Self-assembled chitosan polymer intercalating peptide functionalized gold nanoparticles as nanoprobe for efficient imaging of urokinase plasminogen activator receptor in cancer diagnostics

Micro/nanoengineered agricultural by-products for biomedical and environmental applications

Agriculturally derived by-products generated during the growth cycles of living organisms as secondary products have attracted increasing interest due to their wide range of biomedical and environmental applications. These by-products are considered promising candidates because of their unique characteristics including chemical stability, profound biocompatibility and offering a green approach by producing the least impact on the environment. Recently, micro/nanoengineering based techniques play a significant role in upgrading their utility, by controlling their structural integrity and promoting their functions at a micro and nano scale. Specifically, they can be used for biomedical applications such as tissue regeneration, drug delivery, disease diagnosis, as well as environmental applications such as filtration, bioenergy production, and the detection of environmental pollutants. This review highlights the diverse role of micro/nano-engineering techniques when applied on agricultural by-products with intriguing properties and upscaling their wide range of applications across the biomedical and environmental fields. Finally, we outline the future prospects and remarkable potential that these agricultural by-products hold in establishing a new era in the realms of biomedical science and environmental research.

Design and fabrication of a competitive lateral flow assay using gold nanoparticle as capture probe for the rapid and on-site detection of penicillin antibiotic in food samples

Lateral flow assays (LFAs) are among the utmost cost-efficient, paper-based point-of-care (POC) diagnostic devices. Herein, we have reported the fabrication of a competitive LFA for on-site detection of penicillin. Various parameters such as Ab concentration for conjugation, Pen-BSA conjugate concentration, pore size of membrane, and blocking buffer were standardised for the fabrication of LFA. Different concentrations of penicillin (1 pM-1 mM) were added to the sample pad to observe the color intensity. The visual detection limit (LOD) achieved from the LFA was 10 nM for Penicillin that correlated with the LOD calculated from the 'ColorGrab' colorimeter application. Additionally, LFA showed insignificant cross reactivity with other β-lactam antibiotics and were also validated with spiked food samples such as milk, meat and egg. Hence, the fabricated LFA can be successfully utilised for the POC detection of penicillin in food samples on large scale.

Multifunctional polysaccharide nanoprobes for biological imaging

Imaging and tracking biological targets or processes play an important role in revealing molecular mechanisms and disease states. Bioimaging via optical, nuclear, or magnetic resonance techniques enables high resolution, high sensitivity, and high depth imaging from the whole animal down to single cells via advanced functional nanoprobes. To overcome the limitations of single-modality imaging, multimodality nanoprobes have been engineered with a variety of imaging modalities and functionalities. Polysaccharides are sugar-containing bioactive polymers with superior biocompatibility, biodegradability, and solubility. The combination of polysaccharides with single or multiple contrast agents facilitates the development of novel nanoprobes with enhanced functions for biological imaging. Nanoprobes constructed with clinically applicable polysaccharides and contrast agents hold great potential for clinical translations. This review briefly introduces the basics of different imaging modalities and polysaccharides, then summarizes the recent progress of polysaccharide-based nanoprobes for biological imaging in various diseases, emphasizing bioimaging with optical, nuclear, and magnetic resonance techniques. The current issues and future directions regarding the development and applications of polysaccharide nanoprobes are further discussed.

Nano-assembly of multiwalled carbon nanotubes for sensitive voltammetric responses for the determination of residual levels of endosulfan

Endosulfan (ES) is an extensively utilized agricultural pesticide in developing countries, despite its life-threatening toxic effects. In this study, we propose a sensitive detection method against endosulfan using multiwalled carbon nanotubes (MWCNT). Herein, we have conjugated endosulfan with bovine serum albumin (BSA) via zero-length conjugation method and successfully confirmed with various biophysical techniques. Endosulfan antibodies (ES-Ab) were raised in-house, fabricated on electrodes coupled with MWCNT, and optimized to achieve maximum peak current by varying the parameters such as MWCNT and antibody concentration, scan rate, temperature, pH, and response time using voltammetry. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and impedance spectroscopies (IS) were performed for electrochemical analysis. The fabricated immunosensor was also evaluated for its cross reactivity with isodrin, chlorpyrifos, and monocrotophos. The limit of detection for ES was found to be 0.184 ppt in standard buffer (range 0.001 ppt-100 ppb). Additionally, spiked ES in water, animal feed, root, and leaf extract samples were also analyzed and validated by HPLC. To summarize, the fabricated electrode can be used for successful detection of endosulfan in the agricultural sector to elude the lethal effect at large.

Emerging 0D, 1D, 2D, and 3D nanostructures for efficient point-of-care biosensing

The recent COVID-19 infection outbreak has raised the demand for rapid, highly sensitive POC biosensing technology for intelligent health and wellness. In this direction, efforts are being made to explore high-performance nano-systems for developing novel sensing technologies capable of functioning at point-of-care (POC) applications for quick diagnosis, data acquisition, and disease management. A combination of nanostructures [i.e., 0D (nanoparticles & quantum dots), 1D (nanorods, nanofibers, nanopillars, & nanowires), 2D (nanosheets, nanoplates, nanopores) & 3D nanomaterials (nanocomposites and complex hierarchical structures)], biosensing prototype, and micro-electronics makes biosensing suitable for early diagnosis, detection & prevention of life-threatening diseases. However, a knowledge gap associated with the potential of 0D, 1D, 2D, and 3D nanostructures for the design and development of efficient POC sensing is yet to be explored carefully and critically. With this focus, this review highlights the latest engineered 0D, 1D, 2D, and 3D nanomaterials for developing next-generation miniaturized, portable POC biosensors development to achieve high sensitivity with potential integration with the internet of medical things (IoMT, for miniaturization and data collection, security, and sharing), artificial intelligence (AI, for desired analytics), etc. for better diagnosis and disease management at the personalized level.

Functionalized Silver and Gold Nanomaterials with Diagnostic and Therapeutic Applications

The functionalization of nanomaterials with suitable capping ligands or bioactive agents is an interesting strategy in designing nanosystems with suitable applicability and biocompatibility; the physicochemical and biological properties of these nanomaterials can be highly improved for biomedical applications. In this context, numerous explorations have been conducted in the functionalization of silver (Ag) and gold (Au) nanomaterials using suitable functional groups or agents to design nanosystems with unique physicochemical properties such as excellent biosensing capabilities, biocompatibility, targeting features, and multifunctionality for biomedical purposes. Future studies should be undertaken for designing novel functionalization tactics to improve the properties of Au- and Ag-based nanosystems and reduce their toxicity. The possible release of cytotoxic radicals or ions, the internalization of nanomaterials, the alteration of cellular signaling pathways, the translocation of these nanomaterials across the cell membranes into mitochondria, DNA damages, and the damage of cell membranes are the main causes of their toxicity, which ought to be comprehensively explored. In this study, recent advancements in diagnostic and therapeutic applications of functionalized Au and Ag nanomaterials are deliberated, focusing on important challenges and future directions.

Cyclic RGD functionalized PLGA nanoparticles loaded with noncovalent complex of indocyanine green with urokinase for synergistic thrombolysis

Thrombotic diseases have the characteristics of long latency period, rapid onset, and high mortality rate, which seriously threaten people’s life and health. The aim of this research is to fabricate a novel indocyanine green complex of urokinase (ICG@uPA) and employ the amphiphilic PEG-PLGA polymer to deliver the complex as an enzyme-phototherapeutic synergistic thrombolysis platform. The noncovalent indocyanine green (ICG) complex of urokinase (ICG@uPA) was prepared via supramolecular self-assembly and then encapsulated into cRGD decorated polymeric nanoparticles (cRGD-ICG-uPA NPs) by double-emulsion solvent evaporation method. Then the nanoparticles (NPs) were characterized in terms of particle size, optical properties, in vitro release, etc. The targeting and thrombolytic effect of the nanoparticles were studied both in vitro and in vivo. ICG@uPA and cRGD-ICG-uPA NPs displayed significantly higher photostability and laser energy conversion efficiency than free ICG. Concomitantly, the NPs exhibited selective binding affinity to the activated platelets and specific accumulation in the mouse mesenteric vessel thrombus. Significant thrombolysis was achieved in vivo by photo-assisted synergistic therapy with reduced dose and systemic bleeding risk of uPA. Our results prove that the functional PLGA nanoparticle loaded with the ICG@uPA offers a novel option for effective and safe thrombolytic treatment.

Polymeric biocompatible iron oxide nanoparticles labeled with peptides for imaging in ovarian cancer

Compared with other nanomaterials, surface-modified iron oxide nanoparticles (IONPs) have gained attraction for cancer therapy applications due to its low toxicity, and long retention time. An innocuous targeting strategy was developed by generation of fluorescein isothiocyanate (FITC)-labeled peptide (growth factor domain (GFD) and somatomedin B domain (SMB)) functionalized, chitosan-coated IONPs (IONPs/C). It can be used to target urokinase plasminogen activator receptor (uPAR), which is a surface biomarker, in ovarian cancer. Binding affinity between uPAR and peptides (GFD and SMB) were revealed by in-silico docking studies. The biophysical characterizations of IONPs, IONPs/C, and IONPs/C/GFD-FITC or SMB-FITC nanoprobes were assessed via Vibrating Sample Magnetometer (VSM), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), and Fourier Transform Infrared Spectroscopy (FT-IR). Prussian Blue staining, fluorescence spectroscopy, and fluorescence imaging were performed to confirm the targeting of nanoprobes with the surface receptor uPAR. The combination of IONPs/C/GFD+SMB showed efficient targeting of uPAR in the tumor microenvironment, and thus can be implemented as a molecular magnetic nanoprobe for cancer cell imaging and targeting.

Label-free detection of SARS-CoV-2 Spike S1 antigen triggered by electroactive gold nanoparticles on antibody coated fluorine-doped tin oxide (FTO) electrode

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, also known as 2019-nCov or COVID-19) outbreak has become a huge public health issue due to its rapid transmission making it a global pandemic. Here, we report fabricated fluorine doped tin oxide (FTO) electrodes/gold nanoparticles (AuNPs) complex coupled with in-house developed SARS-CoV-2 spike S1 antibody (SARS-CoV-2 Ab) to measure the response with Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV). The biophysical characterisation of FTO/AuNPs/SARS-CoV-2Ab was done via UV-Visible spectroscopy, Dynamic Light Scattering (DLS), and Fourier Transform Infrared Spectroscopy (FT-IR). The fabricated FTO/AuNPs/SARS-CoV-2Ab immunosensor was optimised for response time, antibody concentration, temperature, and pH. Under optimum conditions, the FTO/AuNPs/Ab based immunosensor displayed high sensitivity with limit of detection (LOD) up to 0.63 fM in standard buffer and 120 fM in spiked saliva samples for detection of SARS-CoV-2 spike S1 antigen (Ag) with negligible cross reactivity Middle East Respiratory Syndrome (MERS) spike protein. The proposed FTO/AuNPs/SARS-CoV-2Ab based biosensor proved to be stable for up to 4 weeks and can be used as an alternative non-invasive diagnostic tool for the rapid, specific and sensitive detection of SARS-CoV-2 Spike Ag traces in clinical samples.

Chitosan Functionalization: Covalent and Non-Covalent Interactions and Their Characterization

Chitosan (CS) is a natural biopolymer that has gained great interest in many research fields due to its promising biocompatibility, biodegradability, and favorable mechanical properties. The versatility of this low-cost polymer allows for a variety of chemical modifications via covalent conjugation and non-covalent interactions, which are designed to further improve the properties of interest. This review aims at presenting the broad range of functionalization strategies reported over the last five years to reflect the state-of-the art of CS derivatization. We start by describing covalent modifications performed on the CS backbone, followed by non-covalent CS modifications involving small molecules, proteins, and metal adjuvants. An overview of CS-based systems involving both covalent and electrostatic modification patterns is then presented. Finally, a special focus will be given on the characterization techniques commonly used to qualify the composition and physical properties of CS derivatives.

Simultaneous Stabilization and Functionalization of Gold Nanoparticles via Biomolecule Conjugation: Progress and Perspectives

Gold nanoparticles (AuNPs) are used in various biological applications because of their small surface area-to-volume ratios, ease of synthesis and modification, low toxicity, and unique optical properties. These properties can vary significantly with changes in AuNP size, shape, composition, and arrangement. Thus, the stabilization of AuNPs is crucial to preserve the properties required for biological applications. In recent years, various polymer-based physical and chemical methods have been extensively used for AuNP stabilization. However, a new stabilization approach using biomolecules has recently attracted considerable attention. Biomolecules such as DNA, RNA, peptides, and proteins are representative of the biomoieties that can functionalize AuNPs. According to several studies, biomolecules can stabilize AuNPs in biological media; in addition, AuNP-conjugated biomolecules can retain certain biological functions. Furthermore, the presence of biomolecules on AuNPs significantly enhances their biocompatibility. This review provides a representative overview of AuNP functionalization using various biomolecules. The strategies and mechanisms of AuNP functionalization using biomolecules are comprehensively discussed in the context of various biological fields.

Urokinase Plasminogen Activator Receptor-Mediated Targeting of a Stable Nanocomplex Coupled with Specific Peptides for Imaging of Cancer

Targeting peptides are a promising tool for early diagnosis and therapy of cancer. Overexpression of urokinase plasminogen activator receptor (uPAR) leads to the progression of tumors including prostate, colorectal, ovarian, and breast cancers. To improve the diagnosis and imaging efficiency, herein we report a stable nanocomplex comprising methoxy-PEG-hydrazide (mPEG-H-M)-modified gold nanoparticles (AuNPs) conjugated to uPAR (urokinase plasminogen activator receptor)-targeting peptides GFD (growth factor domain-G) and SMB (somatomedian B-S) for efficient imaging of uPAR-overexpressing cancer cells. Fluorescently labeled targeting peptides were covalently linked to mPEG-H coated AuNPs, characterized, and analyzed by UV-vis spectroscopy, diffraction light scattering (DLS), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and fluorescence spectroscopy. In vitro evaluation was assessed with a fluorescence-activated cell sorter (FACS), cell adhesion, and fluorescence microscopy. The peptide-functionalized nanocomplex showed a higher uptake of AuNPs@MGS in comparison with AuNPs@G or AuNPs@S alone in uPAR-overexpressing cells and exhibits no toxicity when analyzed with MTT assay. Our results demonstrated that the developed nanocomplex can be used as a platform for imaging and diagnosis of metastatic tumors.