Nafisa Islam | Bangladesh University of Engineering and Technology (original) (raw)

Papers by Nafisa Islam

Frontiers of Environmental Science & Engineering, 2022

The research on the extent and effects of microplastics pollution in the Global South is only get... more The research on the extent and effects of microplastics pollution in the Global South is only getting started. Bangladesh is a South Asian country with one of the fastest growing economies in the world, however, such exponential economic growth has also increased the pollution threats to its natural and urban environment. In this paper, we reviewed the recent primary research on the assessment of the extent of microplastics pollution in Bangladesh. From the online databases, we developed a compilation of emerging research articles that detected and quantified microplastics in different coastal, marine, and urban environments in Bangladesh. Most of the studies focused on the coastal environment (e.g., beach sediment) and marine fish, while limited data were available for the urban environment. We also discussed the relationship of the type of anthropogenic activities with the observed microplastic pollution. The Cox’s Bazar sea beach in south-east Bangladesh experienced microplastics pollution due to tourism activities, while fishing and other anthropogenic activities led to microplastics pollution in the Bay of Bengal. While microplastics larger than 1 mm were prevalent in the beach sediments, smaller microplastics with size below 0.5 mm were prevalent in marine fish samples. Moreover, the differences in microplastic abundance, size, shape, color, and polymer type found were depended on the sampling sites and relevant anthropogenic activities. It is imperative to identify major sources of microplastics pollution in both natural and urban environment, determine potential environmental and human health effects, and develop mitigating and prevention strategies for reducing microplastics pollution.

JMIR Research Protocols

Background e-Waste is a rapidly growing waste stream worldwide, and Bangladesh is a hub of e-wast... more Background e-Waste is a rapidly growing waste stream worldwide, and Bangladesh is a hub of e-waste handling. Informal e-waste recycling operations involve crude methods for dismantling, repairing, sorting, and recycling electronic goods with bare hands and without personal health protections. Direct inhalation or dermal exposure to toxicants during informal recycling is common. Evidence suggests that e-waste–derived toxicants pollute the terrestrial ecosystem and have been linked with adverse health effects. However, e-waste recycling–related occupational health hazards have not been adequately explored in the context of Bangladesh. Objective Our study aims to expand the current understanding of exposure to e-waste. This study will measure the metal concentrations in biological and environmental samples and evaluate the relationship between heavy metals and the biochemical systems of the e-waste workers. Methods The study uses a cross-sectional study design consisting of an exposed ...

Chitosan is an adaptable and multifunctional biopolymer which can be applied in various fields su... more Chitosan is an adaptable and multifunctional biopolymer which can be applied in various fields such as food preservation, medical, agricultural, water treatment etc. The main sources of industrially produced chitosan nowadays are the crustaceans including shrimps, crabs and squids. In this study, two locally obtained fungal species Aspergillus niger and Saccharomyces cerevisiae were studied as alternative sources of chitosan and compared with the chitosan extracted from shrimp shells. The study aimed to optimize the culture conditions for the fungal species to obtain high yields of extraction. Chitosan was extracted from the mycelia of Aspergillus niger and the sporulated yeast cells through similar procedure which involved treatment with NaOH and CH 3 COOH. On the other hand, traditional isolation of chitin from waste shrimp shells included three basic steps: demineralization, deproteinization and decolorization. Chitosan was then obtained by removing the acetyl group from the chit...

Journal of Hazardous Materials Advances

Applied Biochemistry and Biotechnology

Despite being widely available, Saccharomyces cerevisiae has not been widely explored for direct ... more Despite being widely available, Saccharomyces cerevisiae has not been widely explored for direct extraction of chitosan biopolymer for antimicrobial applications. In our study, S. cerevisiae from Baker’s yeast and Aspergillus niger from moldy onion extracts are studied as alternative sources of chitosan; and S cerevisiae chitosan tested for antimicrobial efficacy. The properties of S. cerevisiae chitosan are compared with moldy onion chitosan and shrimp chitosan extracted from shrimp shells. Chitosan extracted from S. cerevisiae is tested for antimicrobial efficacy against Staphylococcus Aureus. The maximum yields of fungal chitosan are 20.85 ± 0.35 mg/g dry S. cerevisiae biomass at 4th day using a culture broth containing sodium acetate, and 16.15 ± 0.95 mg/g dry A. niger biomass at 12th day. The degree of deacetylation (DD%) of the extracted fungal chitosan samples from S. cerevisiae and A. niger is found to be 63.4%, and 61.2% respectively, using Fourier Transform Infrared Spectroscopy. At a concentration of 2 g/L, S. cerevisiae chitosan shows the maximum inhibition zone diameter of 15.48 ± 0.07 mm. Baker’s yeast S cerevisiae biomass and A. niger from moldy onions has not been previously explored as a source of extractible fungal chitosan. This study gives insight that S. cerevisiae and A. niger from agricultural or industrial wastes could be a potential biomass source for production of the chitosan biopolymer. The S. cerevisiae chitosan displayed effective antimicrobial properties against S aureus, indicating the viablitiy of S cerevisae as a resource for extraction of high-quality chitosan.

Process Biochemistry

Abstract Microbial fuel cell (MFC) technology is a promising solution for both organic and inorga... more Abstract Microbial fuel cell (MFC) technology is a promising solution for both organic and inorganic effluent treatment, as it is capable of handling a variety of complex contaminants with simultaneous energy and resource recovery. Unlike conventional treatment technologies, MFCs can achieve removal of organic matter, persistent organic compounds, heavy metals and nutrients from categorically different waste effluents, while recovering energy and valuable substances. This makes the technology economically attractive, and viable for a wide range of industries for their waste treatment applications. However, in order to implement this technology as an on-site treatment unit, limitations pertaining to costs, scale-up and performance have to be addressed, with due emphasis on developing strategies that can be easily applied in industrial settings. This review summarizes the recent progress in the field of waste treatment and environmental remediation using MFCs, and examines these operational challenges. Cost-effective materials that have been implemented on the field and at large scales have also been highlighted. In addition, the review highlights the fact that there is a need to optimize the technology depending on energy or resource recovery. The MFC-based technology utilizes the synergy of bioremediation and bioelectricity production from wastes, offering a sustainable approach to industrial waste management.

Bioconjugate Chemistry

Tris(2-aminoethyl)-amine (TREN), a branched amine, was coupled to planar surfaces of alkanethiol ... more Tris(2-aminoethyl)-amine (TREN), a branched amine, was coupled to planar surfaces of alkanethiol self-assembled monolayers (SAMs) to increase the grafting density of IgG-binding peptide (HWRGWV or HWRGWVG) on gold surfaces. One of the three primary amine pendant groups of TREN anchors onto the SAM, while the other two are available for grafting with the C-termini of the peptide. The ellipsometric peptide density on the SAM-branched amine was 1.24 molecules nm-2. The surfaces carrying the peptides were investigated via surface plasmon resonance (SPR) to quantify the adsorption of IgG and showed maximum binding capacity, Qm of 4.45 mg m-2, and dissociation constant, Kd of 8.7 × 10-7 M. Real-time dynamic adsorption data was used to determine adsorption rate constants, ka values, and the values were dependent on IgG concentration. IgG binding from complex mixtures of Chinese hamster ovary supernatant (CHO) was investigated and regeneration studies were carried out. Compared to the unbranched amine-based surfaces, the branched amines increased the overall sensitivity and selectivity for IgG adsorption from complex mixtures. Regeneration of the branched amine-based surfaces was achieved with 0.1 M NaOH, with less than 10% decline in peptide activity after 12 cycles of regeneration-binding.

In this study, the behavior of a hexameric affinity peptide was characterized in depth and its po... more In this study, the behavior of a hexameric affinity peptide was characterized in depth and its potential as a means of immunoglobulin G (IgG) detection was explored. Surface Plasmon Resonance (SPR) was used to study the binding of human IgG to the hexameric peptide affinity ligand HWRGWV, which is covalently grafted to pure or mixed alkanethiol self-assembled monolayers (SAM) on gold surfaces. The reactive alkanethiol (HS-(CH2)11-(CH2CH2O)6-NH2, shortened notation, EG6NH2) is -NH2 terminated, contains six ethylene glycol units, and was used to create pure monolayers on gold sensor surfaces. The NH2 termini are reactive towards the C-terminus of the peptide ligands. To prepare mixed monolayers with the above thiol, a ‘dilutor’ thiol (HS-(CH2)11-(CH2CH2O)3-OH, shortened notation, EG3OH) with three ethylene glycol units and a hydroxyl terminus group, was utilized. The thiols were mixed at various percentages of EG6NH2 (with 0% denoting pure EG3OH, 100% denoting pure EG6NH2) to form mon...

The Journal of Physical Chemistry C, 2014

ABSTRACT Alkanethiols carrying ethylene glycol units (EGn, n = 3 or 6) with amine termini (EG3NH2... more ABSTRACT Alkanethiols carrying ethylene glycol units (EGn, n = 3 or 6) with amine termini (EG3NH2 or EG6NH2) were coadsorbed with a “diluent”, hydroxyl-terminated alkanethiol (EG3OH), to form mixed self-assembled monolayers (SAMs). The mixed SAMs were characterized, and hexameric peptide ligand His-Trp-Arg-Gly-Trp-Val (HWRGWV), which shows affinity binding toward the Fc (constant fragment) of human immunoglobulin (IgG), was grafted onto different dilutions of EG6NH2–EG3OH mixed SAMs for preparation of IgG detection surfaces. The specificity toward IgG was optimal for peptides grafted on SAMs prepared from 10% EG6NH2 precursor solution, even though this surface did not have the highest number of peptides per unit area. Surface plasmon resonance (SPR) experiments showed that IgG bound to the peptides on the mixed SAM with a dissociation constant Kd of 9.33 × 10–7, maximum binding capacity Qm of 3.177 mg m–2, and adsorption rate constant ka of 1.99 m3 mol–1 s–1. IgG binding from complex mixtures of Chinese Hamster Ovary supernatant (CHO) was investigated on peptides grafted to mixed and pure SAMs. Regeneration of the surfaces was achieved by treatment with 10% acetonitrile in 0.1 M NaOH solution. Overall, the use of peptides grafted on mixed SAMs improved the effectiveness of detection and had an impact on specificity and regeneration of biosensors.

Biosensors and Bioelectronics, 2014

This paper characterizes the potential of novel hexameric peptide ligands for on-line IgG detecti... more This paper characterizes the potential of novel hexameric peptide ligands for on-line IgG detection in bioprocesses. Surface Plasmon Resonance (SPR) was used to study the binding of human IgG to the hexameric peptide ligand HWRGWV, which was covalently grafted to alkanethiol self-assembled monolayers (SAM) on gold surfaces. Peptide coupling on SAMs was verified, followed by covalent grafting of peptides with a removable Fmoc or acetylated N-termini via their C-termini to produce active peptide SPR sensors that were tested for IgG binding. The dynamics and extent of peptide-IgG binding were compared with results from a conventional system using protein A attached on a gold surface via disulfide monolayers. IgG binding to protein A on disulfide monolayers yielded equilibrium dissociation constants of 1.4 Â 10 -7 M. The corresponding dissociation constant value for the acetylated version of the peptide (Ac-HWRGWV) supported on alkanethiol SAM was 5.8 Â 10 -7 M and that for HWRGWV on the alkanethiol SAM (after de-protection of Fmoc-HWRGWVA) was 1.2 Â 10 -6 M. Maximum IgG binding capacities, Q m of 6.7, 3.8, and 4.1 mg m À 2 were determined for the protein A and the two forms of HWRGWV-based biosensors, respectively. Real-time data for the kinetics of adsorption were used to determine the apparent rate constants for adsorption and desorption. The results were analyzed to understand the mechanism of IgG binding to the protein and peptide ligands. It was found that the peptide-IgG binding was reaction controlled, however the protein A-IgG binding mechanism was partially mass transfer (diffusion) controlled. The adsorption rate constants, k a , for the protein A ligand increased with decreasing concentration of analyte and the peptide ligand k a values was constant at different IgG concentrations and flow rates.

Analytical Chemistry, 2013

A new peptide-based system supported on copolymer brushes grafted from gold sensors and with resi... more A new peptide-based system supported on copolymer brushes grafted from gold sensors and with resistance to nonspecific adsorption is reported for selective binding of human immunoglobulin G (IgG). A random copolymer rich in primary amines, poly(2-aminoethyl methacrylate hydrochloride-co-2-hydroxyethyl methacrylate) (poly(AMA-co-HEMA)) was first grafted from initiator-coated gold substrates via activators regenerated by electron transfer-atom transfer radical polymerization (ARGET-ATRP), followed by immobilization of acetylated-HWRGWVA peptide, which has specific binding affinity with IgG. The peptide ligands covalently linked to the soft copolymer layer were characterized by X-ray photoelectron spectroscopy (XPS), water contact angle, ellipsometry, and atomic force microscopy (AFM). The extent of binding, binding affinity, and selectivity for target IgG molecules as well as the capability to minimize nonspecific interactions with other proteins were examined by fluorescence imaging, surface plasmon resonance (SPR), and quartz crystal microgravimetry (QCM). The effect of copolymer molecular composition and analyte concentration was elucidated in order to design systems based on immobilized peptides for high signal-to-noise response and detection limits that meet the requirements for IgG biosensing in fluid matrixes.

ACS Applied Materials & Interfaces, 2013

We demonstrate the specificity, regenerability, and excellent storage stability of short peptide-... more We demonstrate the specificity, regenerability, and excellent storage stability of short peptide-based systems for detection of immunoglobulin G (IgG). The bioactive component consisted of acetylated-HWRGWVA (Ac-HWRGWVA), a peptide with high IgG binding affinity, which was immobilized onto copolymer matrixes of poly(2aminoethyl methacrylate hydrochloride-co-2-hydroxyethyl methacrylate) (poly(AMA-co-HEMA)). Surface plasmon resonance (SPR) and quartz crystal microgravimetry (QCM) were utilized with other complementary techniques to systematically investigate interfacial activities, mainly IgG binding performance as a function of the graft density and degree of polymerization of the poly(AMA-co-HEMA) support layer. Results from sodium dodecyl sulfate polyacrylamide gel electrophoresis and fluorescence microscopy indicate that the bioactive system is highly specific to IgG and resistant to nonspecific interactions when tested in mixed protein solutions.