An overview of polymer surface coated synthetic quantum dots as therapeutics and sensors applications

Quantum dots (QDs) are a class of remarkable materials that have garnered significant attention since their initial discovery. It is noteworthy to mention that it took approximately a decade for these materials to be successfully implemented in practical applications. While QDs have demonstrated notable optical properties, it is important to note that these attributes alone have not rendered them a feasible substitute for traditional organic dyes. Furthermore, it is worth noting that the substance under investigation exhibited inherent toxicity and instability in its initial state, primarily due to the presence of a heavy metal core. In the initial stages of research, it was observed that the integration of nanocomposites had a positive impact on the properties of QDs. The discovery of these nanocomposites was motivated by the remarkable properties exhibited by biocomposites found in nature. Recent discoveries have shed light on the potential utilization of QDs as a viable strategy for drug delivery, offering a promising avenue to enhance the efficacy of current pharmaceuticals and pave the way for the creation of innovative therapeutic approaches. The primary objective of this review was to elucidate the distinctive characteristics that render QDs highly suitable for utilization as nanocarriers. In this study, we will delve into the multifaceted applications of QDs as sensing nanoprobes and their utilization in diverse drug delivery systems. The focus of our investigation was directed toward the utilization of QD/polymer composites in sensing applications, with particular emphasis on their potential as chemical sensors, biosensors, and physical sensors.

Molecular weight of hyaluronic acid crosslinked into biomaterial scaffolds affects angiogenic potential

While hyaluronic acid (HA)-based hydrogels have been used clinically for decades, the mechanisms by which HA exerts molecular weight-dependent bioactivity and how chemical modification and crosslinking may affect molecular weight-dependent bioactivity remain poorly understood. This knowledge gap presents a significant barrier to designing HA hydrogels with predictable bioactivities. As HA has been widely reported to have molecular weight-dependent effects on endothelial cells (ECs), we investigated how the molecular weight of HA in either soluble or crosslinked forms affects angiogenesis and interrogated CD44 clustering on the surface of endothelial cells as a candidate mechanism for these affects. Using soluble HA, our results show high molecular weight (HMW) HA, but not low molecular weight (LMW) HA, increased viability and tube formation in cultured human cerebral microvascular ECs (HCMVECs). No size of HA affected proliferation. When HCMVECs were cultured with crosslinked HA of varying molecular weights in the form of HA-based microporous annealed particle scaffold (HMAPS), the cell response was comparable to when cultured with soluble HA. Similarly, when implanted subcutaneously, HMAPS with HMW HA were more vascularized than those with LMW HA. We also show that antibody-mediated CD44 clustering resulted in HCMVECs with increased viability and tube-like structure formation in a manner comparable to exposure to HMW HA, suggesting that HMW acts through CD44 clustering. STATEMENT OF SIGNIFICANCE: Biomaterials based on hyaluronic acid (HA), a bioactive extracellular matrix polysaccharide, have been used in clinical products for several years. Despite the knowledge that HA molecular weight heavily influences its bioactivity, molecular weight has been largely ignored in the development of HA-based biomaterials. Given the high viscosity of high molecular weight HA typically found in native tissues, lower molecular weight polysaccharides have been used most commonly for biomaterial fabrication. By comparing the ability of injectable, microporous annealed particle scaffolds (MAPS) fabricated from variably sized HA to promote angiogenesis, this study demonstrates that MAPS with high molecular weight HA better support vascularization, likely through an unique ability to induce clustering of CD44 receptors on endothelial cells.

Automated Approach to In Vitro Image-Guided Photothermal Therapy with Top-Down and Bottom-Up-Synthesized Graphene Quantum Dots

Graphene-based materials have been the subject of interest for photothermal therapy due to their high light-to-heat conversion efficiency. Based on recent studies, graphene quantum dots (GQDs) are expected to possess advantageous photothermal properties and facilitate fluorescence image-tracking in the visible and near-infrared (NIR), while surpassing other graphene-based materials in their biocompatibility. Several GQD structures including reduced graphene quantum dots (RGQDs) derived from reduced graphene oxide via top-down oxidation and hyaluronic acid graphene quantum dots (HGQDs) hydrothermally bottom-up synthesized from molecular hyaluronic acid were employed to test these capabilities in the present work. These GQDs possess substantial NIR absorption and fluorescence throughout the visible and NIR beneficial for in vivo imaging while being biocompatible at up to 1.7 mg/mL concentrations. In aqueous suspensions, RGQDs and HGQDs irradiated with a low power (0.9 W/cm2) 808 nm NIR laser facilitate a temperature increase up to 47.0 °C, which is sufficient for cancer tumor ablation. In vitro photothermal experiments sampling multiple conditions directly in the 96-well plate were performed using an automated simultaneous irradiation/measurement system developed on the basis of a 3D printer. In this study, HGQDs and RGQDs facilitated the heating of HeLa cancer cells up to 54.5 °C, leading to the drastic inhibition of cell viability from over 80% down to 22.9%. GQD's fluorescence in the visible and NIR traces their successful internalization into HeLa cells maximized at 20 h suggesting both extracellular and intracellular photothermal treatment capabilities. The combination of the photothermal and imaging modalities tested in vitro makes the GQDs developed in this work prospective agents for cancer theragnostics.

Microfluidic chip enabled one-step synthesis of biofunctionalized CuInS2/ZnS quantum dots

Biofunctionalized quantum dots (QDs) are effective target fluorescent labels for bioimaging. However, conventional synthesis of biofunctionalized I-III-VI core-shell CuInS2/ZnS QDs requires complex bench-top operations, resulting in limited product performance and variety, and is not amenable to a 'one-step' approach. In this work, we have successfully demonstrated a fully automated method for preparing denatured bovine serum albumin (dBSA)-CuInS2/ZnS QDs by introducing microfluidic (MF) chips to synthesize biofunctionalized QDs, hence establishing a 'one-step' procedure. We have also studied and optimized the reaction synthesis parameters. The emission wavelength of the dBSA-CuInS2/ZnS QDs is located in the near-infrared range and can be tuned from 650 to 750 nm by simply varying the reaction parameters. In addition, the 'one-step'-synthesized dBSA-CuInS2/ZnS QDs have a long average fluorescence lifetime of 153.76 ns and a small particle size of 5 ± 2 nm. To demonstrate the applicability of the 'one-step'-synthesized dBSA-CuInS2/ZnS QDs in bioimaging studies, we modified the QDs with folic acid and hyaluronic acid, and then performed target bioimaging and cytotoxicity tests on macrophages, liver cancer cells and pancreatic cancer cells. The cell images show that the red emission signals originate from the QDs, which indicates that the dBSA-CuInS2/ZnS QDs prepared by the MF approach are suitable optical contrast agents for target bioimaging. This 'one-step' MF-based QD synthesis approach could serve as a rapid, cost-effective, and small-scale nanocrystal production platform for complex QD formulations for a wide range of bioapplications.

Natural Polysaccharides for siRNA Delivery: Nanocarriers Based on Chitosan, Hyaluronic Acid, and Their Derivatives

Natural polysaccharides are frequently used in the design of drug delivery systems due to their biocompatibility, biodegradability, and low toxicity. Moreover, they are diverse in structure, size, and charge, and their chemical functional groups can be easily modified to match the needs of the final application and mode of administration. This review focuses on polysaccharidic nanocarriers based on chitosan and hyaluronic acid for small interfering RNA (siRNA) delivery, which are highly positively and negatively charged, respectively. The key properties, strengths, and drawbacks of each polysaccharide are discussed. In addition, their use as efficient nanodelivery systems for gene silencing applications is put into context using the most recent examples from the literature. The latest advances in this field illustrate effectively how chitosan and hyaluronic acid can be modified or associated with other molecules in order to overcome their limitations to produce optimized siRNA delivery systems with promising in vitro and in vivo results.

Multifunctional hyaluronate - nanoparticle hybrid systems for diagnostic, therapeutic and theranostic applications

Diagnostic and therapeutic nanoparticles have been actively investigated for the last few decades as new platforms for biomedical applications. Despite their great versatility and potency, nanoparticles have generally required further modification with biocompatible materials such as biopolymers and synthetic polymers for in vivo administration to improve their biological functions, stability, and biocompatibility. Among a variety of natural and synthetic biomaterials, hyaluronate (HA) has been considered a promising biomolecule with which to construct nanohybrid systems, as it can enable long-term and efficient delivery of nanoparticles to target sites as well as physiological stabilization of nanoparticles by forming hydrophilic shells. In this review, we first describe various kinds of HA derivatives and their interactions with nanoparticles, and discuss how to design and develop optimal HA-nanoparticle hybrid systems for biomedical applications. Furthermore, we show several exemplary applications of HA-nanoparticle hybrid systems and provide our perspectives to their futuristic translational applications.

Targeted cellular delivery of robust enzyme nanoparticles for the treatment of drug-induced hepatotoxicity and liver injury

Direct delivery of proteins into cells has been considered an effective approach for treating the protein-related diseases. However, clinical use of proteins has still been limited due to their instability in the blood and poor membrane permeability. To achieve an efficient cellular delivery of the protein to target cells via a systemic administration, a multifunctional carrier system having desirable stability both in the blood stream and the cells, specific cell-targeting property and endosomal escape functions may be required. In this study, we prepared a catalytic nanoparticle containing an active enzyme by cross-tethering multiple superoxide dismutase (SOD) molecules with catechol-derivatized hyaluronic acid (HA). The permeable shell of hydrophilic HA chains effectively protects the enzyme from degradation in the blood after intravenous administration and provides an additional function for targeting hepatocytes expressing HA receptor (CD44). The structure and catalytic activity of the enzyme molecules in the nanoparticle were not significantly compromised in the nanoparticle. In addition, ultra-small calcium phosphate nanoparticles (USCaP, 2-5 nm) were crystalized and decorated on the surface of the nanoparticle for the efficient endosomal escape after cellular uptake. The SOD-containing nanoparticle fortified with USCaP was used for the treatment of acetaminophen (APAP)-induced fulminant hepatotoxicity and liver injury. The nanoparticle achieved the efficient hepatic cellular delivery of SOD via a systemic administration and resulted in efficient removal of reactive oxygen species (ROS) in the liver and remarkable improvement of APAP-induced hepatotoxicity and liver injury in animals. STATEMENT OF SIGNIFICANCE: Despite the enormous therapeutic potential, the intracellular delivery of proteins has been limited due to their poor membrane permeability and stability. In this study, we demonstrated an active enzyme-containing nanoparticle functionalized by hyaluronic acid and ultra-small size calcium phosphate nanoparticles (2-5 nm) for targeted cellular delivery of superoxide dismutase (SOD). The nanoparticle was designed to integrate all the essential functions, including serum stability, target specificity, and endosomal escape capability, for a systemic delivery of a therapeutic protein to the cells of the liver tissue. The intravenous administration of the nanoparticle efficiently removes reactive oxygen species (ROS) in the liver and remarkably improves the drug-induced hepatotoxicity and the progress of fulminant liver injury in an acetaminophen-overdose animal model.

Hyaluronan-Inorganic Nanohybrid Materials for Biomedical Applications

Nanomaterials, including gold, silver, and magnetic nanoparticles, carbon, and mesoporous materials, possess unique physiochemical and biological properties, thus offering promising applications in biomedicine, such as in drug delivery, biosensing, molecular imaging, and therapy. Recent advances in nanotechnology have improved the features and properties of nanomaterials. However, these nanomaterials are potentially cytotoxic and demonstrate a lack of cell-specific function. Thus, they have been functionalized with various polymers, especially polysaccharides, to reduce toxicity and improve biocompatibility and stability under physiological conditions. In particular, nanomaterials have been widely functionalized with hyaluronan (HA) to enhance their distribution in specific cells and tissues. This review highlights the most recent advances on HA-functionalized nanomaterials for biotechnological and biomedical applications, as nanocarriers in drug delivery, contrast agents in molecular imaging, and diagnostic agents in cancer therapy. A critical evaluation of barriers affecting the use of HA-functionalized nanomaterials is also discussed, and insights into the outlook of the field are explored.

Dendritic nanotubes self-assembled from stiff polysaccharides as drug and probe carriers

AF1-constructed DNTs have promising prospects as carriers, especially in the fields of drug and probe delivery systems.

Hyaluronic acid for anticancer drug and nucleic acid delivery

Hyaluronic acid (HA) is widely used in anticancer drug delivery, since it is biocompatible, biodegradable, non-toxic, and non-immunogenic; moreover, HA receptors are overexpressed on many tumor cells. Exploiting this ligand-receptor interaction, the use of HA is now a rapidly-growing platform for targeting CD44-overexpressing cells, to improve anticancer therapies. The rationale underlying approaches, chemical strategies, and recent advances in the use of HA to design drug carriers for delivering anticancer agents, are reviewed. Comprehensive descriptions are given of HA-based drug conjugates, particulate carriers (micelles, liposomes, nanoparticles, microparticles), inorganic nanostructures, and hydrogels, with particular emphasis on reports of preclinical/clinical results.

Bioimaging of Hyaluronate-Interferon α Conjugates Using a Non-Interfering Zwitterionic Fluorophore

We conducted real-time bioimaging of the hyaluronate-interferon α (HA-IFNα) conjugate using a biologically inert zwitterionic fluorophore of ZW800-1 for the treatment of hepatitis C virus (HCV) infection. ZW800-1 was labeled on the IFNα molecule of the HA-IFNα conjugate to investigate its biodistribution and clearance without altering its physicochemical and targeting characteristics. Confocal microscopy clearly visualized the effective in vitro cellular uptake of the HA-IFNα conjugate to HepG2 cells. After verifying the biological activity in Daudi cells, we conducted the pharmacokinetic analysis of the HA-IFNα conjugate, which confirmed its target-specific delivery to the liver with a prolonged residence time longer than that of PEGylated IFNα. In vivo and ex vivo bioimaging of the ZW800-1-labeled HA-IFNα conjugate directly showed real-time biodistribution and clearance of the conjugate that are consistent with the biological behaviors analyzed by an enzyme-linked immunosorbent assay. Furthermore, the elevated level of OAS1 mRNA in the liver confirmed in vivo antiviral activity of HA-IFNα conjugates. With the data taken together, we could confirm the feasibility of ZW800-1 as a biologically inert fluorophore and target-specific HA-IFNα conjugate for the treatment of HCV infection.

Polysaccharide–porphyrin–fullerene supramolecular conjugates as photo-driven DNA cleavage reagents

Water-soluble polysaccharide–porphyrin–fullerene supramolecular conjugates were constructed, showing the capability of completely cleaving closed supercoiled DNA to nicked DNA.

Hyaluronic acid and neural stem cells: implications for biomaterial design

While in the past hyaluronic acid (HA) was considered a passive structural component, research over the past few decades has revealed its diverse and complex biological functions resulting in a major ideological shift. This review describes recent advances in biological interactions of HA with neural stem cells, with a focus on leveraging these interactions to develop advanced biomaterials that aid regeneration of the central nervous system.

Cationic conjugated polymer/fluoresceinamine-hyaluronan complex for sensitive fluorescence detection of CD44 and tumor-targeted cell imaging

Simple, rapid, and sensitive detection of CD44 is of paramount importance since it plays pivotal roles in tumor initiation, growth and metastasis. Herein, we describe a novel method for sensitive, visual and facile fluorescence detection of CD44 and CD44-mediated cancer cell imaging, using a probe based on cationic conjugated polymer (CCP)-PFEP and fluoresceinamine-hyaluronan (FA-HA). HA is an anionic natural glycosaminoglycan that can specifically bind to the overexpressed CD44 on various kinds of cancer cells. PFEP and FA-HA formed a complex through electronic interactions, resulting in a highly efficient fluorescence resonance energy transfer (FRET) from PFEP to FA-HA; moreover, the efficiencies of FRET correlated with the concentrations of CD44 because the specific binding of HA-CD44 would separate FA-HA away from PFEP. This method did not require laborious and expensive dual-labeling or protein-labeling needed in previously reported detection methods of CD44. Just mix the sample and test solution containing the PFEP/FA-HA complex, and the results allowed naked-eye detection by observing fluorescent color of solutions with the assistance of a UV lamp. Most importantly, the use of a conjugated polymer with excellent amplification property as well as the specific binding of HA-CD44 endowed this method with high sensitivity and specificity, making it applicable for reliable quantitative detection of CD44. Furthermore, the PFEP/FA-HA complex formed nanoparticles in aqueous solution, and the nanoparticles can be selectively taken up by MCF-7 cells (cancer cell) through the HA-CD44 interaction, thereby giving rise to a dual-color tumor-targeted imaging probe with good photostability. The development of this fluorescent probe showed promising potential to make a reliable and routine method available for early diagnosis of cancer.

Hyaluronan: a simple polysaccharide with diverse biological functions

Hyaluronan (HA) is a linear polysaccharide with disaccharide repeats of d-glucuronic acid and N-acetyl-d-glucosamine. It is evolutionarily conserved and abundantly expressed in the extracellular matrix (ECM), on the cell surface and even inside cells. Being a simple polysaccharide, HA exhibits an astonishing array of biological functions. HA interacts with various proteins or proteoglycans to organize the ECM and to maintain tissue homeostasis. The unique physical and mechanical properties of HA contribute to the maintenance of tissue hydration, the mediation of solute diffusion through the extracellular space and the lubrication of certain tissues. The diverse biological functions of HA are manifested through its complex interactions with matrix components and resident cells. Binding of HA with cell surface receptors activates various signaling pathways, which regulate cell function, tissue development, inflammation, wound healing and tumor progression and metastasis. Taking advantage of the inherent biocompatibility and biodegradability of HA, as well as its susceptibility to chemical modification, researchers have developed various HA-based biomaterials and tissue constructs with promising and broad clinical potential. This paper illustrates the properties of HA from a matrix biology perspective by first introducing the principles underlying the biosynthesis and biodegradation of HA, as well as the interactions of HA with various proteins and proteoglycans. It next highlights the roles of HA in physiological and pathological states, including morphogenesis, wound healing and tumor metastasis. A deeper understanding of the mechanisms underlying the roles of HA in various physiological processes can provide new insights and tools for the engineering of complex tissues and tissue models.

Hyaluronic acid conjugates as vectors for the active targeting of drugs, genes and nanocomposites in cancer treatment

Hyaluronic acid (HA) is a naturally-occurring glycosaminoglycan and a major component of the extracellular matrix. Low levels of the hyaluronic acid receptor CD44 are found on the surface of epithelial, hematopoietic, and neuronal cells; it is overexpressed in many cancer cells, and in particular in tumor-initiating cells. HA has recently attracted considerable interest in the field of developing drug delivery systems, having been used, as such or encapsulated in different types of nanoassembly, as ligand to prepare nano-platforms for actively targeting drugs, genes, and diagnostic agents. This review describes recent progress made with the several chemical strategies adopted to synthesize conjugates and prepare novel delivery systems with improved behaviors.

Polysaccharide-based nucleic acid nanoformulations

Therapeutic application of nucleic acids requires their encapsulation in nanosized carriers that enable safe and efficient intracellular delivery. Before the desired site of action is reached, drug-loaded nanoparticles (nanomedicines) encounter numerous extra- and intracellular barriers. Judicious nanocarrier design is highly needed to stimulate nucleic acid delivery across these barriers and maximize the therapeutic benefit. Natural polysaccharides are widely used for biomedical and pharmaceutical applications due to their inherent biocompatibility. At present, there is a growing interest in applying these biopolymers for the development of nanomedicines. This review highlights various polysaccharides and their derivatives, currently employed in the design of nucleic acid nanocarriers. In particular, recent progress made in polysaccharide-assisted nucleic acid delivery is summarized and the specific benefits that polysaccharides might offer to improve the delivery process are critically discussed.

An approach to transgene expression in liver endothelial cells using a liposome-based gene vector coated with hyaluronic acid

Dysfunctional sinusoidal liver endothelial cells (LECs) are associated with liver diseases, such as liver fibrosis, cirrhosis, and portal hypertension. Because of this, gene therapy targeted to LECs would be a useful and productive strategy for directly treating these diseases at the level of genes. Here, we report on the development of a transgene vector that specifically targets LECs. The vector is a liposome-based gene vector coated with hyaluronic acid (HA). HA is a natural ligand for LECs and confers desirable properties on particles, rendering them biodegradable, biocompatible, and nonimmunogenic. In this study, we constructed HA-modified carriers, and evaluated cellular uptake and transfection activity using cultured LECs from KSN nude mice (KSN-LECs). Cellular uptake analyses showed that KSN-LECs recognized the HA-modified carriers more effectively than skin endothelial cells. The transfection assay indicated that the efficient gene expression in KSN-LECs, using the HA-modified carriers, required an adequate lipid composition and a functional device to control intracellular trafficking. This finding contributes to our overall knowledge of transgene expression targeted to LECs.

Role of CD44 in tumour progression and strategies for targeting

CD44 or hyaluronan receptor is a transmembrane receptor associated with aggressive tumour growth, proliferation, and metastasis. In normal physiology, this receptor has a crucial role in cell adhesion, inflammation, and repair processes. However, many tumour cells over-express this receptor and abuse it to become progressive and perpetual units. The article comments from common functioning of the CD44 receptor, to its diabolic multi-dimensional effects in promotion of malignant cells. It also illuminates the relations of CD44 endorsed processes with other biomolecular events in cancer progression. In an end, the review focuses comprehensively at ongoing researches to exploit the CD44 over-expression as a probable target in treatment, management, and diagnosis of malignancy.

Amphiphilic polymeric micelles as the nanocarrier for peroral delivery of poorly soluble anticancer drugs

INTRODUCTION

Many amphiphilic copolymers have recently been synthesized as novel promising micellar carriers for the delivery of poorly water-soluble anticancer drugs. Studies on the formulation and oral delivery of such micelles have demonstrated their efficacy in enhancing drug uptake and absorption, and exhibit prolonged circulation time in vitro and in vivo.

AREAS COVERED

In this review, literature on hydrophobic modifications of several hydrophilic polymers, including polyethylene glycol, chitosan, hyaluronic acid, pluronic and tocopheryl polyethylene glycol succinate, is summarized. Parameters influencing the properties of polymeric micelles for oral chemotherapy are discussed and strategies to overcome main barriers for polymeric micelles peroral absorption are proposed.

EXPERT OPINION

During the design of polymeric micelles for peroral chemotherapy, selecting or synthesizing copolymers with good compatibility with the drug is an effective strategy to increase drug loading and encapsulation efficiency. Stability of the micelles can be improved in different ways. It is recommended to take permeability, mucoadhesion, sustained release, and P-glycoprotein inhibition into consideration during copolymer preparation or to consider adding some excipients in the formulation. Furthermore, both the copolymer structure and drug loading methods should be controlled in order to get micelles with appropriate particle size for better absorption.

Hyaluronic acid-functionalized mesoporous silica nanoparticles for efficient photodynamic therapy of cancer cells

Mesoporous silica nanoparticles (MSN) for photodynamic therapy (PDT) were coated with poly-(L-lysine) and hyaluronic acid (HA) by using the layer-by-layer method. HA is able to target cancer cells over-expressing the corresponding CD44 receptor. MSN functionalized with HA (MSN-HA) were more efficient than MSN without the targeting moiety when PDT was performed at low fluence (14 Jcm(-2)) and low dosage of MSN (20 μgmL(-1)) on HCT 116 colorectal cancer cells, known to over-express the CD44 receptor. Incubation of HCT-116 cancer cells with an excess of HA impaired the PDT effect with MSN-HA thus demonstrating that an active endocytosis mechanism was involved in the uptake of MSN-HA by these cells.

A simple method for the synthesis of hyaluronic acid coated magnetic nanoparticles for highly efficient cell labelling and in vivo imaging

Highly stable colloidal hyaluronic acid coated magnetic nano-particles were prepared via a ligand exchange method. These particles exhibited excellent cell labeling efficiencies and superior potential as MRI contrast agents, which are useful to target tumor cells expressing hyaluronic acid receptors such as CD44.

Continuous-flow reactor-based synthesis of carbohydrate and dihydrolipoic acid-capped quantum dots

A detailed protocol for the large-scale synthesis of carbohydrate and dihydrolipoic acid (DHLA)-coated CdSe/ZnS and CdTe/ZnS nanoparticles using continuous flow reactors is described here. Three continuous flow microreaction systems, operating at three different temperatures, are used for the synthesis of mannose-, galactose- or DHLA-functionalized quantum dots (QDs). In the first step of synthesis, the CdSe and CdTe nanoparticles are prepared. The size and spectral properties of the CdSe core of the nanoparticles are controlled by adjustment of the residence time and the temperature. As a second step, the zinc sulfide capping under homogenous conditions is carried out at a substantially lower temperature than is required for nanoparticle growth in batch processes. Finally, the trioctylphosphine/oleic acid ligand is effectively replaced with either carbohydrate PEG-thiol moieties or DHLA at 60 °C. This new protocol allows the synthesis of biologically active fluorescent QDs in 4 d.

Hyaluronan metabolism in remodeling extracellular matrix: probes for imaging and therapy of breast cancer

Clinical and experimental evidence increasingly support the concept of cancer as a disease that emulates a component of wound healing, in particular abnormal stromal extracellular matrix remodeling. Here we review the biology and function of one remodeling process, hyaluronan (HA) metabolism, which is essential for wound resolution but closely linked to breast cancer (BCA) progression. Components of the HA metabolic cycle (HAS2, SPAM1 and HA receptors CD44, RHAMM/HMMR and TLR2) are discussed in terms of their known functions in wound healing and in breast cancer progression. Finally, we discuss recent advances in the use of HA-based platforms for developing nanoprobes to image areas of active HA metabolism and for therapeutics in breast cancer.

Quantum dots, lighting up the research and development of nanomedicine

Quantum dots (QDs) have proven themselves as powerful inorganic fluorescent probes, especially for long term, multiplexed imaging and detection. The newly developed QDs labeling techniques have facilitated the study of drug delivery on the level of living cells and small animals. Moreover, based on QDs and fluorescence imaging system, multifunctional nanocomplex integrated targeting, imaging and therapeutic functionalities have become effective materials for synchronous cancer diagnosis and treatment. In this review, we will summarize the recent advances of QDs in the research of drug delivery system from the following aspects: surface modification strategies of QDs for drug delivery, QDs as drug nanocarriers, QD-labeled drug nanocarriers, QD-based fluorescence resonance energy transfer (FRET) technique for drug release study as well as the development of multifunctional nanomedicines. Possible perspective in this field will also be discussed.

FROM THE CLINICAL EDITOR

This review discusses the role and significance of quantum dots (QDs) from the following aspects: surface modification strategies of QDs for drug delivery, QDs as drug nanocarriers, QD-labeled drug nanocarriers, QD-based fluorescence resonance energy transfer (FRET) technique for drug release study as well as the development of multifunctional nanomedicines.

Nanostructured hyaluronic acid-based materials for active delivery to cancer

IMPORTANCE OF THE FIELD

Active targeting of bioactive molecules by physicochemical association with hyaluronic acid (HA) is an attractive approach in current nanomedicine because HA is biocompatible, non-toxic and non-inflammatory.

AREAS COVERED IN THIS REVIEW

This review focuses on synthesis, physicochemical characterization and biological properties of different nanoparticulate delivery systems that include HA in their structures. Chemically based approaches to the delivery of small molecule drugs, proteins and nucleic acids in which they become chemically or physically bound to hyaluronic acid are reviewed, including the use of molecular HA conjugates and nanocarriers. The systems are considered in terms of intracellular delivery to different cultured cells that express HA-specific receptors (hyaladherines) differently. The in vivo biodistribution and therapeutic effect of these systems are discussed.

WHAT THE READER WILL GAIN

Different synthetic methodologies for preparations of HA-based nanoparticles are presented extensively. HA nanoparticulate systems of various structures can be compared with respect to their in vitro assays and in vivo biodistribution.

TAKE HOME MESSAGE

To make HA useful as an intravenous targeting carrier, strategies have to be devised to: reduce HA clearance from the blood; suppress the HA uptake by liver and spleen; and provide tumor-triggered mechanisms of release of an active drug from the HA carrier.

Bioimaging for targeted delivery of hyaluronic Acid derivatives to the livers in cirrhotic mice using quantum dots

Liver fibrosis or cirrhosis is one of the representative liver diseases with a high morbidity and mortality worldwide. Over the past decades, many kinds of antifibrotic compounds have been investigated in vitro and in vivo for the treatment of liver cirrhosis. In this work, real-time bioimaging of hyaluronic acid (HA) derivatives was carried out using quantum dots (QDots) to assess the possibility of HA derivatives as target-specific drug delivery carriers for the treatment of liver diseases. HA-QDot conjugates with an HA modification degree of about 22 mol % was synthesized by amide bond formation between carboxyl groups of QDots and amine groups of adipic acid dihydrazide modified HA (HA-ADH). According to in vitro cell culture tests, HA-QDot conjugates were taken up more to the cells causing chronic liver diseases such as hepatic stellate cells (HSC-T6) and hepatoma cells (HepG2) than normal hepatocytes (FL83B). After tail-vein injection, HA-QDot conjugates were target-specific, being delivered to the cirrhotic liver with a slow clearance longer than 8 days. Furthermore, immunofluorescence and flow cytometric analyses of dissected liver tissues revealed the target-specific delivery of HA derivatives to liver sinusoidal endothelial cells (LSEC) and HSC. The results were thought to reflect the feasibility of HA derivatives as novel drug delivery carriers for the treatment of various chronic liver diseases including hepatitis, liver cirrhosis, and liver cancer.

Long acting hyaluronate--exendin 4 conjugate for the treatment of type 2 diabetes

Despite clinical exploitation of exendin 4 for the treatment of type 2 diabetes, the significantly short half-life requiring twice a day injection has limited the wide applications. In this work, a protocol for the synthesis of long acting hyaluronate (HA) - exendin 4 conjugate was successfully developed using Michael addition chemistry between vinyl sulfone modified HA (HA-VS) and thiolated exendin 4. The exendin 4 content could be controlled in the range of 5-30 molecules per single HA chain with a bioconjugation efficiency higher than 90%. The conjugation of exendin 4 with HA resulted in about 20 times improved in vitro serum stability maintaining the hypoglycemic and gluco-regulatory bioactivities of exendin 4. HA - exendin 4 conjugates showed excellent glucose-lowering capabilities in type 2 db/db mice demonstrating protracted hypoglycemic effect up to 3 days after a single subcutaneous injection. Furthermore, insulin immunohistochemical analysis of islets in db/db mice confirmed the improved insulinotropic activity of HA - exendin 4 conjugates. The HA - exendin 4 conjugates will be investigated further as a twice a week injection dosage form for clinical applications.

Guided bone regeneration by poly(lactic-co-glycolic acid) grafted hyaluronic acid bi-layer films for periodontal barrier applications

A novel protocol for the synthesis of biocompatible and degradation controlled poly(lactic-co-glycolic acid) grafted hyaluronic acid (HA-PLGA) was successfully developed for periodontal barrier applications. HA was chemically modified with adipic acid dihydrazide (ADH) in the mixed solvent of water and ethanol, which resulted in a high degree of HA modification up to 85 mol.%. The stability of HA-ADH to enzymatic degradation by hyaluronidase increased with ADH content in HA-ADH. When the ADH content in HA-ADH was higher than 80 mol.%, HA-ADH became soluble in dimethyl sulfoxide and could be grafted to the activated PLGA with N,N'-dicyclohexyl carbodiimide and N-hydroxysuccinimide. The resulting HA-PLGA was used for the preparation of biphasic periodontal barrier membranes in chloroform. According to in vitro hydrolytic degradation tests in phosphate buffered saline, HA-PLGA/PLGA blend film with a weight ratio of 1/2 degraded relatively slowly compared to PLGA film and HA coated PLGA film. Four different samples of a control, OSSIX(TM) membrane, PLGA film, and HA-PLGA/PLGA film were assessed as periodontal barrier membranes for the calvarial critical size bone defects in SD rats. Histological and histomorphometric analyses revealed that HA-PLGA/PLGA film resulted in the most effective bone regeneration compared to other samples with a regenerated bone area of 63.1% covering the bone defect area.

Target specific and long-acting delivery of protein, peptide, and nucleotide therapeutics using hyaluronic acid derivatives

Hyaluronic acid (HA) is a biodegradable, biocompatible, non-toxic, non-immunogenic and non-inflammatory linear polysaccharide, which has been used for various medical applications such as arthritis treatment, ocular surgery, tissue augmentation, and so on. In this review, the effect of chemical modification of HA on its distribution throughout the body was reported for target specific and long-acting delivery applications of protein, peptide, and nucleotide therapeutics. According to the real-time bio-imaging of HA derivatives using quantum dots (QDot), HA-QDot conjugates with 35mol% HA modification maintaining enough binding sites for HA receptors were mainly accumulated in the liver, while those with 68mol% HA modification losing much of HA characteristics were evenly distributed to the tissues in the body. The results are well matched with the fact that HA receptors are abundantly present in the liver with a high specificity to HA molecules. Accordingly, slightly modified HA derivatives were used for target specific intracellular delivery of nucleotide therapeutics and highly modified HA derivatives were used for long-acting conjugation of peptide and protein therapeutics. HA has been also used as a novel depot system in the forms of physically and chemically crosslinked hydrogels for various protein drug delivery. This review will give you a peer overview on novel HA derivatives and the latest advances in HA-based drug delivery systems of various biopharmaceuticals for further clinical development.

Biocompatible near-infrared quantum dots as ultrasensitive probes for long-term in vivo imaging applications

A facile synthesis method to produce monodisperse, biocompatible, lysine crosslinked mercaptoundecanoic acid (MUA) CdSe(0.25)Te(0.75)/CdS near-infrared (NIR) quantum dots and use them as probes to study their long term in vivo distribution, clearance, and toxicity is presented. Large signal enhancements are demonstrated by these quantum dots, which enables their use as efficient and sensitive probes for live-animal imaging. An important finding is that mice intravenously injected with approximately 10.5 mg kg(-1) of NIR QDs survive for more than three months without any apparent adverse effect to their health. Furthermore, it is determined that there is a significant reduction in the number of the QDs in the liver and spleen three months post injection. In addition, histological analysis of heart, kidney, liver, spleen, and lung tissue indicates that there are no acute toxic effects from these lysine cross-linked MUA NIR QDs. This study suggests that these NIR QDs can be potentially used for long-term targeted imaging and therapy studies in vivo.

Target specific intracellular delivery of siRNA/PEI-HA complex by receptor mediated endocytosis

Hyaluronic acid (HA) plays important biological roles in tissue integrity, angiogenesis, wound healing, and cell motility through the interaction with receptors on cell membranes. In this work, we investigated the effect of HA modification on the receptor-mediated endocytosis labeling HA derivatives with quantum dots (QDots). HA-QDot conjugates with a degree of modification less than ca. 25 mol % appeared to be more efficiently taken up to B16F1 cells by HA receptor mediated endocytosis than QDots alone. On the basis of bioimaging study, polyethyleneimine, PEI-HA conjugate with 24.2 mol % PEI content was developed as a target specific intracellular delivery carrier of siRNA. The siRNA/PEI-HA complex exhibited higher gene silencing efficiency in B16F1 cells with HA receptors than siRNA/PEI complex. Anti-PGL3-Luc siRNA/PEI-HA complex appeared to silence PGL3-Luc gene in the range of 50%-85% depending on the serum concentration up to 50 vol %. According to in vivo biodistribution test, siRNA/PEI-HA complex accumulated mainly in the tissues with HA receptors such as liver, kidney, and tumor. Furthermore, intratumoral injection of anti-VEGF siRNA/PEI-HA complex resulted in an effective inhibition of tumor growth by the HA receptor mediated endocytosis to tumor cells in C57BL/6 mice. Considering all these results, anti-VEGF siRNA/PEI-HA complex was thought to be applied successfully as target specific antiangiogenic therapeutics for the treatment of diseases in the tissues with HA receptors, such as liver cancer and kidney cancer.

Tumor targeting and imaging in live animals with functionalized semiconductor quantum rods

In this contribution, we demonstrate that highly luminescent CdSe/CdS/ZnS quantum rods (QRs) coated with PEGylated phospholipids and conjugated with cyclic RGD peptide can be successfully used for tumor targeting and imaging in live animals. The design of these targeted luminescent probes involves encapsulation of hydrophobic CdSe/CdS/ZnS QRs with PEGylated phospholipids, followed by conjugation of these PEGylated phospholipids to ligands that specifically target the tumor vasculature. In vivo optical imaging studies in nude mice bearing pancreatic cancer xenografts, both subcutaneous and orthotopic, indicate that the QR probes accumulate at tumor sites via the cyclic RGD peptides on the QR surface binding to the alpha(V)beta(3) integrins overexpressed in the tumor vasculature, following systemic injection. In vivo tumor detection studies showed no adverse effects even at a dose roughly 6.5 times higher than has been reported for in vivo imaging studies using quantum dots. Cytotoxicity studies indicated the absence of any toxic effect in the cellular and tissue levels arising from functionalized QRs. These results demonstrate the vast potential of QRs as bright, photostable, and biocompatible luminescent probes for the early diagnosis of cancer.