Nanohybrid nanozyme based colourimetric immunosensor for porcine gelatin

Enzyme mimicking nanomaterials, nanozymes, have gained considerable interest in the scientific community because of their superior properties compared to natural enzymes, including their high stability at extreme conditions, cheaper availability, and ease of synthesis. Herein, we report novel colloidal gold nanoparticles - graphene nanoplatelets - chitosan (CS) with peroxidase mimicking properties used to carry out highly sensitive and selective immunoassay for porcine gelatin detection. The interaction between anti-gelatin antibody conjugated nanozyme with porcine gelatin proteins produced an ultrasensitive immunoassay response in the form of a colourimetric signal directly proportional to the porcine gelatin protein concentration. The nanozyme produced a colourimetric response in the presence of its substrate, 3,3',5,5'-tetramethylbenzidine (TMB) and hydrogen peroxide (H2O2), demonstrating its peroxidase mimicking properties. The results revealed that the nanozyme exhibited remarkable selectivity and sensitivity in the assay, detecting proteins at concentrations as low as 86.42 pg/mL. Additionally, the immunosensor demonstrated a broad linear detection range spanning from 200 pg/mL to 2 ng/mL.

Electrochemical Nanoaptasensor Based on Graphitic Carbon Nitride/Zirconium Dioxide/Multiwalled Carbon Nanotubes for Matrix Metalloproteinase-9 in Human Serum and Saliva

In this study, a nanocomposite was synthesized by incorporating graphitic carbon nanosheets, carboxyl-functionalized multiwalled carbon nanotubes, and zirconium oxide nanoparticles. The resulting nanocomposite was utilized for the modification of a glassy carbon electrode. Subsequently, matrix metalloproteinase aptamer (AptMMP-9) was immobilized onto the electrode surface through the application of ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride-N-hydroxysuccinimide (EDC-NHS) chemistry. Morphological characterization of the nanomaterials and the nanocomposite was performed using field-emission scanning electron microscopy (FESEM). The nanocomposite substantially increased the electroactive surface area by 205%, facilitating enhanced immobilization of AptMMP-9. The efficacy of the biosensor was evaluated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under optimal conditions, the fabricated sensor demonstrated a broad range of detection from 50 to 1250 pg/mL with an impressive lower limit of detection of 10.51 pg/mL. In addition, the aptasensor exhibited remarkable sensitivity, stability, excellent selectivity, reproducibility, and real-world applicability when tested with human serum and saliva samples. In summary, our developed aptasensor exhibits significant potential as an advanced biosensing tool for the point-of-care quantification of MMP-9, promising advancements in biomarker detection for practical applications.

CeO2 nanozyme mediated RPA/CRISPR-Cas12a dual-mode biosensor for detection of invA gene in Salmonella

This study reports a novel biosensing system that leverages recombinase polymerase amplification (RPA) in conjunction with clustered regularly interspaced short palindromic repeats (CRISPR)/Cas12a technology, integrated with a nanozyme (NZ) based on cerium dioxide (CeO2). With the integration of CeO2 NZ, a dual-mode detection platform could be developed for Salmonella detection using fluorometric and colourimetric assays. The CRISPR/Cas12a system, when activated in the presence of target DNA, could cleave the FAM-labelled probe to lead to a fluorometric response. Also, when the CeO2 NZ was introduced in the presence of H2O2, a colourimetric response was generated, directly proportional to the concentration of target DNA present. We hypothesise that adding highly reactive H2O2 within the post-CRISPR/Cas12a reaction system allows for increased release of hydroxyl free radicals within the mixture. Thus, the double recognition through NZ and the CRISPR/Cas12a system provided enhanced selectivity and sensitivity to the method. The proposed biosensor could successfully detect Salmonella at concentrations as low as 0.88 pg/μL and 1.28 pg/μL for fluorometric and colourimetric responses, respectively. Furthermore, the developed biosensor could be applied in real sample analysis of raw food samples (chicken, egg, and beef) to give a good recovery in the spiked food samples with varying concentrations of cultured bacterial DNA.

A novel and ultrasensitive electrochemical immunosensor based on nanocellulose-Ti3C2Tx@ZrO2 nano framework for the detection of ovalbumin

A versatile and highly sensitive sensing platform based on nanocellulose/MXene/ZrO2 nano framework has been developed at the surface of a glassy carbon electrode (GCE) for detecting ovalbumin (Ova). To create this innovative nano framework, dialdehyde groups were introduced onto the surface of cellulose nanofibers (CNFs), which were then decorated with MXene nanosheets and nanostructured zirconia. Nanocellulose/MXene/ZrO2 nano framework was used as electrochemical mediator and immobilization environment that provided the large surface area and 197 % increment in the electrochemical signal which allowed the Ova detection in the femtomolar range. Ovalbumin antibody was immobilized on the surface of dialdehyde cellulose nanofiber through covalent bonding between amino groups of Ova and dialdehyde groups of CNFs. The assembly process of nano framework, anti-Ova, and Ova antigen were characterized using electrochemical approaches (CV and DPV). The fabricated immunosensor is further applied to DPV detection of Ova and it demonstrated a linear response to Ova antigen in the linear range of 0.01-1000 pg/mL. With optimal experimental conditions, the detection limit, quantification limit and sensitivity of Ova were found to be 1.1 fg/mL, 0.01 pg/mL and 0.1497 μA pg/mL cm-2, respectively. The fabricated immunosensor exhibited high selectivity, reproducibility, and interference resistance and achieved excellent recoveries in real food samples spiked with Ova, indicating its potential applicability in food safety monitoring.

A CRISPR/Cas12a-based fluorescence aptasensor for the rapid and sensitive detection of ampicillin

This study introduces CRISPR/Cas-based aptasensor for the highly sensitive and specific detection of the antibiotic, ampicillin. Ampicillin (AMPI) is a commonly used antibiotic for treating pathogenic bacteria and is additionally added to livestock feed in agriculture. This study can enable early detection of antibiotic residues, prevent their accumulation in the environment, and ensure compliance with food safety regulations. Herein, the aptasensor was developed with the CRISPR/Cas system by utilizing three different ampicillin-specific aptamers, each conjugated with a biotin at the 5'-end. The ssDNA activator was bound to the aptamers through complementary base pairings. The attraction of the aptamers to the ampicillin target released the bound ssDNA, causing the activation of the CRISPR/Cas system. The DNA reporter probe, labelled with Cy3 and a quencher, turns on the fluorescence signal when cleaved by the activated Cas12a through trans-cleavage measured using a fluorescence spectrophotometer at 590 nm. The fluorescence signal was linearly proportional to the ampicillin target concentration with a 0.01 nM limit of detection and a read-out time of 30 min. This aptasensor showed high sensitivity towards ampicillin even in the presence of other antibiotics. The method was also successfully implemented for ampicillin detection in spiked food samples.

Nanozymes towards Personalized Diagnostics: A Recent Progress in Biosensing

This review highlights the recent advancements in the field of nanozymes and their applications in the development of point-of-care biosensors. The use of nanozymes as enzyme-mimicking components in biosensing systems has led to improved performance and miniaturization of these sensors. The unique properties of nanozymes, such as high stability, robustness, and surface tunability, make them an attractive alternative to traditional enzymes in biosensing applications. Researchers have explored a wide range of nanomaterials, including metals, metal oxides, and metal-organic frameworks, for the development of nanozyme-based biosensors. Different sensing strategies, such as colorimetric, fluorescent, electrochemical and SERS, have been implemented using nanozymes as signal-producing components. Despite the numerous advantages, there are also challenges associated with nanozyme-based biosensors, including stability and specificity, which need to be addressed for their wider applications. The future of nanozyme-based biosensors looks promising, with the potential to bring a paradigm shift in biomolecular sensing. The development of highly specific, multi-enzyme mimicking nanozymes could lead to the creation of highly sensitive and low-biofouling biosensors. Integration of nanozymes into point-of-care diagnostics promises to revolutionize healthcare by improving patient outcomes and reducing costs while enhancing the accuracy and sensitivity of diagnostic tools.

A Review of Cultured Meat and its Current Public Perception

Abstract:

Culturing meat in-vitro cell, also known as cellular agriculture, is an alternative to livestock meat production. By culturing meat instead of relying on conventional meat, the deleterious effects on the environment can be avoided. Moreover, depending on cultured meat resources will help improve animal welfare and aid in tackling the current sustainability challenges associated with animal rearing to produce meat. Multiple tissue culture methods and bioengineering techniques are currently being studied to design various cell types to develop muscle and fat cells for culturing meat. To succeed in the cellular agricultural industry, the public impression of cultured meat must also be considered. To better study and understand cultured meat perception among the public, we extensively studied papers on ‘cultured meat’ and ‘public perception’ from the past decade. Most recent research studies have discussed the public perception of a particular group toward cultured meat. However, to the best of our knowledge, no existing article provides a detailed study on recent advances in cultured meat and the views of public consumers from different backgrounds. Thus, this paper focuses on several religious and regional groups and their perceptions of cultured meat consumption. The consumers’ appeal and acceptability of cultured meat are crucial to manufacturing cultured meat. However, many existing studies on public perception of cultured meat have raised concerns despite their willingness to consume it. Therefore, organisations must carefully navigate for such an industry to reach its full potential. For instance, labels like ‘lab-grown meat’, ‘cultured meat’, or ‘artificial meat’ may elicit negative customer responses. On the contrary, tags like ‘clean meat’ or ‘healthy meat’ may promote better acceptance among consumers. Further research and development, especially on the alternative of serum-free culture media, cultured meat, and cellular agriculture, can transform the meat industry soon.

An electrochemical aptasensor based on AuNRs/AuNWs for sensitive detection of apolipoprotein A-1 (ApoA1) from human serum

For early detection and diagnosis of cancer, it is essential to develop an electrochemical biosensor that is quick, accurate, and sensitive. Here, we use gold nanorod (AuNR) and gold nanowire (AuNW) nanocomposites (AuNR/AuNW/CS) as electrode modifiers on a glassy carbon electrode (GCE) to construct a sensitive label-free electrochemical aptasensor to detect ApoA1. The thiolated ApoA1-specific aptamers were immobilized onto the modified electrode surface through self-assembled monolayers. Electrochemical techniques, such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV), were used to analyze the fabrication steps. The concentration of ApoA1 was measured with DPV on the aptasensor, with a linear range of 0.1 to 1000 pg mL^-1 and a detection limit of 0.04 pg mL^-1. When compared to results from ELISA tests (which have a detection limit of 80 pg mL^-1), the results achieved here were over 2000 times better. The aptasensor's performance was successfully evaluated using human serum spiked with ApoA1, suggesting that it has great potential for practical application. The electrochemical apatsensor additionally demonstrated outstanding selectivity responses and strong stability toward the target analyte.

Recent trends and developments of PCR-based methods for the detection of food-borne Salmonella bacteria and Norovirus

In recent years, rapid detection methods such as polymerase chain reaction (PCR) and quantitative real-time PCR (qPCR) have been continuously developed to improve the detection of food-borne pathogens in food samples. The recent developments of PCR and qPCR in the detection and identification of these food-borne pathogens are described and elaborated throughout this review. Specifically, further developments and improvements of qPCR are discussed in detecting Salmonella and norovirus. Promising advances in these molecular detection methods have been widely used to prevent human food-borne illnesses and death caused by the food-borne pathogens. In addition, this review presents the limitations and challenges of the detection methods which include conventional culture method and conventional PCR method in detecting Salmonella and norovirus. Furthermore, several advances of qPCR such as viability PCR (vPCR) and digital PCR (dPCR) have been discussed in the detection of Salmonella and norovirus. Good practice of analysis of the food-borne pathogens and other contaminants in the food industry as well as the advancement of molecular detection methods will help improve and ensure food safety and food quality.

Medical Knowledge versus Perception of Patients with Abdominal Gas in a Tertiary Level Hospital of Bangladesh

Every human being has gas in abdomen. But patients try to correlate varieties of symptoms with abdominal gas. So this cross sectional symptom based study was designed to see the patients view regarding abdominal gas and its relation with medically explained symptoms at the out patient department of North East Medical College, Sylhet from January 2017 to December 2019. Consecutive patients presenting with complain of abdominal gas were included in this study. Their demographic information and explanation of symptoms resulting from abdominal gas were recorded on a pre-designed data sheet. Statistical analysis was done using SPSS 20.0 version. Total 346 patients, male 239(69.1%), female 107(30.9%), age varying from 17-83 years (mean 38.27) were enrolled. Common symptoms were bloating (fullness) of abdomen (194, 56.1%), abdominal pain (164, 47.41%), belching or eructation (149, 43.1%), heart burn (137, 39.6%), anorexia (124, 35.8%), nausea (120, 34.7%), noisy bowel (88, 25.4%), chest pain (79, 22.8%), headache (56, 16.2%), whole body pain (58, 16.8%), incomplete bowel evacuation (185, 53.5%), excess flatus (76, 22.4%), movement of gas to different part of body including head 87(25.1%) and expulsion of hot air from ear, nose and head in 69(19.9%) patients. Among them 107(30.9%) patients believed abdominal gas to be a curable disease with treatment and 222(64.2%) believed it to be a relapsing disease even after treatment. And 307(88.7%) patients were taking proton pump inhibitor (PPI) as its remedy regularly. Most of the symptoms of patients can be explained by abdominal gas. Again some patients have a misperception regarding some symptoms like heart burn, noisy bowel and sense of incomplete bowel evacuations are also related with abdominal gas. But in some instances causal relations with patients' symptoms and abdominal gas could not be explained by medical knowledge. These differences in perceptions might be related to their personal thinking and social, cultural, educational, economic condition.

Prevalence of Sonologically Detected Non-alcoholic Fatty liver disease Among School Children of Sylhet City

This cross sectional descriptive type of observational study was designed to see the prevalence of NAFLD among school children of Sylhet, Bangladesh from December 2019 to January 2020. School children of three private schools of Sylhet City were randomly selected. Socio-demographic data and anthropometric measurement of them were recorded. Then they underwent screening sonologically for NAFLD. Data analysis was done using SPSS version 20.0. P value <0.05 was taken as significant. Total 174 students, boys 99(56.9%) and girls 75(43.1%) were included. Age of them varied from nine years to 17 years (mean 13.408). In this series 82(47.1%), 52(29.9%) and 40(23.0%) were of normal weight, overweight and obese children respectively. In this study 29(16.7%) children had NAFLD and seven (4.0%) had biliary sludge in gall bladder. NAFLD was significantly higher among children with higher BMI (p=0.00). Female sex, children consuming fast food and playing video games were about two times more prone to develop NAFLD. Biliary sludge was found significantly higher among children consuming fast food (p=0.02). NAFLD among school going children is not uncommon. Higher BMI is a significant risk factor of developing NAFLD. Girls and children consuming fast food and playing video games also are more prone to develop NAFLD. Prevalence of sludge in gall bladder is low among school children.

A solid-state electrochemiluminescence aptasensor for β-lactoglobulin using Ru-AuNP/GNP/Naf nanocomposite-modified printed sensor

An electrochemiluminescence (ECL) aptasensor for the detection of the milk protein allergen β-lactoglobulin (β-LG) using nanocomposite as luminophore was fabricated. The Ru-AuNPs/GNP/Naf complex was formed by combining the Rubpy₃²⁺-AuNPs complex (Ru-AuNPs), prepared by modifying the negatively charged surface of gold nanoparticles (AuNPs) with positively charged Rubpy₃²⁺ through electrostatic interactions and the graphene nanoplatelets-Nafion (GNP/Naf) at a ratio of 2:1. The nanocomposite was coated on the surface of the screen-printed electrode (SPCE) through the film-forming properties of Nafion. A layer of chitosan (CS) was coated onto this modified electrode, and later amine-terminated β-LG aptamers were covalently attached to the CS/Ru-AuNP/GNP/Naf via glutaraldehyde (GLUT) cross-linking. When β-LG was incubated with the aptasensor, a subsequent decrease in ECL intensity was recorded. Under the optimal conditions, the ECL intensity of the aptasensor changed linearly with the logarithmic concentration of β-LG, in the range 0.1 to 1000 pg/ml, and the detection limit was 0.02 pg/mL (3σ/m). The constructed aptasensor displayed simple and fast determination of β-LG with excellent reproducibility, stability, and high specificity. Additionally, the proposed ECL aptasensor displayed high recoveries (92.5-112%) and low coefficients of variation (1.6-7.8%), when β-LG fortified samples were analyzed. Integrating Ru-AuNPs/GNP/Naf nanocomposite in the ECL aptasensor paves the way towards a cost-effective and sensitive detection of the milk allergen β-LG.

Nanozyme-based sensors for detection of food biomarkers: a review

Nanozymes have piqued the curiosity of scientists in recent years because of their ability to demonstrate enzyme-like activity combined with advantages such as high stability, inexpensive availability, robust activity, and tunable properties. These attributes have allowed the successful application of nanozymes in sensing to detect various chemical and biological target analytes, overcoming the shortcomings of conventional detection techniques. In this review, we discuss recent developments of nanozyme-based sensors to detect biomarkers associated with food quality and safety. First, we present a brief introduction to this topic, followed by discussing the different types of sensors used in food biomarker detection. We then highlight recent studies on nanozyme-based sensors to detect food markers such as toxins, pathogens, antibiotics, growth hormones, metal ions, additives, small molecules, and drug residues. In the subsequent section, we discuss the challenges and possible solutions towards the development of nanozyme-based sensors for application in the food industry. Finally, we conclude the review by discussing future perspectives of this field towards successful detection and monitoring of food analytes.

We present a discussion on different types of sensors used in food biomarker detection and highlight recent studies on nanozyme-based sensors to detect markers like toxins, pathogens, antibiotics, growth hormones, metal ions, additives, small molecules, drug residues.

Recent trends in nanomaterial-based signal amplification in electrochemical aptasensors

Ultrasensitive biosensors have become a necessity in the world of scientific research, and several signal enhancement strategies have been employed to attain exceptionally low detection limits. Nanotechnology turns out to be a strong contender for signal amplification, as they can be employed as platform modifiers, catalysts, carriers or labels. Here, we have described the most recent advancements in the utilization of nanomaterials as signal amplification components in aptamer-based electrochemical biosensors. We have briefly reviewed the methods that utilized nanomaterials, namely gold and carbon, as well as nanocomposites such as: graphene, carbon nanotubes, quantum dots, and metal-organic frameworks.

A Rare Case of Polyorchidism: Sonographic and MR Evaluation of Four Testes

Polyorchidism is a rare congenital anomaly reported about 200 cases in the world text. A number of theories have been planned concerning the making of polyorchidism, but the real explanation is still not acknowledged. Here we are going to present a case study of polyorchidism. A 70 years old gentleman complained with left supernumerary testes in the left hemiscrotum. His left hemiscrotum was painless with mass. Polyorchidism without malignancy or any other concomitant features were revealed by both ultrasound and MRI examinations. In most cases the ultrasonograph alone is diagnostic. In complicated cases of polyorchidism MRI may provide additional information.

A Highly Sensitive Label-free Aptasensor Based on Gold Nanourchins and Carbon Nanohorns for the Detection of Lipocalin-2 (LCN-2)

A synergistic nanocomposite film composed of gold nanourchins (AuNU), oxidised carbon nanohorns (CNH), and chitosan functioned as an electrode modifier in the fabrication of the sensitive lipocalin-2 (LCN-2) aptasensor. The AuNUs/CNH/CS composite increased the surface area and thereby amplified the signal transduction. The amine-terminated LCN-2 aptamer was immobilised through the amide bond formed between the carboxyl group of polyglutamic acid (PGA) and the amine group of aptamer. Interaction of LCN-2 with the aptamer caused conformational changes in the structure of the aptamer. This generated higher conductivity, resulting in increased DPV peak current. The DPV signal increased with increasing concentration of LCN-2, and the change in signal was used for quantitative detection. The proposed aptasensor was able to detect LCN-2 in the linear range of 0.1 - 100.0 pg mL^-1, with a low detection limit of 10 fg mL^-1. The aptasensor showed high sensitivity, selectivity, reproducibility, and was able to detect LCN-2 in serum samples.

Molecular Detection of Human Coronavirus from North Central Part of Bangladesh Depending on ORF1ab and N Gene

The Coronavirus disease 2019 (COVID-19) resulted severe respiratory illness such as pneumonia and lung dysfunctions that was first identified at Wuhan, the capital of Hubeiin China during the end of December 2019. The etiological cause of COVID-19 has been confirmed as a novel coronavirus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which was similar with the zoonotic virus SARS-CoV (2002). Now a days for early diagnosis of COVID-19 the nucleic acid based test like RT PCR (real time reverse transcription polymerase chain reaction) is most consistent and used all over the world. In this study among 11,280 cases 825(7.31%) were positive by molecular RT PCR method on June 2020 at Microbiology department of Mymensingh Medical College and the samples are collected from different areas of Northern part of Bangladesh. Among this positive cases 588(71%) N gene, 10 ORF1ab (2%) and 227(27%) both N and ORF gene showed significant curve which is specific for COVID-19 positive patients. Because N and ORF gene of this virus inhibit immune system of human body especially interferon. Out of SARS-CoV-2 positive cases maximum number of N gene were found in male patients and above 40 years old aged group. So, Molecular diagnosis of this pandemic virus especially by N and ORF gene might be helpful to reduce the spread of SARS-CoV-2 as well as early treatment for saving many lives.

Electrochemical Study of Dimensional Specific Carbon Nanomaterials Modified Glassy Carbon Electrode for Highly Sensitive Label-free Detection of Immunoglobulin A

Background:

Immunoglobulin A (IgA) accounts for 15% of total protein production per day and plays a crucial role in the first-line immune defence. Recently, IgA has been established as a vital clinical biomarker for nephropathy, allergic asthma, celiac disease (CD), pneumonia, and asthma as well as some neurological disorders. In this work, we have studied several carbon nanomaterials (CNMs) having different dimensions (D): carbon nano-onions (CNOs) - 0D, single-walled carbon nanotubes (SWCNTs) - 1D, and graphene nanoplatelets (GNPs) - 2D, on glassy carbon electrode (GCE) to identify which CNMs (CNOs/SWCNTs/GNPs) work best to fabricate IgA based electrochemical immunosensor.

Methods:

Different CNMs (CNOs, SWCNTs, GNPs) were tested for high electric current on GCE using square wave voltammetry (SWV), and among them, GNPs modified GCE platform (GNPs/GCE) showcased the highest electric current. Therefore, GNPs/GCE was utilized for the development of highly sensitive label-free electrochemical immunosensor for the detection of Immunoglobulin A using SWV.

Results:

Despite the simple fabrication strategies employed, the fabricated sensor demonstrated a low limit of detection of 50 fg mL-1 with an extensive linear range of detection from 50 fg mL-1 to 0.1 μg mL-1.

Conclusion:

Fabricated immunosensor represented high stability, repeatability, specificity and resistance to most common interferences as well as great potential to analyse the real sample.

An ultra-sensitive label-free electrochemiluminescence CKMB immunosensor using a novel nanocomposite-modified printed electrode

This study presents a novel and ultrasensitive electrochemiluminescence approach for the quantitative assessment of creatine kinase MB (CK-MB). Both carbon, carbon nano-onions (CNOs) and metal-based nanoparticles, such as gold nanoparticles (AuNPs) and iron oxide (Fe3O4), were combined to generate a unique nanocomposite for the detection of CKMB. The immunosensor construction involved the deposition of the nanocomposite on the working electrode, followed by the incubation of an antibody and a blocking agent. Tris(2,2'-bipyridyl)-ruthenium(ii) chloride ([Ru(bpy)3]2+Cl) was used as a luminophore, where tri-n-propylamine (TPrA) was selected as the co-reactant due to its aqueous immobility and luminescence properties. The analytical performance was demonstrated by cyclic voltammetry on ECL. The characterization of each absorbed layer was performed by cyclic voltammetry (CV) and chronocoulometry (CC) techniques in both EC and ECL. For further characterization of iron oxide, gold nanoparticles and carbon nano-onions, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were performed. The proposed immunosensor showcases a wide linear range (10 ng mL-1 to 50 fg mL-1), with an extremely low limit of detection (5 fg mL-1). This CKMB immunosensor also exhibits remarkable selectivity, reproducibility, stability and resistance capability towards common interferences available in human serum. In addition, the immunosensor holds great potential to work with real serum samples for clinical diagnosis.

Huge Splenomegaly with Pancytopenia Due to Gaucher's Disease in a 22 Years Old Woman

Gaucher's disease is one of the important storage disorders. It belongs to the lysosomal storage disorders group. There is defective activity of an enzyme named β-glucosidase which ultimately renders the cell of macrophage lineage loaded with glucocerebrosides. There is multi-organ involvement that manifests as hepatosplenomegaly, variable cytopenias, skeletal disorders, neurological features etc. When serum β-glucosidase level is below 15% of mean normal activity Gaucher's disease is confirmed. Enzyme replacement is the definitive treatment. Here we report a case of type 1 or non-neuropathic form Gauchers disease presented with feeling of a lump in left upper abdomen and progressive generalized weakness and hepatosplenomegaly. Her complete blood count revealed pancytopenia and bone trephine biopsy showed Gaucher's cells. Diagnosis and management may be delayed as this disease is rare. Clinical and bone marrow examination is the mainstay of diagnosis. So emphasis should be given in this regard.

A Label-free Cardiac Troponin T Electrochemiluminescence Immunosensor Enhanced by Graphene Nanoplatelets

In this study, a direct and label-free immunosensor was designed and constructed by modifying the screen-printed electrode with graphene nanoplatelets (GNPs) for the detection of the cardiac troponin T (cTnT). Firstly, GNPs were drop-casted onto carbon working electrode. Monoclonal cTnT antibodies were then immobilized on the GNPs via physical adsorption; finally, BSA was introduced to block non-specific binding sites. The detection of cTnT was performed using an electrochemiluminescence (ECL) technique with tris(bipyridine)ruthenium(II) chloride ([Ru(bpy)₃]Cl₂) used as a luminophore and TPrA (tripropylamine) as a co-reactant. The ECL intensity was demonstrated to be directly proportional to the cTnT concentration where a linear range from 100 pg mL^-1 to 5 fg mL^-1 of the cTnT detection was established. An extremely low limit of detection was achieved to be 0.05 fg mL^-1 with an outstanding specificity. Additionally, this immunosensor showed excellent percentage recovery for real samples analyses in artificially spiked human serum.

Detection of Oncoprotein by a Novel Immunochromatoghaphic Test Depending on Age and Parity of the Patients Attending at Mymensingh Medical College Hospital, Bangladesh

In world wide cervical cancer is the fourth most common among women, with the majority of cases occurring in developing countries. Some HPV infections persist, and a subset of persistent infections may lead to development of cervical intraepithelial neoplasia (CIN) or invasive cancer. Because neoplastic change typically takes some years to occur and it depends on multiple factors among them age and parity play important role. The objective of the cross sectional observational study was detection of oncoprotein depending on age and parity by immunochromatographic test (OncoE6 cervical test). Informed consent was taken from patients and the protocol was approved by IRB, Mymensingh Medical College, Mymensingh, Bangladesh. From April 2016 to March 2017 following universal safety precautions a total of 280 endocervical swabs were collected from VIA outdoor and Colposcopy clinic of Obstetrics and Gynaecology department of Mymensingh Medical College Hospital, Mymensingh, Bangladesh. Laboratory work was done in the department of Microbiology, Mymensingh Medical College. The E6 strip test is an immunochromatographic test based on the detection of HPV-E6 oncoprotein in cervical swab samples. In this study VIA and OncoE6 cervical test were done on 280 cases and among them 120 were VIA positive and sent for colposcopy. From 120 VIA positive cases 70 were positive for colposcopy test. Afterwards 50 cases were selected for histopathological examination and classified into different grades. The present study showed 21(7.5%) cases were OnE6 cervical test positive by OncoE6 cervical test and most of them were found in advance aged <50 (38.09%) and multi parity (women more than two, 32.5%). Based on the findings of the present study, it may be concluded that age and multi parity plays important factor to cause cervical cancer. Now for prevention of cervical cancer we need screening which is an early detection tool. This is a low cost device, easily performed which can detect this HRHPV (High Risk HPV) and it will be helpful to reduce over treatment and high predictability of the disease.

Distribution of HPV-16 and HPV-18 from the Patients Attending At Mymensingh Medical College Hospital by Newly Developed Oncoprotein Detection Assay

Cervical cancer is one of cause of death in women in many developing countries. Persistent infection with Human Papilloma Virus (HPV), primarily high risk types 16 and 18, is recognized as a causal and essential factor for the development of cervical cancer. The objective of this cross sectional observational study is to detect the distribution of HPV-16 and HPV-18 among Onco E6 positive cases. Following universal safety precautions a total of 180 endocervical swabs were collected from Colposcopy clinic of Obstetrics and Gynaecology Department of Mymensingh Medical College Hospital (MMCH), Mymensingh, Bangladesh from January 2016 to December 2016. Laboratory work was done in the department of Microbiology, Mymensingh Medical College. E6 strip test is an immunochromatographic test based on the detection of HPV-E6 oncoprotein in cervical swab samples. Onco E6 cervical test was done on 180cases. Among them 60% were VIA positive and 120% were VIA negative. From this VIA positive cases 12(16.25%) were On E6 cervical test positive and from VIA negative cases 3(2.5%) were positive by this On E6 cervical test. From this 12 Onco E6 cervical test positive cases 10(%) were HPV-16 and 2(%) were HPV-18 and from VIA negative cases 3 were only HPV-16 by this test. Histopathological test done on 35 suspected cases and out of 08 cervical carcinoma cases 07 were positive by this Onco E6 cervical test which was also HPV-16 type. It may be concluded that HPV-16 is most prevalent type to cause cervical cancer and by this newly developed protein detection assay will be helpful to reduce over treatment and save many lives.

Molecular Diagnosis of Human Papilloma Virus by PCR

Cervical cancer is a major world health problem and the fourth most leading cause of death in women around the world. High risk HPV DNA has been shown to be present in 99.7% of cervical cancers worldwide. So detection of HPV DNA by PCR may help in early detection and management of cervical cancer. This cross sectional observational study was done to detect L1 antigen gene of HPV from cervical swab by nested PCR. Following universal safety precautions a total of 141 endocervical swabs were collected from Colposcopy clinic of Obstetrics and Gynaecology department of MMCH from January 2015 to December 2015. Laboratory work was done in the department of Microbiology, Mymensingh Medical College (MMC), Mymensingh, Bangladesh HPV DNA was tested among 141 VIA positive women aged between 20-70 years by nested PCR method. DNA was extracted by phenol-chloroform extraction method. Two pairs of consensus primers MY09-MY11 and GP5-GP6 were used in a nested PCR assay. Histopathological examination was done on 66 samples in the Department of Pathology, MMC, Mymensingh, Bangladesh. A total of 36.9% (52/141) cases were positive for HPV DNA by nested PCR. On Histopathological diagnosis PCR was positive in 42.9% chronic cervicitis, 21.2% CIN cases and 90.9% cervical carcinoma cases. Based on the findings of the study, it may be concluded that the HPV DNA testing has opened the door for an alternative surveillance mechanism to routine cytological screening. Detection of HPV may play an important role in diagnosis and clinical prognosis of precancerous lesions. So PCR may be done for all VIA positive cases for screening of cervical cancer.

Recent developments in colorimetric immunoassays using nanozymes and plasmonic nanoparticles

Enzyme-linked immunosorbent assay (ELISA) is a popular detection technique for the screening and diagnosis of diseases. The sensitivity of ELISA can be increased by the incorporation of nanoparticles. Through this article, we discuss the utilization of nanoparticles in ELISA. Nanoparticles possess an intrinsic biological peroxidase-like activity which allows it to act as an enzyme mimic for the development of an improved analysis method. Different nanoparticles (gold nanoparticles, silver nanoparticles, etc.) carry different peroxidase-mimic characteristics. Besides this, nanoparticles can also perform as a colorimetric substrate in ELISA where it gives a more prominent color change compared to the commonly used colorimetric substrate TMB. This article also focuses on the mechanisms behind this color change including aggregation, in situ nanoparticle growth, seeding, and etching.

Trends in Paper-based Electrochemical Biosensors: From Design to Application

Electrochemical bio-sensing using paper-based detection systems is the main focus of this review. The different existing designs of 2-dimensional and 3-dimensional sensors, and fabrication techniques are discussed. This review highlights the effect of adopting different sensor designs, distinct fabrication techniques, as well as different modification methods, in order to produce reliable and reproducible reading. The use of various nanomaterials have been demonstrated in order to modify the surface of electrodes during fabrication to further enhance the signal for subsequent analysis. The reviewed sensors were classified into categories based on their applications, such as diagnostics, environmental and food testing. One of the major advantages of using paper-based electrochemical sensors is the potential for miniaturization, which only requires relatively small amount of samples, and the low cost for the purpose of mass production. Additionally, most of the devices reviewed were made to be portable, making them well-suited for on-site detection. Finally, paper-based detection is an ideal platform to fabricate cost-effective, user-friendly and sensitive electrochemical biosensors, with large capacity for customization depending on functional needs.

Prevalence of Intestinal Parasites in Raw Vegetables Consumed by Inhabitants of Mymensingh City

Uncooked vegetables are an important part of a healthy diet in different parts of the world. The present descriptive cross sectional type of study was carried out to determine the parasitological contamination of vegetables sold at markets of Mymensingh city of Bangladesh. Parasitological examinations were performed in material derived from 200 specimens of 10 different vegetables to detect intestinal parasites in the department of Microbiology, Mymensingh Medical College, Mymensingh, Bangladesh from July 2015 to July 2016. Each sample was washed with 5 liter distilled water, then washing fluid was centrifuged and resulting sediment was collected for iodine and normal saline wet mount slide preparation to detect human pathogenic intestinal parasites by microscopic examination. Out of 200 vegetable samples, 123(61.5%) were contaminated with different species of parasites. The vegetables red amaranth had the highest contamination rate of 18/20 (90%) followed by jute leaf 17/20 (85%), coriander leaf 15/20 (75%), onion 14/20 (70%), lady's finger 14/20 (70%), radish 13/20 (65%), green pepper 12/20 (60%), carrot 12/20 (60%), cucumber 5/20 (25%), tomato 3/20 (15%). Among the contaminating parasites Ascaris lumbricoides (egg) 36.5% was the most prevalent followed by Strongyloides stercoralis (larva) 35.5%, Entamoeba histolytica ( trophozoite and different cystic stages) 8.5%, Hook worm (egg and larva) 6.5% , Balantidium coli (trophozoite) 4.0%, Enterobius vermicularis (egg) 3.5%, Trichuris trichiura (egg) 1.5%, Giardia lamblia (cyst) 1.0%. To our knowledge, it was the first base line study pursued in Bangladesh. Contamination of raw vegetables from markets with pathogenic parasites would increase the risk of disease to the population that consumes or works with these products. So improperly washed raw eaten vegetables should be considered a potential risk for contracting parasites, particularly helminthes in Mymensingh city.

Trends and Advances in Electrochemiluminescence Nanobiosensors

The rapid and increasing use of the nanomaterials (NMs), nanostructured materials (NSMs), metal nanoclusters (MNCs) or nanocomposites (NCs) in the development of electrochemiluminescence (ECL) nanobiosensors is a significant area of study for its massive potential in the practical application of nanobiosensor fabrication. Recently, NMs or NSMs (such as AuNPs, AgNPs, Fe₃O₄, CdS QDs, OMCs, graphene, CNTs and fullerenes) or MNCs (such as Au, Ag, and Pt) or NCs of both metallic and non-metallic origin are being employed for various purposes in the construction of biosensors. In this review, we have selected recently published articles (from 2014-2017) on the current development and prospects of label-free or direct ECL nanobiosensors that incorporate NCs, NMs, NSMs or MNCs.

Ultrasonographic Evaluation of Malignant Pediatric Abdominal Tumour with Histopathological Correlation

Ultrasonography is a very useful diagnostic tool to evaluate pediatric abdominal mass. This cross sectional study was conducted among clinically suspected patients having malignant abdominal mass attending in the department of Radiology & Imaging, Mymensingh Medical College Hospital, Mymensingh, Bangladesh from January 2008 to December 2009. Total 56 patients were included in this study. Patients were scanned by high resolution gray scale ultrasonography of the abdominal masses. After surgical procedure, biopsy specimen were collected in a container containing 10% formalin and sent for histopathological examination. Mean age of the patients group was 5.91 years with a standard deviation of ±3.21 years. All patients were within 2 to 13 years age. Out of all patients, male were 33(58.9%) and 23(41.1%) were female. Male and female ratio was 1.4:1. Ultrasonographic diagnosis as Wilm's tumour were 27(48.2%), hepatoblastoma 8(14.3%), lymphoma 7(12.5%), neuroblastoma 6(10.7%), suspected malignancy 6(10.7%) and lastly teratoma were 2(3.6%). Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of ultrasonography in the evaluation of Wilm's tumour were 100.0%, 90.6%, 88.9%, 100.0% and 94.6% for neuroblastoma 83.3%, 98.0%, 83.3%, 98.0% and 96.4% for lymphoma 83.3%, 96.0%, 71.4%, 98.0% and 94.6% and for hepatoblastoma 100.0%, 100.0%, 100.0%, 100.0% and 100.0% respectively. It is a noninvasive and cost effective modality. Carefully performed ultrasonographic study would give reliable and accurate information needed in the diagnosis of abdominal malignancy in children.

Colorimetric Nucleic Acid Detection on Paper Microchip Using Loop Mediated Isothermal Amplification and Crystal Violet Dye

Nucleic acid detection is of paramount importance in monitoring of microbial pathogens in food safety and infectious disease diagnostic applications. To address these challenges, a rapid, cost-effective label-free technique for nucleic acid detection with minimal instrumentations is highly desired. Here, we present paper microchip to detect and quantify nucleic acid using colorimetric sensing modality. The extracted DNA from food samples of meat as well as microbial pathogens was amplified utilizing loop-mediated isothermal amplification (LAMP). LAMP amplicon was then detected and quantified on a paper microchip fabricated in a cellulose paper and a small wax chamber utilizing crystal violet dye. The affinity of crystal violet dye toward dsDNA and positive signal were identified by changing the color from colorless to purple. Using this method, detection of Sus scrofa (porcine) and Bacillus subtilis (bacteria) DNA was possible at concentrations as low as 1 pg/μL (3.43 × 10 ^-1 copies/μL) and 10 pg/μL (2.2 × 10³ copies/μL), respectively. This strategy can be adapted for detection of other DNA samples, with potential for development of a new breed of simple and inexpensive paper microchip at the point-of-need.

Detection of Ovarian Tumor by Color Doppler Ultrasonography and CA-125

Ovarian cancer is the most frequent cause of death from all gynaecological malignancies because of its insidious onset, vague symptoms and late presentation. This cross-sectional study was carried out on purposively selected 43 patients with suspected ovarian tumor in the Department of Radiology and Imaging in collaboration with the Department of Gynaecology and Obstetrics and Department of Pathology, Mymensingh Medical College Hospital, Bangladesh from January 2015 to December 2016 to assess the diagnostic performance of color Doppler ultrasonography and CA-125 in a combination described as Novel Index in detection of ovarian tumor. Highest number of patients of ovarian tumor 10(23.26%) were in age group 35 to 44 years and 45 to 54 years with a mean of 37.72±15.65 years with a range of 8-70 years. Histopathology findings revealed 19(44.18%) benign tumors and 24(55.82%) malignant tumors. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of Resistance Index (RI) in diagnosis of ovarian tumor were 91.67%, 89.47%, 91.67%, 89.47% and 90.69% respectively. Sensitivity, specificity, PPV, NPV and accuracy of serum CA-125 were 83.33%, 89.47%, 90.90%, 80.95% and 86.04% respectively. Sensitivity, specificity, PPV, NPV and accuracy of Novel index were 95.83%, 89.47%, 92.00%, 94.44% and 93.02% respectively. Novel index showed better diagnostic performance. Based on the current study it is concluded that the combination of color Doppler ultrasonography and serum CA-125 can be useful for diagnosis of ovarian tumor.

OncoE6 Positivity among VIA Positive Suspected Cases from Colposcopy Clinic of Mymensingh Medical College Hospital, Mymensingh

Cervical cancer is a major world health problem for women. It is the fourth most leading cause of death in women around the world. High risk HPV DNA has been shown to be present in 99.7% of cervical cancers worldwide. Oncoprotein E6 and E7 play an important role in the development of cervical cancer which can be detected by OncoE6 cervical test. This Cross sectional observational study was performed to detect E6 Oncoprotein from cervical swab by OncoE6 cervical test. Following universal safety precautions a total of 47 endocervical swabs were collected from Colposcopy clinic of Obstetrics and Gynaecology department of Mymensingh Medical College Hospital (MMCH), Mymensingh, Bangladesh from January 2015 to December 2015. Laboratory work was done in the department of Microbiology, Mymensingh medical college. E6 strip test is an immunochromatographic test based on the detection of HPV-E6 oncoprotein in cervical swab samples. The swab specimen was treated with lysis solution and conditioning solution. Then the specimen solution was clarified by centrifugation. After that the sample solution was transferred into Detector mAb vial, wash solution vial and finally into developing solution vial. The test unit was then placed on a reading guide. Positive result was indicated by the appearance of purple colored test line. Out of 47 specimens 21(44.68%) were OncoE6 positive by OncoE6 cervical test. Among 21 positive cases 19(90.48%) were HPV-16 and 2 were (9.52%) HPV-18. Histopathologically out of 22 cervical carcinoma cases 20(90.90%) were positive by this test. Based on the findings of the present study, it may be concluded that screening with HPV E6 may minimize the overtreatment as well as the colposcopy referral. So it can be used as primary screening to aid colposcopy and to identify real disease. HPV based screening may help to control cervical cancer in Bangladesh. As HPV is a sexually transmitted infection; so, male screening method should be established.

Nationwide prevalence of Rickettsia felis infections in patients with febrile illness in Bangladesh

From July 2015 to December 2016, the presence of rickettsial pathogens was investigated for 414 patients with unknown fever in eight places in all the divisions of Bangladesh. Rickettsia felis was identified in blood samples from all the regions (overall detection rate, 19.6%), suggesting nationwide prevalence of R. felis infections.