Low-cost Substrate Research Articles

Valorisation of bread wastes via the bacterial cellulose production

AbstractThe short shelf life of bread can be attributed to changes in its textural and sensory properties, a process termed staling, and large amounts of bread residue and waste are generated daily. Because the main component of bread is starch, the use of bread wastes as a substrate for bacterial cellulose (BC) production can significantly contribute to valorisation and reuse of wastes. This study aimed to investigate the BC production potential of various stale breads, convert these wastes into usable forms for food and other industries, and increase their economic value. Stale breads were hydrolyzed with dilute acid, and BC-producing bacteria from Kombucha tea were isolated and identified as Gluconobacter oxydans MG2021 (GO). BCs were produced from bread hydrolysates with GO and Komagataeibacter hansenii GA2016 (KH), and their properties were examined. The results indicated that stale breads represented a good source for BC production, as high BC yields were obtained using GO (8.81%–25.02%) and all BCs had superior properties such as high crystallinity (75.96%–91.39%), thermal stability, liquid holding capacity, and fine fibers (40.16–85.39 nm). This study demonstrated that bread wastes could be used as a low-cost substrate for large-scale BC production, and the abundance of bread wastes demonstrated their potential as a resource for commercial BC producers.

Response surface optimization of lipase production by <i>Pseudomonas sp.</i> on a low-cost shea-nut cake using solid state fermentation

Shea nut cake (SNC) is the solid residue produced after the shea butter extraction process. The SNC could provide a low-cost substrate for bacterial lipase production. Greater yield are among the benefits Solid State Fermentation (SSF). However, there have been less instances of lipase production by bacteria than fungi in SSF. The current study aimed at improving bacterial lipase production on SNC in SSF using Response Surface Methodology. Lipase-producing bacteria (LPB) were isolated from the shea butter mill effluent pond and screened for lipase production on a tributyrin agar plate. The influence of four independent parameters (temperature, pH, moisture content and biosurfactant) on lipase production was studied using Box Behnken Design (BBD) of RSM. Results showed that isolate AO (Pseudomonas sp.) displayed the highest zone of hydrolysis 2 (53 mm). A quadratic regression with R = 0.931 showed that the model is best fitting, and predicted the optimum conditions of significant (P>0.05) growth parameters, including temperature at 40°C, moisture content at 50%, and biosurfactant at 2 mL, which produced 408.25 U/g of experimental lipase. The findings indicate that the model was useful for predicting optimal growth conditions for incresing lipase production in SSF and the low-cost agro- industrial SNC could be a promising substrate for industrial applications.

PRODUCTION OF Adenium obesum (FORSSK.) ROEM. & SCHULT SEEDLINGS IN DIFFERENT SUBSTRATES

Low-cost substrates can potentially reduce production costs for ornamental plants such as Adenium obesum, popularly known as desert rose. The emergence and initial growth of desert rose in different substrates was evaluated. A randomized block design was used, with seven treatments and five replications. The treatments were sandy soil 100%; clay soil 100%; native vegetation soil 100%; sandy soil 50% + sawdust 50%; sandy soil 50% + fish farm sludge 50%; sandy soil 50% + crushed tobacco 50%; sandy soil 50% + pine bark with charcoal 50%. The fish farm sludge provided the highest emergence rate of 65%. At the end of the 180 DAS period, the SSF substrate had the highest average height, at 14.08 cm. The SSF and SPBC substrates had the highest average caudex diameter, at 32.42 mm. The SAN, NV, SSF, and SPBC substrates had the highest number of leaves parameter averages, with 41.80. Tobacco at a concentration of 50% hinders the emergence of desert rose seedlings. The substrate with a mixture of sandy soil and fish sludge provided the best development for the desert rose plants over the 180 days of evaluation.

Techno-economic assessment of biopolymer production from methane and volatile fatty acids: effect of the reactor size and biomass concentration on the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) selling price

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) is a biobased and biodegradable polymer that could efficiently replace fossil-based plastics. However, its widespread deployment is slowed down by the high production cost. In this work, the techno-economic assessment of the process for producing poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from low-cost substrates, such as methane and valeric acid derived from the anaerobic digestion of organic wastes, is proposed. Several strategies for cost abatement, such as the use of a mixed consortium and a line for reagent recycling during downstream, were adopted. Different scenarios in terms of production, from 100 to 100,000 t/y, were analysed, and, for each case, the effect of the reactor volume (small, medium and large size) on the selling price was assessed. In addition, the effect of biomass concentration was also considered. Results show that the selling price of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) is minimum for a production plant with 100,000 t/y capacity, accounting for 18.4 €/kg, and highly influenced by the biomass concentration since it can be reduced up to 8.6 €/kg by increasing the total suspended solids from 5 to 30 g/L, This adjustment aligns the breakeven point of PHBV with the reported average commercial price.

Flexible SERS sensor based on the photodecoration of Au-NPs on Co3O4 NWs/carbon fiber cloth for the ultrasensitive detection of methylene blue in the curved fish surfaces

BackgroundDevelopment of flexible platform via the surface-enhanced Raman spectroscopy (SERS) technique has gained enormous attention as a low-cost and portable substrate for a wide range application. In particular, the fabrication of semiconductors and tuning their surface morphologies with plasmonic nanoparticles are considered to be a fascinating strategy to create numerous hotspots to yield superior SERS enhancement. ResultsThis work involved fabricating a flexible SERS active substrate using the carbon fiber cloth (CFC), which is hydrothermally grown with cobalt oxide nanowires (Co3O4 NWs) and photodecorated with plasmonic gold nanoparticles (Au-NPs) for the ultrasensitive detection of organic dye, methylene blue (MB). The proposed substrate exhibits high enhancement factor (4.5 × 1010), low limit of detection (1.42 × 10−10 M), good uniformity (6.27 %), superior reproducibility (6.30 %) and demonstrate an excellent mechanical strength up to 40 cycles towards the MB detection. The residues of the MB are directly detected on the fish surfaces by adopting a facile swab-sampling technique. Additionally, the proposed flexible SERS sensor exhibit a successful photodegradation of MB at 90 min under UVC light irradiation. Significance and noveltyThe proposed flexible SERS methodology for detecting MB in the curved surfaces exhibited a superior SERS enhancement owing to the synergistic effect raised from the Co3O4 NWs (chemical enhancement) and Au NPs (electromagnetic enhancement). These findings indicate that the CFC-based flexible SERS sensor is a promising candidate for detecting various organic pollutants in real-time and on non-planar surfaces.

Nitrogen-doped carbon nano-onions/polypyrrole nanocomposite based low-cost flexible sensor for room temperature ammonia detection

One of the frontier research areas in the field of gas sensing is high-performance room temperature-based novel sensing materials, and new family of low-cost and eco-friendly carbon nanomaterials with a unique structure has attracted significant attention. In this work, we propose a novel low-cost flexible room temperature ammonia gas sensor based on nitrogen-doped carbon nano-onions/polypyrrole (NCNO-PPy) composite material mounted low-cost membrane substrate was synthesized by combining hydrothermal and in-situ chemical polymerization methods. The proposed flexible sensor revealed high sensing performance when employed as the sensing material for ammonia detection at room temperature. The NCNO-PPy ammonia sensor exhibited 17.32% response for 100 ppm ammonia concentration with a low response time of 26 s. The NCNO-PPy based flexible sensor displays high selectivity, good repeatability, and long-term durability with 1 ppm as the lower detection limit. The proposed flexible sensor also demonstrated remarkable mechanical robustness under extreme bending conditions, i.e., up to 90° bending angle and 500 bending cycles. This enhanced sensing performance can be related to the potential bonding and synergistic interaction between nitrogen-doped CNOs and PPy, the formation of defects from nitrogen doping, and the presence of high reactive sites on the surface of NCNO-PPy composites. Additionally, the computational study was performed on optimized NCNO-PPy nanocomposite for both with and without NH3 interaction. A deeper understanding of the sensing phenomena was proposed by the computation of several electronic characteristics, such as band gap, electron affinity, and ionization potential, for the optimized composite.

In situ electrochemical potential-induced synthesis of metal organic framework membrane on polymer support for H2/CO2 separation

Metal-Organic Framework (MOF) membranes act as selective layers have offered unprecedented opportunities for energy-efficient and cost-effective gas separation. Searching for the green and sustainable synthesis method of dense MOF membrane has received huge attention in both academia and industry. In this work, we demonstrate an in situ electrochemical potential-induced synthesis strategy to aqueously fabricate Metal Azolate Framework-4 (MAF-4) membranes on polypropylene (PP) support. The constant potential can induce the heterogeneous nucleation and growth of MAF-4, resulting an ultrathin membrane with the thickness of only 390 nm. This high-quality membrane exhibits a high H2/CO2 separation performance with the H2 permeance as high as 1565.75 GPU and selectivity of 11.6. The deployment of this environment friendly one-step fabrication method under mild reaction conditions, such as low-cost polymer substrate, water instead of organic solvent, room temperature and ambient pressure shows great promise for the scale-up of MOF membranes.

A Compact Dual-polarized Probe-fed UWB Antenna System for Breast Cancer Detection Applications

This article proposes an electrically small, probe-fed Ultra-Wideband (UWB) monopole antenna on a slotted truncated ground plane for breast cancer detection. The physical footprint of the proposed antenna element is 33 mm × 35 mm × 0.5 mm. This element is designed on the low-cost FR4 Epoxy substrate with a thickness of 0.5 mm. The proposed antenna has an electrical size of 0.33λ × 0.35λ × 0.005λ at the lowest frequency of operation; the radiator offers an impedance bandwidth of 8.34 GHz, which implies a fractional bandwidth of 115.5%. A compact dual-polarized antenna topology with two orthogonally placed probe-fed monopole antennas is proposed to achieve polarization diversity. The impedance characteristics of the individual radiating elements are maintained in spite of the electrical proximity of the radiators. The numerically computed and experimentally measured results of dual-polarized electrically small UWB antenna agree quite well. The proposed dual-polarized antenna topology is investigated for its utility in breast cancer detection in simulation.

Characteristics of 4-inch (100) oriented Mg-doped β-Ga2O3 bulk single crystals grown by a casting method

In this Letter, 4-inch diameter (100) magnesium-doped monoclinic gallium oxide (Mg:β-Ga2O3) bulk single crystals were grown by a casting method. The crystallographic structure, electrical, optical properties, and defects of Mg-doped β-Ga2O3 was thoroughly investigated by XRD rocking curves, AFM, non-contact resistivity measurements, XPS, optical transmission spectra, Raman spectroscopy, and defect-selective chemical etching processes. Comparing to the UID samples, the larger bandgap of 4.75 eV and high resistivity of 3.50×1012 Ω∙cm indicated Mg a proper dopant for fabricating semi-insulating β-Ga2O3 substrates which could be preferred for power devices. XPS spectra exhibited the ability of Mg2+ to inhibit the formation of oxygen vacancy defects in the crystals. Meanwhile, the high crystalline quality and low density of defects demonstrated the advantages of casting method in achieving large-size and high-quality β-Ga2O3 bulk single crystals with changeable resistivity. This result indicates a high potential to achieve high-quality and low-cost substrates which satisfy the requirement of high-performance power electronic devices.

An artificial biocatalytic cascade for efficient synthesis of norepinephrine by combination of engineered L-threonine transaldolase with multi-enzyme expression fine-tuning

Norepinephrine, a kind of β-adrenergic receptor agonist, is commonly used for treating shocks and hypotension caused by a variety of symptoms. The development of a straightforward, efficient and environmentally friendly biocatalytic route for manufacturing norepinephrine remains a challenge. Here, we designed and realized an artificial biocatalytic cascade to access norepinephrine starting from 3, 4-dihydroxybenzaldehyde and L-threonine mediated by a tailored-made L-threonine transaldolase PsLTTA-Mu1 and a newly screened tyrosine decarboxylase ErTDC. To overcome the imbalance of multi-enzymes in a single cell, engineering of PsLTTA for improved activity and fine-tuning expression mode of multi-enzymes in single E.coli cells were combined, leading to a robust whole cell biocatalyst ES07 that could produce 100 mM norepinephrine with 99% conversion, delivering a highest time-space yield (3.38 g/L/h) ever reported. To summarized, the current study proposed an effective biocatalytic approach for the synthesis of norepinephrine from low-cost substrates, paving the way for industrial applications of enzymatic norepinephrine production.

Modified pentagonal fractal antenna for ultra-wideband applications in communication systems

ABSTRACT Due to the recent expansion in the generations of the communications systems, it is utmost priority to transmit a large amount of data over a wideband frequency spectrum. For this single ultra-wideband (UWB) antennas are the prime choice as compared to the multiple narrow band antennas. A modified pentagonal fractal patch antenna with a modified ground plane covering ultra-wideband has been proposed. The antenna has a compact size of 25 mm × 25 mm × 1.6 mm with peak gain of 2.2 dB. The UWB coverage of the design is achieved by implementing modified co-planar ground, modified fractal geometry and coplanar feed. The proposed design possesses the significant resonance and radiation performance with very compact size on low-cost substrate while covering the whole UWB. Finally, the simulated resonating and radiation characteristics have been validated with the measured characteristics of the fabricated prototype and the results are quite promising.

Sequential hydrotalcite precipitation, microbial sulfate reduction and in situ hydrogen sulfide removal for neutral mine drainage treatment

This study proposed and examined a new process flowsheet for treating neutral mine drainage (NMD) from an open-pit gold mine. The process consisted of three sequential stages: (1) in situ hydrotalcite (HT) precipitation; (2) low-cost carbon substrate driven microbial sulfate reduction; and (3) ferrosol reactive barrier for removing biogenic dissolved hydrogen sulfide (H2S). For concept validation, laboratory-scale columns were established and operated for a 140-days period with key process performance parameters regularly measured. At the end, solids recovered from various depths of the ferrosol column were analysed for elemental composition and mineral phases. Prokaryotic microbial communities in various process locations were characterised using 16S rRNA gene sequencing. Results showed that the Stage 1 HT-treatment substantially removed a range of elements (As, B, Ba, Ca, F, Zn, Si, and U) in the NMD, but not nitrate or sulfate. The Stage 2 sulfate reducing bioreactor (SRB) packed with 70 % (v/v) Eucalyptus woodchip, 1 % (w/v) ground (<1 mm) dried Typha biomass, and 10 % (w/v) NMD-pond sediment facilitated complete nitrate removal and stable sulfate removal of ca. 50 % (50 g-SO4 m−3 d−1), with an average H2S generation rate of 10 g-H2S m−3d−1. The H2S-removal performance of the Stage 3 ferrosol column was compared with a synthetic amorphous Fe-oxyhydroxide-amended sand control column. Although both columns facilitated excellent (95–100 %) H2S removal, the control column only enabled a further ca. 10 % sulfate reduction, giving an overall sulfate removal of 56 %. In contrast, the ferrosol enabled an extra 99.9 % sulfate reduction in the SRB effluent, leading to a near complete sulfate removal. Overall, the process successfully eliminated a range of metal/metalloid contaminants, nitrate, sulfate (2500 mg-SO4 L−1 in the NMD to <10 mg-SO4 L−1 in the final effluent) and H2S (>95 % removal). Further optimisation is required to minimise release of ferrous iron from the ferrosol barrier into the final effluent.

Agro-Industrial Wastes as Potential Substrates for Rhamnolipid Production by Pseudomonas aeruginosa USM-AR2.

Rhamnolipid has gained much attention in various fields owing to its distinctive functional properties compared to conventional chemical surfactants, which are mostly derived from petroleum feedstock. Production cost is one of the main challenges in rhamnolipid production, particularly when using refined substrates. One possible solution is to use agro-industrial wastes as substrates for rhamnolipid production. This is a promising strategy due to their abundance and commercially low value, while simultaneously alleviating an agro-industrial waste management problem in the environment. This study aims to evaluate agro-industrial wastes from local crops as possible low-cost alternative substrates for rhamnolipid production by a local isolate, Pseudomonas aeruginosa USM-AR2. Various liquid wastes, namely sugarcane molasses, rice washing water, overly mature coconut (OMC) water, empty fruit bunch (EFB) steam effluent, palm sludge oil (PSO) and palm oil mill effluent (POME) were screened as the main carbon source supplementing mineral salt medium (MSM) in the fermentation of P. aeruginosa USM-AR2. Batch fermentation was carried out in a shake flask system, agitated at 200 rpm and incubated at room temperature, 27 ± 2°C for 120 h. Among the substrates tested, PSO exhibited the highest biomass at 20.78 g/L and rhamnolipid production at 1.07 g/L. This study has shown the potential of agro-industrial wastes in Malaysia as an alternative resource for rhamnolipid production, transforming them into value added products, while reducing the amount of wastes discharged into the environment.

Dual circular complementary split ring resonator based metamaterial sensor with high sensitivity and quality factor for textile material detection

In this paper, a novel metamaterial sensor with excellent sensitivity and quality factor for microwave sensing applications is presented. The designed metamaterial sensor is assembled on a 1.575 mm thickness of low-cost dielectric substrate material (Rogers RT5880), and the copper is used as a resonator. Computer Simulation Technology version 2019 (CST-2019) software is employed to design and analyze the proposed metamaterial sensor. In addition, the Advanced Design System version 2016 (ADS 2016) software is used to validate the CST simulated model. Subsequently, the simulated results were validated using laboratory measurements. The optimized cell is small; its dimension is 10 × 10 mm2, and the obtained resonances are 3.85 and 6.85 GHz with notches of −26.29 and −40.03 dB, respectively. The textile material is detected by the resonance frequency change, and this frequency is dependent on the material’s permittivity values. To test the developed sensor’s sensing capabilities, three types of textiles—wool, fleece, and denim—are used. The effective medium ratio, sensitivity, and Q-factor of the structure are evaluated, and the obtained values are 8.96, 14.57%, and 345, respectively. The sensor for detecting textile materials works in the S and C bands. The resonances are shifted 530 MHz between the air and wool, 420 MHz between the air and fleece, and 640 MHz between the air and denim. The simulated outcomes and laboratory results almost matched. The projected sensor can be employed in the apparel sector to identify textile materials because it is small, inexpensive, has a high quality factor, and has high sensitivity.

Shared and more specific genetic determinants and pathways underlying yeast tolerance to acetic, butyric, and octanoic acids

BackgroundThe improvement of yeast tolerance to acetic, butyric, and octanoic acids is an important step for the implementation of economically and technologically sustainable bioprocesses for the bioconversion of renewable biomass resources and wastes. To guide genome engineering of promising yeast cell factories toward highly robust superior strains, it is instrumental to identify molecular targets and understand the mechanisms underlying tolerance to those monocarboxylic fatty acids. A chemogenomic analysis was performed, complemented with physiological studies, to unveil genetic tolerance determinants in the model yeast and cell factory Saccharomyces cerevisiae exposed to equivalent moderate inhibitory concentrations of acetic, butyric, or octanoic acids.ResultsResults indicate the existence of multiple shared genetic determinants and pathways underlying tolerance to these short- and medium-chain fatty acids, such as vacuolar acidification, intracellular trafficking, autophagy, and protein synthesis. The number of tolerance genes identified increased with the linear chain length and the datasets for butyric and octanoic acids include the highest number of genes in common suggesting the existence of more similar toxicity and tolerance mechanisms. Results of this analysis, at the systems level, point to a more marked deleterious effect of an equivalent inhibitory concentration of the more lipophilic octanoic acid, followed by butyric acid, on the cell envelope and on cellular membranes function and lipid remodeling. The importance of mitochondrial genome maintenance and functional mitochondria to obtain ATP for energy-dependent detoxification processes also emerged from this chemogenomic analysis, especially for octanoic acid.ConclusionsThis study provides new biological knowledge of interest to gain further mechanistic insights into toxicity and tolerance to linear-chain monocarboxylic acids of increasing liposolubility and reports the first lists of tolerance genes, at the genome scale, for butyric and octanoic acids. These genes and biological functions are potential targets for synthetic biology approaches applied to promising yeast cell factories, toward more robust superior strains, a highly desirable phenotype to increase the economic viability of bioprocesses based on mixtures of volatiles/medium-chain fatty acids derived from low-cost biodegradable substrates or lignocellulose hydrolysates.

High enhancement, low cost, large area surface enhanced Raman scattering substrates all by atomic layer deposition on porous filter paper

We successfully developed an atomic layer deposition (ALD) method for making Ag noble nanoparticles on cheap, commercial filter paper consisting of three-dimensional porous glass fibers and investigated the evolution of Ag nanostructures with some key process parameters. By tuning Ag particle sizes and controlling the cycle numbers of ALD deposited Ag films, we were able to obtain high-density isolated Ag nanoparticles with average sizes in 3–9 nm without the formation of agglomerates and continuous Ag films. We proved the presence of strong localized surface plasmon resonance peaks near a target wavelength of 632 nm. We further proved the presence of surface enhanced Raman scattering (SERS) signals on the Ag coated filter paper substrates using pyridine as the test analyte. Our results demonstrate that ALD is a very promising technique for a rational design of SERS substrates and, thus, has great potential for the fabrication of large-area, low-cost SERS substrates for future commercial applications, as compared to other existing techniques.

Solid-state fermentation of brown seaweeds for the production of alginate lyase using marine bacterium Enterobacter tabaci RAU2C.

Alginate lyases have countless potential for application in industries and medicine particularly as an appealing biocatalyst for the production of biofuels and bioactive oligosaccharides. Solid-state fermentation (SSF) allows improved production of enzymes and consumes less energy compared to submerged fermentation. Seaweeds can serve as the most promising biomass for the production of biochemicals. Alginate present in the seaweed can be used by alginate lyase-producing bacteria to support growth and can secrete alginate lyase. In this perspective, the current study was directed on the bioprocessing of brown seaweeds for the production of alginate lyase using marine bacterial isolate. A novel alginate-degrading marine bacterium Enterobacter tabaci RAU2C which was previously isolated in the laboratory was used for the production of alginate lyase using Sargassum swartzii as a low-cost solid substrate. Process parameters such as inoculum incubation period and moisture content were optimized for alginate lyase production. SSF resulted in 33.56 U/mL of alginate lyase under the static condition maintained with 75% moisture after 4days. Further, the effect of different buffers, pH, and temperature on alginate lyase activity was also analyzed. An increase in alginate lyase activity was observed with an increase in moisture content from 60 to 75%. Maximum enzyme activity was perceived with phosphate buffer at pH 7 and 37°C. Further, the residual biomass after SSF could be employed as biofertilizer for plant growth promotion based on the preliminary analysis. To our knowledge, this is the first report stating the usage of seaweed biomass as a substrate for the production of alginate lyase using solid-state fermentation.

Anti-Listerial Activity of Bacteriocin-like Inhibitory Substance Produced by Enterococcus lactis LBM BT2 Using Alternative Medium with Sugarcane Molasses.

Listeria monocytogenes is a foodborne pathogen that contaminates food-processing environments and persists within biofilms on equipment, thus reaching final products by cross-contamination. With the growing demand for clean-label products, the search for natural antimicrobials as biopreservants, such as bacteriocins, has shown promising potential. In this context, this study aimed to evaluate the anti-listerial action of bacteriocins produced by Enterococcus lactis LBM BT2 in an alternative medium containing sugarcane molasses (SCM). Molecular analyses were carried out to characterize the strain, including the presence of bacteriocin-related genes. In the kinetic study on SCM medium E. lactis, LBM BT2 showed biomass and bacteriocin productions similar to those observed on a sucrose-based medium (control), highlighting the potential of the sugarcane molasses as a low-cost substrate. Stability tests revealed that the molecule remained active in wide ranges of pH (4-10) and temperature (60-100 °C). Furthermore, the proteolytic treatment reduced the biomolecule's antimicrobial activity, highlighting its proteinaceous nature. After primary purification by salting out and tangential flow filtration, the bacteriocin-like inhibitory substance (BLIS) showed bacteriostatic activity on suspended L. monocytogenes cells and against biofilm formation at a concentration of 0.625 mg/mL. These results demonstrate the potential of the produced BLIS as a biopreservative in the food industry.

Production and characterization of polyhydroxybutyrate bioplastic precursor from Parageobacillus toebii using low-cost substrates and its potential antiviral activity

There is an increasing desire for bioplastics produced from renewable resources as an alternative to their petrochemical counterparts. These biopolymers have long-unnoticed antiviral properties. This study aimed to produce and characterize bioplastics by Parageobacillus toebii using low-cost substrates and determine their antiviral activity against coxsackievirus B4. Seven low-cost substrates (bagasse, water hyacinth, rice straw, rice water, sesame husks, molasses, and corn syrup) were compared with glucose for bioplastic precursor production. The highest bioplastic produced was from water hyacinth and glucose, followed by molasses, rice straw, rice water, sesame husks, and bagasse. Water hyacinth and glucose media were further optimized to increase the bioplastic precursor yield. The optimization of the media leads to increases in bioplastic precursor yields of 1.8-fold (3.456 g/L) and 1.496-fold (2.768 g/L), respectively. These bioplastics were further characterized by thermogravimetric analysis (TGA), Fourier-transformed infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR), and gas chromatography–mass spectrometry (GC–MS). They are thermostable, and their characterizations confirm the presence of polyhydroxybutyrate. The antiviral assay showed reasonable antiviral effects for bioplastics from water hyacinth (80.33 %) and glucose (55.47 %) media at 250 μg/mL maximum non-toxic concentrations (MNTC). The present investigation demonstrates a low-cost model for producing polyhydroxybutyrate bioplastic precursor for antiviral applications.

Hybrid SERS substrate based on cotton swab for sensitive detection of organic molecules

For the last two decades, the development of substrates for Surface Enhanced Raman Spectroscopy (SERS) has been continuously pushed for better performances. In this research, we designed SERS substrates with better detection capability and more efficient sample collection. In particular, morphology-controlled Ag nanoparticles were deposited onto cotton swab (cotton Q-tip), followed by a thin cover layer of graphene oxide by the dip-coating method. The graphene oxide overlay was expected to not only protect Ag nanoparticles from degradation by the environment but also contribute to sample adsorption and signal enhancement. To demonstrate the performance of the SERS substrates, different concentrations of Rhodamine B as low as 10–10 M were successfully detected and the enhancement factors were estimated to be 3 × 1010–5 × 1010. It is our expectation that these cotton swab-based substrates will contribute to our ongoing efforts toward low-cost, high-efficiency and durable SERS substrate.