In vitro imaging and in vivo liver targeting with carbohydrate capped quantum dots

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.

Sulfation of Heparan and Chondroitin Sulfate Ligands Enables Cell-Specific Homing of Nanoprobes

Demystifying the sulfation code of glycosaminoglycans (GAGs) to induce precise homing of nanoparticles in tumor cells or neurons influences the development of a potential drug- or gene-delivery system. However, GAGs, particularly heparan sulfate (HS) and chondroitin sulfate (CS), are structurally highly heterogeneous, and synthesizing well-defined HS/CS composed nanoparticles is challenging. Here, we decipher how specific sulfation patterns on HS and CS regulate receptor-mediated homing of nanoprobes in primary and secondary cells. We discovered that aggressive cancer cells such as MDA-MB-231 displayed a strong uptake of GAG-nanoprobes compared to mild or moderately aggressive cancer cells. However, there was no selectivity towards the GAG sequences, thus indicating the presence of more than one form of receptor-mediated uptake. However, U87 cells, olfactory bulb, and hippocampal primary neurons showed selective or preferential uptake of CS-E-coated nanoprobes compared to other GAG-nanoprobes. Furthermore, mechanistic studies revealed that the 4,6-O-disulfated-CS nanoprobe used the CD44 and caveolin-dependent endocytosis pathway for uptake. These results could lead to new opportunities to use GAG nanoprobes in nanomedicine.

Design of high-avidity multivalent ligand structures that target cells with high ligand economy

Novel cell-targeting ligand structures are constructed with a spikey core scaffold, where multiple copies of coiled-coil peptide nanorods are conjugated on the surface of a peptide nanosheet. Clustering of carbohydrate and aptamer ligands at the end of the coiled coils optimizes ligand accessibility to cell-surface receptors. Display of the ligand-coil conjugates on the nanosheet generates a patchy ligand pattern bearing two levels of multivalency. With the ligand-scaffold system, high-avidity cell targeting is realized using fewer ligands than ever, which facilitates future applications in cell detection and drug delivery.

Two-Photon Time-Gated In Vivo Imaging of Dihydrolipoic-Acid-Decorated Gold Nanoclusters

Due to the unique advantages of two-photon technology and time-resolved imaging technology in the biomedical field, attention has been paid to them. Gold clusters possess excellent physicochemical properties and low biotoxicity, which make them greatly advantageous in biological imaging, especially for in vivo animal imaging. A gold nanocluster was coupled with dihydrolipoic acid to obtain a functionalized nanoprobe; the material displayed significant features, including a large two-photon absorption cross-section (up to 1.59 × 105 GM) and prolonged fluorescence lifetime (>300 ns). The two-photon and time-resolution techniques were used to perform cell imaging and in vivo imaging.

Lymph Node-Targeted Synthetically Glycosylated Antigen Leads to Antigen-Specific Immunological Tolerance

Inverse vaccines that tolerogenically target antigens to antigen-presenting cells (APCs) offer promise in prevention of immunity to allergens and protein drugs and treatment of autoimmunity. We have previously shown that targeting hepatic APCs through intravenous injection of synthetically glycosylated antigen leads to effective induction of antigen-specific immunological tolerance. Here, we demonstrate that targeting these glycoconjugates to lymph node (LN) APCs under homeostatic conditions leads to local and increased accumulation in the LNs compared to unmodified antigen and induces a tolerogenic state both locally and systemically. Subcutaneous administration directs the polymeric glycoconjugate to the draining LN, where the glycoconjugated antigen generates robust antigen-specific CD4+ and CD8+ T cell tolerance and hypo-responsiveness to antigenic challenge via a number of mechanisms, including clonal deletion, anergy of activated T cells, and expansion of regulatory T cells. Lag-3 up-regulation on CD4+ and CD8+ T cells represents an essential mechanism of suppression. Additionally, presentation of antigen released from the glycoconjugate to naïve T cells is mediated mainly by LN-resident CD8+ and CD11b+ dendritic cells. Thus, here we demonstrate that antigen targeting via synthetic glycosylation to impart affinity for APC scavenger receptors generates tolerance when LN dendritic cells are the cellular target.

Pharmaceutical Applications of Quantum Dots

Nanotechnology has been utilized in developing novel drug formulations with minimal adverse effects. Nanoparticles in a lower size range with great surface area, increased potency, and easy permeability could be an approach for the treatment of cancer and other diseases. Unlike other nanoparticles, quantum dots have specific functional groups, have charges over their surface, and are extremely small in size (2-10nm), which makes them more permeable through tight junctions. Quantum dots are interesting materials that offer diagnosis and treatment concurrently. Quantum dots are reported to have several applications in pharmaceuticals as well as drug delivery, diagnosis, immunolabeling, and cell labeling tools. However, the existence of heavy metals in quantum dots such as cadmium poses a potential challenge for future medical applications, where quantum dots may be deliberately injected into the body. In this review, we are focusing on various pharmaceutical applications of quantum dots. Graphical Abstract.

Recent Developments in the Use of Glyconanoparticles and Related Quantum Dots for the Detection of Lectins, Viruses, Bacteria and Cancer Cells

Carbohydrate-coated nanoparticles—glyconanoparticles—are finding increased interest as tools in biomedicine. This compilation, mainly covering the past five years, comprises the use of gold, silver and ferrite (magnetic) nanoparticles, silicon-based and cadmium-based quantum dots. Applications in the detection of lectins/protein toxins, viruses and bacteria are covered, as well as advances in detection of cancer cells. The role of the carbohydrate moieties in stabilising nanoparticles and providing selectivity in bioassays is discussed, the issue of cytotoxicity encountered in some systems, especially semiconductor quantum dots, is also considered. Efforts to overcome the latter problem by using other types of nanoparticles, based on gold or silicon, are also presented.

Elucidating Carbohydrate-Protein Interactions Using Nanoparticle-Based Approaches

Carbohydrates are present on every living cell and coordinate important processes such as self/non-self discrimination. They are amongst the first molecular determinants to be encountered when cellular interactions are initiated. In particular, they resemble essential molecular fingerprints such as pathogen-, danger-, and self-associated molecular patterns guiding key decision-making in cellular immunology. Therefore, a deeper understanding of how cellular receptors of the immune system recognize incoming particles, based on their carbohydrate signature and how this information is translated into a biological response, will enable us to surgically manipulate them and holds promise for novel therapies. One approach to elucidate these early recognition events of carbohydrate interactions at cellular surfaces is the use of nanoparticles coated with defined carbohydrate structures. These particles are captured by carbohydrate receptors and initiate a cellular cytokine response. In the case of endocytic receptors, the capturing enables the engulfment of exogenous particles. Thereafter, the particles are sorted and degraded during their passage in the endolysosomal pathway. Overall, these processes are dependent on the nature of the endocytic carbohydrate receptors and consequently reflect upon the carbohydrate patterns on the exogenous particle surface. This interplay is still an under-studied subject. In this review, we summarize the application of nanoparticles as a promising tool to monitor complex carbohydrate-protein interactions in a cellular context and their application in areas of biomedicine.

Engineering Carbohydrate-Based Particles for Biomedical Applications: Strategies to Construct and Modify

Carbohydrate-based micro/nanoparticles have gained significant attention for various biomedical applications such as targeted/triggered/controlled drug delivery, bioimaging, biosensing, etc., because of their prominent characteristics like biocompatibility, biodegradability, hydrophilicity, and nontoxicity as well as nonimmunogenicity. Most importantly, the ability of the nanoparticles to recognize specific cell sites by targeting cell surface receptors makes them a promising candidate for designing a targeted drug delivery system. These particles may either comprise polysaccharides/glycopolymers or be integrated with various polymeric/inorganic nanoparticles such as gold, silver, silica, iron, etc., to reduce the toxicity of the inorganic nanoparticles and thus facilitate their cellular insertion. Various synthetic methods have been developed to fabricate carbohydrate-based or carbohydrate-conjugated inorganic/polymeric nanoparticles. In this review, we have highlighted the recently developed synthetic approaches to afford carbohydrate-based particles along with their significance in various biomedical applications.

A Strategy for Tumor Targeting by Higher-Order Glycan Pattern Recognition: Synthesis and In Vitro and In Vivo Properties of Glycoalbumins Conjugated with Four Different N-Glycan Molecules

Natural glycoconjugates that form glycocalyx play important roles in various biological processes based on cell surface recognition through pattern recognition mechanisms. This work represents a new synthesis-based screening strategy to efficiently target the cancer cells by higher-order glycan pattern recognition in both cells and intact animals (mice). The use of the very fast, selective, and effective RIKEN click reaction (6π-azaelectrocyclization of unsaturated imines) allows to synthesize and screen various structurally well-defined glycoalbumins containing two and eventually four different N-glycan structures in a very short time. The importance of glycan pattern recognition is exemplified in both cell- and mouse-based experiments. The use of pattern recognition mechanisms for cell targeting represents a novel and promising strategy for the development of diagnostic, prophylactic, and therapeutic agents for various diseases including cancers.

Nanotechnology as a Platform for the Development of Injectable Parenteral Formulations: A Comprehensive Review of the Know-Hows and State of the Art

Within recent decades, the development of nanotechnology has made a significant contribution to the progress of various fields of study, including the domains of medical and pharmaceutical sciences. A substantially transformed arena within the context of the latter is the development and production of various injectable parenteral formulations. Indeed, recent decades have witnessed a rapid growth of the marketed and pipeline nanotechnology-based injectable products, which is a testimony to the remarkability of the aforementioned contribution. Adjunct to the ability of nanomaterials to deliver the incorporated payloads to many different targets of interest, nanotechnology has substantially assisted to the development of many further facets of the art. Such contributions include the enhancement of the drug solubility, development of long-acting locally and systemically injectable formulations, tuning the onset of the drug’s release through the endowment of sensitivity to various internal or external stimuli, as well as adjuvancy and immune activation, which is a desirable component for injectable vaccines and immunotherapeutic formulations. The current work seeks to provide a comprehensive review of all the abovementioned contributions, along with the most recent advances made within each domain. Furthermore, recent developments within the domains of passive and active targeting will be briefly debated.

Azidophenylselenylation of glycals towards 2-azido-2-deoxy-selenoglycosides and their application in oligosaccharide synthesis

2-Amino-2-deoxy-pyranosyl units are important structural components of cell-wall polymers in prokaryotes, fungi and mammals. With respect to the need for development of novel and efficient vaccines and tools for serodiagnosis of infectious diseases, of particular interest are the oligosaccharide cell-wall antigens of pathogenic bacteria and fungi, which comprise 2-amino-2-deoxy-D-glucopyranose and 2-amino-2-deoxy-D-galactopyranose units as α- or β-anomers. Synthesis of N-acylated α-GlcN and α-GalN containing oligosaccharides is a special challenge due to the presence of a participating group at C2 which favors the formation of β- rather than α-glycoside bond. Herein we overview the efficient two-step approach for preparation of 1,2-cis-glycosides of 2-amino-2-deoxy-D-glucopyranose and 2-amino-2-deoxy-D-galactopyranose, which was recently developed in our laboratory. In the first step, an efficient and straightforward azidophenylselenylation procedure of glycals gives phenyl 2-azido-2-deoxy-1-selenoglycosides as versatile glycosyl donors. In the second step, these donors can be efficiently transformed into α- or β-glycosides depending on the choice of the solvent. In acetonitrile, total β-stereocontrol was achieved, and the use of diethyl ether as a solvent favouring α-stereoselectivity of glycosylations with phenyl 2-azido-2-deoxy-1-selenoglycosides. Besides, it was shown, that low reactivity and nucleophilicity of glycosyl acceptors which are glycosylated with phenyl 2-azido-2-deoxy-1-selenogalactosides facilitated the formation of α-GalN derivatives. To date, homogenous azidophenylselenylation of glycals and glycosylation with phenyl 2-azido-2-deoxy-1-seleno-α-D-glycopyranosides can be regarded as most useful tool for introduction of 2-amino-2-deoxy-D-glycopyranoside residues into complex synthetic oligosaccharides.

Green synthesis of fluorescent PEG-ZnS QDs encapsulated into Co-MOFs as an effective sensor for ultrasensitive detection of copper ions in tap water

In this work, a novel and highly fluorescent (FL) metal-organic framework (MOF)-based host-guest hybrid system was developed through encapsulation of polyethylene glycol (PEG)-capped ZnS quantum dots (QDs) into zeolitic imidazolate framework (ZIF)-67 at ambient temperature. This new composite material was characterized by FT-IR, XRD, TEM, UV-Vis absorption and FL spectroscopy, and then exploited as fluorescence sensor for highly sensitive and selective detection of Cu (II) ions in water samples. The as-prepared PEG-ZnS QDs@ZIF-67 nanohybrids took advantages of both accumulation effect in ZIF-67 and FL sensitivity and selectivity in ZnS QDs toward analyte-Cu²⁺. In this regard, ZIF-67 was treated as absorbents to capture and enrich Cu (II) ions, and ZnS QDs were exploited as tentacle to selectively and sensitively sense the bonding interactions between ZIF-67 and Cu (II) ions, and further transduce these chemical events to the detectable fluorescence signals. By this approach, Cu²⁺ could be detected in a wide concentration range of 3 to 500 nM with a LOD as low as 0.96 nM. The proposed FL-sensor can be promising in the field of preparation of various QDs@MOFs platforms for application in high-performance optical sensing.

Colloidal Nanobioconjugate with Complementary Surface Chemistry for Cellular and Subcellular Targeting

Chemically and biochemically functionalized colloidal nanoparticles with appropriate surface chemistry are essential for various biomedical applications. Although a variety of approaches are now available in making such functional nanoparticles and nanobioconjugates, the lack of complementary surface chemistry often leads to poor performance with respect to intended biomedical applications. This feature article will focus on our efforts to make colloidal nanobioconjugates with appropriate/complementary surface chemistry for better performance of a designed nanoprobe with respect to cellular and subcellular targeting applications. In particular, we emphasize polyacrylate-based coating chemistry followed by a conjugation strategy for transforming <10 nm inorganic nanoparticle to colloidal nanoprobe of 20-50 nm hydrodynamic size. We show that a colloidal nanoprobe can be chemically designed to control the cell-nanoparticle interaction, cellular endocytosis, and targeting/labeling of subcellular compartments. Further study should be directed to adapt this surface chemistry to different nanoparticles, fine tune the surface chemistry for targeting/imaging on the subcellular/molecular length scale, and develop a delivery nanocarrier for subcellular compartments.

Imaging and Targeting of the α(2-6) and α(2-3) Linked Sialic Acid Quantum Dots in Zebrafish and Mouse Models

Sialic acid-conjugated nanocarriers have emerged as attractive biomarkers with promising biomedical applications. The translation of these nanocarriers into clinical applications requires in-depth assessment in animal models. However, due to the complexity, ethical concerns, and cost of the high-order animal system, there is an immediate need of information-rich simple animal models to decipher the biological significance. Herein, we performed in vivo head-to-head comparison of Neu5Acα(2-6) and α(2-3)Gal conjugated quantum dots (QDs) toxicity, biodistribution, and sequestration in wild-type zebrafish ( Danio rerio) and mouse model (C57BL). The fluorescent properties and cadmium composition of quantum dots were used to map the blood clearance, biodistribution, and sequestration of the sialylated QDs in major organs of both models. We observed that α(2-6) sialylated QDs preferentially have prolonged circulating half-life and broader biodistribution in both models. On the contrary, α(2-3) sialic acid and galactose-conjugated QDs have shortened blood circulation time and are sequestered in the liver, and cleared after several hours in both models. These results demonstrate the applicability of the zebrafish and sialylated QDs to target specific organs, as well as drug delivery and biomedical diagnostics.

Peptide-based nanoprobes for molecular imaging and disease diagnostics

Pathological changes in a diseased site are often accompanied by abnormal activities of various biomolecules in and around the involved cells. Identifying the location and expression levels of these biomolecules could enable early-stage diagnosis of the related disease, the design of an appropriate treatment strategy, and the accurate assessment of the treatment outcomes. Over the past two decades, a great diversity of peptide-based nanoprobes (PBNs) have been developed, aiming to improve the in vitro and in vivo performances of water-soluble molecular probes through engineering of their primary chemical structures as well as the physicochemical properties of their resultant assemblies. In this review, we introduce strategies and approaches adopted for the identification of functional peptides in the context of molecular imaging and disease diagnostics, and then focus our discussion on the design and construction of PBNs capable of navigating through physiological barriers for targeted delivery and improved specificity and sensitivity in recognizing target biomolecules. We highlight the biological and structural roles that low-molecular-weight peptides play in PBN design and provide our perspectives on the future development of PBNs for clinical translation.

Glycyrrhetinic acid as a hepatocyte targeting unit for an anticancer drug delivery system with enhanced cell type selectivity

Herein, we explore glycyrrhetinic acid (GA) as an active targeting ligand for hepatocellular carcinoma (HCC) using a small molecule approach.

Presenting Precision Glycomacromolecules on Gold Nanoparticles for Increased Lectin Binding

Glyco-functionalized gold nanoparticles have great potential as biosensors and as inhibitors due to their increased binding to carbohydrate-recognizing receptors such as the lectins. Here we apply previously developed solid phase polymer synthesis to obtain a series of precision glycomacromolecules that allows for straightforward variation of their chemical structure as well as functionalization of gold nanoparticles by ligand exchange. A novel building block is introduced allowing for the change of spacer building blocks within the macromolecular scaffold going from an ethylene glycol unit to an aliphatic spacer. Furthermore, the valency and overall length of the glycomacromolecule is varied. All glyco-functionalized gold nanoparticles show high degree of functionalization along with high stability in buffer solution. Therefore, a series of measurements applying UV-Vis spectroscopy, dynamic light scattering (DLS) and surface plasmon resonance (SPR) were performed studying the aggregation behavior of the glyco-functionalized gold nanoparticles in presence of model lectin Concanavalin A. While the multivalent presentation of glycomacromolecules on gold nanoparticles (AuNPs) showed a strong increase in binding compared to the free ligands, we also observed an influence of the chemical structure of the ligand such as its valency or hydrophobicity on the resulting lectin interactions. The straightforward variation of the chemical structure of the precision glycomacromolecule thus gives access to tailor-made glyco-gold nanoparticles (glyco-AuNPs) and fine-tuning of their lectin binding properties.

Responsive Photonic Crystal Carbohydrate Hydrogel Sensor Materials for Selective and Sensitive Lectin Protein Detection

Lectin proteins, such as the highly toxic lectin protein, ricin, and the immunochemically important lectin, jacalin, play significant roles in many biological functions. It is highly desirable to develop a simple but efficient method to selectively detect lectin proteins. Here we report the development of carbohydrate containing responsive hydrogel sensing materials for the selective detection of lectin proteins. The copolymerization of a vinyl linked carbohydrate monomer with acrylamide and acrylic acid forms a carbohydrate hydrogel that shows specific "multivalent" binding to lectin proteins. The resulting carbohydrate hydrogels are attached to 2-D photonic crystals (PCs) that brightly diffract visible light. This diffraction provides an optical readout that sensitively monitors the hydrogel volume. We utilize lactose, galactose, and mannose containing hydrogels to fabricate a series of 2-D PC sensors that show strong selective binding to the lectin proteins ricin, jacalin, and concanavalin A (Con A). This binding causes a carbohydrate hydrogel shrinkage which significantly shifts the diffraction wavelength. The resulting 2-D PC sensors can selectively detect the lectin proteins ricin, jacalin, and Con A. These unoptimized 2-D PC hydrogel sensors show a limit of detection (LoD) of 7.5 × 10^-8 M for ricin, a LoD of 2.3 × 10^-7 M for jacalin, and a LoD of 3.8 × 10^-8 M for Con A, respectively. This sensor fabrication approach may enable numerous sensors for the selective detection of numerous lectin proteins.

Glycosidase Inhibition by Multivalent Presentation of Heparan Sulfate Saccharides on Bottlebrush Polymers

We report herein the first-time exploration of the attachment of well-defined saccharide units onto a synthetic polymer backbone for the inhibition of a glycosidase. More specifically, glycopolymers endowed with heparan sulfate (HS) disaccharides were established to inhibit the glycosidase, heparanase, with an IC50 value in the low nanomolar range (1.05 ± 0.02 nm), a thousand-fold amplification over its monovalent counterpart. The monomeric moieties of these glycopolymers were designed in silico to manipulate the well-established glycotope of heparanase into an inhitope. Studies concluded that (1) the glycopolymers are hydrolytic stable toward heparanase, (2) longer polymer length provides greater inhibition, and (3) increased local saccharide density (monoantennary vs diantennary) is negligible due to hindered active site of heparanase. Furthermore, HS oligosaccharide and polysaccharide controls illustrate the enhanced potency of a multivalent scaffold. Overall, the results on these studies of the multivalent presentation of saccharides on bottlebrush polymers serve as the platform for the design of potent glycosidase inhibitors and have potential to be applied to other HS-degrading proteins.

Core-shell hybrid nanostructured delivery platforms for advanced RNAi therapeutics

AIM

Study was aimed at combining the advantages of nonclassical RNAi-triggering oligonucleotides with nanoparticle-based advanced delivery platforms for developing efficient therapeutic systems.

MATERIALS & METHODS

We utilized a core-shell hybrid nanostructured platform for effectively delivering nonclassical RNAi triggers, namely long double stranded interfering RNA and tripodal interfering RNA. Core-shell structure was prepared by stably anchoring thiol-modified cationic polymer on the surface of growing crystal gold (Au) seeds, and the resulting particles were further complexed with nonclassical RNAi candidates via electrostatic interactions.

RESULTS

Our studies clearly demonstrated that the unique combination of nonclassical RNAi structures with an advanced core-shell hybrid nanostructured platform is an effective module for advanced RNAi-based therapeutic development.

Parallel comparative studies on toxicity of quantum dots synthesized and surface engineered with different methods in vitro and in vivo

Quantum dots (QDs) have been considered to be promising probes for biosensing, bioimaging, and diagnosis. However, their toxicity issues caused by heavy metals in QDs remain to be addressed, in particular for their in vivo biomedical applications. In this study, a parallel comparative investigation in vitro and in vivo is presented to disclose the impact of synthetic methods and their following surface modifications on the toxicity of QDs. Cellular assays after exposure to QDs were conducted including cell viability assessment, DNA breakage study in a single cellular level, intracellular reactive oxygen species (ROS) receptor measurement, and transmission electron microscopy to evaluate their toxicity in vitro. Mice experiments after QD administration, including analysis of hemobiological indices, pharmacokinetics, histological examination, and body weight, were further carried out to evaluate their systematic toxicity in vivo. Results show that QDs fabricated by the thermal decomposition approach in organic phase and encapsulated by an amphiphilic polymer (denoted as QDs-1) present the least toxicity in acute damage, compared with those of QDs surface engineered by glutathione-mediated ligand exchange (denoted as QDs-2), and the ones prepared by coprecipitation approach in aqueous phase with mercaptopropionic acid capped (denoted as QDs-3). With the extension of the investigation time of mice respectively injected with QDs, we found that the damage caused by QDs to the organs can be gradually recovered. This parallel comparative investigation suggests that synthetic methods and their resulting surface microenvironment play vital roles in the acute toxicity profiles of QDs. The present study provides updated insights into the fabrication and surface engineering of QDs for their translational applications in theranostics.

Mapping the Glyco-Gold Nanoparticles of Different Shapes Toxicity, Biodistribution and Sequestration in Adult Zebrafish

Glyconanotechnology offers a broad range of applications across basic and translation research. Despite the tremendous progress in glyco-nanomaterials, there is still a huge gap between the basic research and therapeutic applications of these molecules. It has been reported that complexity and the synthetic challenges in glycans synthesis, the cost of the high order in vivo models and large amount of sample consumptions limited the effort to translate the glyco-nanomaterials into clinical applications. In this regards, several promising simple animal models for preliminary, quick analysis of the nanomaterials activities has been proposed. Herein, we have studied a systematic evaluation of the toxicity, biodistribution of fluorescently tagged PEG and mannose-capped gold nanoparticles (AuNPs) of three different shapes (sphere, rod, and star) in the adult zebrafish model, which could accelerate and provide preliminary results for further experiments in the higher order animal system. ICP-MS analysis and confocal images of various zebrafish organs revealed that rod-AuNPs exhibited the fast uptake. While, star-AuNPs displayed prolong sequestration, demonstrating its potential therapeutic efficacy in drug delivery.

Cell membrane-derived nanomaterials for biomedical applications

The continued evolution of biomedical nanotechnology has enabled clinicians to better detect, prevent, manage, and treat human disease. In order to further push the limits of nanoparticle performance and functionality, there has recently been a paradigm shift towards biomimetic design strategies. By taking inspiration from nature, the goal is to create next-generation nanoparticle platforms that can more effectively navigate and interact with the incredibly complex biological systems that exist within the body. Of great interest are cellular membranes, which play essential roles in biointerfacing, self-identification, signal transduction, and compartmentalization. In this review, we explore the major ways in which researchers have directly leveraged cell membrane-derived biomaterials for the fabrication of novel nanotherapeutics and nanodiagnostics. Such emerging technologies have the potential to significantly advance the field of nanomedicine, helping to improve upon traditional modalities while also enabling novel applications.

Glucose-Modified Silicon Nanoparticles for Cellular Imaging

Luminescent silicon nanoparticles have recently attracted attention due to their remarkable stability, covalent functionalisation and tunable photoemission properties. Owing to their biocompatibility, low toxicity, and the small particle size that can be achieved by different synthetic approaches, these nanomaterials are candidates as cellular probes in the field of bioimaging, and potentially for in vivo applications. Tailoring the surface of the particles with active biomolecules such as sugar moieties can be an interesting strategy to increase the kinetics of internalisation or to vary the localisation of nanosystems in living cells. In this study, we synthesised and modified ultrasmall silicon nanoparticles with glucose covalently linked on their surface. Moreover, by varying the ratio between the amount of silicon nanoparticles and the saccharide groups, the amount of glucose, as a capping moiety, can be well controlled. FTIR spectroscopy, NMR spectroscopy, zeta potential measurements and anisotropy decay analysis confirmed the covalent binding of glucose to the nanoparticles. The photophysical behaviour of the surface-functionalised silicon quantum dots was not significantly different to that of the unmodified nanoparticles. In vitro studies demonstrated faster internalisation of the glucose-functionalised nanoparticles into HeLa cells. Different localisation and uptake kinetics of the glucose-modified particles compared to the unmodified particles are discussed in order to reveal the role played by the sugar molecules.

Sequential Double "Clicks" toward Structurally Well-Defined Heterogeneous N-Glycoclusters: The Importance of Cluster Heterogeneity on Pattern Recognition In Vivo

Structurally well-defined heterogeneous N-glycoclusters are prepared on albumin via a double click procedure. The number of glycan molecules present, in addition to the spatial arrangement of glycans in the heterogeneous glycoclusters, plays an important role in the in vivo kinetics and organ-selective accumulation through glycan pattern recognition mechanisms.

A ruthenium-nitrosyl-functionalized nanoplatform for the targeting of liver cancer cells and NIR-light-controlled delivery of nitric oxide combined with photothermal therapy

A multifunctional nanoplatform is capable of targeting liver cancer cells for NIR-light-controlled NO-release, and achieving both photodynamic and photothermal therapies.

In vitro evaluation of folic acid-conjugated redox-responsive mesoporous silica nanoparticles for the delivery of cisplatin

The use of cisplatin(IV) prodrugs for the delivery of cisplatin have gained significant attention, because of their low toxicity and reactivity. Recent studies have shown that targeted cisplatin(IV)-prodrug nanoparticle-based delivery systems can improve the internalization of the cisplatin(IV) prodrug. We hypothesized that folic acid-conjugated mesoporous silica nanoparticles (MSNs) containing cisplatin(IV) prodrug could target cancer cells that overexpress the folate receptor and deliver the active cisplatin drug upon intracellular reduction. To prove this hypothesis, internalization and localization studies in HeLa cancer cells were performed using flow cytometry and confocal microscopy. The ability of MSNs to escape from the endolysosomal compartments, the formation of DNA adducts, and the cytotoxic effects of the MSNs were also evaluated. Our results confirmed that this MSN-based delivery platform was capable of delivering cisplatin into the cytosol of HeLa cells, inducing DNA adducts and subsequent cell death.

Three-minute synthesis of sp3 nanocrystalline carbon dots as non-toxic fluorescent platforms for intracellular delivery

A one-pot, three-minute, gram-scale synthesis of novel sp³-nanocrystalline, water-soluble, and fluorescent carbon dots (FCDs), from simple and cheap sugar starting materials is described. Mechanism studies showed that NH₂-FCD formation proceeds via a crucial imine intermediate derived from reaction between a sugar hemiacetal and an amine. Moreover, we successfully demonstrate the utility of lactose functionalized FCDots (Lac-FCDots) as non-toxic fluorescent intracellular delivery vehicles.

Glyco-gold nanoparticle shapes enhance carbohydrate-protein interactions in mammalian cells

Advances in shape-dependent nanoparticle (NP) research have prompted a close scrutiny of the behaviour of nanostructures in vitro and in vivo. Data pertaining to cellular uptake and site specific sequestration of different shapes of NPs will undoubtedly assist researchers to design better nano-probes for therapeutic and imaging purposes. Herein, we investigated the shape dependent uptake of glyco-gold nanoparticles (G-AuNPs) in different cancer cell lines. Specifically, we have compared the behaviour of spherical, rod and star AuNPs with mannose and galactose conjugations. In vitro experiments showed that the rod-AuNPs exhibited the highest uptake over that of the star and spherical counterparts. Further, an investigation of the mechanism of the uptake clearly demonstrated clathrin mediated endocytosis of the specific G-AuNPs. These results reveal the benefits of different G-AuNP shapes in carbohydrate-mediated interactions.

Visualizing Trimming Dependence of Biodistribution and Kinetics with Homo- and Heterogeneous N-Glycoclusters on Fluorescent Albumin

A series of N-glycans, each sequentially trimmed from biantennary sialoglycans, were homo- or heterogeneously clustered efficiently on fluorescent albumin using a method that combined strain-promoted alkyne-azide cyclization and 6π-azaelectrocyclization. Noninvasive in vivo kinetics and dissection analysis revealed, for the first time, a glycan-dependent shift from urinary to gall bladder excretion mediated by sequential trimming of non-reducing end sialic acids. N-glycoalbumins that were trimmed further, in particular, GlcNAc- and hybrid biantennary-terminated congeners, were selectively taken up by sinusoidal endothelial and stellate cells in the liver, which are critical for diagnosis and treatment of liver fibrillation. Our glycocluster strategy can not only reveal the previously unexplored extracellular functions of N-glycan trimming, but will be classified as the newly emerging glycoprobes for diagnostic and therapeutic applications.

Glyconanomaterials for biosensing applications

Nanomaterials constitute a class of structures that have unique physiochemical properties and are excellent scaffolds for presenting carbohydrates, important biomolecules that mediate a wide variety of important biological events. The fabrication of carbohydrate-presenting nanomaterials, glyconanomaterials, is of high interest and utility, combining the features of nanoscale objects with biomolecular recognition. The structures can also produce strong multivalent effects, where the nanomaterial scaffold greatly enhances the relatively weak affinities of single carbohydrate ligands to the corresponding receptors, and effectively amplifies the carbohydrate-mediated interactions. Glyconanomaterials are thus an appealing platform for biosensing applications. In this review, we discuss the chemistry for conjugation of carbohydrates to nanomaterials, summarize strategies, and tabulate examples of applying glyconanomaterials in in vitro and in vivo sensing applications of proteins, microbes, and cells. The limitations and future perspectives of these emerging glyconanomaterials sensing systems are furthermore discussed.

Analysis of Carbohydrate-Carbohydrate Interactions Using Sugar-Functionalized Silicon Nanoparticles for Cell Imaging

Protein-carbohydrate binding depends on multivalent ligand display that is even more important for low affinity carbohydrate-carbohydrate interactions. Detection and analysis of these low affinity multivalent binding events are technically challenging. We describe the synthesis of dual-fluorescent sugar-capped silicon nanoparticles that proved to be an attractive tool for the analysis of low affinity interactions. These ultrasmall NPs with sizes of around 4 nm can be used for NMR quantification of coupled sugars. The silicon nanoparticles are employed to measure the interaction between the cancer-associated glycosphingolipids GM3 and Gg3 and the associated kD value by surface plasmon resonance experiments. Cell binding studies, to investigate the biological relevance of these carbohydrate-carbohydrate interactions, also benefit from these fluorescent sugar-capped nanoparticles.