Three-dimensional nitrogen-doped mesoporous carbon nanomaterials derived from plant biomass: Cost-effective construction of label-free electrochemical aptasensor for sensitively detecting alpha-fetoprotein

Recent advances in carbon-based materials derived from diverse green biowaste for sensing applications: a comprehensive overview from the perspective of synthesis method and application

The rapid increase in global waste, driven by population growth, has raised significant environmental concerns. Among different types of wastes, green biowastes (BWs) containing organic matter have attracted considerable attention. The conversion of BW, particularly from herbaceous and animal sources, to carbon-based materials (CBMs) introduces a suitable platform for waste management and resource recovery. Furthermore, this strategy creates valuable materials from low-value waste for various applications, sensing included. The abundance of these wastes provides a sustainable and affordable raw material and enhances the feasibility of fabricating these materials. Generally, the presence of carbon in their structure can present an accessible resource for producing different carbon materials, especially carbon dots (CDs), carbon quantum dots (CQDs), and graphene quantum dots (GQDs). The performance of these CBMs has been enhanced by optimizing synthesis processes, incorporating functional groups, and integrating various materials. The synthesized CBMs possess desirable features, such as biocompatibility, excellent physical, chemical, and electrical conductivity. These materials have been used in different sensors such as electrochemical (EC) and optical sensors for presenting high performance sensing probes with several benefits such as real-time monitoring, rapid detection, and high sensitivity. The first section of this review is dedicated to the preparation of CBMs, derived from green BWs, by different synthesized methods for use in different fields including biomedical application, food safety, and environmental monitoring. In addition, the challenges, limitations, and future directions in the development of these CBMs were completely discussed to improve their performance.

Seafood waste derived carbon nanomaterials for removal and detection of food safety hazards

Nanobiotechnology and the engineering of nanomaterials are currently the main focus of many researches. Seafood waste carbon nanomaterials (SWCNs) are a renewable resource with large surface area, porous structure, high reactivity, and abundant active sites. They efficiently adsorb food contaminants through π-π conjugated, ion exchange, and electrostatic interaction. Furthermore, SWCNs prepared from seafood waste are rich in N and O functional groups. They have high quantum yield (QY) and excellent fluorescence properties, making them promising materials for the removal and detection of pollutants. It provides an opportunity by which solutions to the long-term challenges of the food industry in assessing food safety, maintaining food quality, detecting contaminants and pretreating samples can be found. In addition, carbon nanomaterials can be used as adsorbents to reduce environmental pollutants and prevent food safety problems from the source. In this paper, the types of SWCNs are reviewed; the synthesis, properties and applications of SWCNs are reviewed and the raw material selection, preparation methods, reaction conditions and formation mechanisms of biomass-based carbon materials are studied in depth. Finally, the advantages of seafood waste carbon and its composite materials in pollutant removal and detection were discussed, and existing problems were pointed out, which provided ideas for the future development and research directions of this interesting and versatile material. Based on the concept of waste pricing and a recycling economy, the aim of this paper is to outline current trends and the future potential to transform residues from the seafood waste sector into valuable biological (nano) materials, and to apply them to food safety.

Biosensing of Alpha-Fetoprotein: A Key Direction toward the Early Detection and Management of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is currently one of the most prevalent cancers worldwide. Associated risk factors include, but are not limited to, cirrhosis and underlying liver diseases, including chronic hepatitis B or C infections, excessive alcohol consumption, nonalcoholic fatty liver disease (NAFLD), and exposure to chemical carcinogens. It is crucial to detect this disease early on before it metastasizes to adjoining parts of the body, worsening the prognosis. Serum biomarkers have proven to be a more accurate diagnostic tool compared to imaging. Among various markers such as nucleic acids, circulating genetic material, proteins, enzymes, and other metabolites, alpha-fetoprotein (AFP) is a protein marker primarily used to diagnose HCC. However, current methods need a large sample and carry a high cost, among other challenges, which can be improved using biosensing technology. Early and accurate detection of AFP can prevent severe progression of the disease and ensure better management of HCC patients. This review sheds light on HCC development in the human body. Afterward, we outline various types of biosensors (optical, electrochemical, and mass-based), as well as the most relevant studies of biosensing modalities for non-invasive monitoring of AFP. The review also explains these sensing platforms, detection substrates, surface modification agents, and fluorescent probes used to develop such biosensors. Finally, the challenges and future trends in routine clinical analysis are discussed to motivate further developments.

Laser-scribing graphene-based electrochemical biosensing devices for simultaneous detection of multiple cancer biomarkers

In this study, a graphene electrochemical sensor based on laser graphene polymer material was proposed to induce graphene formation on polyimide substrates via fiber laser. The laser produces stable power and results to achieve the benefits of consistency, conductivity, and flexibility. The electrochemical three-electrodes were manufactured on polyimide to replace the traditional three-electrodes by achieving small size and portability. An electrode activation is the modification of laser-scribed graphene electrodes (LSG) to facilitate the binding of liver cancer sites. The evaluation is performed by differential pulse Voltammetry (DPV) to detect cancer proteins in the phosphate buffer saline (PBS) buffer and serum. In a serum environment, the concentrations of alpha-fetoprotein (AFP) and Carcinoembryonic antigen (CEA) were detected from 0.75 ng ml-1 to 100 ng ml-1, AFP and CEA electrodes have a good linear range (R2 = 0.96 and R2 = 0.98), indicating the sensor's sensitivity and specificity for cancer detection. In addition, two types of carcinogenic proteins were monitored in the PBS and successfully detected in this experiment. Based on the results, the appropriate LSG sensor may be used for monitoring with limited resources. Electrode manufacturing is simple, fast, low-cost, small in size, convenient to carry, stable, instant detection, and flexible.

Biosensors based on DNA-functionalized CdTe quantum dots for the enhanced electrochemical detection of human-IgG

Electrochemical detection of human-IgG via biosensors is vital in clinical diagnostics, owing to their simple equipment, facile operation, high selectivity, economical, short diagnostic time, fast response, and easy miniaturization, but the need to improve sensitivity for protein detection is still a barrier limiting its wider practical applications. A hypersensitized electrochemical biosensor based on steric effects for IgG detection was developed in this work. The results indicate that IgG-modified sig-DNA attached to CdTe quantum dots (CdTe-sig-DNA) limited the ability of CdTe-sig-DNA or CdTe-sig-DNA-IgG conjugate to hybridize through the captured DNA strand (cap-DNA) immobilized on a chitosan/nitrogen-doped carbon nanocomposite (CS/N-C) modified glassy carbon electrode surface (GCE). The concentration of IgG based on CdTe concentration was detected by differential pulse anode stripping voltammetry (DPASV) on the electrode surface. The efficiency for hybridizing CdTe-sig-DNA with cap-DNA was found to be logarithmically inverse to the concentration of IgG attached. A highly sensitive and selective detection of IgG from 5 pM to 50 μM with a relatively low detection limit of 1.7 pM was achieved. Therefore, the steric hindrance effect of IgG limited the quantity of DNA that could be functionalized on CdTe QDs, significantly improving the signal, and providing a practical strategy for the clinical analysis of IgG.

Current Update on Biomarkers for Detection of Cancer: Comprehensive Analysis

Early and effective diagnosis of cancer is decisive for its proper management. In this context biomarker-based cancer diagnosis is budding as one of the promising ways for early detection, disease progression monitoring, and effective cancer therapy. Integration of Biosensing devices with different metallic/nonmetallic nanoparticles offers amplification and multiplexing capabilities for simultaneous detection of cancer biomarkers (CB's). This study provides a comprehensive analysis of the most recent designs and fabrication methodologies designed for developing electrochemical biosensors (EB) for early detection of cancers. The role of biomarkers in cancer therapeutics is also discussed.

Optical and Electrochemical Aptasensors Developed for the Detection of Alpha-Fetoprotein

Early diagnosis of hepatocellular carcinoma (HCC), a leading cause of cancer mortality, is decisive for successful treatment of this type of cancer and increasing the patients' survival rate. Alpha-fetoprotein (AFP) is a glycoprotein that has been currently employed as a potential serological biomarker for determination of HCC and several other cancers. Achieving highly sensitive and specific detection of this biomarker is an effective strategy to inhibit developing issues caused by the cancer. Though, traditional procedures cannot meet the requirements due to the technical drawbacks. Recently, growing number of aptamer-based biosensors (aptasensors) attracted important attention as superior diagnostic tools because of their unique properties such as high stability, target versatility and remarkable affinity and selectivity. Nanomaterials, which broadly employed in the structure of these aptasensors, can considerably enhance the detection limit and sensitivity of analytes determination. Therefore, this review selectively investigated the recent progresses in several different optical and electrochemical aptasensors and nano-aptasensors designed for AFP assay.

Biorecognition Engineering Technologies for Cancer Diagnosis: A Systematic Literature Review of Non-Conventional and Plausible Sensor Development Methods

Cancer is the second cause of mortality worldwide. Early diagnosis of this multifactorial disease is challenging, especially in populations with limited access to healthcare services. A vast repertoire of cancer biomarkers has been studied to facilitate early diagnosis; particularly, the use of antibodies against these biomarkers has been of interest to detect them through biorecognition. However, there are certain limitations to this approach. Emerging biorecognition engineering technologies are alternative methods to generate molecules and molecule-based scaffolds with similar properties to those presented by antibodies. Molecularly imprinted polymers, recombinant antibodies, and antibody mimetic molecules are three novel technologies commonly used in scientific studies. This review aimed to present the fundamentals of these technologies and address questions about how they are implemented for cancer detection in recent scientific studies. A systematic analysis of the scientific peer-reviewed literature regarding the use of these technologies on cancer detection was carried out starting from the year 2000 up to 2021 to answer these questions. In total, 131 scientific articles indexed in the Web of Science from the last three years were included in this analysis. The results showed that antibody mimetic molecules technology was the biorecognition technology with the highest number of reports. The most studied cancer types were: multiple, breast, leukemia, colorectal, and lung. Electrochemical and optical detection methods were the most frequently used. Finally, the most analyzed biomarkers and cancer entities in the studies were carcinoembryonic antigen, MCF-7 cells, and exosomes. These technologies are emerging tools with adequate performance for developing biosensors useful in cancer detection, which can be used to improve cancer diagnosis in developing countries.

Aptamers and New Bioreceptors for the Electrochemical Detection of Biomarkers Expressed in Hepatocellular Carcinoma

Hepatocellular carcinoma is a malignancy associated with high mortality and increasing incidence. Early detection of this disease could help increase survival and overall patient benefit. Non-invasive strategies for the diagnosis of this medical condition are of utmost importance. In this scope, the detection of hepatocellular carcinoma biomarkers could provide a useful diagnostic tool. Aptamers represent as short, single-stranded DNAs or RNAs that can specifically bind selected analytes, and also as pseudo-biorecognition elements that can be employed for electrode functionalization. Also, other types of DNA sequences can be used for the construction of DNA-based biosensors applied for the quantification of hepatocellular carcinoma biomarkers. Herein, we will be analyzing recent examples of aptasensors and DNA biosensors for the detection of hepatocellular carcinoma biomarkers like micro-RNAs, long non-coding RNAs, exosomes, circulating tumor cells and proteins. The literature data is discussed comparatively in a critical manner highlighting the advantages of using electrochemical biosensors in diagnosis, as well as the use of nanomaterials and biocomponents in the functionalization of electrodes for improved sensitivity and selectivity.

A love-mode surface acoustic wave aptasensor with dummy fingers based on monolayer MoS2/Au NPs nanocomposites for alpha-fetoprotein detection

The detection of cancer markers still has shortages of low sensitivity, time-consuming operation, the use of unstable and expensive antibodies. In this work, a novel Love-mode surface acoustic wave (LSAW) aptasensor with dummy fingers based on the monolayer molybdenum disulfide/gold nanoparticles (monolayer MoS₂/Au NPs) was developed for the highly sensitive and rapid determination of alpha-fetoprotein (AFP) in serum. Interdigital electrodes (IDTs) with dummy fingers were designed and applied to improve the acoustic characteristic of the LSAW aptasensor. The less energy dissipation and wave-front distortion of the LSAW aptasensor were confirmed by COMSOL simulation and test results. The newly-developed sensing film monolayer MoS₂/Au NPs/Apt/6-mercaptohexanol (MCH) was applied for the specific detection of AFP and significantly improved the sensitivity of the LSAW aptasensor. The excellent performance of the LSAW aptasensor allowed the sensitive and rapid detection of AFP in serum in the range of 0.01 ⁓ 100 ng/mL with a low detection limit of 4.79 pg/mL. Additionally, the proposed LSAW aptasensor exhibited excellent selectivity, long-term stability, and reproducibility, and could be used to detect other cancer biomarkers.

Design Strategies for Electrochemical Aptasensors for Cancer Diagnostic Devices

Improved outcomes for many types of cancer achieved during recent years is due, among other factors, to the earlier detection of tumours and the greater availability of screening tests. With this, non-invasive, fast and accurate diagnostic devices for cancer diagnosis strongly improve the quality of healthcare by delivering screening results in the most cost-effective and safe way. Biosensors for cancer diagnostics exploiting aptamers offer several important advantages over traditional antibodies-based assays, such as the in-vitro aptamer production, their inexpensive and easy chemical synthesis and modification, and excellent thermal stability. On the other hand, electrochemical biosensing approaches allow sensitive, accurate and inexpensive way of sensing, due to the rapid detection with lower costs, smaller equipment size and lower power requirements. This review presents an up-to-date assessment of the recent design strategies and analytical performance of the electrochemical aptamer-based biosensors for cancer diagnosis and their future perspectives in cancer diagnostics.

Electrochemical aptasensor for analyzing alpha-fetoprotein using RGO-CS-Fc nanocomposites integrated with gold-platinum nanoparticles

Herein, a label-free electrochemical aptasensor for alpha-fetoprotein (AFP) analysis was established. The AFP aptamer (AFP-Apt), as the recognition molecule, was immobilized on the surface of a screen-printed carbon electrode, which was modified by gold-platinum metallic nanoparticles and reduced graphene oxide-chitosan-ferrocene nanohybrids (Au-Pt NPs/RGO-CS-Fc), to build the AFP electrochemical aptasensor. The construction process of the aptasensor was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and electrochemical impedance spectroscopy. With the addition of AFP, the formation of the AFP-aptamer conjugation blocked the electron transfer reaction, reducing the differential pulse voltammetric responses of the current of Fc in the RGO-CS-Fc nanohybrids. By optimizing the experimental parameters, AFP could be detected with the dynamic concentration range of 0.001 to 10.0 μg mL^-1 and with a detection limit of 0.3013 ng mL^-1. In addition, the approach was manifested to have good selectivity, reproducibility, and stability. The fabricated aptasensor had a good recovery rate of 102.36% to 118.09% in real human serum samples. This work demonstrates that the electrochemical aptasensor is a useful tool for analyzing AFP inexpensively, rapidly, and accurately.

Facile Synthesis of Co3O4-Incorporated Multichannel Carbon Nanofibers for Electrochemical Applications

Considering their superior electrochemical performances, extensive studies have been carried out on composite nanomaterials based on porous carbon nanofibers. However, the introduction of inorganic components into a porous structure is complex and has a low yield. In this study, we propose a simple synthesis of cobalt-oxide-incorporated multichannel carbon nanofibers (P-Co-MCNFs) as electrode materials for electrochemical applications. The cobalt oxide component is directly formed in the carbon structure by a simple oxygen plasma exposure of the phase-separated polymer nanofibers. P-Co-MCNF displays high specific capacitance (815 F g^-1 at 2.0 A g^-1), rate capability (821 F g^-1 at 1 A g^-1 and 786 F g^-1 at 20 A g^-1), and cycle stability (92.1% for 5000 cycles) as a supercapacitor electrode. Moreover, excellent sensitivity (down to 1 nM) and selectivity to the glucose molecule is demonstrated for nonenzyme sensor applications.

Application of Nanomaterials in Regulating the Fate of Adipose-derived Stem Cells

Adipose-derived stem cells are adult stem cells which are easy to obtain and multi-potent. Stem-cell therapy has become a promising new treatment for many diseases, and plays an increasingly important role in the field of tissue repair, regeneration and reconstruction. The physicochemical properties of the extracellular microenvironment contribute to the regulation of the fate of stem cells. Nanomaterials have stable particle size, large specific surface area and good biocompatibility, which has led them being recognized as having broad application prospects in the field of biomedicine. In this paper, we review recent developments of nanomaterials in adipose-derived stem cell research. Taken together, the current literature indicates that nanomaterials can regulate the proliferation and differentiation of adipose-derived stem cells. However, the properties and regulatory effects of nanomaterials can vary widely depending on their composition. This review aims to provide a comprehensive guide for future stem-cell research on the use of nanomaterials.

Metal-Free Chemoselective Hydrogenation of Nitroarenes by N-Doped Carbon Nanotubes via In Situ Polymerization of Pyrrole

Chemoselective hydrogenation of nitroarenes to anilines is of great importance for the manufacture of pharmaceuticals, fine chemicals, and dyes. In this study, a series of metal-free N-doped carbon nanotubes (NCNTs) have been prepared by the carbonization of in situ polymerized pyrrole on CNTs. The concentration of pyrrole, pyrolysis temperature, and the outside diameter of CNTs were investigated to improve the catalytic performance. As characterized by Raman and X-ray photoelectron spectroscopy (XPS), the optimal catalyst (NCNTs-800) possessed a unique structure doped with the same content of pyrrolic N and graphitic N. The activity and selectivity of NCNTs-800 have been evaluated for the selective hydrogenation of substituted nitroarenes. Highly selective hydrogenation of the nitro group of 12 different substrates has been achieved on NCNTs-800, even in the presence of a fragile iodo group. The hydrogenation reaction on N-doped CNTs from polypyrrole involved a mixture of different hydrogen species including nonpolar H radicals. In addition, stability and recyclability of NCNTs-800 have been tested.

Aptamers in nanostructure-based electrochemical biosensors for cardiac biomarkers and cancer biomarkers: A review

Heart disease (especially myocardial infarction (MI)) and cancer are major causes of death. Recently, aptasensors with the applying of different nanostructures have been able to provide new windows for the early and inexpensive detection of these deadly diseases. Early, inexpensive, and accurate diagnosis by portable devices, especially aptasensors can increase the likelihood of survival as well as significantly reduce the cost of treatment. In this review, recent studies based on the designed aptasensors for the diagnosis of these diseases were collected, ordered, and reviewed. The biomarkers for the diagnosis of each disease were discussed separately. The primary constituent elements of these aptasensors including, analyte, aptamer sequence, type of nanostructure, diagnostic technique, analyte detection range, and limit of detection (LOD), were evaluated and compared.