Wireless electrostimulation for cancer treatment: An integrated nanoparticle/coaxial fiber mesh platform.

Cancer, namely breast and prostate cancers, is the leading cause of death in many developed countries. Controlled drug delivery systems are key for the development of new cancer treatment strategies, to improve the effectiveness of chemotherapy and tackle off-target effects. In here, we developed a biomaterials-based wireless electrostimulation system with the potential for controlled and on-demand release of anti-cancer drugs. The system is composed of curcumin-loaded poly(3,4-ethylenedioxythiophene) nanoparticles (CUR/PEDOT NPs), encapsulated inside coaxial poly(glycerol sebacate)/poly(caprolactone) (PGS/PCL) electrospun fibers. First, we show that the PGS/PCL nanofibers are biodegradable, which allows the delivery of NPs closer to the tumoral region, and have good mechanical properties, allowing the prolonged storage of the PEDOT NPs before their gradual release. Next, we demonstrate PEDOT/CUR nanoparticles can release CUR on-demand (65 % of release after applying a potential of -1.5 V for 180 s). Finally, a wireless electrostimulation platform using this NP/fiber system was set up to promote in vitro human prostate cancer cell death. We found a decrease of 67 % decrease in cancer cell viability. Overall, our results show the developed NP/fiber system has the potential to effectively deliver CUR in a highly controlled way to breast and prostate cancer in vitro models. We also show the potential of using wireless electrostimulation of drug-loaded NPs for cancer treatment, while using safe voltages for the human body. We believe our work is a stepping stone for the design and development of biomaterial-based future smarter and more effective delivery systems for anti-cancer therapy.

Mechanical Properties of Smart Polypropylene Meshes: Effects of Mesh Architecture, Plasma Treatment, Thermosensitive Coating, and Sterilization Process.

Smart polypropylene (PP) hernia meshes were proposed to detect surgical infections and to regulate cell attachment-modulated properties. For this purpose, lightweight and midweight meshes were modified by applying a plasma treatment for subsequent grafting of a thermosensitive hydrogel, poly(N-isopropylacrylamide) (PNIPAAm). However, both the physical treatment with plasma and the chemical processes required for the covalent incorporation of PNIPAAm can modify the mechanical properties of the mesh and thus have an influence in hernia repair procedures. In this work, the mechanical performance of plasma-treated and hydrogel-grafted meshes preheated at 37 °C has been compared with standard meshes using bursting and the suture pull out tests. Furthermore, the influence of the mesh architecture, the amount of grafted hydrogel, and the sterilization process on such properties have been examined. Results reveal that although the plasma treatment reduces the bursting and suture pull out forces, the thermosensitive hydrogel improves the mechanical resistance of the meshes. Moreover, the mechanical performance of the meshes coated with the PNIPAAm hydrogel is not influenced by ethylene oxide gas sterilization. Micrographs of the broken meshes evidence the role of the hydrogel as reinforcing coating for the PP filaments. Overall, results confirm that the modification of PP medical textiles with a biocompatible thermosensitive hydrogel do not affect, and even improve, the mechanical requirements necessary for the implantation of these prostheses in vivo.

Multimodal Biomedical Implant with Plasmonic and Simulated Body Temperature Responses.

This work presents a novel nanoparticle-based thermosensor implant able to reveal the precise temperature variations along the polymer filaments, as it contracts and expands due to changes in the macroscale local temperature. The multimodal device is able to trace the position and the temperature of a polypropylene mesh, employed in abdominal hernia repair, by combining plasmon resonance and Raman spectroscopy with hydrogel responsive system. The novelty relies on the attachment of the biocompatible nanoparticles, based on gold stabilized by a chitosan-shell, already charged with the Raman reporter (RaR) molecules, to the robust prosthesis, without the need of chemical linkers. The SERS enhanced effect observed is potentiated by the presence of a quite thick layer of the copolymer (poly(N-isopropylacrylamide)-co-poly(acrylamide)) hydrogel. At temperatures above the LCST of PNIPAAm-co-PAAm, the water molecules are expulsed and the hydrogel layer contracts, leaving the RaR molecules more accessible to the Raman source. In vitro studies with fibroblast cells reveal that the functionalized surgical mesh is biocompatible and no toxic substances are leached in the medium. The mesh sensor opens new frontiers to semi-invasive diagnosis and infection prevention in hernia repair by using SERS spectroscopy. It also offers new possibilities to the functionalization of other healthcare products.

Smart Design of Sensor-Coated Surgical Sutures for Bacterial Infection Monitoring.

Virtually, all implantable medical devices are susceptible to infection. As the main healthcare issue concerning implantable devices is the elevated risk of infection, different strategies based on the coating or functionalization of biomedical devices with antiseptic agents or antibiotics are proposed. In this work, an alternative approach is presented, which consists of the functionalization of implantable medical devices with sensors capable of detecting infection at very early stages through continuous monitoring of the bacteria metabolism. This approach, which is implemented in surgical sutures as a representative case of implantable devices susceptible to bacteria colonization, is expected to minimize the risk of worsening the patient's clinical condition. More specifically, non-absorbable polypropylene/polyethylene (PP/PE) surgical sutures are functionalized with conducting polymers using a combination of low-pressure oxygen plasma, chemical oxidative polymerization, and anodic polymerization, to detect metabolites coming from bacteria respiration. Functionalized suture yarns are used for real-time monitoring of bacteria growth, demonstrating the potential of this strategy to fight against infections.

Immediate-sustained lactate release using alginate hydrogel assembled to proteinase K/polymer electrospun fibers.

This work proposes a microfibers-hydrogel assembled composite as delivery vehicle able to combine into a single system both burst and prolonged release of lactate. The prolonged release of lactate has been achieved by electrospinning a mixture of polylactic acid and proteinase K (26.0 mg of proteinase K and 0.99 g of PLA dissolved in 6 mL of 2:1 chloroform:acetone in the optimal case), which is a protease that catalyzes the degradation of polylactic acid into lactate. The degradation of microfibers into lactate reflects that proteinase K preserves its enzymatic activity even after the electrospinning process because of the mild operational conditions used. Besides, burst release is obtained from the lactate-loaded alginate hydrogel. The successful assembly between the lactate-loaded hydrogel and the polylactic acid/proteinase K fibers has been favored by applying a low-pressure (0.3 mbar at 300 W) oxygen plasma treatment, which transforms hydrophobic fibers into hydrophilic while the enzymatic activity is still maintained. The composite displays both fast (< 24 h) and sustained (> 10 days) lactate release, and allows the modulation of the release by adjusting either the amount of loaded lactate or the amount of active enzyme.

Electroresponsive and pH-Sensitive Hydrogel as Carrier for Controlled Chloramphenicol Release.

Multiresponsive hydrogels, which are smart soft materials that respond to more than one external stimulus, have emerged as powerful tools for biomedical applications, such as drug delivery. Within this context and with the aim of eliminating the systematic administration of antibiotics, special attention is being paid to the development of systems for controlled delivery of antibiotic for topical treatment of bacterial infections. In this work, an electro-chemo responsive hydrogel able to release chloramphenicol (CAM), a broad spectrum antibiotic also used for anticancer therapy, is proposed. This has been prepared by grafting poly(acrylic acid) (PAA) to sodium alginate (Alg) and in situ encapsulation of poly(3,4-ethylenedioxythiophene) nanoparticles loaded with CAM (PEDOT/CAM NPs), which were obtained by emulsion polymerization. Although the response to electrical stimuli of PEDOT was the main control for the release of CAM from PEDOT/CAM NPs, the release by passive diffusion had a relatively important contribution. Conversely, the passive release of antibiotic from the whole engineered hydrogel system, Alg-g-PAA/PEDOT/CAM, was negligible, whereas significant release was achieved under electrostimulation in an acid environment. Bacterial tests and assays with cancer cells demonstrated that the biological activity of CAM remained after release by electrical stimulation. Notably, the successful dual-response of the developed hydrogel to electrical stimuli and pH changes evidence the great prospect of this smart material in the biomedical field, as a tool to fight against bacterial infections and to provide local cancer treatment.

Preparation and Characterization of Functionalized Surgical Meshes for Early Detection of Bacterial Infections.

Isotactic polypropylene (i-PP) nonabsorbable surgical meshes are modified by incorporating a conducting polymer (CP) layer to detect the adhesion and growth of bacteria by sensing the oxidation of nicotinamide adenine dinucleotide (NADH), a metabolite produced by the respiration reactions of such microorganisms, to NAD+. A three-step process is used for such incorporation: (1) treat pristine meshes with low-pressure O2 plasma; (2) functionalize the surface with CP nanoparticles; and (3) coat with a homogeneous layer of electropolymerized CP using the nanoparticles introduced in (2) as polymerization nuclei. The modified meshes are stable and easy to handle and also show good electrochemical response. The detection by cyclic voltammetry of NADH within the interval of concentrations reported for bacterial cultures is demonstrated for the two modified meshes. Furthermore, Staphylococcus aureus and both biofilm-positive (B+) and biofilm-negative (B-) Escherichia coli cultures are used to prove real-time monitoring of NADH coming from aerobic respiration reactions. The proposed strategy, which offers a simple and innovative process for incorporating a sensor for the electrochemical detection of bacteria metabolism to currently existing surgical meshes, holds considerable promise for the future development of a new generation of smart biomedical devices to fight against post-operative bacterial infections.

The metabolic phenotype of the patient influences the reduction in carotid intima-media thickness achieved following metabolic surgery.

OBJECTIVES: To determine whether metabolic phenotype is associated with the change in carotid intima-media thickness (CIMT) in patients undergoing bariatric /metabolic surgery (BMS). METHODS: We performed a case-control study of BMS candidates who had metabolically unhealthy obesity (MUO) or metabolically healthy obesity (MHO). We measured the change in CIMT during the 9 months following BMS. The plasma tumor necrosis factor-α, interleukin-1ß, adiponectin, leptin, nitric oxide (NO), vascular endothelial growth factor A (VEGF-A), and malondialdehyde concentrations were determined, adipocyte area was measured histologically, and adipose tissue area was estimated using computed tomography. RESULTS: Fifty-six patients (mean age 44.5 years, mean body mass index 44.9 kg/m2, 53% women, and 53% had MUO) were studied. Nine months following BMS, the MUO phenotype was not associated with a significant reduction in CIMT, and that of the MHO group was larger. In addition, fewer participants achieved a 10% reduction in CIMT in the MUO group. A CIMT reduction was associated with lower VEGF-A and NO in the MUO group, while that in the MHO group was associated with a higher NO concentration. CONCLUSION: The metabolic phenotype of patients may influence their change in CIMT following BMS, probably through circulating vasodilatory and pro-inflammatory molecules.

Dendritic Self-assembled Structures from Therapeutic Charged Pentapeptides.

CRENKA [Cys-Arg-(NMe)Glu-Lys-Ala, where (NMe)Glu refers to N-methyl-Glu], an anti-cancer pentapeptide that induces prostate tumor necrosis and significant reduction in tumor growth, was engineered to increase the resistance to endogenous proteases of its parent peptide, CREKA (Cys-Arg-Glu-Lys-Ala). Considering their high tendency to aggregate, the self-assembly of CRENKA and CREKA into well-defined and ordered structures has been examined as a function of peptide concentration and pH. Spectroscopic studies and atomistic molecular dynamics simulations reveal significant differences between the secondary structures of CREKA and CRENKA. Thus, the restrictions imposed by the (NMe)Glu residue reduce the conformational variability of CRENKA with respect to CREKA, which significantly affects the formation of well-defined and ordered self-assembly morphologies. Aggregates with poorly defined morphology are obtained from solutions with low and moderate CREKA concentrations at pH 4, whereas well-defined dendritic microstructures with fractal geometry are obtained from CRENKA solutions with similar peptide concentrations at pH 4 and 7. The formation of dendritic structures is proposed to follow a two-step mechanism: (1) pseudo-spherical particles are pre-nucleated through a diffusion-limited aggregation process, pre-defining the dendritic geometry, and (2) such pre-nucleated structures coalesce by incorporating conformationally restrained CRENKA molecules from the solution to their surfaces, forming a continuous dendritic structure. Instead, no regular assembly is obtained from solutions with high peptide concentrations, as their dynamics is dominated by strong repulsive peptide-peptide electrostatic interactions, and from solutions at pH 10, in which the total peptide charge is zero. Overall, results demonstrate that dendritic structures are only obtained when the molecular charge of CRENKA, which is controlled through the pH, favors kinetics over thermodynamics during the self-assembly process.

Dual-Responsive Polypropylene Meshes Actuating as Thermal and SERS Sensors.

Polypropylene (PP) surgical meshes, with different knitted architectures, were chemically functionalized with gold nanoparticles (AuNPs) and 4-mercaptothiazole (4-MB) to transform their fibers into a surface enhanced Raman scattering (SERS) detectable plastic material. The application of a thin layer of poly[N-isopropylacrylamide-co-N,N'-methylene bis(acrylamide)] (PNIPAAm-co-MBA) graft copolymer, covalently polymerized to the mesh-gold substrate, caused the conversion of the inert plastic into a thermoresponsive material, resulting in the first PP implantable mesh with both SERS and temperature stimulus responses. AuNPs were homogeneously distributed over the PP yarns, offering a clear SERS recognition together with higher PNIPAAm lower critical solution temperature (LCST ∼ 37 °C) than without the metallic particles (LCST ∼ 32 °C). An infrared thermographic camera was used to observe the polymer-hydrogel folding-unfolding process and to identify the new value of the LCST, connected with the heat generation by plasmonic-resonance gold NPs. The development of SERS PP prosthesis will be relevant for the bioimaging and biomarker detection of the implant by using the plasmonic effect and Raman vibrational spectroscopy for minimally invasive interventions (such as laparoscopy), to prevent patient inflammatory processes. Furthermore, Raman sources have been proved to not damage the cells, like happens with near-infrared irradiation, representing another advantage of moving to SERS approaches. The findings reported here offer unprecedented application possibilities in the biomedical field by extrapolating the material functionalization to other nonabsorbable polymer made devices (e.g., surgical sutures, grapes, wound dressings, among others).

Biomass-derived isosorbide-based thermoresponsive hydrogel for drug delivery.

Herein, we describe the design and synthesis of a new variety of bio-based hydrogel films using a Cu(I)-catalyzed photo-click reaction. These films exhibited thermal-triggered swelling-deswelling and were constructed by crosslinking a triazide derivative of glycerol ethoxylate and dialkyne structures derived from isosorbide, a well-known plant-based platform molecule. The success of the click reaction was corroborated through infrared spectroscopy (FTIR) and the smooth surface of the obtained films was confirmed by scanning electron microscopy (SEM). The thermal characterization was carried out in terms of thermogravimetry (TGA) and differential scanning calorimetry (DSC), from which the decomposition onset and glass transition temperatures were determined, respectively. Additionally, mechanical properties of the samples were estimated by stress-strain experiments. Then, their swelling and deswelling properties were systematically examined in PBS buffer, revealing a thermoresponsive behavior that was successfully tested in the release of the anticancer drug doxorubicin. We also confirmed the non-cytotoxicity of these materials, which is a fundamental aspect for their potential use as drug carriers or tissue engineering matrices.

Self-assembly pathways in a triphenylalanine peptide capped with aromatic groups.

Peptide derivatives and, most specifically, their self-assembled supramolecular structures are being considered in the design of novel biofunctional materials. Although the self-assembly of triphenylalanine homopeptides has been found to be more versatile than that of homopeptides containing an even number of residues (i.e. diphenylalanine and tetraphenylalanine), only uncapped triphenylalanine (FFF) and a highly aromatic analog blocked at both the N- and C-termini with fluorenyl-containing groups (Fmoc-FFF-OFm), have been deeply studied before. In this work, we have examined the self-assembly of a triphenylalanine derivative bearing 9-fluorenylmethyloxycarbonyl and benzyl ester end-capping groups at the N- and C-termini, respectively (Fmoc-FFF-OBzl). The antiparallel arrangement clearly dominates in ß-sheets formed by Fmoc-FFF-OBzl, whereas the parallel and antiparallel dispositions are almost isoenergetic in Fmoc-FFF-OFm ß-sheets and the parallel one is slightly favored for FFF. The effects of both the peptide concentration and the medium on the self-assembly process have been examined considering Fmoc-FFF-OBzl solutions in a wide variety of solvent:co-solvent mixtures. In addition, Fmoc-FFF-OBzl supramolecular structures have been compared to those obtained for FFF and Fmoc-FFF-OFm under identical experimental conditions. The strength of π-π stacking interactions involving the end-capping groups plays a crucial role in the nucleation and growth of supramolecular structures, which determines the resulting morphology. Finally, the influence of a non-invasive external stimulus, ultrasounds, on the nucleation and growth of supramolecular structures has been examined. Overall, FFF-based peptides provide a wide range of supramolecular structures that can be of interest in the biotechnological field.

Poly(aspartic acid) Biohydrogel as the Base of a New Hybrid Conducting Material.

In the present study, a composite made of conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), and a biodegradable hydrogel of poly(aspartic acid) (PASP) were electrochemically interpenetrated with poly(hydroxymethyl-3,4-ethylenedioxythiophene) (PHMeDOT) to prepare a new interpenetrated polymer network (IPN). Different cross-linker and PEDOT MPs contents, as well as different electropolymerization times, were studied to optimize the structural and electrochemical properties. The properties of the new material, being electrically conductive, biocompatible, bioactive, and biodegradable, make it suitable for possible uses in biomedical applications.

Self-standing, conducting and capacitive biomimetic hybrid nanomembranes for selective molecular ion separation.

Hybrid free-standing biomimetic materials are developed by integrating the VDAC36 ß-barrel protein into robust and flexible three-layered polymer nanomembranes. The first and third layers are prepared by spin-coating a mixture of poly(lactic acid) (PLA) and poly(vinyl alcohol) (PVA). PVA nanofeatures are transformed into controlled nanoperforations by solvent-etching. The two nanoperforated PLA layers are separated by an electroactive layer, which is successfully electropolymerized by introducing a conducting sacrificial substrate under the first PLA nanosheet. Finally, the nanomaterial is consolidated by immobilizing the VDAC36 protein, active as an ion channel, into the nanoperforations of the upper layer. The integration of the protein causes a significant reduction of the material resistance, which decreases from 21.9 to 3.9 kΩ cm2. Electrochemical impedance spectroscopy studies using inorganic ions and molecular metabolites (i.e.l-lysine and ATP) not only reveal that the hybrid films behave as electrochemical supercapacitors but also indicate the most appropriate conditions to obtain selective responses against molecular ions as a function of their charge. The combination of polymers and proteins is promising for the development of new devices for engineering, biotechnological and biomedical applications.

Identification of adipose tissue-related predictors of the reduction in cardiovascular risk induced by metabolic surgery.

OBJECTIVES: We aimed to determine whether parameters associated with adipose tissue (adipocyte density and the circulating concentrations of markers of adipose tissue pathology) predict cardiovascular risk (CVR) modification after metabolic surgery (MS). METHODS: We performed a case-control study of patients with morbid obesity who were candidates for MS. CVR was defined using flow-mediated dilation (FMD) and carotid intima media thickness (CIMT), which were measured during the 9 months following MS. Subgroups of CVR reduction were defined using the following cut-offs: CIMT 10% and/or a two-fold increase in FMD. RESULTS: We studied 40 patients with morbid obesity (mean age 44.5 years, 75% women, mean body mass index 46.4 kg/m2) and high prevalences of the metabolically unhealthy obesity phenotype, hypertension, and diabetes mellitus. A significant reduction in CVR was associated with lower vascular endothelial growth factor-A concentration (6.20 vs. 1.59 pg/mL, respectively), low adipocyte density in visceral adipose tissue (100 vs. 80 cells/field), low infiltration with CD68+ cells (18 vs. 8 cells/field) and higher concentrations of lipid peroxidation markers and malondialdehyde (313.7 vs. 405.7 ng/mL). CONCLUSION: The characteristics of adipose tissue and the circulating concentrations of markers of adipose pathology might represent useful predictors of the reduction in CVR following MS.Clinical trial registration number: NCT0356198 (https://clinicaltrials.gov).

Plasma-Functionalized Isotactic Polypropylene Assembled with Conducting Polymers for Bacterial Quantification by NADH Sensing.

Rapid detection of bacterial presence on implantable medical devices is essential to prevent biofilm formation, which consists of densely packed bacteria colonies able to withstand antibiotic-mediated killing. In this work, a smart approach is presented to integrate electrochemical sensors for detecting bacterial infections in biomedical implants made of isotactic polypropylene (i-PP) using chemical assembly. The electrochemical detection is based on the capacity of conducting polymers (CPs) to detect extracellular nicotinamide adenine dinucleotide (NADH) released from cellular respiration of bacteria, which allows distinguishing prokaryotic from eukaryotic cells. Oxygen plasma-functionalized free-standing i-PP, coated with a layer (≈1.1 µm in thickness) of CP nanoparticles obtained by oxidative polymerization, is used as working electrode for the anodic polymerization of a second CP layer (≈8.2 µm in thickness), which provides very high electrochemical activity and stability. The resulting layered material, i-PPf /CP2 , detects the electro-oxidation of NADH in physiological media with a sensitivity 417 µA cm-2 and a detection limit up to 0.14 × 10-3 m, which is below the concentration of extracellular NADH found for bacterial cultures of biofilm-positive and biofilm-negative strains.

Structural preferences of an anti-fouling peptide: From single chain to small molecular assemblies.

The structural features of a tripeptide constituted by two different non-coded amino acids, 3,4-dihydroxy-L-phenylalanine (L-DOPA) and 4-fluoro-Phenylalanine, (Phe(4F)), have been investigated by means of classical mechanics simulations. This tripeptide had been characterised as an antifouling agent with great adhesion capabilities. In this work, its conformational preferences have been described in two different environments (gas phase and water solution), at three different pHs and with different degrees of terminal capping. At the same time, the structural dynamics of small aggregates of the tripeptide have been investigated and their ability to stabilise ß-sheet based assemblies has been studied. The reported results describe the complexity of the tripeptide conformational preferences due to both the amphiphilic nature of its side chains, and the effect of the ionisation state resulting from the solution conditions. The investigations performed with small tripeptide assemblies in water solution reproduced the previously reported structural features, such as the polymorphism of its aggregates as a function of the pH. At edge pH values, the electrostatic screening imposed by the ions present in the solution facilitates the aggregation of the tripeptide chains, while at neutral pH and low concentrations of ionised species, the polar groups and the hydrogen bond capable groups impose their strength and lead to the disaggregation of the peptide clusters by favouring the solvation of individual chains rather than stabilising the aggregated states.

Enlarged adipocytes from subcutaneous vs. visceral adipose tissue differentially contribute to metabolic dysfunction and atherogenic risk of patients with obesity.

Morphological characteristics and source of adipose tissue as well as adipokines may increase cardiometabolic risk. This study aimed to explore whether adipose tissue characteristics may impact metabolic and atherogenic risks. Subcutaneous Adipose Tissue (SAT), Visceral Adipose Tissue (VAT) and peripheral blood were obtained from obese patients submitted to bariatric surgery. Adipose tissue (morphometry), plasma adiponectin, TNF-α, resistin (multiplexing) and biochemical chemistry were analyzed; as well as endothelial dysfunction (Flow Mediated Dilation, FMD) and atherogenesis (Carotid Intima Media Thickness, CIMT). Subgroups divided by adipocyte size and source were compared; as well as correlation and multivariate analysis. Sixty patients 36.6% males, aged 44 years-old, BMI 46.7 kg/m2 were included. SAT's adipocytes showed a lower range of size expandability than VAT's adipocytes. Independent from their source, larger adipocytes were associated with higher glucose, lower adiponectin and higher CIMT. Particularly, larger adipocytes from SAT were associated with higher blood pressure, lower insulin and HDL-cholesterol; and showed positive correlation with glucose, HbA1c, systolic/diastolic values, and negatively correlated with insulin and adiponectin. VAT's larger adipocytes particularly associated with lower resistin and lower FMD values. Gender and Diabetes Mellitus significantly impacted the relation of adipocyte size/source with the metabolic and atherogenic risk. Multivariable analysis suggested hypertension-resistin-HbA1c interactions associated with SAT's larger adipocytes; whereas potential insulin-adiponectin associations were observed for VAT's larger adipocytes. Adipocyte morphology and source are differentially related with cardiometabolic and atherogenic risk in population with obesity, which are potentially affected by gender and Diabetes Mellitus.

Effect of conducting/thermoresponsive polymer ratio on multitasking nanogels.

Semi-interpenetrated nanogels (NGs) able to release and sense diclofenac (DIC) have been designed to act as photothermal agents with the possibility to ablate cancer cells using mild-temperatures (<45 °C). Combining mild heat treatments with simultaneous chemotherapy appears as a very promising therapeutic strategy to avoid heat resistance or damaging the surrounding tissues. Particularly, NGs consisted on a poly(N-isopropylacrylamide) (PNIPAM) and dendritic polyglycerol (dPG) mesh containing a semi-interpenetrating network (SIPN) of poly(hydroxymethyl 3,4-ethylenedioxythiophene) (PHMeEDOT). The PHMeEDOT acted as photothermal and conducting agent, while PNIPAM-dPG NG provided thermoresponsivity and acted as stabilizer. We studied how semi-interpenetration modified the physicochemical characteristics of the thermoresponsive SIPN NGs and selected the best condition to generate a multifunctional photothermal agent. The thermoswitchable conductiveness of the multifunctional NGs and the redox activity of DIC could be utilized for its electrochemical detection. Besides, as proof of the therapeutic concept, we investigated the combinatorial effect of photothermal therapy (PTT) and DIC treatment using the HeLa cancer cell line in vitro. Within 15 min NIR irradiation without surpassing 45 °C we were able to kill 95% of the cells, demonstrating the potential of SIPN NGs as drug carriers, sensors and agents for mild PTT.

Aggregation propensity of therapeutic fibrin-homing pentapeptides: insights from experiments and molecular dynamics simulations.

CREKA (Cys-Arg-Glu-Lys-Ala) and its engineered analogue CRMeEKA, in which Glu has been replaced by N-methyl-Glu to provide resistance against proteolysis, are emerging pentapeptides that were specifically designed to bind fibrin-fibronectin complexes accumulated in the walls of tumour vessels. However, many of the intrinsic properties of CREKA and CRMeEKA, which are probably responsible for their different behaviour when combined with other materials (such as polymers) for diagnosis and therapeutics, remain unknown yet. The intrinsic tendency of these pentapeptides to form aggregates has been analysed by combining experimental techniques and atomistic Molecular Dynamics (MD) simulations. Dynamic light scattering assays show the formation of nanoaggregates that increase in size with the peptide concentration, even though aggregation occurs sooner for CRMeEKA, independently of the peptide concentration. FTIR and circular dichroism spectroscopy studies suggest that aggregated pentapeptides do not adopt any secondary structure. Atomistic MD trajectories show that CREKA aggregates faster and forms bigger molecular clusters than CRMeEKA. This behaviour has been explained by stability of the conformations adopted by un-associated peptide strands. While CREKA molecules organize by forming intramolecular backbone - side chain hydrogen bonds, CRMeEKA peptides display main chain - main chain hydrogen bonds closing very stable γ- or ß-turns. Besides, energetic analyses reveal that CRMeEKA strands are better solvated in water than CREKA ones, independent of whether they are assembled or un-associated.