramolecular capabilities for the loading of antineoplastic drugs. A straightforward, modular, and versatile strategy based on the click aza-Michael addition reaction of vinyl sulfones (VSs) allows the grafting of BPs targeting ligands and βCD carrier appendages to the PEI polymeric scaffold. The in vitro evaluation (cytotoxicity, cellular uptake, internalization routes, and subcellular distribution) for the ternary conjugates and their doxorubicin inclusion complexes in different bone-related cancer cell lines (MC3T3-E1 osteoblasts, MG-63 sarcoma cells, and MDA-MB-231 breast cancer cells) confirmed specificity, mitochondrial targeting, and overall capability to mediate a targeted drug transport to those cells. The in vivo evaluation using xenografts of MG-63 and MDA-MB-231 cells on mice also confirmed the targeting of the conjugates., Ministry of Science and Innovation, Spain (MICINN) Spanish Government CTQ2014-55474-C2-2-R CTQ2017-86125-P, European Commission, Fundacion Marcelino Botin

We report the application of the click Michael-type addition reaction to vinyl sulfone or vinyl sulfonate groups in the synthesis of rotaxanes through the threading-and-capping method. This methodology has proven to be efficient and versatile as it allowed the preparation of rotaxanes using template approaches based on different noncovalent interactions (i.e., donor-acceptor π-π interactions or hydrogen bonding) in yields of generally 60-80 % and up to 91 % aided by the mild conditions required (room temperature or 0 °C and a mild base such as Et3 N or 4-(N,N-dimethylamino)pyridine (DMAP)). Furthermore, the use of vinyl sulfonate moieties, which are suitable motifs for coupling-and-decoupling (CAD) chemistry, implies another advantage because it allows the controlled chemical disassembly of the rotaxanes into their components through nucleophilic substitution of the sulfonates resulting from the capping step with a thiol under mild conditions (Cs2 CO3 and room temperature).

Two simple boron-dipyrromethene-type fluorophore (azaBODIPYs) dyes are synthesized and tested for the determination of CO2 gas by an inner filter process. The indicators are noncovalently entrapped in suitable polymers according to their polarity, featuring absorption maxima at 620 nm and fluorescent emission maxima in the range 675–720 nm. Molar absorptivity and fluorescence quantum yield data were determined for these two synthesized azaBODIPYs. These indicators have high molar absorption coefficients of 7.1 × 104 and 2.1 × 104 M−1 cm−1 and quantum yields of 21 and 9%. The pKa values of the indicators are determined from absorbance and fluorescence measurements with values of 7.9 and 8.5, depending on the positioning of the substitution pattern of the electron-donating functionalities. The two azaBODIPYs present excellent photostability, making them suitable for long duration measurements. These azaBODIPY dyes act as fluorescent pH indicators in a polymeric sensing membrane along with microcrystalline powder of chromium-doped gadolinium aluminium borate as the luminophore, a transfer phase agent (tetraoctyl or tetramethyl ammonium hydroxide) and a plasticizer or surfactant to improve membrane permeability to gaseous CO2. The response time ranges from 42 to 60 s and recovery time from 103 to 120 s, with a detection limit of 0.04 and 0.57% CO2. The store time of the sensing membranes is longer than 570 days in the best case, and it does not need to be kept in any special atmosphere other than darkness.

Several studies have shown that the determination of pH in sweat, which is one of the most accessible body fluids, can be an indicator of health and wellness, and even be used for potential disease diagnosis. On that basis, we present herein a wearable wristband for continuous and wireless monitoring of sweat pH with potential applications in the field of personal health assessment. The developed wristband consists of two main parts: a microfluidic cloth analytical device (μCAD) to collect continuously the sweat from skin with a color-based pH sensing area; and a readout and processing module with a digital color sensor to obtain the pH of sweat from the color changes in the μCAD. In addition, the readout module includes a low-power Bluetooth interface to transmit the measurements in real-time to a custom-designed smartphone application. To allow continuous operation, an absorbent pad was included in the design to retire and store thsweat from the sensing area through a passive pump path. It was found that the Hue parameter (H) in the HSV color space can be related to the sweat pH and fitted to a Boltzmann equation (R2 = 0.997). The range of use of the wristband device goes from 6 to 8, which includes the pH range of sweat, with a precision at different pH values from 3.6 to 6.0 %. Considering the typical human sweat rate, the absorbent pad allows continuous operation up to more than 1000 min.

This work was supported by grants CTQ2014-55474-C2-1-R, CTQ2014-55474-C2-2-R and CTQ2017-86125-P from the Ministerio Economia, Industria y Competitividad (co-financed by FEDER funds). SP is supported by a FPU fellowship (FPU17/ 04749). We acknowledge the University of Granada (Spain) cell culture, animal and microscopy central facilities (CIC-UGR)., The use of the specific binding properties of monoclonal antibody fragments such as single-chain variable fragments (ScFv) for the selective delivery of antitumor therapeutics for cancer cells is attractive due to their smaller size, low immunogenicity, and low-cost production. Although covalent strategies for the preparation of such ScFv-based therapeutic conjugates are prevalent, this approach is not straightforward, as it requires prior chemical activation and/or modification of both the ScFv and the therapeutics for the application of robust chemistries. A non-covalent alternative based on ScFv fused to maltose-binding protein (MBP) acting as a binding adapter is proposed for active targeted delivery. MBP-ScFv proves to be a valuable modular platform to synergistically bind maltose-derivatized therapeutic cargos through the MBP, while preserving the targeting competences provided by the ScFv. The methodology has been tested by using a mutated maltose-binding protein (MBP I334W) with an enhanced affinity toward maltose and an ScFv coding sequence toward the human epidermal growth factor receptor 2 (HER2). Non-covalent binding complexes of the resulting MBP-ScFv fusion protein with diverse maltosylated therapeutic cargos (a near-infrared dye, a maltosylated supramolecular beta-cyclodextrin container for doxorubicin, and non-viral polyplex gene vector) were easily prepared and characterized. In vitro and in vivo assays using cell lines that express or not the HER2 epitope, and mice xenografts of HER2 expressing cells demonstrated the capability and versatility of MBP-ScFv for diagnosis, imaging, and drug and plasmid active targeted tumor delivery. Remarkably, the modularity of the MBP-ScFv platform allows the flexible interchange of both the cargos and the coding sequence for the ScFv, allowing ad hoc solutions in targeting delivery without any further optimization since the MBP acts as a pivotal element., Ministerio Economia, Industria y Competitividad - FEDER funds CTQ2014-55474-C2-1-R CTQ2014-55474-C2-2-R CTQ2017-86125-P, Spanish Government FPU17/04749

Magnetite nanoparticles (MNPs) coated by branched poly (ethylene-imine) (PEI) were synthesized in a one-pot. Three molecular weights of PEI were tested, namely, 1.8 kDa (sample MNP-1), 10 kDa (sample MNP-2), and 25 kDa (sample MNP-3). The MNP-1 particles were further functionalized with folic acid (FA) (sample MNP-4). The four types of particles were found to behave magnetically as superparamagnetic, with MNP-1 showing the highest magnetization saturation. The particles were evaluated as possible hyperthermia agents by subjecting them to magnetic fields of 12 kA/m strength and frequencies ranging between 115 and 175 kHz. MNP-1 released the maximum heating power, reaching 330 W/g at the highest frequency, in the high side of reported values for spherical MNPs. In vitro cell viability assays of MNP-1 and MNP-4 against three cell lines expressing different levels of FA receptors (FR), namely, HEK (low expression), and HeLa (high expression), and HepG2 (high expression), demonstrated that they are not cytotoxic. When the cells were incubated in the presence of a 175 kHz magnetic field, a significant reduction in cell viability and clone formation was obtained for the high expressing FR cells incubated with MNP-4, suggesting that MNP-4 particles are good candidates for magnetic field hyperthermia and active targeting., Spanish Institutions: Ministerio de Ciencia, Innovación y Universidades (PGC2018-098770-B-I00 and CTQ2017-86125-P), Junta de Andalucía (ProgramaOperativo FEDER 2014-2020, grants B-FQM-141-UGR18, A1-FQM-341-UGR-18, C-FQM-497-UGR18)

Trans-sialidases (TS) are important constitutive macromolecules of the secretome present on the surface of Trypanosoma cruzi (T. cruzi) that play a central role as a virulence factor in Chagas disease. These enzymes have been related to infectivity, escape from immune surveillance and pathogenesis exhibited by this protozoan parasite. In this work, atomic force microscopy (AFM)-based single molecule-force spectroscopy is implemented as a suitable technique for the detection and location of functional TS on the surface of extracellular vesicles (EVs) released by tissue-culture cell-derived trypomastigotes (Ex-TcT). For that purpose, AFM cantilevers with functionalized tips bearing the anti-TS monoclonal antibody mAb 39 as a sense biomolecule are engineered using a covalent chemical ligation based on vinyl sulfonate click chemistry; a reliable, simple and efficient methodology for the molecular recognition of TS using the antibody-antigen interaction. Measurements of the breakdown forces between anti-TS mAb 39 antibodies and EVs performed to elucidate adhesion and forces involved in the recognition events demonstrate that EVs isolated from tissue-culture cell-derived trypomastigotes of T. cruzi are enriched in TS. Additionally, a mapping of the TS binding sites with submicrometer-scale resolution is provided. This work represents the first AFM-based molecular recognition study of Ex-TcT using an antibody-tethered AFM probe., ERANet program ERANet17/HLH-0142, Spanish Government PGC2018-099424-B-I00

A microfluidic paper-based analytical device integrating carbon dot (CDs) is fabricated and used for a fluorometric off-on assay of biothiols. Vinyl sulfone (VS) click immobilization of carbon dots (CDs) on paper was accomplished by a one-pot simplified protocol that uses divinyl sulfone (DVS) as a homobifunctional reagent. This reagent mediated both the click oxa-Michael addition to the hydroxyl groups of cellulose and ulterior covalent grafting of the resulting VS paper to NH2-functionalized CDs by means of click aza-Michael addition. The resulting cellulose nanocomposite was used to engineer an inexpensive and robust microfluidic paper-based analytical device (μPAD) that is used for a reaction-based off-on fluorometric assay of biothiols (GSH, Cys, and Hcy). The intrinsic blue fluorescence of CDs (with excitation/emission maxima at 365/450 nm) is turned off via the heavy atom effect of an introduced iodo group. Fluorescence is turned on again due to the displacement of iodine by reaction with a biothiol. The increase in fluorescence is related to the concentration over a wide range (1 to 200 μM for GSH and 5–200 μM for Cys and Hcy, respectively), and the assay exhibits a low detection limit (0.3 μM for GSH and Cys and 0.4 μM for Hcy). The method allows for rapid screening and can also be used in combination with a digital camera readout.

Directed evolution has revolutionized protein engineering. Still, enzyme optimization by random library screening remains sluggish, in large part due to futile probing of mutations that are catalytically neutral and/or impair stability and folding. FuncLib is a novel approach which uses phylogenetic analysis and Rosetta design to rank enzyme variants with multiple mutations, on the basis of predicted stability. Here, we use it to target the active site region of a minimalist-designed, de novo Kemp eliminase. The similarity between the Michaelis complex and transition state for the enzymatic reaction makes this system particularly challenging to optimize. Yet, experimental screening of a small number of active-site variants at the top of the predicted stability ranking leads to catalytic efficiencies and turnover numbers ( 2 104 M 1 s 1 and 102 s 1) for this anthropogenic reaction that compare favorably to those of modern natural enzymes. This result illustrates the promise of FuncLib as a powerful tool with which to speed up directed evolution, even on scaffolds that were not originally evolved for those functions, by guiding screening to regions of the sequence space that encode stable and catalytically diverse enzymes. Empirical valence bond calculations reproduce the experimental activation energies for the optimized eliminases to within 2 kcal mol 1 and indicate that the enhanced activity is linked to better geometric preorganization of the active site. This raises the possibility of further enhancing the stabilityguidance of FuncLib by computational predictions of catalytic activity, as a generalized approach for computational enzyme design, Knut and Alice Wallenberg Foundation (Wallenberg Academy Fellowship) 2018.0140, Human Frontier Science Program RGP0041/2017, FEDER Funds/Spanish Ministry of Science, Innovation and Universities BIO2015-66426-R RTI2018-097142-B-100, FEDER/Junta de Andalucia - Consejeria de Economia y Conocimiento E.FQM.113.UGR18, Swedish National Infrastructure for computing (SNAC) 2018/2-3 2019/2-1

Chromophore-appended cyclodextrins combine the supramolecular loading capabilities of cyclodextrins (CDs) with the optical properties of the affixed chromophores. Among fluorescent materials, carbon dots (CNDs) are attractive and the feasibility of CND-appended CDs as sensors has been demonstrated by different authors. However, CNDs are intrinsically heterogeneous materials and their ulterior functionalization yields hybrid composites that are not well defined in terms of structure and composition. Inspired by the fluorescence properties of 5-oxo-1,2,3,5-tetrahydroimidazo[1,2-a]pyridine-7-carboxylic acid (IPCA), the most paradigmatic of the molecular fluorophores detected in CNDs, herein we report two highly efficient synthetic chemical strategies for the preparation of IPCA-appended CDs that behave as CND-based CD “turn off–on” biosensors suitable for the analysis of cholesterol and β-galactosidase activity. We have deconstructed the CND–CD systems to demonstrate that (i) the role of CNDs is limited to acting as a support for the molecular fluorophores produced during their synthesis and (ii) the molecular fluorophores suffice for the determination of the enzymatic activity based on the quenching by p-nitrophenol as a sacrificial quencher., Ministerio de Economía, Industria y Competitividad, Spain CTQ2017-86125-P CTQ2016-78754-C2-1-R

Directed evolution has revolutionized protein engineering. Still, enzyme optimization by random library screening remains a sluggish process, in large part due to futile probing of mutations that are catalytically neutral and/or impair stability and folding. FuncLib (funclib-weizmann.ac.il) is a novel automated computational procedure which uses phylogenetic analysis and Rosetta design to rank enzyme variants with multiple mutations, on the basis of a stability metric. Here, we use it to target the active site region of a minimalist-designed, de novo Kemp eliminase. The similarity between the Michaelis complex and transition state for the enzymatic reaction makes this a particularly challenging system to optimize. Yet, experimental screening of a very small number of active-site, multi-point variants at the top of the predicted stability ranking leads to catalytic efficiencies and turnover numbers (~2·104 M-1 s-1 and ~102 s-1) that compare well with modern natural enzymes, and that approach the catalysis levels for the best Kemp eliminases derived from extensive screening. This result illustrates the promise of FuncLib as a powerful tool with which to speed up directed evolution, by guiding screening to regions of the sequence space that encode stable and catalytically diverse enzymes. Empirical valence bond calculations reproduce the experimental activation energies for the optimized eliminases to within ~2 kcal·mol-1 and indicate that the improvements in activity are linked to better geometric preorganization of the active site. This raises the possibility of further enhancing the stability-guidance of FuncLib by EVB-based computational predictions of catalytic activity, as a generalized approach for computational enzyme design.

Gold nanoparticles (AuNPs) can be obtained from HAuCl4 by using polyethyleneimine (PEI) as both reductant and stabilizing agent. However, the known affinity of PEI for different materials has not been exploited to coat them and turn their surface into catalytic. We demonstrate that the irradiation of a solution of HAuCl4 and branched PEI 1800 (bPEI2K) with microwave (MW) yields PEI-stabilized AuNPs (MW-PEI@AuNPs) with an average size of 7.6 nm that are catalytically active in the reduction with NaBH4 of different nitroarenes functionalized with a variety of functional groups. Moreover, the as-prepared MW-PE@-AuNPs show affinity for different materials such as polystyrene (standard spectrophotometry disposal cuvettes), polypropylene (falcon-type tubes) and silica (Silica gel 60), turning their surface into catalytic without any additional synthetic step. This feature is exploited to transform standard tubings (Tygon, PEEK and stainless steel) into flow reactors by simple passage of a solution of MW-PEI@AuNPs. This straightforward functionalization is especially appealing in the case of the stainless steel tubing, one of the materials more widely used in HPLC, being of interest in the context of flow nanocatalysis.

We present a new chemistry to determine nitrites implemented in a microfluidic paper-based analytical device (µPAD). The device is fabricated in cellulose paper with a sample reception area and three replicate detection areas with recognition chemistry immobilized by adsorption. The method involves the use of nitrite in an acid medium reaction to generate nitrous acid, which produces the oxidation of s-dihydrotetrazine: 1,2-dihydro-3,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazine (DHBPTz), which change the detection zone from colorless to pink. We used a digital camera and smartphone for the quantitative analysis of nitrite with the color coordinate S of the HSV color space as the analytical parameter. Parameters such as concentration and volume of s-dihydrotetrazine, pH, sample volume and reaction time were studied. The detection limit for this method is 1.30µM nitrite. To estimate the selectivity of the method an interference study of common ions in water samples was performed. The procedure was applied to natural water and compared with reference procedures.

The term coupling-and-decoupling (CAD) chemistry refers to applications in which efficient bond formation and subsequent cleavage between two moieties is required. Within this context, the scope of the vinyl sulfonate (VSO) group as an efficient tool for CAD chemistry is reported. The coupling step relies on the click features of the Michael-type addition of diverse nucleophiles to vinyl sulfonates as a valuable methodology. The feasibility of this strategy has been proved by the high yields obtained in mild conditions with model VSO derivatives. Cleavage of the resulting sulfonate adducts either through nucleophilic substitution with different nucleophiles (for alkyl VSO groups) or through hydrolysis (for both alkyl and aryl VSO) are successful strategies for the decoupling step, the former being the most promising, as the reaction proceeds under milder conditions with thiol nucleophiles. Moreover, the click VSO coupling chemistry proves to be orthogonal with the click CuAAC reaction, which enables the VSO-CAD methodology for the preparation of hetero-bifunctional clickable and cleavable linkers for double click modular strategies. The potential of the VSO-CAD chemistry is demonstrated in two biologically relevant examples: the decoupling of sulfonates with glutathione (GSH) under conditions compatible with those of living systems; and the synthesis of homo- and heterogeneous multivalent glycosylated systems from 1-thio and 1-azido or 1-azidoethyl sugar derivatives and bis-vinyl sulfonates (homo systems) or alkynyl-VSO bifunctional clickable-cleavable linkers (hetero systems). As proof of concept, the cleavable character of these multivalent systems was demonstrated by using one of them as a reversible linker for the non-covalent assembling and chemical decoupling of two model lectins.

Gene transfection mediated by the cationic polymer polyethylenimine (PEI) is considered a standard methodology. However, while highly branched PEIs form smaller polyplexes with DNA that exhibit high transfection efficiencies, they have significant cell toxicity. Conversely, low molecular weight PEIs (LMW-PEIs) with favorable cytotoxicity profiles display minimum transfection activities as a result of inadequate DNA complexation and protection. To solve this paradox, a novel polyelectrolyte complex was prepared by the ionic cross-linking of branched 1.8 kDa PEI with citric acid (CA). This system synergistically exploits the good cytotoxicity profile exhibited by LMW-PEI with the high transfection efficiencies shown by highly branched and high molecular weight PEIs. The polyectrolyte complex (1.8 kDa-PEI@CA) was obtained by a simple synthetic protocol based on the microwave irradiation of a solution of 1.8 kDa PEI and CA. Upon complexation with DNA, intrinsic properties of the resulting particles (size and surface charge) were measured and their ability to form stable polyplexes was determined. Compared with unmodified PEIs the new complexes behave as efficient gene vectors and showed enhanced DNA binding capability associated with facilitated intracellular DNA release and enhanced DNA protection from endonuclease degradation. In addition, while transfection values for LMW-PEIs are almost null, transfection efficiencies of the new reagent range from 2.5- to 3.8-fold to those of Lipofectamine 2000 and 25 kDa PEI in several cell lines in culture such as CHO-k1, FTO2B hepatomas, L6 myoblasts, or NRK cells, simultaneously showing a negligible toxicity. Furthermore, the 1.8 kDa-PEI@CA polyelectrolyte complexes retained the capability to transfect eukaryotic cells in the presence of serum and exhibited the capability to promote in vivo transfection in mouse (as an animal model) with an enhanced efficiency compared to 25 kDa PEI. Results support the polyelectrolyte complex of LMW-PEI and CA as promising generic nonviral gene carriers.

Polymer-based nanotheranostics are appealing tools for cancer treatment and diagnosis in the fast-growing field of nanomedicine. A straightforward preparation of novel engineered PEI-based nanotheranostics incorporating NIR fluorescence heptamethine cyanine dyes (NIRF-HC) to enable them with tumor targeted gene delivery capabilities is reported. Branched PEI-2 kDa (b2kPEI) is conjugated with IR-780 and IR-783 dyes by both covalent and noncovalent simple preparative methodologies varying their stoichiometry ratio. The as-prepared set of PEI-NIR-HC nanocarriers are assayed in vitro and in vivo to evaluate their gene transfection efficiency, cellular uptake, cytotoxicity, internalization and trafficking mechanisms, subcellular distribution, and tumor specific gene delivery. The results show the validity of the approach particularly for one of the covalent IR783-b2kPEI conjugates that exhibit an enhanced tumor uptake, probably mediated by organic anion transporting peptides, and favorable intracellular transport to the nucleus. The compound behaves as an efficient nanotheranostic transfection agent in NSG mice bearing melanoma G361 xenographs with concomitant imaging signal and gene concentration in the targeted tumor. By this way, advanced nanotheranostics with multifunctional capabilities (gene delivery, tumor-specific targeting, and NIR fluorescence imaging) are generated in which the NIRF-HC dye component accounts for simultaneous targeting and diagnostics, avoiding additional incorporation of additional tumor-specific targeting bioligands.

The aim of this study was to evaluate the crosslinking abilities of divinyl sulfone (DVS) for the preparation of novel water-insoluble cyclodextrin-based polymers (CDPs) capable of forming inclusion complexes with different guest molecules. Reaction of DVS with native α-cyclodextrin (α-CD), β-cyclodextrin (β-CD) and/or starch generates a variety of homo- and hetero-CDPs with different degrees of crosslinking as a function of the reactants' stoichiometric ratio. The novel materials were characterized by powder X-ray diffraction, electron microscopy and for their sorption of phenol and 4-nitrophenol. They were further evaluated as sorbents with phenolic pollutants (bisphenol A and β-naphthol) and bioactive compounds (the hormone progesterone and curcumin). Data obtained from the inclusion experiments show that the degree of cross-linking has a minor influence on the yield of inclusion complex formation and highlight the important role of the CDs, supporting a sorption process based on the formation of inclusion complexes. In general, the inclusion processes are better described by a Freundlich isotherm although an important number of them can also be fitted to the Langmuir isotherm with R2 ≥ 0.9, suggesting a sorption onto a monolayer of homogeneous sites.

Protein engineering studies often suggest the emergence of completely new enzyme functionalities to be highly improbable. However, enzymes likely catalysed many different reactions already in the last universal common ancestor. Mechanisms for the emergence of completely new active sites must therefore either plausibly exist or at least have existed at the primordial protein stage. Here, we use resurrected Precambrian proteins as scaffolds for protein engineering and demonstrate that a new active site can be generated through a single hydrophobic-to-ionizable amino acid replacement that generates a partially buried group with perturbed physico-chemical properties. We provide experimental and computational evidence that conformational flexibility can assist the emergence and subsequent evolution of new active sites by improving substrate and transition-state binding, through the sampling of many potentially productive conformations. Our results suggest a mechanism for the emergence of primordial enzymes and highlight the potential of ancestral reconstruction as a tool for protein engineering., This work was supported by Feder Funds, Grants from the Spanish Ministry of Economy and Competitiveness BIO2015-66426-R (J.M.S.-R.), CSD2009-00088 (J.M.S.-R.), CTQ2011-29299-C02-01 (F.S.-G.), CTQ2011-22514 (M.B.), BIO2016-74875-P (J.A.G.), ‘Factoría Española de Cristalización˜’, Consolider-Ingenio 2010 (J.A.G.) and CEI BioTic V19-2015 (V.A.R.), a Wallenberg Academy Fellowship (S.C.L.K.) and DuPont Young Professor Award (E.A.G.) and Grants NNX13AI08G and NNX13AI10G (E.A.G.) from NASA Exobiology. The European Research Council has provided financial support under the European Community’s Seventh Framework Programme (FP7/2007–2013)/ERC Grant Agreement No. 306474.

The receptor for advanced glycation end products (RAGE) is involved in diabetes or angiogenesis in tumors. Under pathological conditions, RAGE is overexpressed and upon ligand binding and internalization stimulates signaling pathways that promote cell proliferation. In this work, amino dendritic polymers PEI 25 kDa and alkylated derivatives of PAMAM-G2 were engineered by the nonenzymatic Maillard glycation reaction to generate novel AGE-containing gene delivery vectors targeting the RAGE. The glycated dendritic polymers were easily prepared and retained the capability to bind and protect DNA from endonucleases. Furthermore, while glycation decreased the transfection efficiency of the dendriplexes in CHO-k1 cells which do not express RAGE, glycated dendriplexes acted as efficient transfection reagents in CHO-k1 cells which stably express recombinant RAGE. In addition, preincubation with BSA-AGEs, a natural ligand of the RAGE, or dansyl cadaverine, an inhibitor of the RAGE internalization, blocked transfection, confirming their specificity toward RAGE. The results were confirmed in NRK and RAW264.7 cell lines, which naturally express the receptor. The glycated compounds retain their transfection efficiency in the presence of serum and promote in vivo transfection in a mouse model. Accordingly, RAGE is a suitable molecular target for the development of site-directed engineered glycated nonviral gene vectors.

This chelating capability allowsthem to be used as antidotes against metal poisoning, inanalytical determination, or in waste water treatment ofheavy metals. Furthermore, this strong binding capacitymeans that numerous DTC metal complexes can act as in-hibitors of enzymes, with a profound effect on biologicalsystems.

Fernando Rodríguez-Serrano,1,* Nuria Mut-Salud,1,* Teresa Cruz-Bustos,2 Mercedes Gomez-Samblas,2 Esther Carrasco,1 Jose Manuel Garrido,3 F Javier López-Jaramillo,4 Francisco Santoyo-Gonzalez,4 Antonio Osuna2 1Institute of Biopathology and Regenerative Medicine, 2Molecular Biochemistry and Parasitology Research Group, Department of Parasitology, Faculty of Sciences, Institute of Biotechnology, University of Granada, 3Department of Cardiovascular Surgery, Virgen de las Nieves Hospital, 4Department of Organic Chemistry, Faculty of Sciences, Institute of Biotechnology, University of Granada, Granada, Spain *These authors contributed equally to this work Background: Around 20%–30% of breast cancers overexpress the proto-oncogene human epidermal growth receptor 2 (HER2), and they are characterized by being very invasive. Therefore, many current studies are focused on testing new therapies against tumors that overexpress this receptor. In particular, there exists major interest in new strategies to fight breast cancer resistant to trastuzumab (Tmab), a humanized antibody that binds specifically to HER2 interfering with its mitogenic signaling. Our team has previously developed immunostimulating complexes (ISCOMs) as nanocapsules functionalized with lipid vinyl sulfones, which can incorporate protein A and bind to G immunoglobulins that makes them very flexible nanocarriers.Methods and results: The aim of this in vitro study was to synthesize and evaluate a drug delivery system based on protein A-functionalized ISCOMs to target HER2-overexpressing cells. We describe the preparation of ISCOMs, the loading with the drugs doxorubicin and paclitaxel, the binding of ISCOMs to alkyl vinyl sulfone-protein A, the coupling of Tmab, and the evaluation in both HER2-overexpressing breast cancer cells (HCC1954) and non-overexpressing cells (MCF-7) by flow cytometry and fluorescence microscopy. Results show that the uptake is dependent on the level of overexpression of HER2, and the analysis of the cell viability reveals that targeted drugs are selective toward HCC1954, whereas MCF-7 cells remain unaffected.Conclusion: Protein A-functionalized ISCOMs are versatile carriers that can be coupled to antibodies that act as targeting agents to deliver drugs. When coupling to Tmab and loading with paclitaxel or doxorubicin, they become efficient vehicles for the selective delivery of the drug to Tmab-resistant HER2-overexpressing breast cancer cells. These nanoparticles may pave the way for the development of novel therapies for poor prognosis resistant patients. Keywords: targeted drug delivery, doxorubicin, HER2, nanoparticle, paclitaxel, protein A, trastuzumab

A novel one-pot method for the synthesis of polyethyleneimine (PEI)-coated gold nanoparticles (AuPEI-NPs) that combines the reductant-stabilizer properties of PEI with microwave irradiation starting from hydrogen tetrachloroaurate acid (HAuCl4 ) and branched PEI 25 kDa (b25kPEI) was explored. The method was straightforward, green, and low costing, for which the Au/PEI ratio (1:1 to 1:128 w/w) was a key parameter to modulate their capabilities as DNA delivery nanocarriers. Transfection assays in CHO-k1 cells demonstrated that AuPEI-NPs with 1:16 and 1:32 w/w ratios behaved as effective DNA gene vectors with improved transfection efficiencies (twofold) and significantly lower toxicity than unmodified b25kPEI and Lipofectamine 2000. The transfection mediated by these AuPEI-NP-DNA polyplexes preferentially used the caveolae-mediated route for intracellular internalization, as shown by studies performed by using specific internalization inhibitors as well as colocalization with markers of clathrin- and caveolae-dependent pathways. The AuPEI-NP polyplexes preferentially used the more efficient caveolae internalization pathway to promote transfection, a fact that supports their higher transfection efficiency relative to that of Lipofectamine 2000. In addition, intracellular trafficking of the AuPEI-NPs was studied by transmission electron microscopy.

[EN] Most methodologies for covalent immobilization of enzymes usually take place at high pH values to enhance the nucleophilicity of protein reactive residues; however, many enzymes inactivate during the immobilization process due to their intrinsic instability at alkaline pH values. Vinyl sulfone (VS)-activated carriers may react with several protein side-chains at neutral pHs. In this work, levansucrase-an alkaline unstable enzyme of technological interest because it forms fructooligosaccharides (FOS) and levan from sucrose-was covalently attached to VS-activated silica at pH 7.0 in a short time (5 h). Theoretical immobilization yields were close to 95% but the apparent activity did not surpass 25%, probably due to random attachment with unproductive orientations and rigidification of the enzyme structure. Due to diffusional hindrance and/or local microenvironmental effects caused by the silica surface, the immobilized levansucrase was unable to produce levan but synthesized a similar amount of FOS than the free enzyme [95 g L in 28 h, with a major contribution of FOS of the β(2 → 1) type]. The VS-activated biocatalysts showed a notable operational stability in batch reactors., Spanish Ministry of Economy and Competitiveness (BIO2013-48779-C4-1-R). We thank the support of COST-Action CM1303 on Systems Biocatalysts. P. S.-M. thanks the Spanish Ministry of Education for FPU Grant (FPU13/01185).

The immobilization of biomolecules on magnetic nanoparticles is an issue with high potential in different fields. We describe herein a new strategy to immobilize biomolecules on super-paramagnetic nanoparticles based on the reactivity of vinyl sulfone groups with naturally occurring functional groups present in biomolecules (amine and thiol). A new monomer containing a polymerizable methacryloyl group and a secondary amine group was synthesized and used to prepare super-paramagnetic hybrid nanoparticles (SP-HNPs) by two-step miniemulsion polymerization. The Michael addition reaction of divinyl sulfone (DVS) to the secondary amine groups localized on the nanoparticles surface allows the introduction of the vinyl sulfone function in the SP-HNPs (SP-HNPs-VS). The morphology of the functionalized SP-HNPs was characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), dynamic light scattering, and magnetic susceptibility. The capacity of SP-HNPs-VS for the immobilization of biomolecules was evaluated with three model proteins: avidin, invertase, and horseradish peroxidase (HRP). The model proteins were successfully immobilized in mild aqueous conditions compatible with the biological nature of the enzymes. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Received: October 19, 2011; Revised: March 8, 2012; Published online: && &&, 0000Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201100813.Abstract: A one-pot, three-component methodologyinvolving tandem azidation and click copper(I)-cata-lyzed azide-alkyne cycloaddition (CuAAC) of cyclicsulfates or cyclic sulfamidates in the presence ofsodium azides and alkynes is reported. The devel-oped protocol takes also advantage of the concomi-tant use of microwave (MW) irradiation and hetero-geneous catalysis. The protocol allows the fast andefficient preparation of (alkyl sulfate)- and (alkylsulfamidate)-1H-1,2,3-triazoles in a simple manner.Keywords: click chemistry; cyclic sulfamidates; cyclicsulfates; cycloadditions; multi-component reactions

Amphiphilic dendrimer-based gene delivery vectors bearing peripheral alkyl sulfonyl hydrophobic tails were constructed using low-generation PAMAM-G2 as the core and functionalized by means of the aza-Michael type addition of its primary amino groups to vinylsulfone derivatives as an efficient tool for surface engineering. While the unmodified PAMAM-G2 was unable to efficiently transfect eukaryotic cells, functionalized PAMAM-G2 dendrimers were able to bind DNA at low N/P ratios, protect DNA from digestion with DNase I and showed high transfection efficiencies and low cytotoxicity. Dendrimers with a C18 alkyl chain produced transfection efficiencies up to 3.1 fold higher than LipofectAMINE™ 2000 in CHO-k1 cells. The dendriplexes based in functionalized PAMAM-G2 also showed the ability to retain their transfection properties in the presence of serum and the ability to transfect different eukaryotic cell lines such as Neuro-2A and RAW 264.7. Taking advantage of the vinylsulfone chemistry, fluorescent PAMAM-G2 derivatives of these vectors were prepared as molecular probes to determine cellular uptake and internalization through a clathrin-independent mechanism.

Novel supported chelating adsorbents bearing diverse multidentate nitrogenated ligands with strong copper(I) affinities are easily prepared in non-magnetic and magnetic variants using silica and silica-coated magnetite nanoparticles as suitable supports and the aza-Michael-type addition of vinyl sulfones as the ligation tool. These adsorbents are versatile materials with applications in the copper-catalyzed alkyne-azide cycloaddition (CuAAC) click chemistry where their complexation abilities enable them to act either as heterogeneous click catalysts when used in their complexed form or as copper(I) scavengers when used in their uncomplexed form. In the first instance, they proved to be robust and efficient heterogeneous catalysts to promote click reactions using extremely low doses and showing negligible copper leaching, particularly in the case of the silica-based non-magnetic adsorbents, allowing a simple operational protocol for their rapid and easy removal by filtration or magnetic decantation and showing good recyclability properties. In their uncomplexed form, the non-magnetic chelating adsorbents are very efficient copper scavengers that are able to remove any traces of metal contamination and that can be applied in tandem with any heterogeneous supported copper(I) catalysts or as stand-alone copper removing system in any click protocol allowing the isolation of metal-free clicked compounds.

The largest group of plant thioredoxins (TRXs) consists of the so-called h-type; their great number raises questions about their specific or redundant roles in plant cells. Pisum sativum thioredoxin h1 (PsTRXh1) and Pisum sativum thioredoxin h2 (PsTRXh2) are both h-type TRXs from pea (Pisum sativum) previously identified and biochemically characterized. While both are involved in redox regulation and show a high-sequence identity (60%), they display different behavior during in vitro and in vivo assays. In this work, we show that these two proteins display different specificity in the capturing of protein targets in vitro, by the use of a new stringent method. PsTRXh2 interacted with classical antioxidant proteins, whereas PsTRXh1 showed a completely different pattern of targeted proteins, and was able to capture a transcription factor. We also showed that the two proteins display very different thermal and chemical stabilities. We suggest that the differences in thermal and chemical stability point to a distinct and characteristic pattern of protein specificity.

The easy functionalization of tags and solid supports with the vinyl sulfone function is a valuable tool in omic sciences that allows their coupling with the amine and thiol groups present in the proteogenic residues of proteins, in mild and green conditions compatible with their biological function.

The efficient synthesis of structurally diverse, multivalent, heterogeneous neoglycoconjugates by means of a series of different click-based strategies is described. The methodology is highly efficient and versatile allowing for easy access to a series of mannose (α-Man)-containing glycoconjugates differing in their valency, nature of the scaffold, nature of the constitutive sugars and length of the linker. The influence of those structural parameters on the binding affinities of these glycomimics toward Concanavalin A (Con A) was evaluated.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Mannose (α-Man)-containing neoglycoconjugates possessing aliphatic-, aromatic-, and carbohydrate-centered architectures and differing in structural characteristics such as valency, topology, and nature of the linker have been synthesized using click chemistry that shows its value as an efficient and versatile methodology for accessing tailor-made multivalent neoglycoconjugates. The binding behaviour of these glycomimics toward Concanavalin A (Con A) has been evaluated to determine the influence of the structural parameters. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

We have covalently coupled fluorophore 4-(2-hydroxyethoxy)-7-nitro-2,1,3-benzoxadiazole (NBD) to the external ferritin shell through lysine residues. An increase in the luminescence quantum yield of the fluorescent ferritin particles and a blue shift in its emission peak compared to individual fluorophore were observed. The study of the particles by transmission electron microscopy showed that the native iron core ferritin is intact and that no degradation occurs during chemical functionalization of the protein shell. The NBD-labeled ferritin particles are water soluble, which allowed their controlled deposition by the Langmuir–Blodgett (LB) technique. Superparamagnetic and fluorescent properties of the particles are preserved within the LB film.

We report two methods that have allowed the attachment of glu- cose, mannose and lactose to one or both of the cyclopentadienyl rings of ferrocene. The resulting ferrocene-car- bohydrate conjugates were synthesised by the reaction of thioglycosides with ferrocenemethanol and 1,1'-ferrocene- dimethanol in acidic media. A second method based on the regiospecific cop- per(I)-catalysed cycloaddition of prop- argyl glycoside, azidomethyl and bis- Arocene as well as azi- doethyl glycoside and ethynylferrocene was also used and led to the synthesis of 1,2,3-triazole-containing glycoconju- gates. The electrochemical behaviour of the synthesised glycoconjugates was investigated. In addition, their binding interactions with b-cyclodextrin were studied by means of NMR spectrosco- py, isothermal titration calorimetry, and cyclic and differential pulse vol- tammetric experiments. These tech- niques allowed the determination of the thermodynamic parameters of the complexes, the stability constants for the complexes formed with both the neutral and the oxidised states of the ferrocenyl glycoconjugates, the mode of inclusion and the diffusion coeffi- cients for both the glycoconjugates and the complexes.

The synthesis of a variety of calixarene-based cavitands (capped and functional calixarenes) and calix nanotubes is easily performed in good to high yields using "click chemistry" methodology through the Cu(I)-catalyzed ligation of adequate bis-alkyne and bis-azide derivatives.

In this work, we have used a second-generation PAMAM grafted with octadecyl sulfonyl chains to condense plasmid DNA. The influence of this modification at different levels was investigated by comparison with original PAMAM G2. The condensation process and temporal stability of the complexes was studied with DLS, finding that the aliphatic chains influence DNA compaction via hydrophobic forces and markedly improve the formation and temporal stability of a single populated system with a hydrodynamic diameter below 100 nm. Interaction with a cell membrane model was also evaluated with a pendant drop tensiometer, resulting in further incorporation of the C18-PAMAM dendriplexes onto the interface. The improvement observed in transfection with our C18 grafted PAMAM is ascribed to the size, stability, and interfacial behavior of the complexes, which in turn are consequence of the DNA condensation process and the interactions involved.