Green synthesis of bioactive polysaccharide-capped gold nanoparticles for lymph node CT imaging

HAuCl4-mediated green synthesis of highly stable Au NPs from natural active polysaccharides: Synthetic mechanism and antioxidant property

Polysaccharide-functionalized gold nanoparticles (Polysaccharide-Au NPs) with high stability were successfully prepared by a straightforward method. Notably, the Au (III) ion acts as a strong Lewis acid to facilitate glycosidic bond breaking. Subsequently, the polysaccharide conformation was transformed to an open-chain form, exposing highly reduced aldehyde or ketone groups that reduce Au (III) to Au (0) crystal species, further growing into Au NPs. As-prepared Au NPs displayed excellent stability over a longer storage period (more than 70 days), a wide range of temperatures (25-60 °C), and pH range (3-11), varying concentrations (0-200 mM) and types of salt ions (Na+, K+, Ca2+, Mg2+), and glutathione solutions (5 mM). More interestingly, polysaccharide-Au NPs retained the antioxidant activity of polysaccharides and reduced oxidative damage at the cellular level through decreased reactive oxygen species (ROS) production. The intracellular levels of ROS pretreated with polysaccharide and polysaccharide-Au NPs were decreased 53.12-75.85 % compared to the H2O2 group, respectively. Therefore, the green synthesized Au NPs from natural active polysaccharides exhibit potential applications in biomedical fields.

Polysaccharide-based gold nanomaterials: Synthesis mechanism, polysaccharide structure-effect, and anticancer activity

Polysaccharide-based gold nanomaterials have attracted great interest in biomedical fields such as cancer therapy and immunomodulation due to their prolonged residence time in vivo and enhanced immune response. This review aims to provide an up-to-date and comprehensive summary of polysaccharide-based Au NMs synthesis, including mechanisms, polysaccharide structure-effects, and anticancer activity. Firstly, research progress on the synthesis mechanism of polysaccharide-based Au NMs was addressed, which included three types based on the variety of polysaccharides and reaction environment: breaking of glycosidic bonds via Au (III) or base-mediated production of highly reduced intermediates, reduction of free hydroxyl groups in polysaccharide molecules, and reduction of free amino groups in polysaccharide molecules. Then, the potential effects of polysaccharide structure characteristics (molecular weight, composition of monosaccharides, functional groups, glycosidic bonds, and chain conformation) and reaction conditions (the reaction temperature, reaction time, pH, concentration of gold precursor and polysaccharides) on the size and shape of Au NMs were explored. Finally, the current status of polysaccharide-based Au NMs cancer therapy was summarized before reaching our conclusions and perspectives.

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.

Process Optimization for the Bioinspired Synthesis of Gold Nanoparticles Using Cordyceps militaris, Its Characterization, and Assessment of Enhanced Therapeutic Efficacy

The promising therapeutic implications of nanoparticles have spurred their development for biomedical applications. An eco-friendly methodology synthesizes gold nanoparticles using Cordyceps militaris, an edible mushroom (Cord-Au-NPs), using a quality-by-design approach (central composite design). UV-visible spectroscopy analysis revealed an absorption peak at 540-550 nm, thus confirming the synthesis of gold nanoparticles. Cord-Au-NPs have a crystalline structure, as evidenced by the diffraction peaks. The zeta potential value of -19.42 mV signifies the stability of Cord-Au-NPs. XRD study shows gold facets and EDX analysis revealed a strong peak of spherical nanoparticles in the gold region with a mean particle size of 7.18 nm and a polydispersity index of 0.096. The obtained peaks are closely associated with phenolic groups, lipids, and proteins, as examined by FTIR, suggesting that they function as the reducing agent. Cord-Au-NPs exhibited dose-dependent antioxidant, antidiabetic, and antibacterial activity. The method is eco-friendly, nontoxic, less time-consuming, and does not use synthetic materials, leading to higher capabilities in biomedical applications.

Nanoparticles for Lymph Node-Directed Delivery

Lymph nodes are organs that control immune cells and provide a major pathway for primary tumors to metastasize. A nanoparticles-based strategy has several advantages that make it suitable for achieving effective lymphatic delivery. First, the size of nanoparticles can be tailored to meet a size range appropriate for lymphatic migration. In addition, functionalized nanoparticles can target cells of interest for delivery of drugs or imaging probes. Existing lymph node contrast agents map all lymph nodes regardless of metastasis status; however, by using nanoparticles, it is possible to selectively target lymphatic metastases. Moreover, using functionalized nanoparticles, it is possible to specifically deliver anticancer drugs to metastatic lymph nodes. In this review, we introduce the use of nanoparticles for lymphatic mapping, in particular highlighting design considerations for detecting metastatic lymph nodes. Furthermore, we assess trends in lymph node-targeting nanoparticles in clinical practice and suggest future directions for lymph node-targeting nanoparticles.

Locoregional Lymphatic Delivery Systems Using Nanoparticles and Hydrogels for Anticancer Immunotherapy

The lymphatic system has gained significant interest as a target tissue to control cancer progress, which highlights its central role in adaptive immune response. Numerous mechanistic studies have revealed the benefits of nano-sized materials in the transport of various cargos to lymph nodes, overcoming barriers associated with lymphatic physiology. The potential of sustained drug delivery systems in improving the therapeutic index of various immune modulating agents is also being actively discussed. Herein, we aim to discuss design rationales and principles of locoregional lymphatic drug delivery systems for invigorating adaptive immune response for efficient antitumor immunotherapy and provide examples of various advanced nanoparticle- and hydrogel-based formulations.

Polysaccharide-Based Theranostic Systems for Combined Imaging and Cancer Therapy: Recent Advances and Challenges

Designing novel systems for efficient cancer treatment and improving the quality of life for patients is a prime requirement in the healthcare sector. In this regard, theranostics have recently emerged as a unique platform, which combines the benefits of both diagnosis and therapeutics delivery. Theranostics have the desired contrast agent and the drugs combined in a single carrier, thus providing the opportunity for real-time imaging to monitor the therapy results. This helps in reducing the hazards related to treatment overdose or underdose and gives the possibility of personalized therapy. Polysaccharides, as natural biomolecules, have been widely explored to develop theranostics, as they act as a matrix for simultaneously loading both contrast agents and drugs for their utility in drug delivery and imaging. Additionally, their remarkable physicochemical attributes (biodegradability, satisfactory safety profile, abundance, and diversity in functionality and charge) can be tuned via postmodification, which offers numerous possibilities to develop theranostics with desired characteristics. Hence, we provide an overview of recent advances in polysaccharide matrix-based theranostics for drug delivery combined with magnetic resonance imaging, computed tomography, positron emission tomography, single photon emission computed tomography, and ultrasound imaging. Herein, we also summarize the toxicity assessment of polysaccharides, associated contrast agents, and nanotoxicity along with the challenges and future research directions.

Multifunctional Gold Nanoparticles for Improved Diagnostic and Therapeutic Applications: A Review

The medical properties of metals have been explored for centuries in traditional medicine for the treatment of infections and diseases and still practiced to date. Platinum-based drugs are the first class of metal-based drugs to be clinically used as anticancer agents following the approval of cisplatin by the United States Food and Drug Administration (FDA) over 40 years ago. Since then, more metals with health benefits have been approved for clinical trials. Interestingly, when these metals are reduced to metallic nanoparticles, they displayed unique and novel properties that were superior to their bulk counterparts. Gold nanoparticles (AuNPs) are among the FDA-approved metallic nanoparticles and have shown great promise in a variety of roles in medicine. They were used as drug delivery, photothermal (PT), contrast, therapeutic, radiosensitizing, and gene transfection agents. Their biomedical applications are reviewed herein, covering their potential use in disease diagnosis and therapy. Some of the AuNP-based systems that are approved for clinical trials are also discussed, as well as the potential health threats of AuNPs and some strategies that can be used to improve their biocompatibility. The reviewed studies offer proof of principle that AuNP-based systems could potentially be used alone or in combination with the conventional systems to improve their efficacy.

Innovations in lymph node targeting nanocarriers

Lymph nodes are secondary lymphoid tissues in the body that facilitate the co-mingling of immune cells to enable and regulate the adaptive immune response. They are also tissues implicated in a variety of diseases, including but not limited to malignancy. The ability to access lymph nodes is thus attractive for a variety of therapeutic and diagnostic applications. As nanotechnologies are now well established for their potential in translational biomedical applications, their high relevance to applications that involve lymph nodes is highlighted. Herein, established paradigms of nanocarrier design to enable delivery to lymph nodes are discussed, considering the unique lymph node tissue structure as well as lymphatic system physiology. The influence of delivery mechanism on how nanocarrier systems distribute to different compartments and cells that reside within lymph nodes is also elaborated. Finally, current advanced nanoparticle technologies that have been developed to enable lymph node delivery are discussed.

Synthesis, Characterization, Applications, and Toxicity of Green Synthesized Nanoparticles

Nanotechnology is a cutting-edge area with numerous industrial applications. Nanoparticles are structures that have dimensions ranging from 1-100 nm which exhibit significantly different mechanical, optical, electrical, and chemical properties when compared with their larger counterparts. Synthetic routes that use natural sources, such as plant extracts, honey, and microorganisms are environmentally friendly and low-cost methods that can be used to obtain nanoparticles. These methods of synthesis generate products that are more stable and less toxic than those obtained using conventional methods. Nanoparticles formed by titanium dioxide, zinc oxide, silver, gold, and copper, as well as cellulose nanocrystals are among the nanostructures obtained by green synthesis that have shown interesting applications in several technological industries. Several analytical techniques have also been used to analyze the size, morphology, hydrodynamics, diameter, and chemical functional groups involved in the stabilization of the nanoparticles as well as to quantify and evaluate their formation. Despite their pharmaceutical, biotechnological, cosmetic, and food applications, studies have detected their harmful effects on human health and the environment; and thus, caution must be taken in uses involving living organisms. The present review aims to present an overview of the applications, the structural properties, and the green synthesis methods that are used to obtain nanoparticles, and special attention is given to those obtained from metal ions. The review also presents the analytical methods used to analyze, quantify, and characterize these nanostructures.

New insights into the synthesis, toxicity and applications of gold nanoparticles in CT imaging and treatment of cancer

The past decades have witnessed enormous development of gold nanoparticles (AuNPs) and their applications in the biomedical field, an area in which they show infinite potential. Abundant investigations have been conducted in improving AuNP synthesis, aimed at obtaining water-dispersible ultrasmall AuNPs, which can exhibit biocompatibility, renal clearance and minimal toxicity. Due to their excellent x-ray attenuation ability, special optical properties and surface modification properties, AuNPs are reported to be promising as computed tomography contrast agents and can be applied in radiotherapy, photothermal and photodynamic therapies, and drug delivery. In this review, synthesis methods and toxicity of AuNPs have been summarized, emphasizing the preparation of ultra-small AuNPs. Applications of AuNPs in computed tomography imaging and cancer treatment are also considered, revealing their potential in the clinic.

A Dendrimer-Based Dual Radiodense Element-Containing Nanoplatform for Targeted Enhanced Tumor Computed Tomography Imaging

The exploration of original computed tomography (CT) imaging contrast agents with enhanced sensitivity and specificity is currently one of the major challenging tasks for precision medicine. Herein, we develop an innovative nanoprobe of dendrimer-stabilized gold nanoparticles (Au DSNs) linked with folic acid (FA) as a targeting ligand and diatrizoic acid (DTA) for specific enhanced tumor CT imaging. In current work, poly(amidoamine) (PAMAM) dendrimers of generation 5 (G5) with amine termini were adopted to entrap Au NPs through a stepwise complexation/reduction method to achieve a higher Au loading than the conventional one-step complexation/reduction method. The prepared [(Au⁰)₁₂₀-G5.NH₂] NPs were sequentially functionalized with diatrizoic acid (DTA), a typical CT contrast agent based on iodine(I), FA through a poly(ethylene glycol) (PEG) spacer, and carboxylated PEG monomethyl ether (mPEG-COOH), ended with complete acetylation of the leftover dendrimer amine termini. The generated Au DSNs-DTA-FA (Au core diameter = 5.9 nm) were thoroughly characterized. Our data reveal that the Au DSNs-DTA-FA containing Au and I dual radiodense elements are stable, display enhanced CT imaging performance, much higher than the single-radiodense elemental material solely based on Au or I, and possess a quite good cytocompatibility. With the demonstrated FA-rendered specific targeting, the developed Au DSNs-DTA-FA can be employed as a highly efficient nanoprobe for targeted enhanced CT imaging of cancer cells and a subcutaneous tumor model. Overall, the created Au DSNs-DTA-FA may be a powerful nanoprobe for specific enhanced CT imaging of various kinds of FA receptor-expressing tumors or biosystems.

Protecting the Normal Physiological Functions of Articular and Periarticular Structures by Aurum Nanoparticle-Based Formulations: an Up-to-Date Insight

Taking the articular and periarticular structures as a litmus test for gold-based nanoformulations, the potential of gold nanoparticles in protecting the normal physiological functions of these structures particularly in geriatric patients is one of the research areas of current interest. Aside from its use to make the traditional and fashionable ornaments for human usage, the gold metal is also known for its rich therapeutic activity. This is especially true when the gold is converted from its bulk form into nanosized form before its administering into the human body. Since it is the age of nanocomponents in medical and pharmaceutical research areas, this review is therefore mainly focused on nanoparticulate systems consisting of aurum. Accumulating research reports nevertheless show concrete evidence indicating the potential of gold-based nanoformulations to manage joint syndromes such as osteoarthritis and rheumatoid arthritis. This review embarks from preparation techniques and characterization methods to therapeutical application potentials of gold-based nanoformulations.

Optimizing a Novel Au-Grafted Lipid Nanoparticle Through Chelation Chemistry for High Photothermal Biologic Activity

Gold nanoparticles through nucleation of Au clusters have been extensively studied. However, due to low potency, prolonged tissue retention, and irreversible accumulation, the safety considerations have limited their therapeutic and diagnostic applications. Novel gold nanostructures with retained physical properties and higher biodegradability could be prepared by alternative approaches. Previously, a lipid nanoparticle (LNP) platform carrying gadolinium (Gd³⁺) has been reported to eliminate through the biliary without accumulation in the liver or kidney within 24 h. Inspired by this discovery, we investigated a new approach of forming gold nanoparticles using preformed LNPs grafting diethylenetriamine-pentaacetic acid as a chelating agent. Tiny Au nanoparticles are formed by simply mixing Au³⁺ with preformed diethylenetriamine-pentaacetic acid-LNP. The Au³⁺ associates stably to these LNPs after a systematic optimization. The Au-grafted LNPs are scalable and showed excellent photothermal effects when subjected to near-infrared light irradiation. They exhibit enhanced light-induced tumor cell killing at higher efficiency, compared with that of classical gold nanoparticles (citrated reduced). Given an additional small dose (2 Gy) of gamma irradiation, Au-grafted LNP could produce synergistic photothermal and radiotherapeutic effects under reduced light dose. The simple and adaptive nanoparticle design may enhance the margin of safety of gold nanoparticles in the treatment of cancers and other diseases.

Multifunctionality of gold nanoparticles: Plausible and convincing properties

In a couple of decades, nanotechnology has become a trending area in science due to it covers all subject that combines diverse range of fields including but not limited to chemistry, physics and medicine. Various metal and metal oxide nanomaterials have been developed for wide range applications. However, the application of gold nanostructures and nanoparticles has been received more attention in various biomedical applications. The unique property of gold nanoparticles (AuNPs) is surface plasmon resonance (SPR) that determine the size, shape and stability. The wide surface area of AuNPs eases the proteins, peptides, oligonucleotides, and many other compounds to tether and enhance the biological activity of AuNPs. AuNPs have multifunctionality including antimicrobial, anticancer, drug and gene delivery, sensing applications and imaging. This state-of-the-art review is focused on the role of unique properties of AuNPs in multifunctionality and its various applications.

Plasmonic gold nanoparticles: Optical manipulation, imaging, drug delivery and therapy

Over the past two decades, the development of plasmonic nanoparticle (NPs), especially gold (Au) NPs, is being pursued more seriously in the medical fields such as imaging, drug delivery, and theranostic systems. However, there is no comprehensive review on the effect of the physical and chemical parameters of AuNPs on their plasmonic properties as well as the use of these unique characteristic in medical activities such as imaging and therapeutics. Therefore, in this literature the surface plasmon resonance (SPR) modeling of AuNPs was accurately captured toward precision medicine. Indeed, we investigated the importance of plasmonic properties of AuNPs in optical manipulation, imaging, drug delivery, and photothermal therapy (PTT) of cancerous cells based on their physicochemical properties. Finally, some challenges regarding the commercialization of AuNPs in future medicine such as, cytotoxicity, lack of standards for medical applications, high cost, and time-consuming process were discussed.

Recent progress in the industrial and biomedical applications of tragacanth gum: A review

Natural polymers have distinct advantages over synthetic polymers because of their abundance, biocompatibility, and biodegradability. Tragacanth gum, an anionic polysaccharide, is a natural polymer which is derived from renewable sources. As a biomaterial, tragacanth gum has been used in industrial settings such as food packaging and water treatment, as well as in the biomedical field as drug carriers and for wound healing purposes. The present review provides an overview on the state-of-the-art in the field of tragacanth gum applications. The structure, properties, cytotoxicity, and degradability as well as the recent advances in industrial and biomedical applications of tragacanth gum are reviewed to offer a backdrop for future research.

Green synthesis of multifunctional PEG-carboxylate π back-bonded gold nanoconjugates for breast cancer treatment

BACKGROUND

Surface functionalization of gold nanoparticles (AuNPs) has emerged as a promising field of research with enormous biomedical applications. The folate (FA)-attached polymer-gold nanoconjugates play vital role in targeting the cancer cells.

METHODS

AuNPs were synthesized by using di- or tri-carboxylate-polyethylene glycol (PEG) polymers, including citrate-PEG (CPEG), malate-PEG (MAP), and tartrate-PEG (TAP), as a reducing and stabilizing agent. After synthesis of polymer-AuNPs, the freely available hydroxyl and carboxylate groups of CPEG, MAP, and TAP were used to attach a cancer cell-targeting agent, FA, via a 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxy succinimide coupling reaction to obtain FA-CPEG-AuNP, FA-MAP-AuNP, and FA-TAP-AuNP nanocon-jugates, respectively. The 5-fluorouracil (5FU) was attached to π back-bonded carbonyl oxygens of the nanoconjugates, and the in vitro drug release profile was studied by high pressure liquid chromatography. Biocompatibility profiles of the FA-CPEG-AuNP, FA-MAP-AuNP, and FA-TAP-AuNP nanoconjugates were investigated using adult human dermal fibroblasts. Anti-breast cancer activity of 5FU-loaded nanoconjugates was investigated using MCF-7 breast cancer cells.

RESULTS

X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy analyses confirmed that AuNPs attached to CPEG, MAP, or TAP via the formation of π back bonding between AuNPs and the ester carbonyl group. The π back-bonded nanoconjugates exhibited sustained release of 5FU up to 27 days. FA-MAP-AuNPs exhibited an IC50 at 5 µg/mL, while FA-CPEG-AuNPs and FA-TAP-AuNPs showed the IC50 at 100 µg/mL toward MCF-7 cancer cells.

CONCLUSION

The developed polymer π back-bonded multifunctional gold nanoconjugates could be used as a potential drug delivery system for targeting MCF-7 cancer cells.

Synthesis of Gold Nanoparticles Using Leaf Extract of Ziziphus zizyphus and their Antimicrobial Activity

(1) Background: There is a growing need for the development of new methods for the synthesis of nanoparticles. The interest in such particles has raised concerns about the environmental safety of their production methods; (2) Objectives: The current methods of nanoparticle production are often expensive and employ chemicals that are potentially harmful to the environment, which calls for the development of “greener” protocols. Herein we describe the synthesis of gold nanoparticles (AuNPs) using plant extracts, which offers an alternative, efficient, inexpensive, and environmentally friendly method to produce well-defined geometries of nanoparticles; (3) Methods: The phytochemicals present in the aqueous leaf extract acted as an effective reducing agent. The generated AuNPs were characterized by Transmission electron microscopy (TEM), Scanning electron microscope (SEM), and Atomic Force microscopy (AFM), X-ray diffraction (XRD), UV-visible spectroscopy, energy dispersive X-ray (EDX), and thermogravimetric analyses (TGA); (4) Results and Conclusions: The prepared nanoparticles were found to be biocompatible and exhibited no antimicrobial or antifungal effect, deeming the particles safe for various applications in nanomedicine. TGA analysis revealed that biomolecules, which were present in the plant extract, capped the nanoparticles and acted as stabilizing agents.