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The growth-associated metabolites are produced during the exponential phase; however, this phase terminates due to substrate depletion or product inhibition. In the present study, a semicontinuous mode with a fill-and-draw strategy was applied to extend the exponential phase of the biosurfactant production to overcome the product inhibition and in turn, enhance the yield. Bioreactor studies were performed in batch mode, followed by the semicontinuous operation. A potential biosurfactant producer Bacillus subtilis RSL2 was used in this study at the previously optimized conditions of pH 6.6, temperature 41 °C and 5% (w/v) of molasses. A better mass transfer was achieved in the bioreactor as compared to the shake flask study. In the batch bioreactor study, 90% of sugar was utilized with simultaneous 13.7 g L

Background: Hydroxyapatite (HAp) is one of the most studied biomimetic method for biomedical applications. Especially, nano-HAp has been utilized for bone tissue engineering and various other orthopedic applications. HAp possesses different suitable properties such as bioactivity, biodegradability, and cell proliferation efficiency for bone tissue engineering applications. Yet, it lacks in self-antibacterial activity, high surface area, and target efficiency. Results: In this direction, researchers have focused on exploring the required surface as well as the inherent properties of HAp at the nanoscale. These properties are largely dependent on the composition, size, and morphology of the nano-HAp. Hence, nano-HAp has been found to be an excellent candidate with an attractive combination of properties for selection and use in biomedical applications, those required to enhanced biological responses. Further, depending on the type of application, these factors can be tuned to optimize the performance. Conclusion: In this review article, we focus on the chemical structure of HAp and the routes chosen and used for the synthesis of the nano-HAp. The role of various parameters in controlling synthesis at the nanoscale is presented and briefly discussed. In addition, we provide an overview of the various applications for the pristine and doped nano-HAp with recent examples in areas spanning the following: (i) bone tissue engineering applications, (ii) drug delivery applications, (iii) surface coatings, and (iv) scaffolds. The effect of chemical composition on the mechanical properties, surface properties, and biological properties are also highlighted. Nano-HAp is found to be highly proficient in its biomedical applications, especially bone tissue engineering applications. The nano-- sized properties enhance the biological responses. The dopant ions that replace the Ca ion into the hydroxyapatite (HAp) lattice play a crucial role in its biomedical applications.

Over the decades the presence of aquatic weeds has caused immense biodiversity loss to the ecosystem. The use of herbicides has arisen emergence of herbicide-resistant weeds and loss of inherent flora and fauna due to the recalcitrant nature of the chemicals used. Hence, there is a need to use nontoxic, ecosustainable, low-cost, and efficient biological molecules that are analogous to chemical herbicides. Various plants, bacteria, fungi as well a few viruses are reported to secrete allelopathic biomolecules that inhibit the growth and development of weeds. However, majorly fungal pathogens and their metabolites are found to be effective biocontrol agents for the water hyacinth. The present review puts forward major findings and interventions in the biological control of the weed, water hyacinth. The biosynthesis, mechanism of action and factors regulating the activity of bioherbicides are discussed. In addition, the issues associated with the in situ application of these bioherbicides are also conferred focusing on the available mode of applications and formulation used. The major factors include the type and concentration of allelopathic biomolecules, age, type, and morphology of targeted weed, formulation type, mode of application and other physiological and environmental factors. Among various modes for the application of bioherbicides, emulsions are found to be most effective for the control of water hyacinth. Most of the toxicity studies indicated no toxicity of this fungal pathogen to other ecological plant species except water hyacinth. Yet, in-depth investigations are needed of these allelochemicals and toxins before field applications. Overall, lab-scale studies have shown promising results and highlighted a few potential fungi that need to be further explored for optimizing their bioherbicidal activity.

Hydroxyapatite (HAp) is one of the most studied biomaterials for orthopaedic applications, yet its commercialization holds in a few of the lags, such as non-antibacterial activity and target deficiency. In this context, we aimed to design a biphasic nanoassembly of Ferric-HAp-Zincite (ZFHAp) via a one-step co-precipitation method. Ferric-HAp obtained Ca9·333Fe1·167(PO4)7 phase in all the samples, and the secondary phases such as Ca9Fe(PO4)7 and Ca28·8Fe3·2(PO4)21O0.5 were governed by the Fe dopant concentration. Along with ferric-HAp, zincite phases were present in all the samples depending on the concentration of Zn precursor. The synthesized ZFHAp samples were hexagonal in structure with size

The polymeric scaffolds are one of the most studied systems for biomedical applications. Yet, their enzymatic degradation and non-antibacterial ability are the major challenges for the researchers. In this regard, we designed Fe(III) doped ZnO integrated hydroxyapatite ZFHAp nanoparticles and prepared the natural biopolymer-based chitosan- carboxymethyl cellulose-ZFHAp scaffolds suitable for bone tissue engineering. The nanoparticles were successfully characterized with XRD and RAMAN spectroscopy and were found to be in hexagonal wurtzite HAp phase with Ca + Zn + Fe/P ratio of 1.7. The prepared nano-biocomposite scaffolds were microporous in structure (25–123 µm), and their biochemical behaviours such as porosity (60–80%), swelling, and enzymatic degradation (21–50%) were dependent on the concentrations of ZFHAp. The swelling and degradation of the prepared scaffolds were linearly related. The presence of 5% ZFHAp in the scaffolds (SCA-5) resulted in pore size of 92 ± 10 µm and 50% degradation time of 42 days. This scaffolds SCA-5 also showed self-antibacterial activities along with excellent cell proliferation ability. The present study designates the SCA-5 as plausible scaffolds for bone tissue engineering.

We report the tuneable spin angular momentum transfer (spin pumping) from Co60Fe20B20 (CFB) amorphous alloy into the Ta heavy metal nanolayers. All the films are grown on Si (100) substrate at room temperature using ion-beam sputtering technique. Structural studies reveal that the grown Ta films over amorphous CFB are crystalline even at ultrathin regime. The bilayers possess very low interface roughness (i.e., follows ballistic spin transport) in two series of CFB (4nm)/Ta (0-10nm) and CFB(6nm)/Ta (0-10nm) bilayers, which is characteristic of normal spin pumping. However, the anomalous behaviour has been observed for CFB (8nm)/Ta (0-10nm) bilayer series where the spin current generated in Ta with the thicker CFB behaves oppositely. The results demonstrate the strong dependence of ferromagnet thickness on the spin pumping into the Ta nanolayers. This study paves the way to choose suitable ferromagnetic layer thickness for spin current induced switching applications in spintronics.

Magnetoresistance (MR) in thin films stems from different types of scattering mechanism present in the film. We report a systematic study of the temperature-dependent magnetoresistance behaviour in the pulsed DC magnetron sputtered Ni81Fe19 thin film on Si (100). X-ray diffraction study reveals the polycrystalline nature of the film along with the presence of preferred orientation. X-ray reflectivity measurement shows very low interface roughness (0.55 ± 0.04 nm). Temperature-dependent resistivity measurement is performed over a temperature range of 25–300 K, unveiling the dominance of electron-magnon scattering and impurity scattering at lower temperature (25–250 K) and electron-phonon scattering at higher temperature (above 250 K). In the investigated temperature range (30–300 K), the MR magnitude is found to reduce from 0.97 to 0.51% with increment in measurement temperature from 30 to 300 K. This reduction is attributed to the enhancement in phonon scattering at higher temperatures, and relatively suppressed ordering influence of magnetic field at higher temperature due to higher thermal activation energy and impurity scattering.

The preferable mechanical properties of Mg alloys along with excellent compatibility with human bone have established their applicability as implant biomaterials. However, a higher corrosion/degradation rate of Mg alloys in body fluids limits its biomedical applications. In this direction, surface modification and coating are explored as appropriate strategies to mode the degradation rate of Mg alloys. The constituents of bioactive glass (BG) provide strength, bio-inertness and bone bonding capability. Hence, researchers have explored the coating of BG on Mg alloys and investigated chemical, mechanical and biological properties of the coated alloys. In this review, we have made an attempt to compile the literature works done on the coating of BG on Mg alloys and its features. Underlying interfacial aspects of the coated substrates towards the degradation behavior are highlighted. The way forward to further improve the coating characteristics of BG coated Mg alloys are remarked.

The spreading of coronavirus from contacting surfaces and aerosols created a pandemic around the world. To prevent the transmission of SARS-CoV-2 virus and other contagious microbes, disinfection of contacting surfaces is necessary. In this study, a disinfection box equipped with infrared (IR) radiation heating and ultraviolet-C (UV-C) radiation is designed and tested for its disinfection ability against pathogenic bacteria and SARS-CoV-2 spike protein. The killing of a Gram-positive, namely, S. aureus and a Gram-negative namely, S. typhi bacteria was studied followed by the inactivation of the spike protein. The experimental parameters were optimized using a statistical tool. For the broad-spectrum antibacterial activity, the optimum condition was holding at 65.61 °C for 13.54 min. The killing of the bacterial pathogen occurred via rupturing the cell walls as depicted by electron microscopy. Further, the unfolding of SARS-CoV-2 spike protein and RNase A was studied under IR and UV-C irradiations at the aforesaid optimized condition. The unfolding of both the proteins was confirmed by changes in the secondary structure, particularly an increase in β-sheets and a decrease in α-helixes. Remarkably, the higher penetration depth of IR waves up to subcutaneous tissue resulted in lower optimum disinfection temperature,70 °C in vogue. Thus, the combined UV-C and IR radiation is effective in killing the pathogenic bacteria and denaturing the glycoproteins.

Crude oil bioremediation requires a correct selection of potential biodegraders to address the hazard. The present study investigates biodegradation kinetics of single aliphatic (Hexadecane, HEX), aromatic (Phenanthrene, PHE), and binary mixture (HEX + PHE) as co-contaminants by axenic cultures of A. fabrum SLAJ 731, B. subtilis RSL2 and P. aeruginosa P7815 and their consortium. A proposed integrated kinetic model combining first-order exponential decay and the Monod equation is well-fitted to degradation data. Maximum degradations of both the substrates were observed for microcosm, indicating synergistic effects of selected strains. The degradation rate indicated parallel utilization of HEX while serial utilization of PHE by selected strains. Maximum HEX and PHE degradations of 92.4 and 88.7 % were achieved by microconsortium, which increased to 97.2 and 91.9 % for the binary mixture. The biodegradation efficiencies of HEX and PHE were linearly correlated with Alkane hydroxylase and Catechol-2,3-dioxygenase activities, respectively.

The outermost surfaces of Personal Protective Equipments (PPEs) interact with virus surface-protein as the first step during its transmission from aerosols and contacting surfaces, which can be tun...

Nanoemulsions are one of the systems being used for targeted drug delivery. Lipopeptide possesses antibacterial and anticancer activities, and eucalyptus essential oil offers antimicrobial and anti...

Microbial surface attachment negatively impacts a wide range of devices from water purification membranes to biomedical implants. Mimics of antimicrobial peptides (AMPs) constituted from poly(N‐substituted glycine) „peptoids“ are of great interest as they resist proteolysis and can inhibit a wide spectrum of microbes. We investigate how terminal modification of a peptoid AMP‐mimic and its surface immobilization affect antimicrobial activity. We also demonstrate a convenient surface modification strategy for enabling alkyne–azide „click“ coupling on amino‐functionalized surfaces. Our results verified that the N‐ and C‐terminal peptoid structures are not required for antimicrobial activity. Moreover, our peptoid immobilization density and choice of PEG tether resulted in a „volumetric“ spatial separation between AMPs that, compared to past studies, enabled the highest AMP surface activity relative to bacterial attachment. Our analysis suggests the importance of spatial flexibility for membrane activity and that AMP separation may be a controlling parameter for optimizing surface anti‐biofouling., Efficient anti‐biofouling: We show that an archetypical antimicrobial peptoid could retain high activity even with terminal modifications. Immobilization by alkyne–azide „click“ coupling on one‐step modified amino‐surfaces was demonstrated. Appropriate spatial separation between immobilized peptoids, rather than increasing surface density, was found to promote both resistance against bacterial attachment and AMP surface activity.

The article investigates electrically active ceramic composite of $$\mathrm{Ca}_{10}(\mathrm{PO}_4)_6(\mathrm{OH})_2$$ Ca 10 ( PO 4 ) 6 ( OH ) 2 (HAP) and $$\mathrm{Ba}_{0.5}\mathrm{Sr}_{0.5}\mathrm{TiO}_{3}$$ Ba 0.5 Sr 0.5 TiO 3 (BST) for biomedical applications. The study is a systematic blend of the materials science aspect of composites with a special focus on the dielectric and biological properties and their relationships. The article emphasized primarily extracting the dielectric constant ($$\epsilon _r)$$ ϵ r ) of the specimens (that lay in the range of 3–65) and related them to microstructural properties like the grain size and at.% of BST. A broad outlook on the importance of $$\epsilon _r$$ ϵ r in determining the suitability of bioceramics for clinical applications is presented. Bioactivity analysis of the specimens led to probing the surface charges (that were negative), and it was found crucial to the growth of dense apatite layers. Furthermore, the cytocompatibility of the specimens displayed cell viability above 100% for Day 1, which increased substantially for Day 3. To reveal other biological properties of the composites, protein adsorption studies using bovine serum albumin (BSA) and fetal bovine serum (FBS) was carried out. Electrostatic interactions govern the adsorption, and the mathematical dependence on surface charges is linear. The protein adsorption is also linearly correlated with the $$\epsilon _r$$ ϵ r , intrinsic to the biomaterials. We delve deeper into protein–biomaterials interactions by considering the evolution of the secondary structure of BSA adsorbed into the specimens. Based on the investigations, 20 at.% HAP–80 at.% BST (20H–80B) was established as a suitable composite comprising the desired features of HAP and BST. Such explorations of electrical and biological properties are interesting for modulating the behavior of bioceramic composites. The results project the suitability of 20H–80B for designing electrically active smart scaffolds for the proposed biomedical applications and are expected to incite further clinical trials.

Biosurfactants play a vital role in the microbial biodegradation of various hazardous contaminants such as heavy metals and recalcitrant hydrocarbons. However, their application is limited due to scarcity in microbial biosurfactant productivity. Optimization of microbial culture conditions can improve this paucity to a greater extent. Various researchers have categorized pH, temperature, Carbon to Nitrogen (C/N) ratio, and salinity as key factors associated with biosurfactants production. Carbon and nitrogen sources and their concentrations drive the metabolic flux towards biomass and secondary metabolites production, however, a high C/N ratio is preferred for biosurfactant production. Various bacterial species (i.e. Rhodococcus, Bacillus and Pseudomonas) have profoundly produced biosurfactants under extreme temperatures. Studies have also evidenced the improved extracellular release of biosurfactant by the cells at slightly acidic pH, suggesting the importance of culture media pH for the biosurfactant extraction. Hence, biosurfactant production involves complex metabolic reactions regulated by various mutually inclusive physiological parameters. The design of experiment is a widely accepted technique for optimizing such multifactor systems. Taguchi model and Plackett–Burman designs provide precise model designs yet are ineffective in unveiling the mutual interaction within the factors. Response surface methodology such as central composite design and Box–Behnken design are more accurate in dealing with such interlinked factors optimization. Advancements in artificial neural networks and genetic algorithms have achieved more precise prediction of experiments hence, widely practiced for maximizing the biosurfactant yield in recent decades. This chapter aims to summarize the various optimization factors and design techniques associated with maximizing biosurfactant production.

Heavy metal and petroleum contaminated sites comprise a mixed culture of inherent microbial species yet the occurrence of competition for nutrients causes interference within species cooperating the biodegradation. Insights into the biodiversity of the contaminated sites and extreme conditions of oil reservoirs decipher the presence of both hydrocarbon degraders and biosurfactant-producing microbes. Biosurfactant-producing strains improves the bioavailability of hydrocarbons by emulsifying them or solubilize them using micellar structure formation, making it easy for the hydrocarbon degraders to metabolize them. Such inherent microbes can be designed into a stable microbial consortium harboring resilience, division of labor and resistance to extreme environmental drifts in order to improve the overall biodegradation efficiency. A top-down approach involves selectively enriching the active degraders within the inherent microbes. Yet, non-cultivable microbes are neglected in this approach reducing the overall biodegradation efficiency. Another bottom-up approach allows the inclusion of engineered microbes with equipped enzymes with the indigenous microbes for improving the overall consortium performance. Studies support the suitability of mutualism and commensalism as key interactions for consortium stability. Various phenomena such as syntrophy, biotransformation, detoxification and biofilm formation are the result of such interaction within a consortium. However, the culture conditions for these mutually interactive species need to be further optimized to improve the overall biodegradation and biosurfactant production. This chapter reports the various micro-consortium designs prepared to improve the overall biodegradation efficiency over axenic cultures.

In this chapter, the recent case studies of in-situ and ex-situ MEOR have been discussed elaborately, concentrating mainly on the major contributing microorganisms and consortia, their isolation sites all over the world, metabolite production (majorly biosurfactants), relevant surface characteristics (surface tension, interfacial tension, emulsifying activity and wettability) along with their role in oil retrieval. The systematic approach of scaling up the technology from the lab-scale to industrial scale and in the field trials has also been highlighted for their practical implementations to maximize the oil recovery after the conventional approaches. The effects of growth stimulators, i.e. nutrients, temperature, pressure and aeration along with reservoir properties for the implementation of in-situ MEOR have been highlighted. In some of the investigations both the types of MEOR processes have been performed simultaneously hence the comparative analyses as well as the pros and cons of each category, have also been mentioned in order to identify the parameters and their range convenient for each kind of MEOR.

The demand for crude oil is continuously increasing every year, and the discovery of new oil reservoirs is declining. Crude oil recovery from the mature and developed fields is somewhere between 20 and 40% of the original oil in place. Therefore, it is necessary to boost the production from the existing mature fields. Secondary recovery of hydrocarbon involves techniques that compensate the natural energy of the reservoir by injecting fluids, usually water or gas. Tertiary recovery methods are implemented to recover the crude oil trapped within the capillaries of the reservoir rocks. Tertiary recovery is the process in which different combinations of chemicals or thermal energy, or microbes are infused into the reservoir, which alters the reservoir rock and fluid properties, relative permeability, capillary pressure within the porous medium, interfacial tension, and wettability to recover crude oil and helps in additional crude oil recovery. The mechanism involved in the process and the selection of secondary and tertiary oil recovery methods are discussed in this chapter with a brief introduction of core flooding experiments and reservoir simulators.

Hydrocarbons are trapped and stored in the earth’s subsurface in a wide distribution of interconnected pore networks originating in sedimentary rocks. The investigations of the physicochemical properties of these rocks are of critical importance to the petroleum industry for the extraction of hydrocarbons from the discovered petroleum reservoirs. The geological setting of the petroleum reservoirs significantly influences porosity, permeability, compressibility, pay zone thickness, reservoir fluid properties, and reservoir drive mechanism. It is vital to determine the drive mechanisms contributing to fluid production of the reservoir at the earliest to understand the nature of the reservoir and evaluate production profiles. A comprehensive summary on the formation, identification, characterization, and importance of the physicochemical properties of petroleum reservoirs, along with the reservoir drive performance index of different drive mechanisms, has been discussed in this chapter.

Chemical-induced oil recovery has the potential to recover trapped oil, which is not possible to obtain by primary pressure difference and secondary water flooding methods. However, the implementation of chemical-enhanced oil recovery schemes requires a deeper understanding of the process for its successful implementation. The comprehension of mechanisms such as interfacial tension, emulsification, displacement efficiency, mobility ratio and wettability alteration can severely reduce the complexities involved in the system. Therefore, the roles of different mechanisms involved and their impacts on crude oil recovery, screening criteria for chemicals like alkali, surfactant, polymer or their combination depending on crude oil and heterogeneous reservoir properties are developed. Alkali–surfactant–polymer (ASP) flooding due to their synergistic effect offers a huge potential to recover residual oil. The understanding of the system or process is essential for the formulation of an optimum ASP slug that can maximize oil recovery. In this chapter, the overall screening criteria necessary for ASP flooding are formulated and discussed. The recovery of residual oil by ASP flooding in laboratories, pilot or commercial field scale in different parts of the world is summarized.