This contribution provides the synthesis and characterization of nickel oxide nanoparticles (NiO NPs) which were prepared by green synthesis method using natural extract oranges peel skin (Peel Citrus Sinensis) as an effective bio-oxidizing/bio-reducing agent. The effect of different calcination temperatures on the size of the NiO NPs was investigated. The prepared nanoparticles were characterized by various techniques such as X-rays diffraction (XRD) results indicated that all the samples have a face-centered cubic (FCC) structure and confirmed the presence of high degree of crystallinity nature NiO NPs. The functional group composition of NiO NPs were investigated by using attenuated total reflection-Fourier transform infrared (ART-FTIR), Photoluminescence (PL), and Scanning electron microscopy (SEM).

In techniques such as Dynamic Light Scattering (DLS), Fluorescence Correlation Spectroscopy, and image mining, motion is tracked by the autocorrelation of a signal over logarithmic time scales. For instance the tracking signal in DLS is the scattered light intensity; it remains correlated at time scales where scant changes in the arrangement of the scattering particles occur, but decays exponentially at the time scales of their diffusion. When there are multiple time scales of motion (for instance due to scatterers of different sizes), the correlation curve has more than one exponential fall. Extracting the decay constants or hydrodynamic sizes due to each exponential fall in a multi-species field correlation curve becomes an ill-conditioned mathematical problem. We describe a new algorithm to invert a multi-modal correlation curve by Sequential Extraction of the Late Exponentials (SELE). The idea is that while the inversion of a multi-exponential equation may be ill posed, that of a single exponential is not. So we fit data windows towards to base of the correlation curve to extract the largest contribution species, remove the species contribution from the correlation curve, and repeat the process with the remnant curve. The single exponent can be robustly fitted by least-square minimization with initial guesses generated by an adapted cumutant technique (power-series) that includes stretch coefficients (measure of sample dispersity). The proposed algorithm resolves particle sizes separated by 3X, and is reliable against fluctuations in the correlation curve and to localized regions of suboptimal data. The algorithm can be used to track particle dynamics in solution in multi-species problems such as self-assembly.

Most of the photochemical activity of bacterial photosynthetic apparatuses occurs in the reaction center, a transmembrane protein complex which converts photons into charge-separated states across the membrane with a quantum yield close to unity, fuelling the metabolism of the organism. Integrating the reaction center from the bacterium Rhodobacter sphaeroides onto electroactive surfaces, it is possible to technologically exploit the efficiency of this natural machinery to generate a photovoltage upon Near Infra-Red illumination, which can be used in electronic architectures working in the electrolytic environment such as electrolyte-gated organic transistors and bio-photonic power cells. Here, photovoltage generation in reaction center-based bio-hybrid architectures is investigated by means of chronopotentiometry, isolating the contribution of the functionalisation layers and defining novel surface functionalization strategies for photovoltage tuning.

Bioelectronics requires versatile, efficient, and low-cost interfaces between the biological entities and the conductive unit. Conductive polymers represent a valid choice to assemble such interfaces able to extract or impinge charges between the biological units and the conductive electronic systems. A drawback in the use of such systems is that the polymerization reaction often takes place in environments whose chemical and physical characteristics clash with the mild conditions required for living biological systems. In the present work, we successfully prove that the conductive polymer poly(gallic acid) can be synthesized in medium designed for bacterial growth, characterised by the presence of several adverse conditions including numerous chemicals, high ionic strength, and almost neutral pH. The gallic acid successfully polymerizes within few hours and with a 40% yield, by exploiting the catalytic activity of the enzyme laccase from the polypore mushroom Trametes versicolor. The resulting polymer is characterised by absorption and Nuclear Magnetic Resonance spectroscopies. The viability of Rhodobacter sphaeroides culture, assessed via the coffee-ring technique, shows an important, but not complete detrimental effect of the gallic acid on the bacterial growth.

Particular attention has been recently devoted to the development of biohybrid photoconverters based on the bacterial Reaction Center (RC) of Rhodobacter sphaeroides. This highly efficient photoenzyme has a conversion yield close to unit that makes it extremely appealing in the field of artificial photosynthesis. Isolated RCs suffer of a limited absorption cross-section in the visible spectral region that limits their applicative employment. Here we report the synthesis of two heptamethine cyanine molecules, whose photophysical properties make them potentially suitable as light harvesting antennas for the RC.

Sunlight is the most environmental friendly energy source available on Earth; many efforts devoted to design artificial photoconversion systems are ongoing, nevertheless they are still expensive and poorly efficient. Photoconversion devices made with organic-biological hybrids, or biohybrids, based on the photosynthetic reaction center (RC) have been introduced. In these systems, the photoenzyme is garnished with artificial antennas to enhance the photoactivity of the RC. Here we present a newly synthesized heptamethine cyanine dye that fulfills requisites to act as efficient RC light harvesting antenna.

Manufacturing has historically followed a mass production approach due to economies of scale and the engineering challenges of large-scale customization, leading to a one-size-fits-all paradigm. This manufacturing-centric approach has forced consumers and patients to adapt to medical devices in terms of anatomical fit and biological performance, often significantly decreasing their quality of life. In order to improve the biological interface with the human body, the materials science and bioengineering communities are rapidly adopting three-dimensional (3D) printing, which promises high precision, automation, and a customized fit. However, numerous design and engineering constraints, many posed by the fragile nature of living cells and soft gels, suggest exciting opportunities for further research in materials synthesis, characterization, and integration. Specifically, materials innovations in bioinks and support materials, coupled with improved 3D bioprinting processes for multiple materials, have the potential to empower the next generation of biology by enabling precision engineered tissues, organoids, and eventually whole organs.

Multimaterial bioprinting technologies offer promising avenues to create mini-organ models with enhanced tissue heterogeneity and complexity. This article focuses on the application of three-dimensional bioprinting to fabricate organ-on-a-chip systems for in vitro drug testing and screening. We illustrate the capabilities and limitations of a bioprinting approach compared to microfabrication in constructing an organ-on-a-chip device. Further, we propose strategies in multimaterial integration for printing microphysiological tissue models. With these analyses, key challenges and future directions are highlighted.

Peptide nanotubes based on short dipeptide diphenylalanine (FF) attract a lot of attention due to their unique physical properties ranging from strong piezoelectricity to extraordinary mechanical rigidity. In this work, we present the results of high-resolution Piezoresponse Force Microscopy (PFM) measurements in FF microtubes prepared from the solution. First in-situ temperature measurements show that the effective shear piezoelectric coefficient d15 (proportional to axial polarization) significantly decreases (to about half of the initial value) under heating up to 100 oC. The piezoresponse becomes inhomogeneous over the surface being higher in the center of the tubes. Further, PFM study of a composite consisting of FF microtubes and reduced graphene oxide (rGO) was performed. We show that piezoelectric properties of peptide microtubes are significantly modified and radial (vertical) piezoresponse appears in the presence of rGO as confirmed via PFM analysis. The results are rationalized in terms of molecular approach in which π – π molecular interaction between rGO and dipeptide is responsible for the appearance of radial component of polarization in such hybrid structures.

A review of recent literature supports the notion that organisms may achieve nanoscale control over the hierarchical assembly of organic–inorganic materials by compartmentalizing reactions into small volumes containing specifically functionalized macromolecules. Such confinement may introduce a degree of determinism to the stochastic process of nucleation by greatly reducing the number of nucleation events, allowing an organism to control nucleation using “soft” organic substrates. In this way, the polymorph, orientation, shape, and size of a crystalline building block can be selected, and its assembly into a larger structure orchestrated by the organic matrix.

Polypeptides are receiving increasing attention as building blocks to create nanostructures for biomedical applications. The first goal of this investigation was to explore the influence of the reaction conditions in the synthesis of well-defined dendritic graft (arborescent) polypeptides from amine-terminated poly(γ-benzyl L-glutamate) (PBG) chains. The optimization was carried out in terms of the reaction temperature, solvent, reaction time, and mole ratio of reactants and coupling agents. Size exclusion chromatography served to evaluate the grafting reaction in terms of grafting yield (fraction of side chains coupled with the substrate) and coupling efficiency (fraction of coupling sites consumed on the substrate). The maximum grafting yield and coupling efficiency achieved were 67% and 74%, respectively. These arborescent PBG substrates were subsequently grafted with poly(ethylene oxide) segments forming a hydrophilic shell, to obtain water-dispersible unimolecular micelles useful as delivery vehicles for doxorubicin.

Tissue engineering scaffolding is the external media or structure in which cell growth, migration and reproduction is enabled in order to stimulate tissue regeneration. In order to promote tissue regeneration, scaffolding materials are required to have certain properties such as biocompatibility, adequate mechanical properties and surface topographical features in order to provide specific biological signals to promote cell attachment and proliferation [1].

Cellulose is the most abundant, inexpensive and readily available carbohydrate polymer in the world and it is traditionally extracted from plants or their wastes [2]. Although the plant itself is the major contributor of cellulose, various types of bacteria are able to produce cellulose and it is termed bacterial cellulose [3]. Bacterial cellulose is a well suited scaffold for tissue regeneration due to its biocompatibility, mechanical properties and its ability to be combined with other structures such calcium phosphates [4], which can create composites with intrinsic properties that meet the requirements of the different tissues of the human body [5].

Through additive manufacturing, highly complex structures can be created which are similar to those found in nature. This work will explore the different ways to produce biomimetic structures for tissue engineering applications through the combination of bacterial cellulose and additive manufacturing producing complex structures of a highly a biocompatible material for a range of different biomedical applications [6]. In addition to the manufacturing and processing techniques, the use of mango (juice/peel) as a complex carbon source for the production of bacterial cellulose was investigated.

The photosynthetic reaction center (RC) from the purple Rhodobacter (R.)sphaeroides bacterium is a protein with unique photoconversioncapability that can be exploited in hybrid systems for energy conversion. Wehave developed a tailored aryleneethynylene organic fluorophore (AE750) actingas efficient light harvesting antenna and successfully bioconjugated it to thephotosynthetic RC. We have also demonstrated that, under suitable conditions,the biohybrid AE750-RC system can outperform the energy photoconversion abilityof the native protein.

Biomineralization is the matrix-directed calcification of tissue in living organisms. The deposition of different polymorphs of calcium phosphate or calcium carbonate is a highly regulated process. It may involve cell-controlled mechanisms with vesicular delivery of inorganic material to the extracellular matrix and cell-independent processes mediated by dedicated matrix proteins. These proteins promote the formation of microscopic crystals of defined size and shape, which combine to form bio-inorganic materials with unique properties. Successful biomineralization is correlated with structural elements, such as matrix proteins involved in the nucleation process. Circular dichroism (CD) is a spectroscopic technique for the determination of a secondary structure of proteins and has therefore been applied for studying numerous biomineralization promoter proteins. This article reviews and compares CD data on matrix proteins from different contexts, such as eggs, seashells, and teeth. It highlights the potential of CD for secondary structure determination and quantification and points out pitfalls that may lead to misinterpretation of CD spectra. The data suggest that most biomineralization promoter proteins contain domains of different secondary structure with predominantly unordered conformation. However, they may acquire a higher degree of order initiated by environmental factors such as pH, presence of cations, or charged surfaces.

Biomineralization is the process by which living organisms orchestrate the synthesis and organization of minerals (biominerals), and it may be viewed as an ancient process for accumulation of metal ions in living systems. The structure and properties of biominerals have yet to be rivaled by any synthetic effort by scientists to date. Therefore, deciphering the assembly algorithms and the components that initiate and promote hierarchical deposition of cations has significant implications for the development of nanocomposites and nanotechnology as a whole. This issue of MRS Bulletin highlights some of the challenges in characterizing and replicating the biomineralization processes, and the role of non-collagenous proteins in the biomineralization process.

Organ shortage is a severe challenge worldwide. Three-dimensional (3D) printing, a rapidly developing engineering and materials science tool, holds considerable promise in generating implantable organ scaffolds that may reduce or eliminate organ shortage. However, translation of 3D printing into clinical therapies has been astonishingly slow and certainly has not matched the pace of technology development. This review outlines challenges and opportunities for the application of 3D printing in tissue and organ regeneration, with emphasis on in vivo applications of 3D-printed scaffolds. Three-dimensional-printed scaffolds for the regeneration of complex tissues and organs, including bone, cartilage, tooth, and skin, serve as prototypes for 3D printing of other tissues and organs such as the liver, kidney, or heart. The aspiration to reduce or eliminate organ shortage appears to hinge on the translation of 3D bioprinting technologies into preclinical studies and clinical trials. The remaining challenges of cell survival, directed differentiation, angiogenesis, and metabolic exchange are far from trial and need to be addressed. Three-dimensional-printed materials will remain a biomaterials and engineering showcase unless applications in preclinical and clinical models are realized. In balance, 3D printing holds considerable promise in regenerative medicine as a unique approach to address organ shortage.

Organic biological hybrid systems, accessible by covalent functionalization of photosynthetic proteins with molecular antennas, represent a promising novelty to enhance natural photosynthesis. In this paper, we present the successful bioconjugation of a commercial fluorophore, fluorescein isothiocyanate (FITC), to the photosynthetic reaction center RC from the bacterium Rhodobacter sphaeroides strain R26. The resulting hybrid outperforms the pristine protein in hole-electron couple generation yield, exclusively at wavelengths where the fluorophore absorbs while the protein does not.

Covalent functionalization of reduced graphene oxide (rGO) with the photosynthetic reaction center (RC) from Rhodobacter sphaeroides R26 via click chemistry reaction has been performed. The hybrid system was characterized by flash photolysis and infrared spectroscopy and the RC was found to retain its photoactivity and structural integrity. The strategy is applicable for the fabrication of hybrid bio-electronic devices capable of absorbing and converting solar energy.

We have studied multigeneration effects of plasma irradiation to seeds of Arabidopsis thaliana (L.) and Zinnia peruviana (L.) on their growth using a scalable DBD device. Atmospheric plasma irradiation enhances growth of these plants in multi-generations. For Arabidopsis thaliana (L.) in the third generation, the leaf area is 2 times larger than that without plasma irradiation and the stem length is 1.5 times longer than that without plasma. For Zinnia peruviana (L.) in the second generation, the stem length is 2 times longer than that without plasma.

Droplet interface bilayers (DIBs) are physical lipid bilayers that mimic real membranes in living cells, and they are formed quickly using droplets of water and lipids in oil (Fig. 1A). DIBs allow biomolecular sensing and direct detection of transmembrane proteins or peptides and small molecules such as drugs, anesthetics, or even ions. Cell-free expression systems allow in vitro protein synthesis using actual natural machinery extracted from organisms (Fig. 1B). Previous attempts to combine DIBs with cell-free extracts (CFE) encountered bilayer destabilization due to components in the expression system. This study evaluates incorporation of Promega’s T7 S30 High Yield (HY) Expression system with DIBs to pave the way for future in situ expression of light-activated bacteriorhodopsin (BR) and other complex transmembrane proteins in DIBs. A secondary output includes establishing a method for real-time monitoring and modeling of CF expression reactions using minimal volume. The ability to quantify CF output in such small volumes reduces cost per reaction from $20 to around $0.40, and synthesized protein levels reach tens to hundreds of micrograms per milliliter in less than 1 hour at 37°C.