Limestone and yellow gypsum can reduce cadmium accumulation in groundnut (Arachis hypogaea): A study from a three-decade old landfill site.

Cadmium (Cd) toxicity has cropped up as an important menace in the soil-plant system. The use of industrial by-products to immobilise Cd in situ in polluted soils is an interesting remediation strategy. In the current investigation, two immobilizing amendments of Cd viz., Limestone (traditionally used) and Yellow gypsum (industrial by-product) have been used through a green-house pot culture experiment. Soil samples were collected from four locations based on four graded levels of DTPA extractable Cd as Site 1 (0.43 mg kg-1), Site 2 (0.92 mg kg-1), Site 3 (1.77 mg kg-1) and Site 4 (4.48 mg kg-1). The experiment was laid out in a thrice replicated Factorial Complete Randomized Design, with one factor as limestone (0, 250, 500 mg kg-1) and the other being yellow gypsum (0, 250, 500 mg kg-1) on the collected soils and groundnut was grown as a test crop. Results revealed that the DTPA-extractable Cd content in soil and Cd concentration in plants decreased significantly with the increasing doses of amendments irrespective of initial soil available Cd and types of amendment used. The effect of amendment was soil specific and in case of Site 1 (low initial Cd) the effect was more prominent. The reduction in DTPA-extractable Cd in combined application of limestone and yellow gypsum @500 mg kg-1 over the absolute control in soil under groundnut for the sites was by far the highest with the values of 83.72%, 77.17%, 48.59% and 40.63% respectively. With the combined application, Target Cancer Risk (TCR) of Cd was also reduced. Hence, combined application of limestone and yellow gypsum can be beneficial in the long run for mitigating Cd pollution.

Mapping of QTLs associated with yield and related traits under reproductive stage drought stress in rice using SNP linkage map.

BACKGROUND: Drought stress is a major constraint for rice production worldwide. Reproductive stage drought stress (RSDS) leads to heavy yield losses in rice. The prospecting of new donor cultivars for identification and introgression of QTLs of major effect (Quantitative trait locus) for drought tolerance is crucial for the development of drought-resilient rice varieties. METHODS AND RESULTS: Our study aimed to map QTLs associated with yield and its related traits under RSDS conditions. A saturated linkage map was constructed using 3417 GBS (Genotyping by sequencing) derived SNP (Single nucleotide polymorphism) markers spanning 1924.136 cM map length with an average marker density of 0.56 cM, in the F3 mapping population raised via cross made between the traditional ahu rice cultivar, Koniahu (drought tolerant) and a high-yielding variety, Disang (drought susceptible). Using the Inclusive composite interval mapping approach, 35 genomic regions governing yield and related traits were identified in pooled data from 198 F3 and F4 segregating lines evaluated for two consecutive seasons under both RSDS and irrigated control conditions. Of the 35 QTLs, 23 QTLs were identified under RSDS with LOD (Logarithm of odds) values ranging between 2.50 and 7.83 and PVE (phenotypic variance explained) values of 2.95-12.42%. Two major QTLs were found to be linked to plant height (qPH1.29) and number of filled grains per panicle (qNOG5.12) under RSDS. Five putative QTLs for grain yield namely, qGY2.00, qGY5.05, qGY6.16, qGY9.19, and qGY10.20 were identified within drought conditions. Fourteen QTL regions having ≤ 10 Mb QTL interval size were further analysed for candidate gene identification and a total of 4146 genes were detected out of these 2263 (54.63%) genes were annotated to at least one gene ontology (GO) term. CONCLUSION: Several QTLs associated with grain yield and yield components and putative candidate genes were identified. The putative QTLs and candidate genes identified could be employed to augment drought resilience in rice after further validation through MAS strategies.

Cisplatin-Conjugated Polyurethane Capsule for Dual Drug Delivery to a Cancer Cell.

This paper describes the synthesis of a polymer-prodrug conjugate, its aqueous self-assembly, noncovalent encapsulation of a second drug, and stimuli-responsive intracellular dual drug delivery. Condensation polymerization between a functionalized diol and a commercially available diisocyanate in the presence of poly(ethylene glycol) hydroxide (PEG-OH) as the chain stopper produces an ABA-type amphiphilic block copolymer (PU-1) in one pot, with the middle hydrophobic block being a polyurethane containing a pendant tert-butyloxycarbonyl (Boc)-protected amine in every repeating unit. Deprotection of the Boc group, followed by covalent attachment of the Pt(IV) prodrug using the pendant amine groups, produces the polymer-prodrug conjugate PU-Pt-1, which aggregates to nanocapsule-like structures in water with a hydrophilic interior. In the presence of sodium ascorbate, the Pt(IV) prodrug can be detached from the polymer backbone, producing the active Pt(II) drug. Cell culture studies show appreciable cell viability by the parent polymer. However, the polymer-prodrug conjugate nanocapsules exhibit cellular uptake and intracellular release of the active drug under a reducing environment. The capsule-like aggregates of the polymer-prodrug conjugate were used for noncovalent encapsulation of a second drug, doxorubicin (Dox), and Dox-loaded PU-Pt-1 aggregate showed a significantly superior cell killing efficiency compared to either of the individual drugs, highlighting the promising application of such a dual-drug-delivery approach.

Polyglutamate-based nanoconjugates for image-guided surgery and post-operative melanoma metastases prevention.

Rationale: Cutaneous melanoma is the most aggressive and deadliest of all skin malignancies. Complete primary tumor removal augmented by advanced imaging tools and effective post-operative treatment is critical in the prevention of tumor recurrence and future metastases formation. Methods: To meet this challenge, we designed novel polymeric imaging and therapeutic systems, implemented in a two-step theranostic approach. Both are composed of the biocompatible and biodegradable poly(α,L-glutamic acid) (PGA) nanocarrier that facilitates extravasation-dependent tumor targeting delivery. The first system is a novel, fluorescent, Turn-ON diagnostic probe evaluated for the precise excision of the primary tumor during image-guided surgery (IGS). The fluorescence activation of the probe occurs via PGA degradation by tumor-overexpressed cathepsins that leads to the separation of closely-packed, quenched FRET pair. This results in the emission of a strong fluorescence signal enabling the delineation of the tumor boundaries. Second, therapeutic step is aimed to prevent metastases formation with minimal side effects and maximal efficacy. To that end, a targeted treatment containing a BRAF (Dabrafenib - mDBF)/MEK (Selumetinib - SLM) inhibitors combined on one polymeric platform (PGA-SLM-mDBF) was evaluated for its anti-metastatic, preventive activity in combination with immune checkpoint inhibitors (ICPi) αPD1 and αCTLA4. Results: IGS in melanoma-bearing mice led to a high tumor-to-background ratio and reduced tumor recurrence in comparison with mice that underwent surgery under white light (23% versus 33%, respectively). Adjuvant therapy with PGA-SLM-mDBF combined with ICPi, was well-tolerated and resulted in prolonged survival and prevention of peritoneal and brain metastases formation in BRAF-mutated melanoma-bearing mice. Conclusions: The results reveal the great clinical potential of our PGA-based nanosystems as a tool for holistic melanoma treatment management.

Functional Surfactants for Molecular Fishing, Capsule Creation, and Single-Cell Gene Expression.

Creating a single surfactant that is open to manipulation, while maintaining its surface activity, robustness, and compatibility, to expand the landscape of surfactant-dependent assays is extremely challenging. We report an oxidation-responsive precursor with thioethers and multiple 1,2-diols for creating a variety of functional surfactants from one parent surfactant. Using these multifunctional surfactants, we stabilize microfluidics-generated aqueous droplets. The droplets encapsulate different components and immerse in a bioinert oil with distinct interfaces where an azide-bearing surfactant allow fishing of biomolecules from the droplets, aldehyde-bearing surfactant allow fabrication of microcapsules, and hydroxyl-bearing surfactants, with/without oxidized thioethers, allow monitoring of single-cell gene expression. Creating multifunctional surfactants poses opportunities for broad applications, including adsorption, bioanalytics, catalysis, formulations, coatings, and programmable subset of emulsions.

Molecular Recognition Driven Bioinspired Directional Supramolecular Assembly of Amphiphilic (Macro)molecules and Proteins.

Bioinspired self-assembly has been explored with diverse synthetic scaffolds, among which amphiphiles are perhaps the most extensively studied systems. Classical surfactants or amphiphilic block copolymers, depending on the hydrophobic-hydrophilic balance, produce distinct nanostructures, which hold promise for applications ranging from biology to materials sciences. Nevertheless, their immiscibility-driven aggregation does not provide the opportunity to precisely regulate the internal order, morphology, or functional group display, which is highly desirable, especially in the context of biological applications.A new class of amphiphiles have emerged in the recent past in which the hydrophilic segment(s) is appended with a hydrophobic supramolecular-structure-directing-unit (SSDU), consisting of a π-conjugated chromophore and a H-bonding group. Self-recognition of the SSDU by attractive directional interactions governs the supramolecular assembly, which is fundamentally different than the repulsive solvent-immiscibility driven aggregation of traditional amphiphiles. Such SSDU-appended hydrophilic polymers exhibit entropy-driven highly stable self-assembly producing distinct nanostructures depending on the H-bonding functional group. For example, polymers with the hydrazide-functionalized SSDU attached form a polymersome, while in a sharp contrast, the same polymers when connected to an amide containing SSDU produce a cylindrical micelle via a spherical-micelle intermediate. This relationship holds true for a series of SSDU-attached hydrophilic polymers irrespective of the hydrophobic/hydrophilic balance or chemical structure, indicating that the supramolecular-assembly is primarily controlled by the specific molecular-recognition motif of the SSDU, instead of the packing parameter-based norms. Beyond synthetic polymers, SSDU-attached proteins also exhibit similar molecular-recognition driven self-assembly as well as coassembly with SSDU-attached polymers or hydrophilic wedges, producing multi-stimuli-responsive nanostructures in which the protein gains remarkable protection from thermal denaturation or enzymatic hydrolysis and exhibits redox-responsive enzymatic activity.Furthermore, SSDU-derived bola-shape π-amphiphiles have been recognized as a useful scaffold for the synthesis of unsymmetric polymersomes, rarely reported in the literature. The building block consists of a hydrophobic naphthalene-diimide (NDI) π-system attached to a hydrophilic functional group (ionic or nonionic) and a nonionic wedge on its two opposite arms. Extended H-bonding among the hydrazide groups, placed only on one side of the central chromophore by design, ensures stacking of the NDIs with parallel orientation and induces a preferred direction of curvature so that the H-bonded chain and consequently the functional groups attached to the same side remain at the inner-wall of the supramolecular polymersome. Automatically, the functional groups, located on the other side, are displayed at the outer surface. This design works for different amphiphiles, which by virtue of efficient and predictable functional group display, strongly influences the multivalent binding with different biological targets resulting in efficient enzyme inhibition, glycocluster effect, or antibacterial activity, depending on the nature of the functional group. By taking advantage of the electron accepting nature of the NDI, electron rich pyrene-containing amphiphiles can be costacked in alternating sequence, producing temperature and redox-responsive supramolecular polymers with NDI/pyrene stoichiometry-dependent morphology, lower critical solution temperature (LCST), functional group display, and antibacterial activity.

Meet me halfway: Are in vitro 3D cancer models on the way to replace in vivo models for nanomedicine development?

The complexity and diversity of the biochemical processes that occur during tumorigenesis and metastasis are frequently over-simplified in the traditional in vitro cell cultures. Two-dimensional cultures limit researchers' experimental observations and frequently give rise to misleading and contradictory results. Therefore, in order to overcome the limitations of in vitro studies and bridge the translational gap to in vivo applications, 3D models of cancer were developed in the last decades. The three dimensions of the tumor, including its cellular and extracellular microenvironment, are recreated by combining co-cultures of cancer and stromal cells in 3D hydrogel-based growth factors-inclusive scaffolds. More complex 3D cultures, containing functional blood vasculature, can integrate in the system external stimuli (e.g. oxygen and nutrient deprivation, cytokines, growth factors) along with drugs, or other therapeutic compounds. In this scenario, cell signaling pathways, metastatic cascade steps, cell differentiation and self-renewal, tumor-microenvironment interactions, and precision and personalized medicine, are among the wide range of biological applications that can be studied. Here, we discuss a broad variety of strategies exploited by scientists to create in vitro 3D cancer models that resemble as much as possible the biology and patho-physiology of in vivo tumors and predict faithfully the treatment outcome.

Potential of cotton for remediation of Cd-contaminated soils.

The present research was conducted to study the potential of cotton for the remediation of soils contaminated with Cd, to understand the biochemical basis of its tolerance to, and to investigate the plant-microbe interaction in the rhizosphere for enhancement of phytoextraction of Cd. Cotton (Bt RCH-2) was exposed to four Cd levels (0, 50, 100, and 200 mg/kg soil) in a completely randomised design and found that the plant could tolerate up to 200 mg/kg soil. Cd stress increased the total phenol, proline, and free amino acid contents in the plant leaf tissue compared with control but inhibited basal soil respiration, fluorescein diacetate hydrolysis, and activities of several enzymes viz. dehydrogenase, phosphatases, and ß-glucosidase in the soil over control. The concentration of Cd in the shoot was less than the critical concentration of 100 µg/g dry weight, and bioconcentration and translocation factors were < 1 to classify the plant as a hyperaccumulator of Cd. This was further confirmed by another experiment in which the cotton plant was exposed various higher levels of Cd (200, 400, 600, 800, and 1000 mg/kg soil). Though the concentration of Cd in the shoot was > 100 µg g -1dw beyond 600 mg Cd/kg soil, the bioconcentration and translocation factors were < 1. The study on plant-microbe (Aspergillus awamori) interaction revealed that the fungus did not affect the absorption of Cd by cotton. It was concluded that the cotton was classified as an excluder of Cd and therefore could be suitable for the phytostabilization of Cd-contaminated soils.

Tolerance of cotton to elevated levels of Pb and its potential for phytoremediation.

Two experiments were conducted to determine the cotton plant's tolerance to Pb and its remediation potential. In the first experiment, the phytoremediation potential was determined by exposing the plant to four levels of Pb (0, 500, 750, and 1000 mg kg-1). The cotton plant exhibited an excellent tolerance index at Pb 1000 mg kg-1 (root 78.65% and shoot 93.08%) and lower grade of growth inhibition (root 21.35% and shoot 6.92%). Pb stress resulted in higher leakage of electrolytes and increased the synthesis of higher proline, total phenol, and free amino acid contents to mitigate stress. The plant could not meet the criteria of a hyperaccumulator of Pb. The concentration of Pb in the shoot was a mere 96 µg g-1 dry wt (< the critical judging concentration of 1000 µg g-1 dry wt), and bioconcentration and translocation factors were <1. The study established that cotton exhibited an exclusion mechanism of Pb. Further, the translocation efficiency (TE %) was very low, i.e., <50% (ranged from 49% at 500 mg kg-1 to 42% at 1000 mg kg -1), and the % of Pb removed by the crop was too little (on an average 0.1%). Pb inhibited the dehydrogenase activity (DHA) by 76%, fluorescein diacetate (FDA) hydrolysis by 60%, and ß-glucosidase activity by 20%. However, applied Pb increased the population of actinomycetes by 3.21 times, but significantly decreased heterotrophic bacteria by 3.40 times and N2 fixers by over 53% over control. In the second experiment, the plant was exposed to very high Pb (0, 1000, 1500, 2000, 2500, and 3000 mg kg -1) to determine the concentration up to which the plant will survive. The investigation revealed that plants could survive up to Pb 3000 mg kg-1. It confirmed the first experiment in the tolerance index, grade of growth inhibition, bioconcentration factor, translocation factor, and partitioning of Pb. Therefore, it was concluded that the cotton plant was an excluder of Pb and could be effectively cultivated for the phytostabilization of soils polluted with Pb.

Evaluation of Furcraea foetida (L.)Haw. for phytoremediation of cadmium contaminated soils.

In the present study, we evaluated Furcraea foetida for the phytoremediation of cadmium (Cd)-contaminated soils. We selected F. foetida because it is a drought-resistant plant, produces high biomass, and needs minimum maintenance. It belongs to the leaf fiber group of plants and therefore has economic importance. Since it is a non-edible crop, there is no danger of food chain contamination. Despite possessing these ideal characteristics, surprisingly, to date, the plant is underutilized for phytoremediation purposes. Therefore, to evaluate the phytoremediation potential of the plant, we exposed it to five levels of cadmium (0, 25, 50, 100, and 200 mg Cd kg-1 soil) and studied its influence on growth, dry matter production, uptake, and translocation efficiency. The plant showed good tolerance to Cd 200 mg kg-1 soil without exhibiting any visible toxicity symptoms. The metal mainly accumulated in the roots (233 µg g-1dw), followed by leaf (51 µg g-1 dw). The bioconcentration factor was > 1, but the translocation factor was < 1. The plant was not classified as a hyperaccumulator of Cd; however, because of its high uptake (897 µ g-1 plant) and translocation efficiency (78%), we concluded that the plant could be utilized for phytoextraction of Cd from soils with low to moderately contaminated soils.

Shape-Dependent Cellular Uptake of Nanostructures Produced from Supramolecular Structure-Directing Unit-Appended Hydrophilic Polymers.

Cellular uptake is an important event in drug delivery and other biomedical applications. Amphiphilic polymers produce aggregates of different size and shape depending on the intrinsic structural differences and the packing parameter. Although they have been explored for various biomedical applications with immense interest, the relationship between the shape of the aggregate and cellular uptake has been studied only in limited examples. This work reports two polymers (P1 and P2), both of which contain a hydrophobic supramolecular structure-directing unit (SSDU) at the chain-end of a fluorescence dye-labeled hydrophilic polymer. Depending on the difference in the structure of the single H-bonding functional group (hydrazide or amide) of the SSDU, P1 and P2 produce polymersomes (NS1) and spherical micelles (NS2), respectively. An aged solution of P2 produces cylindrical micelles (NS3). Confocal microscopy studies reveal that the uptake of these nanostructures in HeLa cells greatly depends on the shape of the aggregate. Spherical NS1 and NS2 show appreciable uptake at 1 or 4 h of incubation, whereas NS3 shows negligible uptake. Temperature-dependent cellular uptake studies reveal an energy-dependent endocytosis pathway. Kinetic studies show gradual increase in the cellular uptake with time, and at 24 h the relative uptake ratio (NS1:NS2:NS3) is 1.0:0.2:<0.1, implying the polymersome morphology (NS1) is most efficient for cellular uptake compared to the spherical or cylindrical micelles. The same trend was also noticed for MDA-MB 231 cells. Confocal microscopy studies further reveal cellular internalization and intracellular location of NS1, which showed maximum cellular uptake. As the intrinsic difference in the chemical structure of the two polymers is negligible, the observed difference can be explicitly assigned to their difference in shape.

Controlled supramolecular polymerization of π-systems.

Supramolecular polymers, albeit having precise internal order, largely lack precision in the mesoscopic scale because in most examples supramolecular polymerization occurs under thermodynamic control through spontaneous self-assembly. Recent reports have exemplified that by varying experimental parameters including cooling rate, solvent composition, interplay of intra- vs. inter-molecular H-bonding and others, it is possible to retard the spontaneous nucleation, and isolate a dormant kinetically controlled monomeric/aggregated state which in turn can serve as the monomer pool to undergo controlled supramolecular polymerization (CSP) through a chain-growth mechanism in the presence of an aggregated/molecular initiator (seed) or by an external stimuli like light. Supramolecular polymers with narrow dispersity, predictable length or stereo-selectivity have been achieved by CSP. Chain extension (similar to "living" polymerization) in such seed initiated CSP is now possible by batch wise addition of monomers, allowing synthesis of supramolecular block copolymers. This feature article describes recent developments in CSP (primarily under kinetic control) of various π-conjugated building blocks.

Disulfide chemistry in responsive aggregation of amphiphilic systems.

The dynamic nature of the disulfide bond has enhanced the potential for disulfide based amphiphiles in the emerging biomedical field. Disulfide containing amphiphiles have extensively been used for constructing wide ranging soft nanostructures as potential candidates for delivery of drugs, proteins and genes owing to their degradable nature in the presence of intracellular glutathione (present in a many fold excess compared to the extracellular milieu). This degradable nature of amphiphiles is not only useful to deliver therapeutics but it also eliminates the toxicity issues associated with the carrier after delivery of such therapeutics. Therefore, these bioreducible and biocompatible nano-aggregates inspired researchers to use them as vehicles for therapeutic delivery and as a result the literature of disulfide containing amphiphiles has been intensified. This review article highlights the structural diversity in disulfide containing amphiphilic small molecule and polymeric systems, structural effects on their aqueous aggregation, redox-responsive disassembly and biological applications. Furthermore, the use of disulfide chemistry towards the design of cell penetrating polymers has also been discussed. Finally a brief perspective on some future opportunities of these systems is provided.

Dendronized fluorosurfactant for highly stable water-in-fluorinated oil emulsions with minimal inter-droplet transfer of small molecules.

Fluorosurfactant-stabilized microfluidic droplets are widely used as pico- to nanoliter volume reactors in chemistry and biology. However, current surfactants cannot completely prevent inter-droplet transfer of small organic molecules encapsulated or produced inside the droplets. In addition, the microdroplets typically coalesce at temperatures higher than 80 °C. Therefore, the use of droplet-based platforms for ultrahigh-throughput combination drug screening and polymerase chain reaction (PCR)-based rare mutation detection has been limited. Here, we provide insights into designing surfactants that form robust microdroplets with improved stability and resistance to inter-droplet transfer. We used a panel of dendritic oligo-glycerol-based surfactants to demonstrate that a high degree of inter- and intramolecular hydrogen bonding, as well as the dendritic architecture, contribute to high droplet stability in PCR thermal cycling and minimize inter-droplet transfer of the water-soluble fluorescent dye sodium fluorescein salt and the drug doxycycline.

Synthesis and Self-assembly of a Helical Polymer Grafted from a Foldable Polyurethane Scaffold.

Herein a polyurethane graft poly-l-glutamate amphiphilic copolymer was synthesized from a polyurethane (PU)-based macro-initiator (containing pendant primary amine groups) through the ring opening polymerization of N-carboxy anhydride of γ-benzyl-l-glutamate (BLG-NCA). On average, twenty two l-glutamic acids were grafted from each amino group which was pendant on the polyurethane chain with 10 repeating units. The grafted polymer (PU-PP-1) exhibits self-assembly to produce a hydrogel in a wide pH window ranging from pH 5.0 to 8.0 with a critical gelation concentration (CGC) of 5.0 wt % (w/v) at pH 7.4. Furthermore, circular dichroism study revealed the transition of the α-helix to a random coil upon increasing the pH. Due to the protonation of side chains at pH 4.0, PU-PP-1 adopted an α-helical conformation whereas at pH >8.0 the side-chain carboxylic acid groups of the PLGAs were ionized, leading to the formation of an extended random coil conformation as a result of charge repulsion. Conformational switching was also supported by FTIR spectroscopy.

Design and Synthesis of PEG-Oligoglycerol Sulfates as Multivalent Inhibitors for the Scavenger Receptor LOX-1.

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a cell surface scavenger receptor. The protein is involved in binding and internalization of oxidized low-density lipoprotein (oxLDL), which leads under pathophysiological circumstances to plaque formation in arteries and initiation of atherosclerosis. A structural feature of LOX-1 relevant to oxLDL binding is the "basic spine" motif consisting of linearly aligned arginine residues stretched over the dimer surface. Inhibition of LOX-1 can be done by blocking these positively charged motifs. Here we report on the design, synthesis, and evaluation of a series of novel LOX-1 inhibitors having different numbers of sulfates and polyethylene glycerol (PEG) spacer. Two molecules, compounds 6b and 6d, showed binding affinity in the low nM range, i.e. 45.8 and 47.4 nM, respectively. The in vitro biological studies reveal that these molecules were also able to block the interaction of LOX-1 with its cognate ligands oxLDL, aged RBC, and bacteria.

Biomimetic sulfated polyethylene glycol hydrogel inhibits proteoglycan loss and tumor necrosis factor-α-induced expression pattern in an osteoarthritis in vitro model.

This study aimed to evaluate the potential of an anti-inflammatory polyethylene glycol (PEG) hydrogel for osteoarthritis (OA) management in an OA in vitro model. Freshly isolated porcine chondrocytes were maintained in high-density cultures to form cartilage-like three-dimensional micromasses. Recombinant porcine tumor necrosis factor-alpha (TNF-α) was used to induce OA-like changes. Normal and OA-like micromasses were treated with dendritic polyglycerol sulfate-based PEG hydrogel. Live/dead staining showed that all micromasses remained vital and presented similar morphological characteristics. Safranin-O staining demonstrated a typical depletion of glycosaminoglycans in TNF-α-treated micromasses but not in the presence of the hydrogel. There was no distinct difference in immunohistochemical detection of type II collagen. Microarray data showed that rheumatoid arthritis and TNF signaling pathways were down regulated in hydrogel-treated OA-like micromasses compared to nontreated OA-like micromasses. The hydrogel alone did not affect genes related to OA such as ANPEP, COMP, CXCL12, PTGS2, and TNFSF10, but it prevented their regulation caused by TNF-α. This study provides valuable insights toward a fully synthetic hydrogel for the intra-articular treatment of OA. The findings proved the potential of this hydrogel to prevent the development of TNF-α-induced OA with regard to proteoglycan loss and TNF-α-induced expression pattern without additional signs of differentiation and inflammation. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 490-500, 2019.

Interaction of human serum albumin with dendritic polyglycerol sulfate: Rationalizing the thermodynamics of binding.

We study the thermodynamics of the interaction between human serum albumin (HSA) and dendritic polyglycerol sulfate (dPGS) of different sizes (generations) by isothermal titration calorimetry (ITC) and computer simulations. The analysis by ITC revealed the formation of a 1:1 complex for the dPGS-G2 of second generation. The secondary structure of HSA remained unchanged in the presence of dPGS-G2, as shown by circular dichroism. For higher generations, several HSA are bound to one polymer (dPGS-G4: 2; dPGS-G5.5: 4). The Gibbs free energy ΔG b was determined at different temperatures and salt concentrations. The binding constant K b exhibited a logarithmic dependence on the salt concentration thus indicating a marked contribution of counterion-release entropy to ΔG b. The number of released counterions (∼4) was found to be independent of temperature. In addition, the temperature dependence of ΔG b was small, whereas the enthalpy ΔH ITC was found to vary strongly with temperature. The corresponding heat capacity change ΔC p,ITC for different generations was of similar values [8 kJ/(mol K)]. The nonlinear van't Hoff analysis of ΔG b revealed a significant heat capacity change ΔC p,vH of similar magnitude [6 kJ/(mol K)] accompanied by a strong enthalpy-entropy compensation. ΔG b obtained by molecular dynamics simulation with implicit water and explicit ions coincided with experimental results. The agreement indicates that the enthalpy-entropy compensation assigned to hydration effects is practically total and the binding affinity is fully governed by electrostatic interactions.

Enhanced Permeability and Retention-like Extravasation of Nanoparticles from the Vasculature into Tuberculosis Granulomas in Zebrafish and Mouse Models.

The enhanced permeability and retention (EPR) effect is the only described mechanism enabling nanoparticles (NPs) flowing in blood to reach tumors by a passive targeting mechanism. Here, using the transparent zebrafish model infected with Mycobacterium marinum we show that an EPR-like process also occurs allowing different types of NPs to extravasate from the vasculature to reach granulomas that assemble during tuberculosis (TB) infection. PEGylated liposomes and other NP types cross endothelial barriers near infection sites within minutes after injection and accumulate close to granulomas. Although ∼100 and 190 nm NPs concentrated most in granulomas, even ∼700 nm liposomes reached these infection sites in significant numbers. We show by confocal microscopy that NPs can concentrate in small aggregates in foci on the luminal side of the endothelium adjacent to the granulomas. These spots are connected to larger foci of NPs on the ablumenal side of these blood vessels. EM analysis suggests that NPs cross the endothelium via the paracellular route. PEGylated NPs also accumulated efficiently in granulomas in a mouse model of TB infection with Mycobacterium tuberculosis, arguing that the zebrafish embryo model can be used to predict NP behavior in mammalian hosts. In earlier studies we and others showed that uptake of NPs by macrophages that are attracted to infection foci is one pathway for NPs to reach TB granulomas. This study reveals that when NPs are designed to avoid macrophage uptake, they can also efficiently target granulomas via an alternative mechanism that resembles EPR.

Multivalent Flexible Nanogels Exhibit Broad-Spectrum Antiviral Activity by Blocking Virus Entry.

The entry process of viruses into host cells is complex and involves stable but transient multivalent interactions with different cell surface receptors. The initial contact of several viruses begins with attachment to heparan sulfate (HS) proteoglycans on the cell surface, which results in a cascade of events that end up with virus entry. The development of antiviral agents based on multivalent interactions to shield virus particles and block initial interactions with cellular receptors has attracted attention in antiviral research. Here, we designed nanogels with different degrees of flexibility based on dendritic polyglycerol sulfate to mimic cellular HS. The designed nanogels are nontoxic and broad-spectrum, can multivalently interact with viral glycoproteins, shield virus surfaces, and efficiently block infection. We also visualized virus-nanogel interactions as well as the uptake of nanogels by the cells through clathrin-mediated endocytosis using confocal microscopy. As many human viruses attach to the cells through HS moieties, we introduce our flexible nanogels as robust inhibitors for these viruses.