Gold Nanoparticles Functionalized with RGD‐Semipeptides: A Simple yet Highly Effective Targeting System for αVβ3Integrins

A Laser-Driven Microrobot for Thermal Stimulation of Single Cells

Here, the study presents a thermally activated cell-signal imaging (TACSI) microrobot, capable of photothermal actuation, sensing, and light-driven locomotion. The plasmonic soft microrobot is specifically designed for thermal stimulation of mammalian cells to investigate cell behavior under heat active conditions. Due to the integrated thermosensitive fluorescence probe, Rhodamine B, the system allows dynamic measurement of induced temperature changes. TACSI microrobots show excellent biocompatibility over 72 h in vitro, and they are capable of thermally activating single cells to cell clusters. Locomotion in a 3D workspace is achieved by relying on thermophoretic convection, and the microrobot speed is controlled within a range of 5-65 µm s-1 . In addition, light-driven actuation enables spatiotemporal control of the microrobot temperature up to a maximum of 60 °C. Using TACSI microrobots, this study targets single cells within a large population, and demonstrates thermal cell stimulation using calcium signaling as a biological output. Initial studies with human embryonic kidney 293 cells indicate a dose dependent change in intracellular calcium content within the photothermally controlled temperature range of 37-57 °C.

Cyclic Ruthenium-Peptide Conjugates as Integrin-Targeting Phototherapeutic Prodrugs for the Treatment of Brain Tumors

To investigate the potential of tumor-targeting photoactivated chemotherapy, a chiral ruthenium-based anticancer warhead, Λ/Δ-[Ru(Ph₂phen)₂(OH₂)₂]²⁺, was conjugated to the RGD-containing Ac-MRGDH-NH₂ peptide by direct coordination of the M and H residues to the metal. This design afforded two diastereoisomers of a cyclic metallopeptide, Λ-[1]Cl₂ and Δ-[1]Cl₂. In the dark, the ruthenium-chelating peptide had a triple action. First, it prevented other biomolecules from coordinating with the metal center. Second, its hydrophilicity made [1]Cl₂ amphiphilic so that it self-assembled in culture medium into nanoparticles. Third, it acted as a tumor-targeting motif by strongly binding to the integrin (K_d = 0.061 μM for the binding of Λ-[1]Cl₂ to α_IIbβ₃), which resulted in the receptor-mediated uptake of the conjugate in vitro. Phototoxicity studies in two-dimensional (2D) monolayers of A549, U87MG, and PC-3 human cancer cell lines and U87MG three-dimensional (3D) tumor spheroids showed that the two isomers of [1]Cl₂ were strongly phototoxic, with photoindexes up to 17. Mechanistic studies indicated that such phototoxicity was due to a combination of photodynamic therapy (PDT) and photoactivated chemotherapy (PACT) effects, resulting from both reactive oxygen species generation and peptide photosubstitution. Finally, in vivo studies in a subcutaneous U87MG glioblastoma mice model showed that [1]Cl₂ efficiently accumulated in the tumor 12 h after injection, where green light irradiation generated a stronger tumoricidal effect than a nontargeted analogue ruthenium complex [2]Cl₂. Considering the absence of systemic toxicity for the treated mice, these results demonstrate the high potential of light-sensitive integrin-targeted ruthenium-based anticancer compounds for the treatment of brain cancer in vivo.

Biomacromolecule-Functionalized Nanoparticle-Based Conjugates for Potentiation of Anticancer Therapy

Cancer is a rapidly growing life-threatening disease that affected 18.1 million people worldwide in 2018. Various conventional techniques like surgery, radiation, and chemotherapy are considered as a mainstream treatment for patients but show some limitations like cytotoxicity due to off-targeted action, poor intra-tumor localization, development of multi-drug resistance by tumor cells, physical and psychological stresses, etc. Such limitations have motivated the scientists to work towards more patient-centric and precision therapy using advanced drug delivery systems like liposomes, nanoparticles, nanoconjugates, etc. However, these carriers also face limitations like poor biocompatibility, lesser payload capacity, leakage of encapsulated drug, and short-term stability. So, this review article explores the profound insights for the development of biomacromolecule-functionalized nanoconjugates to potentiate the anticancer activity of therapeutic agents for various cancers like lung, colorectal, ovarian, breast and liver cancer. Researchers have shown interest in biofunctionalized nanoconjugates because of advantages like biocompatibility, site-specificity with better localization, higher entrapment with long-term stability and lesser off-target toxicity. The progressive trend of biomacromolecule nanoconjugates will encourage further research for the development of effective transport of drugs, nutraceuticals and phytoconstituents for on-site effect at cancer microenvironment and tumor cells with higher safety profile.

New 4-Aminoproline-Based Small Molecule Cyclopeptidomimetics as Potential Modulators of α4β1 Integrin

Integrin α₄β₁ belongs to the leukocyte integrin family and represents a therapeutic target of relevant interest given its primary role in mediating inflammation, autoimmune pathologies and cancer-related diseases. The focus of the present work is the design, synthesis and characterization of new peptidomimetic compounds that are potentially able to recognize α₄β₁ integrin and interfere with its function. To this aim, a collection of seven new cyclic peptidomimetics possessing both a 4-aminoproline (Amp) core scaffold grafted onto key α₄β₁-recognizing sequences and the (2-methylphenyl)ureido-phenylacetyl (MPUPA) appendage, was designed, with the support of molecular modeling studies. The new compounds were synthesized through SPPS procedures followed by in-solution cyclization maneuvers. The biological evaluation of the new cyclic ligands in cell adhesion assays on Jurkat cells revealed promising submicromolar agonist activity in one compound, namely, the c[Amp(MPUPA)Val-Asp-Leu] cyclopeptide. Further investigations will be necessary to complete the characterization of this class of compounds.

Nanotechnology Addressing Cutaneous Melanoma: The Italian Landscape

Cutaneous melanoma is one of the most aggressive solid tumors, with a low survival for the metastatic stage. Currently, clinical melanoma treatments include surgery, chemotherapy, targeted therapy, immunotherapy and radiotherapy. Of note, innovative therapeutic regimens concern the administration of multitarget drugs in tandem, in order to improve therapeutic efficacy. However, also, if this drug combination is clinically relevant, the patient's response is not yet optimal. In this scenario, nanotechnology-based delivery systems can play a crucial role in the clinical treatment of advanced melanoma. In fact, their nano-features enable targeted drug delivery at a cellular level by overcoming biological barriers. Various nanomedicines have been proposed for the treatment of cutaneous melanoma, and a relevant number of them are undergoing clinical trials. In Italy, researchers are focusing on the pharmaceutical development of nanoformulations for malignant melanoma therapy. The present review reports an overview of the main melanoma-addressed nanomedicines currently under study in Italy, alongside the state of the art of melanoma therapy. Moreover, the latest Italian advances concerning the pre-clinical evaluation of nanomedicines for melanoma are described.

One-pot synthesis of 68Ga-doped ultrasmall gold nanoclusters for PET/CT imaging of tumors

Gold nanoclusters (AuNCs) have attracted much attention for tumor theranostics in recent years because of their ability of renal clearance and to escape the reticuloendothelial system (RES) sequestration. In this study, we presented a novel method to synthesize ⁶⁸Ga-doped (labeled) AuNCs by simultaneous reduction of ⁶⁸GaCl₃ and HAuCl₄ by glutathione. As synthesized ⁶⁸Ga-doped, glutathione-coated AuNCs (⁶⁸Ga-GSH@AuNCs) were ultrasmall in size (<2 nm), highly stable under physiological conditions and renally clearable, and had high efficiency for tumor targeting. To demonstrate the universality of this ⁶⁸Ga labeling method and further enhance tumor targeting efficiency, arginine-glycine-aspartate (RGD)-containing peptide was introduced as co-reductant to synthesize RGD peptide and glutathione co-coated, ⁶⁸Ga-labeled AuNCs (⁶⁸Ga-RGD-GSH@AuNCs). Introduction of RGD peptide did not interfere the synthesis process but significantly enhanced the tumor targeting efficiency of the AuNCs. Our study demonstrated that it was feasible to label AuNCs with gallium-68 by direct reduction of the radioisotope and HAuCl₄ with reductant peptides, holding a great potential for clinical translation for PET/CT detection of tumors.

A glycoconjugate-based gold nanoparticle approach for the targeted treatment of Pseudomonas aeruginosa biofilms

In this study, "core-shell" gold nanoparticles (AuNPs) have been functionalised using a simple one-pot approach to form fucose-based glycoconjugate AuNPs (Fuc-AuNPs) and galactose-based glycoconjugate AuNPs (Gal-AuNPs), respectively. Owing to the selective carbohydrate-based recognition of the key virulence factors of P. aeruginosa, LecB (fucose-specific lectin)/LecA (galactose-specific lectin), Fuc-AuNPs and Gal-AuNPs-based imaging and therapeutic strategies were evaluated towards P. aeruginosa. Both Fuc-AuNPs and Gal-AuNPs were non-covalently loaded with the fluorophore dicyanomethylene 4H-pyran (DCM) to afford two highly selective fluorescence imaging agents for the visualisation of P. aeruginosa. The loading of Fuc-AuNPs and Gal-AuNPs with the known antibiotic Ceftazidime (CAZ) exhibited an enhanced therapeutic effect, illustrating the significance of this targeted drug delivery strategy. Exploiting the phototherapeutic properties of AuNPs, photoirradiation (600 nm) of Fuc-AuNP@CAZ/Gal-AuNP@CAZ provided both photothermal and photodynamic therapeutic (PTT/PDT) effects, which facilitated the release of CAZ. Fuc-AuNP@CAZ and Gal-AuNP@CAZ were shown to be effective photo/chemotherapeutics resulting in almost complete eradication of P. aeruginosa biofilms formed on clinically relevant surfaces (glass slides and steel surface).

Advancing Cell-Instructive Biomaterials Through Increased Understanding of Cell Receptor Spacing and Material Surface Functionalization

Abstract

Regenerative medicine is aimed at restoring normal tissue function and can benefit from the application of tissue engineering and nano-therapeutics. In order for regenerative therapies to be effective, the spatiotemporal integration of tissue-engineered scaffolds by the native tissue, and the binding/release of therapeutic payloads by nano-materials, must be tightly controlled at the nanoscale in order to direct cell fate. However, due to a lack of insight regarding cell–material interactions at the nanoscale and subsequent downstream signaling, the clinical translation of regenerative therapies is limited due to poor material integration, rapid clearance, and complications such as graft-versus-host disease. This review paper is intended to outline our current understanding of cell–material interactions with the aim of highlighting potential areas for knowledge advancement or application in the field of regenerative medicine. This is achieved by reviewing the nanoscale organization of key cell surface receptors, the current techniques used to control the presentation of cell-interactive molecules on material surfaces, and the most advanced techniques for characterizing the interactions that occur between cell surface receptors and materials intended for use in regenerative medicine.

Lay Summary

The combination of biology, chemistry, materials science, and imaging technology affords exciting opportunities to better diagnose and treat a wide range of diseases. Recent advances in imaging technologies have enabled better understanding of the specific interactions that occur between human cells and their immediate surroundings in both health and disease. This biological understanding can be used to design smart therapies and tissue replacements that better mimic native tissue. Here, we discuss the advances in molecular biology and technologies that can be employed to functionalize materials and characterize their interaction with biological entities to facilitate the design of more sophisticated medical therapies.

Directional Immobilization of Proteins on Gold Nanoparticles Is Essential for Their Biological Activity: Leptin as a Case Study

Gold nanomaterials hold great potential for biomedical applications. While this field is evolving rapidly, little attention has been paid to precise nanoparticle design and functionalization. Here, we show that when using proteins as targeting moieties, it is fundamental to immobilize them directionally to preserve their biological activity. Using full-length leptin as a case study, we have developed two alternative conjugation strategies for protein immobilization based on either a site-selective or a nonselective derivatization approach. We show that only nanoparticles with leptin immobilized site-selectively fully retain the ability to interact with the cognate leptin receptor. These results demonstrate the importance of a specified molecular design when preparing nanoparticles labeled with proteins.

Cell-targeted c(AmpRGD)-sunitinib molecular conjugates impair tumor growth of melanoma

Drug resistance and off-organ toxicity remain unsolved issues in chemotherapy of advanced-stage melanoma patients. Thus, the creation of new molecular conjugates able to combine a selective accumulation, high ability of internalization and signaling pathway inhibition, are highly requested. Recently, we reported a new class of molecular conjugates, compounds 1-3, where the anti-α_Vβ₃ integrin peptidomimetic c(AmpRGD), which is a selective ligand for α_Vβ₃ integrin, was covalently bound to the tyrosine kinase inhibitor sunitinib. Here, we report that these c(AmpRGD)-sunitinib conjugates and, in particular, compound 3, are selectively internalized by human melanoma cells through α_Vβ₃ receptor-mediated endocytosis. Compound 3 is more effective than sunitinib in reducing in vitro melanoma cells proliferation, cloning efficiency, migration, and invasion. More interestingly, compound 3 is able to significantly reduce the growth of xenografted melanoma tumor developed in immune-compromised mice, more efficiently than an equimolar dose of sunitinib. Indeed, its targeting ability was demonstrated by the selective localization at the tumor level with respect to healthy tissues. Thus, c(AmpRGD)-sunitinib conjugates such as compound 3 could serve as intriguing multiple-target agents to selectively reach melanoma cells and interfere with the progression of the disease.