Ammonium release in synthetic and human urine by a urease immobilized nanoconstruct

In this work, we have studied the ability of urease immobilized on glutaraldehyde crosslinked chitosan coated magnetic iron oxide nanoparticles (Urease/GA/CS/MIONPs), for the hitherto unreported comparative hydrolysis of urea in synthetic (SUr) and real human urine (HUr). The prepared Urease/GA/CS/MIONPs were characterized by a combination of Fourier transform infrared spectroscopy (FTIR), field emission-scanning-electron-microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and dynamic light scattering (DLS). The nanoconstructs display the highest ammonium ion liberation post-urea hydrolysis in 1/20 or 1/24-fold dilutions of SUr and HUr, respectively. The optimum activity of immobilized urease is observed at pH 7, and the nanoconstructs facilitate efficient urea-hydrolysis till at least 45 °C. Kinetic analysis of the immobilized urease shows km and vmax of 14.81 mM, 12.36 mM, and 18.55 μM min-1 and 10.10 μM min-1, towards SUr and HUr, respectively. The magnetization of the immobilized urease is suitable for reuse across multiple cycles of urea hydrolysis in SUr and HUr. The robust performance of Urease/GA/CS/MIONPs in SUr and HUr is promising for generating ammonium as a useable source of nitrogen from human urine, and underscores the suitability of SUr as a urine mimic for such interventions.

Structural DNA nanotechnology at the nexus of next-generation bio-applications: challenges and perspectives

DNA nanotechnology has significantly progressed in the last four decades, creating nucleic acid structures widely used in various biological applications. The structural flexibility, programmability, and multiform customization of DNA-based nanostructures make them ideal for creating structures of all sizes and shapes and multivalent drug delivery systems. Since then, DNA nanotechnology has advanced significantly, and numerous DNA nanostructures have been used in biology and other scientific disciplines. Despite the progress made in DNA nanotechnology, challenges still need to be addressed before DNA nanostructures can be widely used in biological interfaces. We can open the door for upcoming uses of DNA nanoparticles by tackling these issues and looking into new avenues. The historical development of various DNA nanomaterials has been thoroughly examined in this review, along with the underlying theoretical underpinnings, a summary of their applications in various fields, and an examination of the current roadblocks and potential future directions.

Banana Peel Derived Chitosan-Grafted Biocomposite for Recovery of NH4+ and PO43

Biomass-derived adsorbents afford accessible and inexpensive harvesting of nitrogen and phosphorus from wastewater sources. Human urine is widely accepted as a rich source of nitrogen and phosphorus. However, direct use of urine in agriculture is untenable because of its unpleasant smell, pathogen contamination, and pharmaceutical residues. In this work, we have grafted chitosan onto dried and crushed banana peel (DCBP) to generate the biocomposite DCBP/Ch. A combination of FTIR, TGA, XRD, FESEM, EDX, and NMR analyses were used to characterize DCBP/Ch and reveal condensation-aided covalent conjugation between O-H functionalities of DCBP and chitosan. The adsorption performance of DCBP/Ch toward NH4+ and PO43- is in sync with its attractive surface porosity, elevated crystallinity, and thermostability. The maximum adsorption capacity of DCBP/Ch toward NH4+/PO43- was estimated as 42.16/15.91 mg g-1 at an operating pH of 7/4, respectively, and ranks highly when compared to previously reported bioadsorbents. DCBP/Ch performs admirably when tested on artificial urine. While nitrogen and phosphorus harvesting from human urine using single techniques has been reported previously, this is the first report of a single adsorbent for recovery of NH4+ and PO43-. The environmental compatibility, ease of preparation, and economic viability of DCBP/Ch present it as an attractive candidate for deployment in waste channels.

Bacteria-derived topologies of Cu2O nanozymes exert a variable antibacterial effect

The ability of bacteria to facilitate fabrication of nanomaterials has been adapted towards bacterial sensing applications. In this work, we fabricate spherical, cubic and truncated octahedron topologies of Cu2O nanoparticles via E. coli-facilitated redox reaction in an electrochemical setup. The Cu2O nanoparticles exhibit cytochrome c oxidase-like activity with the spherical topology displaying higher catalytic rate compared to the other geometries. The topology-dependent catalytic behavior of Cu2O nanoparticles has not been reported previously. The Cu2O nanozymes also display E. coli killing activity in a topology-correlated manner. The E. coli mediated redox reaction in an electrochemical setup is being reported for the first time for synthesis of different topologies of Cu2O which also exert a variable antibacterial effect.

Red emitting carbon dots: surface modifications and bioapplications

Quantum dots (QDs), and carbon quantum dots (CDs) in particular, have received significant attention for their special characteristics. These particles, on the scale of several nanometers, are often produced using simple and green methods, with naturally occurring organic precursors. In addition to facile production methods, CDs present advantageous applications in the field of medicine, primarily for bioimaging, antibacterial and therapeutics. Also, CDs present great potential for surface modification through methods like doping or material mixing during synthesis. However, the bulk of current literature focuses on CDs emitting in the blue wavelengths which are not very suitable for biological applications. Red emitting CDs are therefore of additional interest due to their brightness, photostability, novelty and deeper tissue penetration. In this review article, red CDs, their methods of production, and their biological applications for translational research are explored in depth, with emphasis on the effects of surface modifications and doping.

Crystal structure of Synechococcus phycocyanin: implications of light-harvesting and antioxidant properties

Phycobiliproteins is a family of chromophore-containing proteins having light-harvesting and antioxidant capacity. The phycocyanin (PC) is a brilliant blue coloured phycobiliprotein, found in rod structure of phycobilisome and has been widely studied for their therapeutic and fluorescent properties. In the present study, the hexameric assembly structure of phycocyanin (Syn-PC) from Synechococcus Sp. R42DM is characterized by X-ray crystallography to understand its light-harvesting and antioxidant properties. The crystal structure of Syn-PC is solved with 2.15 Å resolution and crystallographic R-factors, Rwork/Rfree, 0.16/0.21. The hexamer of Syn-PC is formed by heterodimer of two polypeptide chains, namely, α- and β-subunits. The structure is analysed at atomic level to reveal the chromophore microenvironment and possible light energy transfer mechanism in Syn-PC. The chromophore arrangement in hexamer, deviation angle and distance between the chromophore contribute to the energy transfer efficiency of protein. The structural attributes responsible for the antioxidant potential of Syn-PC are recognized and annotated on its 3-dimensional structure.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03665-1.

Spatiotemporal dynamics of DNA nanocage uptake in zebrafish embryos for targeted tissue bioimaging applications

Three-dimensional DNA nanocages have attracted significant attention for various biomedical applications including targeted bioimaging in vivo. Despite the numerous advantages, the use and in vivo exploration of DNA nanocages are limited as the cellular targeting and intracellular fate of these DNA nanocages within various model systems have not been explored well. Herein, using a zebrafish model system, we provide a detailed understanding of time-, tissue- and geometry-dependent DNA nanocage uptake in developing embryos and larvae. Of all the geometries tested, tetrahedrons showed significant internalization in 72 hours post-fertilized larvae upon exposure, without disturbing the expression of genes involved in embryo development. Our study provides a detailed understanding of the time and tissue-specific uptake of DNA nanocages in the zebrafish embryos and larvae. These findings will provide valuable insights into the internalization and biocompatible potential of DNA nanocages and will help to predict their candidature for biomedical applications.

Mitochondria Targeted AIE Probes for Cancer Phototherapy

In recent years, mitochondrion (powerhouse of the cells) gained lots of interest as one of the unorthodox targets for futuristic cancer therapy. As a result, novel small molecules were developed to damage and image mitochondria in cancer models. In this context, aggregation-induced emission probes (AIEgens) received immense attention due to their applications in mitochondria-targeted biosensing, imaging, and biomedical theranostics. On the other hand, phototherapy (photodynamic and photothermal) has emerged as a powerful alternative to manage cancer due to its less invasive nature. However, merging these two areas to engineer mitochondria-targeted phototherapeutic probes for cancer diagnosis and treatment has remained a major challenge. In this mini-review, we will outline the development of novel mitochondria-targeted small molecule AIEgens as imaging agents and photosensitizers for photodynamic therapy along with dual photodymanic-phototheramal therapy and chemo-photodynamic therapy. We will also highlight the current challenges in developing mitochondria-targeted photothermal therapy probes for future biomedical theranostic applications to manage cancer.

Isobaric Vapor-Liquid Equilibrium Data for Tetrahydrofuran + Acetic Acid and Tetrahydrofuran + Trichloroethylene Mixtures

Vapor-liquid equilibrium (VLE) data for the binary systems tetrahydrofuran (THF) + acetic acid (AA) and THF + trichloroethylene (TCE) were measured under isobaric conditions using an ebulliometer. The boiling temperatures for the systems (THF + AA/THF + TCE) are reported for 13/15 compositions and five/six different pressures ranging from 50.2/60.0 to 101.1/101.3 kPa, respectively. The THF + AA system shows simple phase behavior with no azeotrope formation. The THF + TCE system does not exhibit azeotrope formation but seems to have a pinch point close to the pure end of TCE. The nonrandom two-liquid (NRTL) and universal quasichemical (UNIQUAC) activity coefficient models were used to accurately fit the binary (PTx) data. Both models were able to fit the binary VLE data satisfactorily. However, the NRTL model was found to be slightly better than UNIQUAC model in fitting the VLE data for both systems. The results can be used for designing liquid-liquid extraction and distillation processes involving mixtures of THF, AA, and TCE.

Structural differences in 3C-like protease (Mpro) from SARS-CoV and SARS-CoV-2: molecular insights revealed by Molecular Dynamics Simulations

Novel coronavirus SARS-CoV-2 has infected millions of people with thousands of mortalities globally. The main protease (Mpro) is vital in processing replicase polyproteins. Both the CoV's Mpro shares 97% identity, with 12 mutations, but none are present in the active site. Although many therapeutics and vaccines are available to combat SARS-CoV-2, these treatments may not be practical due to their high mutational rate. On the other hand, Mpro has a high degree of conservation throughout variants, making Mpro a stout drug target. Here, we report a detailed comparison of both the monomeric Mpro and the biologically active dimeric Mpro using MD simulation to understand the impact of the 12 divergent residues (T35V, A46S, S65N, L86V, R88K, S94A, H134F, K180N, L202V, A267S, T285A and I286L) on the molecular microenvironment and the interaction between crucial residues. The present study concluded that the change in the microenvironment of residues at the entrance (T25, T26, M49 and Q189), near the catalytic site (F140, H163, H164, M165 and H172) and in the substrate-binding site (V35, N65, K88 and N180) is due to 12 mutations in the SARS-CoV-2 Mpro. Furthermore, the involvement of F140, E166 and H172 residues in dimerization stabilizes the Mpro dimer, which should be considered. We anticipate that networks and microenvironment changes identified here might guide repurposing attempts and optimization of new Mpro inhibitors.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11224-022-02089-6.

Rationalizing the Effect of Polymer-Controlled Growth of Perovskite Single Crystals on Optoelectronic Properties

To improve and modulate the optoelectronic properties of single-crystal (SC) metal halide perovskites (MHPs), significant progress has been achieved. Polymer-assisted techniques are a great approach to control the growth rate of SCs effectively. However, the resultant optoelectrical properties induced by polymers are ambiguous and need to be taken into the consideration. In this study, we have synthesized methylammonium lead triiodide (MAPbI₃) SCs using polyethylene glycol (PEG) and polystyrene (PS) polymers where PEG contains oxygen functionalities and PS does not. We studied the electrical properties of these SCs under dark and illumination conditions. It was observed that PEG-assisted SCs showed few defects with lower photocurrent as compared to the PS-assisted ones because of defect-mediated conductivity. The results are further verified by transient current response, responsivity, and capacitance-frequency measurements. The present study sheds light on the polymer selection for the growth of MHP SCs and their optoelectronic properties.