Probiotic cellulose: Antibiotic-free biomaterials with enhanced antibacterial activity

The alarming increase of antibiotic-resistant bacteria, causing conventional treatments of bacterial infections to become increasingly inefficient, is one of the biggest threats to global health. Here, we have developed probiotic cellulose, an antibiotic-free biomaterial for the treatment of severe skin infections and chronic wounds. This composite biomaterial was in-depth characterized by Gram stain, scanning electron microscopy (SEM) and confocal fluorescence microscopy. Results demonstrated that probiotic cellulose consists of dense films of cellulose nanofibers, free of cellulose-producing bacteria, completely invaded by live probiotics (Lactobacillus fermentum or Lactobacillus gasseri). Viability assays, including time evolution of pH and reducing capacity against electrochromic polyoxometalate, confirmed that probiotics within the cellulose matrix are not only alive but also metabolically active, a key point for the use of probiotic cellulose as an antibiotic-free antibacterial biomaterial. Antibacterial assays in pathogen-favorable media, a real-life infection scenario, demonstrated that probiotic cellulose strongly reduces the viability of Staphylococcus aureus (SA) and Pseudomonas aeruginosa (PA), the most active pathogens in severe skin infections and chronic wounds. Likewise, probiotic cellulose was also found to be effective to inhibit the proliferation of methicillin-resistant SA (MRSA). The combination of the properties of bacterial cellulose as wound dressing biomaterial and the antibacterial activity of probiotics makes probiotic cellulose an alternative to antibiotics for the treatment of topical infections, including severe and hard-to-heal chronic wounds. In addition, probiotic cellulose was obtained by a one-pot synthetic approach under mild conditions, not requiring the long and expensive chemical treatments to purify the genuine bacterial cellulose.

Crystal structure and photophysical properties of a novel polyoxomolybdate porphyrin

A novel polyoxomolybdate with a diprotonated porphyrin as counter-cation, namely, 5,10,15,20-tetrakis(4-carboxyphenyl)-21H,22H,23H,24H-porphine(2+) hexamolybdate(VI) pentahydrate, (C₄₈H₃₂N₄O₈)[Mo₆O₁₉]·5H₂O or (H₂TCPP)[Mo₆O₁₉]·5H₂O, I, was prepared via the hydrothermal reaction of MoCl₅, 5,10,15,20-tetrakis(4-carboxyphenyl)-21H,23H-porphine (TCPP) and distilled water. The crystal structure of hydrated polyoxometalate (POM) salt I was characterized by single-crystal X-ray diffraction. The compound is characterized by an isolated (zero-dimensional, 0D) structure, because it cannot extend via covalent bonds. The structure contains one [Mo₆O₁₉]^2- anion, one (H₂TCPP)²⁺ cation and five lattice water molecules. Each of the Mo⁶⁺ ions is six-coordinated and displays a distorted octahedral motif. The (H₂TCPP)²⁺ cation displays a distorted saddle motif. A three-dimensional (3D) supramolecular framework is formed via hydrogen-bonding interactions. The compound shows a red photoluminescence emission.

Nanolipid-loaded Preyssler polyoxometalate: Synthesis, characterization and invitro inhibitory effects on HepG2 tumor cells

Polyoxometalate-based drugs have been selected by some researchers as alternative antitumor substances with promising results in suppression of tumor growth because of low toxicity towards the human body and high activity. In this research, for the first time, nanolipid-loaded Preyssler polyoxometalate with diameters of 230-250 nm was synthesized and characterized by the Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX), Atomic Force Microscopy (AFM), and Infrared (IR) spectroscopy. The nanoliposomes were found to be nearly spherical, without any agglomeration with the Entrapment Efficiency of 53.8%. In -vitro antitumor activity of the synthesized nanoliposomes was investigated using the MTT method on HepG2 tumor cells. Our findings showed enhanced anticancer activity for the nanolipid-loaded Preyssler (NLP) compared to the Sorafenib as a commercially drug at 72 h. Selectivity of the synthesized NLP and Sorafenib for cancer cells versus primary HFF cells was obtained as 4.2 and 2.2, respectively. The IC50 value of the loaded nanoliposomes for cancer cells and normal cells was equal to 470 and 2000 μg/mL, respectively at 72 h, which was much better compared to that of the Sorafenib (7 and 16 μg/mL, respectively).

Preparations, Structures and Luminescence Properties of Penta-rare-earth Incorporated Tetravacant Dawson Selenotungstates and Their Ho3+ /Tm3+ Co-doped Derivatives

A family of penta-rare-earth incorporated tetravacant Dawson selenotungstates [H₂ N(CH₃ )₂ ]₁₀ H₃ [SeO₄ RE₅ (H₂ O)₇ (Se₂ W₁₄ O₅₂ )₂ ] ⋅ 40H₂ O [RE=Ho³⁺ (1), Er³⁺ (2), Tm³⁺ (3), Tb³⁺ (4)] were synthesized. It should be noted that a penta-RE [SeO₄ RE₅ (H₂ O)₇ ]¹¹⁺ central core connecting two tetra-vacant Dawson-type [Se₂ W₁₄ O₅₂ ]^12- subunits generates a dimeric assembly of [SeO₄ RE₅ (H₂ O)₇ (Se₂ W₁₄ O₅₂ )₂ ]^13- in the structures of 1-4. Meanwhile, a class of Ho³⁺ /Tm³⁺ co-doped derivatives based on 1 with a Ho³⁺ /Tm³⁺ molar ratio of 0.75:0.25-0.25:0.75 were also prepared and characterized by energy-dispersive spectroscopy (EDS) analyses. Moreover, their luminescence properties were systematically investigated, which indicate that Tm³⁺ ions can sensitize the emission of Ho³⁺ ions in the visible region and prolong the fluorescence lifetime of Ho³⁺ ions to some extent. Energy transfer from Tm³⁺ ions to Ho³⁺ ions was probed by time-resolved emission spectroscopy (TRES), and the CIE 1931 diagram has been applied to evaluate all possible luminescence colors.

Effective inhibitory activity against MCF-7, A549 and HepG2 cancer cells by a phosphomolybdate based hybrid solid

A novel P₂Mo₅ cluster based hybrid solid [{4,4′-H₂bpy}{4,4′-Hbpy}₂{H₂P₂Mo₅O₂₃}]·5H₂O with effective anti-proliferation activity against MCF-7, HepG2 and A549 cancer cells comparable with a routinely used chemotherapeutic agent, methotrexate (MTX).

AuNPs@PMo12nanozyme: highly oxidase mimetic activity for sensitive and specific colorimetric detection of acetaminophen

The design of a highly specific and sensitive approach for the quantitative and qualitative determination of acetaminophen (AP) is crucial from a human health point of view. In this study, AuNPs@PMo₁₂, as a nanozyme, has been developed for the highly sensitive and selective detection of AP with 3,3′,5,5′-tetramethylbenzidine (TMB) within a few seconds without adding oxidizing reagents (e.g. H₂O₂). Synthesized nanosensors are able to oxidize TMB to yellow-brown oxidized TMB (oxTMB). The maximum peak wavelength of oxTMB was observed at 450 nm. The addition of AP and then increasing its concentration led to the production of different products in blue color. In experimental measurements, the limit of detection was obtained as 14.52 mg L⁻¹. The quantitative determination of AP concentrations can be carried out using UV-vis spectroscopy. The design of nanosensors is cost-effective and application of them in H₂O₂-free and enzyme-free conditions provides a rapid sensing approach for practical use in disease monitoring and diagnosis.

The design of a highly specific and sensitive approach for the quantitative and qualitative determination of acetaminophen (AP) is crucial from a human health point of view.

Sonochemical synthesis of polyoxometalate-stabilized gold nanoparticles for point-of-care determination of acetaminophen levels: preclinical study in an animal model

The aim of this study is the accurate and rapid detection of acetaminophen (AP) for point-of-care (POC) clinical diagnosis. Acetaminophen overdose causes acute liver failure and currently there is a lack of rapid quantitative detection methods for this drug in the emergency room. Here, low-frequency sonication (20 kHz) in the presence of phosphomolybdic acid (PMo₁₂) was used to reduce Au³⁺ to Au⁰ and stabilize the resulting spherical Au⁰ nanoparticles (herein AuNPs). These AuNPs@PMo₁₂ were used as nano-probes for the selective detection of acetaminophen in the presence of other commercial drugs. The optical sensing method we describe is based on the aggregation of AuNPs@PMo₁₂ in the presence of acetaminophen, which produces a red-shift in the absorption spectrum of the AuNPs@PMo₁₂, which is characterised by a color change from red to purple that is visible to the naked eye. Furthermore, the quantitative determination of acetaminophen concentrations can be carried out using the eyedropper function in Microsoft's PowerPoint or open access ImageJ software, using RGB (red, green, and blue) values. To prove the feasibility of this novel nanosensor, the concentration of acetaminophen was measured in over-the-counter pharmaceutical tablets and in serum samples taken from mice. This simple sensing approach offers high stability, selectivity, rapid detection time, and cost saving compared to other detection methods, which therefore opens the way for the development of quantitative POC acetaminophen detection using polyoxometalate-stabilized metal nanoparticles.

The aim of this study is the accurate detection of acetaminophen (AP) for point-of-care (POC) clinical diagnosis. The concentration of acetaminophen was measured in over-the-counter pharmaceutical tablets and in serum samples taken from mice.

Electrochromic Sensors Based on Conducting Polymers, Metal Oxides, and Coordination Complexes

Electrochromic sensors offer multi-mode registration of analytical signal based on combination of electrochemical and optical techniques. This emerging direction of analytical chemistry is relatively new; therefore, it has very high potential for various applications in chemical and biochemical analysis. Properties of sensors based on various electrochromic materials such as polymers, polymer derivatives, polymer composites, metal oxides, metal oxide complexes, phthalocyanines, porphyrins, and dyes are critically overviewed, evaluated, and compared. The most promising directions in analytical application of electrochromic polymers are highlighted.

Skin color-specific and spectrally-selective naked-eye dosimetry of UVA, B and C radiations

Spectrally-selective monitoring of ultraviolet radiations (UVR) is of paramount importance across diverse fields, including effective monitoring of excessive solar exposure. Current UV sensors cannot differentiate between UVA, B, and C, each of which has a remarkably different impact on human health. Here we show spectrally selective colorimetric monitoring of UVR by developing a photoelectrochromic ink that consists of a multi-redox polyoxometalate and an e- donor. We combine this ink with simple components such as filter paper and transparency sheets to fabricate low-cost sensors that provide naked-eye monitoring of UVR, even at low doses typically encountered during solar exposure. Importantly, the diverse UV tolerance of different skin colors demands personalized sensors. In this spirit, we demonstrate the customized design of robust real-time solar UV dosimeters to meet the specific need of different skin phototypes. These spectrally-selective UV sensors offer remarkable potential in managing the impact of UVR in our day-to-day life.

Identification of the key excreted molecule by Lactobacillus fermentum related to host iron absorption

We have taken a vital step towards understanding why probiotic bacteria increase iron absorption in the gastrointestinal tract. We show here that Lactobacillus fermentum, one of the main probiotics of the microbiota, exhibits an extraordinary ferric-reducing activity. This activity is predominantly due to an excreted molecule: p-hydroxyphenyllactic acid (HPLA). Reduction of Fe(III) to Fe(II) is essential for iron absorption in the gastrointestinal tract. By reducing Fe(III), HPLA boosts Fe(II) absorption through the DMT1 channels of enterocytes. An in vitro experiment tested and confirmed this hypothesis. This discovery opens new avenues for the treatment of iron deficiency in humans, one of the most common and widespread nutritional disorders in the world.

Degradable Organically-Derivatized Polyoxometalate with Enhanced Activity against Glioblastoma Cell Line

High efficacy and low toxicity are critical for cancer treatment. Polyoxometalates (POMs) have been reported as potential candidates for cancer therapy. On accounts of the slow clearance of POMs, leading to long-term toxicity, the clinical application of POMs in cancer treatment is restricted. To address this problem, a degradable organoimido derivative of hexamolybdate is developed by modifying it with a cleavable organic group, leading to its degradation. Of note, this derivative exhibits favourable pharmacodynamics towards human malignant glioma cell (U251), the ability to penetrate across blood brain barrier and low toxicity towards rat pheochromocytoma cell (PC12). This line of research develops an effective POM-based agent for glioblastoma inhibition and will pave a new way to construct degradable anticancer agents for clinical cancer therapy.

Heteropoly acids triggered self-assembly of cationic peptides into photo- and electro-chromic gels

A series of cationic peptides with alternating lysines and hydrophobic residues were designed and synthesized. These kinds of short peptides with protonated lysines can complex with anionic heteropoly acids (HPAs) to form a stable gel in water/ethanol mixed solution. Circular dichroism spectroscopy showed that the short peptides adopted a mixed conformation (β-sheet and random-coil) within the gel matrix. Scanning and transmission electron microscopy revealed that the heteropoly acids, acting as nanosized cross-linkers, first initiated the self-assembly of the cationic peptides into spherical nanostructures. Then these nanospheres accumulated with each other through hydrogen bonds and hydrophobic interactions to form large sheet-like assemblies, which further interconnected with each other forming continuous 3D network structures. Fourier-transform infrared spectroscopy showed that the structural integrity of the HPAs was maintained during the gelation process. The resultant hybrid gels showed reversible photo- and elecrtro-chromic properties. X-ray photoelectron spectroscopy revealed that the hybrid gels, capable of persistent and reversible changes of their colour, are attributed to the intervalence charge-transfer transition of the HPAs. Reversible information writing and erasing were demonstrated through a repeated photo-lithograph or electric stimuli without significant loss of the gel performance.

Electrochromic/supercapacitive dual functional fibres

Wearable electronics have shown great potential to improve our lifestyle and health.

Preparation of polyoxometalate stabilized gold nanoparticles and composite assembly with graphene oxide: enhanced electrocatalytic performance

P₅W₃₀ stabilized Au nanoparticles and graphene oxide were fabricated to form composite films exhibiting good electrocatalytic activity for H₂O₂ reduction.