Click chemistry functionalized polymeric nanoparticles target corneal epithelial cells through RGD-cell surface receptors

Surface-functionalised polymeric nanoparticles for breast cancer treatment: processes and advances

The World Health Organization (WHO) reported that of all the non-communicable diseases, cancer is considered the second cause of death worldwide. This has driven the big pharma companies to prioritise anticancer products in their pipeline. In addition, research has focused on exploration of new anticancer molecules and design of suitable dosage forms to achieve effective drug delivery to the tumour site. Nanotechnology is a valuable tool to build nano delivery systems with controlled and targeted drug release properties. Nanoparticles can be fabricated by robust, scalable and economic techniques using various polymers. Moreover, specific functional groups can be introduced to the surface of nanoparticles enabling targeting to a specific tissue; besides, they exhibit versatile drug release patterns according to the rate of polymer degradation. This review outlines the processes and advances in surface functionalisation of nanoparticles employed for treatment of breast cancer. The therapeutic molecules, the polymers used to fabricate nanoparticles, the techniques used to prepare the nanoparticles have been reviewed with a focus on the processes employed to functionalise these nanoparticles with suitable ligands to target different types of breast cancer.

Click-functionalized hydrogel design for mechanobiology investigations

The advancement of click-functionalized hydrogels in recent years has coincided with rapid growth in the fields of mechanobiology, tissue engineering, and regenerative medicine. Click chemistries represent a group of reactions that possess high reactivity and specificity, are cytocompatible, and generally proceed under physiologic conditions. Most notably, the high level of tunability afforded by these reactions enables the design of user-controlled and tissue-mimicking hydrogels in which the influence of important physical and biochemical cues on normal and aberrant cellular behaviors can be independently assessed. Several critical tissue properties, including stiffness, viscoelasticity, and biomolecule presentation, are known to regulate cell mechanobiology in the context of development, wound repair, and disease. However, many questions still remain about how the individual and combined effects of these instructive properties regulate the cellular and molecular mechanisms governing physiologic and pathologic processes. In this review, we discuss several click chemistries that have been adopted to design dynamic and instructive hydrogels for mechanobiology investigations. We also chart a path forward for how click hydrogels can help reveal important insights about complex tissue microenvironments.

Chitotriazolan (poly(β(1-4)-2-(1H-1,2,3-triazol-1-yl)-2-deoxy-d-glucose)) derivatives: Synthesis, characterization, and evaluation of antibacterial activity

Here we describe the first synthesis of a new type of polysaccharides derived from chitosan. In these structures, the 2-amino group on the pyranose ring was quantitively replaced by an aromatic 1,2,3-triazole moiety. The 2-amino group of chitosan and di-TBDMS chitosan was converted into an azide by diazo transfer reaction. The chitosan azide and TBDMS-chitosan azide were poorly soluble but could be fully converted to triazoles by "copper-catalysed Huisgen cycloaddition" in DMF or DMSO. The reaction could be done with different alkynes but derivatives lacking cationic or anionic groups were poorly soluble or insoluble in tested aqueous and organic solvents. Derivatives with N,N-dimethylaminomethyl, N,N,N-trimethylammoniummethyl, sulfonmethyl, and phosphomethyl groups linked to the 4-position of the triazole moiety were soluble in water at neutral or basic conditions and could be analyzed by ¹H, ¹³C APT, COSY, and HSQC NMR. The quaternized cationic chitotriazolan's had high activity against S. aureus and E. coli, whereas the anionic chitotriazolan's lacked activity.

Advancements in folate receptor targeting for anti-cancer therapy: A small molecule-drug conjugate approach

Targeted delivery combined with controlled release of drugs has a crucial role in future of personalized medicine. The majority of cancer drugs are intended to interfere with one or more cellular events. Anticancer agents can also be toxic to healthy cells, as healthy cells may also need to proliferate and avoid apoptosis. The focus of this review covers the principles, advantages, drawbacks and summarize criteria that must be met for design of small molecule-drug conjugates (SMDCs) to achieve the desired therapeutic potency with minimal toxicity. SMDCs are composed of a targeting ligand, a releasable bridge, a spacer, and a therapeutic payload. We summarize the criteria for the effective design that influences the selection of tumor specific receptor and optimum elements in the design of SMDCs. We also discuss the criteria for selecting the optimal therapeutic drug payload, spacer and linker. The linker chemistries and cleavage strategies are also discussed. Finally, we review the folate receptor targeting SMDCs that are in preclinical development and in clinical trials.

LHRH-Targeted Redox-Responsive Crosslinked Micelles Impart Selective Drug Delivery and Effective Chemotherapy in Triple-Negative Breast Cancer

Systemic chemotherapy is efficacious against triple-negative breast cancer (TNBC), but it is often associated with serious side effects. Here, a luteinizing hormone-releasing hormone (LHRH) receptor-targeted and tumor microenvironment-responsive nanoparticle system to selectively deliver chemotherapeutic drugs to TNBC cells, is reported. This delivery system (termed "LHRH-DCMs") contains poly(ethylene glycol) and dendritic cholic acid as a micellar carrier, reversible intra-micellar disulfide bond as a redox-responsive crosslink, and synthetic high-affinity (D-Lys)-LHRH peptide as a targeting moiety. LHRH-DCMs exhibit high drug loading efficiency, optimal particle size, good colloidal stability, and glutathione-responsive drug release. As expected, LHRH-DCMs are more efficiently internalized into human TNBC cells through receptor-mediated endocytosis, resulting in stronger cytotoxicity against these cancer cells than the non-targeted counterpart when encapsulated with paclitaxel (PTX). Furthermore, near-infrared fluorescence and magnetic resonance imaging demonstrate that LHRH-DCMs facilitate the tumor distribution and penetration of payloads in three different animal models of breast cancer, including cell line-derived xenograft (CDX), patient-derived xenograft (PDX), and transgenic mammary carcinoma. Finally, in vivo therapeutic studies show that PTX-LHRH-DCMs outperform both the corresponding nontargeted PTX-DCMs and the current clinical formulation (Taxol) in an orthotopic TNBC model. These results provide new insights into approaches for precise drug delivery of TNBC.

Antibody-mediated drug delivery

Passive and active targeted nanoparticulate delivery systems show promise to compensate for lacking properties of conventional therapy such as side effects, insufficient efficiency and accumulation of the drug at target site, poor pharmacokinetic properties etc. For active targeting, physically or covalently conjugated ligands, including monoclonal antibodies and their fragments, are consistently used and researched for targeting delivery systems or drugs to their target site. Currently, there are several FDA approved actively targeted antibody-drug conjugates, whereas no active targeted delivery system is in clinical use at present. However, efforts to successfully formulate actively targeted delivery systems continue. The scope of this review will be the use of monoclonal antibodies and their fragments as targeting ligands. General information about targeted delivery and antibodies will be given at the first half of the review. As for the second half, fragmentation of antibodies and conjugation approaches will be explained. Monoclonal antibodies and their fragments as targeting ligands and approaches for conjugating these ligands to nanoparticulate delivery systems and drugs will be the main focus of this review, polyclonal antibodies will not be included.

A comparison of acyl-moieties for noncovalent functionalization of PLGA and PEG-PLGA nanoparticles with a cell-penetrating peptide

Noncovalent functionalization with acylated cell-penetrating peptides achieves an efficient cellular uptake of PLGA and PEG-PLGA nanoparticles.

Stimulus-cleavable chemistry in the field of controlled drug delivery

This review comprehensively summarises stimulus-cleavable linkers from various research areas and their cleavage mechanisms, thus provides an insightful guideline to extend their potential applications to controlled drug release from nanomaterials.

Gelatin Nanoparticles-HPMC Hybrid System for Effective Ocular Topical Administration of Antihypertensive Agents

The increment in ocular drug bioavailability after topical administration is one of the main challenges in pharmaceutical technology. For several years, different strategies based on nanotechnology, hydrogels or implants have been evaluated. Nowadays, the tolerance of ophthalmic preparations has become a critical issue and it is essential to the use of well tolerated excipients. In the present work, we have explored the potential of gelatin nanoparticles (GNPs) loaded with timolol maleate (TM), a beta-adrenergic blocker widely used in the clinic for glaucoma treatment and a hybrid system of TM-GNPs included in a hydroxypropyl methylcellulose (HPMC) viscous solution. The TM- loaded nanoparticles (mean particle size of 193 ± 20 nm and drug loading of 0.291 ± 0.019 mg TM/mg GNPs) were well tolerated both in vitro (human corneal cells) and in vivo. The in vivo efficacy studies performed in normotensive rabbits demonstrated that these gelatin nanoparticles were able to achieve the same hypotensive effect as a marketed formulation (0.5% TM) containing a 5-fold lower concentration of the drug. When comparing commercial and TM-GNPs formulations with the same TM dose, nanoparticles generated an increased efficacy with a significant (p < 0.05) reduction of intraocular pressure (IOP) (from 21% to 30%) and an augmentation of 1.7-fold in the area under the curve (AUC)(0-12h). On the other hand, the combination of timolol-loaded nanoparticles (TM 0.1%) and the viscous polymer HPMC 0.3%, statistically improved the IOP reduction up to 30% (4.65 mmHg) accompanied by a faster time of maximum effect (tmax = 1 h). Furthermore, the hypotensive effect was extended for four additional hours, reaching a pharmacological activity that lasted 12 h after a single instillation of this combination, and leading to an AUC(0-12h) 2.5-fold higher than the one observed for the marketed formulation. According to the data presented in this work, the use of hybrid systems that combine well tolerated gelatin nanoparticles and a viscous agent could be a promising alternative in the management of high intraocular pressure in glaucoma.

Nitrone-Modified Gold Nanoparticles: Synthesis, Characterization, and Their Potential as 18F-Labeled Positron Emission Tomography Probes via I-SPANC

A novel bioorthogonal gold nanoparticle (AuNP) template displaying interfacial nitrone functional groups for bioorthogonal interfacial strain-promoted alkyne-nitrone cycloaddition reactions has been synthesized. These nitrone-AuNPs were characterized in detail using 1H nuclear magnetic resonance spectroscopy, transmission electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy, and a nanoparticle raw formula was calculated. The ability to control the conjugation of molecules of interest at the molecular level onto the nitrone-AuNP template allowed us to create a novel methodology for the synthesis of AuNP-based radiolabeled probes.

Overcoming the Anatomical and Physiological Barriers in Topical Eye Surface Medication Using a Peptide-Decorated Polymeric Micelle

The sealed anatomical features of the eye and its physiological activity that rapidly removes drugs are called anatomical and physiological barriers, which are the cause of more than 90% of drug loss. This aspect remains a critical issue in eye surface medication. Thus, promoting tissue permeability of drugs as well as prolonging their retention on the eye surface can improve their bioavailability and enhance their therapeutic effects. Thanks to the existence of a negatively charged mucin layer on the eye surface, several peptide-decorated polymeric micelles were prepared to enhance the interaction between the micelle and eye surface, thus prolonging the drug retention on the eye surface and promoting its tissue permeability. Tacrolimus (also known as FK506) is a hydrophobic macrolide immunosuppressant used to treat dry eye syndrome and other eye diseases. However, its hydrophobic nature makes its delivery as a topical eye surface medication difficult, with the risk of side effects due to overdoses. Therefore, the aim of this work is to evaluate the ability of FK506 micelles in promoting their permeability on the eye surface. Our results showed that the positively charged nanomicelles could significantly prolong FK506 retention on the eye surface and enhance its corneal permeability in ex vivo and in vivo conditions. FK506 nanomicelles exhibited superior curing effects against dry eye diseases than the FK506 suspension and a commercial FK506 formula. It exerted better inhibitory effects on eye surface inflammation and corneal epithelium apoptosis when examined by a slip lamp and a transferase-mediated dUTP nick end labeling assay, respectively. Further assays revealed the higher suppressive effects on the expression of several inflammation-related factors at an mRNA and protein level. Hence, our results suggested that these positively charged nanomicelles might be a good drug delivery system for ocular surface medication.

Breakthroughs in medicine and bioimaging with up-conversion nanoparticles

Nanomedicine is a medical application of biochemistry incorporated with materials chemistry at the scale of nanometer for the purpose of diagnosis, prevention, and treatment. New models and approaches are typically associated with nanomedicine for precise multifunctional diagnostic systems at molecular level. Hence, employing nanoparticles (NPs) has unveiled new opportunities for efficient therapies and remedy of difficult-to-cure diseases. Among all types of inorganic NPs, lanthanide-doped up-conversion nanoparticles (UCNPs) have shown excellent potential for biomedical applications, especially for multimodal bioimaging including fluorescence and electron microscopy. Association of these visualization techniques plus the capability for transporting biomaterials and drugs make them superior agents in the field of nanomedicine. Accordingly, in this review, we firstly presented a fundamental understanding of physical and optical properties of UCNPs and secondly, we illustrated some of the prominent associations with bioimaging, theranostics, cancer therapy, and optogenetics.

Integrin αvβ3-Targeted [64Cu]CuS Nanoparticles for PET/CT Imaging and Photothermal Ablation Therapy

Copper sulfide (CuS) nanoparticles have been considered one of the most clinical relevant nanosystems because of their straightforward chemistry, small particle size, low toxicity, and intrinsic theranostic characteristics. In our previous studies, radioactive [⁶⁴Cu]CuS nanoparticles were successfully developed to be used as efficient radiotracers for positron emission tomography and for photothermal ablation therapy of cancer cells using near-infrared laser irradiation. However, the major challenge of CuS nanoparticles as a theranostic platform is the lack of a means for effective targeted delivery to the tumor site. To overcome this challenge, we designed and synthesized angiogenesis-targeting [⁶⁴Cu]CuS nanoparticles, which are coupled with cyclic RGDfK peptide [c(RGDfK)] through polyethylene glycol (PEG) linkers using click chemistry. In assessing their tumor-targeting efficacy, we found that the tumor uptakes of [⁶⁴Cu]CuS-PEG-c(RGDfK) nanoparticles at 24 h after intravenous injection were significantly greater (8.6% ± 1.4% injected dose/gram of tissue) than those of nontargeted [⁶⁴Cu]CuS-PEG nanoparticles (4.3% ± 1.2% injected dose/gram of tissue, p < 0.05). Irradiation of tumors in mice administered [⁶⁴Cu]CuS-PEG-c(RGDfK) nanoparticles induced 98.7% necrotic areas. In contrast, irradiation of tumors in mice administered nontargeted CuS-PEG nanoparticles induced 59% necrotic areas ( p < 0.05). The angiogenesis-targeting [⁶⁴Cu]CuS nanoparticles may serve as a promising platform for image-guided ablation therapy with high efficacy and minimal side effects in future clinical translation of this novel class of multifunctional nanomaterials.

177Lu-labeled cyclic Asn-Gly-Arg peptide tagged carbon nanospheres as tumor targeting radio-nanoprobes

This study explores the potential of ¹⁷⁷Lu-labeled carbon nanospheres as radio-nanoprobes for molecular imaging and therapy. The carboxyl functionalized surface of carbon nanospheres (CNS) was conjugated with [Gly-Gly-Gly-c(Asn-Gly-Arg)], G3-cNGR peptide through amide bond for targeting tumor vasculature and with [2-(4-Aminobenzyl)-1,4,7,10-tetraazacyclododecane tetraacetic acid], p-NH₂-Bz-DOTA for chelation with ¹⁷⁷Lu. The nanosphere-peptide conjugate, DOTA-CNS-cNGR, was characterized by dynamic light scattering and zeta potential measurements, IR and UV experiments and did not show any in vitro cytotoxicity. The pharmacokinetics and biodistribution of ¹⁷⁷Lu-labeled nanosphere-peptide conjugate, ¹⁷⁷Lu-DOTA-CNS-cNGR was compared with ¹⁷⁷Lu-DOTA-CNS (without the peptide) as well as with ¹⁷⁷Lu-DOTA-cNGR (without carbon nanospheres). The radiolabeled nanosphere-peptide conjugate exhibited higher tumor accumulation than nanosphere-free radiolabeled peptide. The accumulation of the two radiolabeled probes in the tumor reduced to half during blocking studies with unlabeled G3-cNGR peptide. ¹⁷⁷Lu-DOTA-CNS exhibited higher tumor uptake than ¹⁷⁷Lu-DOTA-CNS-cNGR but rapid clearance of the latter nanoprobe from non-target organs resulted in significantly higher (p < 0.05) tumor-to-blood and tumor-to-muscle ratios at 24 and 48 h p.i. It is evident from this study that carbon nanospheres conjugated to specific vectors shall form an important part of targeted radionanomedicine in future.

Nanoparticles for drug delivery to the anterior segment of the eye

Commercially available ocular drug delivery systems are effective but less efficacious to manage diseases/disorders of the anterior segment of the eye. Recent advances in nanotechnology and molecular biology offer a great opportunity for efficacious ocular drug delivery for the treatments of anterior segment diseases/disorders. Nanoparticles have been designed for preparing eye drops or injectable solutions to surmount ocular obstacles faced after administration. Better drug pharmacokinetics, pharmacodynamics, non-specific toxicity, immunogenicity, and biorecognition can be achieved to improve drug efficacy when drugs are loaded in the nanoparticles. Despite the fact that a number of review articles have been published at various points in the past regarding nanoparticles for drug delivery, there is not a review yet focusing on the development of nanoparticles for ocular drug delivery to the anterior segment of the eye. This review fills in the gap and summarizes the development of nanoparticles as drug carriers for improving the penetration and bioavailability of drugs to the anterior segment of the eye.

Forming next-generation antibody-nanoparticle conjugates through the oriented installation of non-engineered antibody fragments

Enabling oriented installation of non-engineered antibody fragments on nanoparticle surfaces to create next-generation antibody–nanoparticle conjugates.

The successful development of targeted nanotherapeutics is contingent upon the conjugation of therapeutic nanoparticles to target-specific ligands, with particular emphasis being placed on antibody-based ligands. Thus, new methods that enable the covalent and precise installation of targeting antibodies to nanoparticle surfaces are greatly desired, especially those which do not rely on costly and time-consuming antibody engineering techniques. Herein we present a novel method for the highly controlled and oriented covalent conjugation of non-engineered antibody F(ab) fragments to PLGA–PEG nanoparticles using disulfide-selective pyridazinedione linkers and strain-promoted alkyne–azide click chemistry. Exemplification of this method with trastuzumab and cetuximab showed significant improvements in both conjugation efficiency and antigen binding capability, when compared to commonly employed strategies for antibody–nanoparticle construction. This new approach paves the way for the development of antibody-targeted nanomedicines with improved paratope availability, reproducibility and uniformity to enhance both biological activity and ease of manufacture.

Condition responsive nanoparticles for managing infection and inflammation in keratitis

Keratitis is a major cause of avoidable visual impairment. About 30% of patients with fungal keratitis eventually become permanently blind in the developing world. Proteases, secreted by the pathogen and the host, damage the cornea before the infection is resolved. Treating keratitis is a challenge because both infection and inflammation need to be addressed. An additional challenge is to maintain a therapeutic dose at the corneal surface as blinking and tear film wash away the drugs, administered as eye drops. We have developed a nanoparticle-based drug delivery system that enhances the drug residence time by anchoring to the cornea, down-regulates inflammation and releases the antifungal drug: all in a condition-responsive manner. The expression of Toll-Like Receptors (TLR4) on the corneal epithelial cells increases in response to infection. We have conjugated anti-TLR4 antibodies on the surface of ketoconazole-encapsulated gelatin nanoparticles. The anti-TLR4 antibody not only facilitates binding of nanoparticles to the cornea, enhancing their residence time, but also reduces the levels of inflammatory cytokines. Host and fungal proteases degrade the gelatin nanoparticle, an alternative substrate for proteases, thereby reducing corneal damage and releasing the encapsulated drug, ketoconazole, proportional to the severity of infection. After testing the efficacy of the system with human corneal epithelial cells, we have extended our studies to a rat model of keratitis. The results show a significantly increased corneal retention, suppressed inflammation and resolution of infection in the infected eyes. We believe that this will be an excellent approach to manage keratitis as well as other topical ocular infections.

Heat-induced-radiolabeling and click chemistry: A powerful combination for generating multifunctional nanomaterials

A key advantage of nanomaterials for biomedical applications is their ability to feature multiple small reporter groups (multimodality), or combinations of reporter groups and therapeutic agents (multifunctionality), while being targeted to cell surface receptors. Here a facile combination of techniques for the syntheses of multimodal, targeted nanoparticles (NPs) is presented, whereby heat-induced-radiolabeling (HIR) labels NPs with radiometals and so-called click chemistry is used to attach bioactive groups to the NP surface. Click-reactive alkyne or azide groups were first attached to the nonradioactive clinical Feraheme (FH) NPs. Resulting "Alkyne-FH" and "Azide-FH" intermediates, like the parent NP, tolerated 89Zr labeling by the HIR method previously described. Subsequently, biomolecules were quickly conjugated to the radioactive NPs by either copper-catalyzed or copper-free click reactions with high efficiency. Synthesis of the Alkyne-FH or Azide-FH intermediates, followed by HIR and then by click reactions for biomolecule attachment, provides a simple and potentially general path for the synthesis of multimodal, multifunctional, and targeted NPs for biomedical applications.

One pot synthesis of amine-functionalized and angular-shaped superparamagnetic iron oxide nanoparticles for MR/fluorescence bimodal imaging application

Herein, we report the simple preparation of water dispersible angular-shaped amine-functionalized super-paramagnetic iron oxide nanoparticles (A-SPIONs).

Receptor-targeted drug delivery: current perspective and challenges

Receptor-targeted drug delivery has been extensively explored for active targeting. However, the scarce clinical applications of such delivery systems highlight the implicit hurdles in development of such systems. These hurdles begin with lack of knowledge of differential expression of receptors, their accessibility and identification of newer receptors. Similarly, ligand-specific challenges range from proper choice of ligand and conjugation chemistry, to release of drug/delivery system from ligand. Finally, nanocarrier systems, which offer improved loading, biocompatibility and reduced premature degradation, also face multiple challenges. This review focuses on understanding these challenges, and means to overcome such challenges to develop efficient, targeted drug-delivery systems.

177Lu-labeled carbon nanospheres: a new entry in the field of targeted radionanomedicine

¹⁷⁷Lu-labeled carbon nanospheres loaded with cRGDfK peptide have been developed as radionanoprobes with favorable pharmacokinetics for integrin α_vβ₃-mediated active targeting.

Qualitative sensing of mechanical damage by a fluorogenic “click” reaction

A simple and unique damage-sensing tool mediated by a Cu(i)-catalyzed [3+2] cycloaddition reaction is reported, where a fluorogenic “click”-reaction highlights physical damage by a strong fluorescence increase accompanied by in situ monitoring of localized self-healing.

Dual-function fluorescent probe for cancer imaging and therapy

To date, several fluorescent probes modified by a single targeting agent have been explored. However, studies on the preparation of dual-function quantum dot (QD) fluorescent probes with dual-targeting action and a therapeutic effect are rare. Here, a dual-targeting CdTe/CdS QD fluorescent probe with a bovine serum albumin-glycyrrhetinic acid conjugate and arginine-glycine-aspartic acid was successfully prepared that could induce the apoptosis of liver cancer cells and showed enhanced targeting in in vitro cell imaging. Therefore, the as-prepared fluorescent probe in this work is an efficient diagnostic tool for the simultaneous detection of liver cancer and breast cancer cells.

In situ modulation of cell behavior via smart dual-ligand surfaces

Due to the highly complex nature of the extracellular matrix (ECM), the design and implementation of dynamic, stimuli-responsive surfaces that present well-defined ligands and serve as model ECM substrates have been of tremendous interest to biomaterials, biosensor, and cell biology communities. Such tools provide strategies for identifying specific ligand-receptor interactions that induce vital biological consequences. Herein, we report a novel dual-ligand-presenting surface methodology that modulates dynamic ECM properties to investigate various cell behaviors. Peptides PHSRN, cRGD, and KKKTTK, which mimic the cell- and heparan sulfate-binding domains of fibronectin, and carbohydrates Gal and Man were combined with cell adhesive RGD to survey possible synergistic or antagonist ligand effects on cell adhesion, spreading, growth, and migration. Soluble molecule and enzymatic inhibition assays were also performed, and the levels of focal adhesion kinase in cells subjected to different ligand combinations were quantified. A redox-responsive trigger was incorporated into this surface strategy to spontaneously release ligands in the presence of adhered cells, and cell spreading, growth, and migration responses were measured and compared. The identity and nature of the dual-ligand combination directly influenced cell behavior.

Molecular docking characterization of a four-domain segment of human fibronectin encompassing the RGD loop with hydroxyapatite

Fibronectin adsorption on biomaterial surfaces plays a key role in the biocompatibility of biomedical implants. In the current study, the adsorption behavior of the 7–10th type III modules of fibronectin (FN-III_7–10) in the presence of hydroxyapatite (HAP) was systematically investigated by using molecular docking approach. It was revealed that the FN-III₁₀ is the most important module among FN-III_7–10 in promoting fibronectin binding to HAP by optimizing the interaction energy; the arginine residues were observed to directly interact with the hydroxyl group of HAP through electrostatic forces and hydrogen bonding. Moreover, it was found that the HAP-binding sites on FN-III₁₀ are mainly located at the RGD loop region, which does not affect the interaction between the fibronectin protein and its cognate receptors on the cell surface.

Retro-inverso carbohydrate mimetic peptides with annexin1-binding selectivity, are stable in vivo, and target tumor vasculature

Previous research suggests that carbohydrate mimetic peptide IF7 (IFLLWQR) has an excellent targeting property to annexin1 (Anxa1), a specific marker on the tumor endothelium. However, IF7 is susceptible to proteolysis and has a poor stability in vivo. We prepared a D-amino acid, reverse sequence peptide of IF7, designated RIF7, to confer protease resistance while retaining bioactivity. Experimental results indicate that RIF7 had significantly increased stability and an increased receptor binding affinity than IF7, and this new moiety may represent a clinically relevant vehicle for anticancer drugs.

Carbodiimide versus click chemistry for nanoparticle surface functionalization: a comparative study for the elaboration of multimodal superparamagnetic nanoparticles targeting αvβ3 integrins

Superparamagnetic fluorescent nanoparticles targeting αvβ3 integrins were elaborated using two methodologies: carbodiimide coupling and click chemistries (CuACC and thiol-yne). The nanoparticles are first functionalized with hydroxymethylenebisphonates (HMBP) bearing carboxylic acid or alkyne functions. Then, a large number of these reactives functions were used for the covalent coupling of dyes, poly(ethylene glycol) (PEG), and cyclic RGD. Several methods were used to characterize the nanoparticle surface functionalization, and the magnetic properties of these contrast agents were studied using a 1.5 T clinical MRI. The affinity toward integrins was evidenced by solid-phase receptor-binding assay. In addition to their chemoselective natures, click reactions were shown to be far more efficient than the carbodiimide coupling. The grafting increase was shown to enhance targeting affinity to integrin without imparing MRI and fluorescent properties.

Gene therapy in corneal transplantation

Corneal transplantation is the most commonly performed organ transplantation. Immune privilege of the cornea is widely recognized, partly because of the relatively favorable outcome of corneal grafts. The first-time recipient of corneal allografts in an avascular, low-risk setting can expect a 90% success rate without systemic immunosuppressive agents and histocompatibility matching. However, immunologic rejection remains the major cause of graft failure, particularly in patients with a high risk for rejection. Corticosteroids remain the first-line therapy for the prevention and treatment of immune rejection. However, current pharmacological measures are limited in their side-effect profiles, repeated application, lack of targeted response, and short duration of action. Experimental ocular gene therapy may thus present new horizons in immunomodulation. From efficient viral vectors to sustainable alternative splicing, we discuss the progress of gene therapy in promoting graft survival and postulate further avenues for gene-mediated prevention of allogeneic graft rejection.

Alkyne-azide "click" chemistry in designing nanocarriers for applications in biology

The alkyne-azide cycloaddition, popularly known as the "click" reaction, has been extensively exploited in molecule/macromolecule build-up, and has offered tremendous potential in the design of nanomaterials for applications in a diverse range of disciplines, including biology. Some advantageous characteristics of this coupling include high efficiency, and adaptability to the environment in which the desired covalent linking of the alkyne and azide terminated moieties needs to be carried out. The efficient delivery of active pharmaceutical agents to specific organelles, employing nanocarriers developed through the use of "click" chemistry, constitutes a continuing topical area of research. In this review, we highlight important contributions click chemistry has made in the design of macromolecule-based nanomaterials for therapeutic intervention in mitochondria and lipid droplets.

Click conjugated polymeric immuno-nanoparticles for targeted siRNA and antisense oligonucleotide delivery

Efficient and targeted cellular delivery of small interfering RNAs (siRNAs) and antisense oligonucleotides (AONs) is a major challenge facing oligonucleotide-based therapeutics. The majority of current delivery strategies employ either conjugated ligands or oligonucleotide encapsulation within delivery vehicles to facilitate cellular uptake. Chemical modification of the oligonucleotides (ONs) can improve potency and duration of activity, usually as a result of improved nuclease resistance. Here we take advantage of innovations in both polymeric delivery vehicles and ON stabilization to achieve receptor-mediated targeted delivery of siRNAs or AONs for gene silencing. Polymeric nanoparticles comprised of poly(lactide-co-2-methyl, 2-carboxytrimethylene carbonate)-g-polyethylene glycol-furan/azide are click-modified with both anti-HER2 antibodies and nucleic acids on the exterior PEG corona. Phosphorothioate (PS), 2'F-ANA, and 2'F-RNA backbone chemical modifications improve siRNA and AON potency and duration of activity. Importantly, delivery of these nucleic acids on the exterior of the polymeric immuno-nanoparticles are as efficient in gene silencing as lipofectamine transfection without the associated potential toxicity of the latter.

Identification of an aminothiazole with antifungal activity against intracellular Histoplasma capsulatum

As eukaryotes, fungi possess relatively few molecules sufficiently unique from mammalian cell components to be used as drug targets. Consequently, most current antifungals have significant host cell toxicity. Primary fungal pathogens (e.g., Histoplasma) are of particular concern, as few antifungals are effective in treating them. To identify additional antifungal candidates for the treatment of histoplasmosis, we developed a high-throughput platform for monitoring Histoplasma growth and employed it in a phenotypic screen of 3,600 commercially available compounds. Seven hit compounds that inhibited Histoplasma yeast growth were identified. Compound 41F5 has fungistatic activity against Histoplasma yeast at micromolar concentrations, with a 50% inhibitory concentration (IC50) of 0.87 μM, and has the greatest selectivity for yeast (at least 62-fold) relative to host cells. Structurally, 41F5 consists of an aminothiazole core with an alicyclic substituent at the 2-position and an aromatic substituent at the 5-position. 41F5 inhibits Histoplasma growth in liquid culture and similarly inhibits yeast cells within macrophages, the actual host environment of this fungal pathogen during infection. Importantly, 41F5 protects infected host cells from Histoplasma-induced macrophage death, making this aminothiazole hit compound an excellent candidate for development as an antifungal for Histoplasma infections.

Dendrimer nanoparticles for ocular drug delivery

Eye is a unique organ of perfection and complexity, and is a microcosm of the body in many ways. It represents a great opportunity for nanomedicine, since it is readily accessible-allowing for direct drug/gene delivery to maximize the therapeutic effect and minimize side effects. The development of appropriate delivery systems that can sustain and deliver therapeutics to the target tissues is a key challenge that can be addressed by nanotechnology. Dendrimers are tree-like, nanostructured polymers that have received significant attention as ocular drug delivery systems, due to their well-defined size, tailorable structure, and potentially favorable ocular biodistribution. In this review, we highlight recent developments in dendrimer-based ocular therapies for both anterior and posterior segment diseases.