Design, Synthesis and Characterization of a Visible-Light-Sensitive Molecular Switch and Its PEGylation Towards a Self-Assembling Molecule.

HBDI-like chromophores represent a novel set of biomimetic switches mimicking the fluorophore of the green fluorescent protein that are currently studied with the hope to expand the molecular switch/motor toolbox. However, until now members capable of absorbing visible light in their neutral (i. e. non-anionic) form have not been reported. In this contribution we report the preparation of an HBDI-like chromophore based on a 3-phenylbenzofulvene scaffold capable of absorbing blue light and photoisomerizing on the picosecond timescale. More specifically, we show that double-bond photoisomerization occurs in both the E-to-Z and Z-to-E directions and that these can be controlled by irradiating with blue and UV light, respectively. Finally, as a preliminary applicative result, we report the incorporation of the chromophore in an amphiphilic molecule and demonstrate the formation of a visible-light-sensitive nanoaggregated state in water.

Functionalization of Metal and Carbon Nanoparticles with Potential in Cancer Theranostics.

Cancer theranostics is a new concept of medical approach that attempts to combine in a unique nanoplatform diagnosis, monitoring and therapy so as to provide eradication of a solid tumor in a non-invasive fashion. There are many available solutions to tackle cancer using theranostic agents such as photothermal therapy (PTT) and photodynamic therapy (PDT) under the guidance of imaging techniques (e.g., magnetic resonance-MRI, photoacoustic-PA or computed tomography-CT imaging). Additionally, there are several potential theranostic nanoplatforms able to combine diagnosis and therapy at once, such as gold nanoparticles (GNPs), graphene oxide (GO), superparamagnetic iron oxide nanoparticles (SPIONs) and carbon nanodots (CDs). Currently, surface functionalization of these nanoplatforms is an extremely useful protocol for effectively tuning their structures, interface features and physicochemical properties. This approach is much more reliable and amenable to fine adjustment, reaching both physicochemical and regulatory requirements as a function of the specific field of application. Here, we summarize and compare the most promising metal- and carbon-based theranostic tools reported as potential candidates in precision cancer theranostics. We focused our review on the latest developments in surface functionalization strategies for these nanosystems, or hybrid nanocomposites consisting of their combination, and discuss their main characteristics and potential applications in precision cancer medicine.

Size-isolation of superparamagnetic iron oxide nanoparticles improves MRI, MPI and hyperthermia performance.

Superparamagnetic iron oxide nanoparticles (SPION) are extensively used for magnetic resonance imaging (MRI) and magnetic particle imaging (MPI), as well as for magnetic fluid hyperthermia (MFH). We here describe a sequential centrifugation protocol to obtain SPION with well-defined sizes from a polydisperse SPION starting formulation, synthesized using the routinely employed co-precipitation technique. Transmission electron microscopy, dynamic light scattering and nanoparticle tracking analyses show that the SPION fractions obtained upon size-isolation are well-defined and almost monodisperse. MRI, MPI and MFH analyses demonstrate improved imaging and hyperthermia performance for size-isolated SPION as compared to the polydisperse starting mixture, as well as to commercial and clinically used iron oxide nanoparticle formulations, such as Resovist® and Sinerem®. The size-isolation protocol presented here may help to identify SPION with optimal properties for diagnostic, therapeutic and theranostic applications.

Arginine-Rich Peptidomimetic Ampicillin/Gentamicin Conjugate To Tackle Nosocomial Biofilms: A Promising Strategy To Repurpose First-Line Antibiotics.

Combined therapy with penicillins and aminoglycosides has been proved beneficial to address many persistent bacterial infections with possible synergistic effects. However, the different pharmacokinetic profiles of these two antibiotic classes may not guarantee a concerted spatio-temporal delivery at the site of action, decreasing the efficacy of this combination and promoting resistance. Herein, we propose a multifunctional antibiotic-polymer conjugate, designed to colocalize ampicillin and gentamicin to tackle persistent biofilm infections. The two antibacterial molecules were grafted along with the amino acid l-arginine to a biocompatible polymer backbone with peptidomimetic hydrophilic structure, obtaining the antimicrobial poly(argilylaspartamide-co-aspartic) acid-ampicillin, gentamicin (PAA-AG) conjugate. The PAA-AG conjugate displayed excellent biocompatibility on human cell lines if compared with free drugs, potentially enlarging their therapeutic window and safety, and suitable mucoadhesive characteristics which may help local treatments of mucosal infections. Studies on planktonic cultures of clinical and reference strains of S. aureus, P. aeruginosa, and E. coli revealed that PAA-AG holds a broad-spectrum antibacterial efficacy, revealing high potency in inhibiting the growth of the tested strains. More interestingly, PAA-AG exhibited excellent antibiofilm activity on both Gram+ and Gram- communities, showing inhibition of their formation at subMIC concentrations as well as inducing the regression of mature biofilms. Given the high biocompatibility and broad antibiofilm efficacy, combined with the opportunity for synchronous co-delivery, the PAA-AG conjugate could be a valuable tool to increase the success of ampicillin/gentamicin-based antibiotic multitherapy.

In vivo efficacy of verteporfin loaded gold nanorods for combined photothermal/photodynamic colon cancer therapy.

The high incidence of cancer recurrences and the frequent occurrence of multidrug resistance often stem from a poorly selective and inefficient antineoplastic therapy, responsible for the onset of undesired side effects as well. A combination of minimal-invasive approaches could thus be a useful strategy to surmount these shortcomings, achieving a safe and solid cancer therapy. Herein, a multi-therapeutic nanotool was designed by merging the photothermal properties of gold nanorods (AuNRs) with the photodynamic activity of the photosensitizer verteporfin. AuNRs were coated with the natural materials lipoic acid and gellan gum (AuNRs_LA,GG) and subsequently loaded with verteporfin (AuNRs_LA,GG/Vert) producing stable colloidal dispersions. AuNRs_LA,GG/Vert were characterized in terms of stability, size and morphology. The hyperthermia exhibited after NIR excitation (810 nm) was also evaluated to highlight the effect on increasing the drug released profile in intra-tumoral mimicking media, as well as cytotoxicity on human colon cancer cell line (HCT116). In vivo studies on HCT116 murine xenograft models were carried out to prove the ability of AuNRs_LA,GG to arrest the tumor growth via NIR laser-triggered hyperthermia. Furthermore, the complete xenograft depletion was demonstrated upon AuNRs_LA,GG/Vert administration by combined photothermal (PTT) and photodynamic (PDT) effects.

Galactosylated Polymer/Gold Nanorods Nanocomposites for Sustained and Pulsed Chemo-Photothermal Treatments of Hepatocarcinoma.

In this paper, we propose a rational design of a hybrid nanosystem capable of locally delivering a high amount of hydrophobic anticancer drugs (sorafenib or lenvatinib) and heat (hyperthermia) in a remote-controlled manner. We combined in a unique nanosystem the excellent NIR photothermal conversion of gold nanorods (AuNRs) with the ability of a specially designed galactosylated amphiphilic graft copolymer (PHEA-g-BIB-pButMA-g-PEG-GAL) able to recognize hepatic cells overexpressing the asialoglycoprotein receptor (ASGPR) on their membranes, thus giving rise to a smart composite nanosystem for the NIR-triggered chemo-phototherapy of hepatocarcinoma. In order to allow the internalization of AuNRs in the hydrophobic core of polymeric nanoparticles, AuNRs were coated with a thiolated fatty acid (12-mercaptododecanoic acid). The drug-loaded hybrid nanoparticles were prepared by the nanoprecipitation method, obtaining nanoparticles of about 200 nm and drug loadings of 9.0 and 5.4% w/w for sorafenib and lenvatinib, respectively. These multifunctional nanosystems have shown to convert NIR radiation into heat and release charged drugs in a remote-controlled manner. Then, the biocompatibility and synergistic effects of a chemo-phototherapy combination, as well the receptor-mediated internalization, were evaluated by an in vitro test on HepG2, HuH7, and NHDF. The results indicate that the proposed nanoparticles can be considered to be virtuous candidates for an efficient and selective dual-mode therapy of hepatocarcinoma.

Effect of actively targeted copolymer coating on solid tumors eradication by gold nanorods-induced hyperthermia.

Efforts in the field of anticancer therapy are increasingly focusing on the development of localized and selective treatments. Photothermal therapy (PTT) can lead to a spatially confined death of cancer cells, exploiting an increasing in temperature generated after UV-NIR irradiation of peculiar materials. Herein, a new actively targeted gold-based drug delivery system, named PHEA-LA-Fol-AuNRs/Iri, was explored for hyperthermia and chemotherapy colon cancer treatment. Gold nanorods were stabilized using a folate-derivative of α,ß-poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEA-LA-PEG-FA) as coating agent and then loaded with the antineoplastic drug irinotecan (Iri). The efficacy of empty and irinotecan-bearing systems was investigated in vitro on human colon cancer (HCT116) cell line, as well as in vivo, employing a xenograft mouse model of colon cancer. After laser treatment, both nanostructures tested induced a considerable deceleration in tumor growth overtime, achieving the total eradication of the cancer when the nanosystems produced were intratumorally administered. Biodistribution data showed that the polymer coated nanorods were able to preferentially accumulate in the tumor site. Considering the excellent stability in aqueous media, the capacity to reach the tumor site and, finally, the in vivo efficacy, PHEA-LA-Fol-AuNRs/Iri might be recommended as an effective tool in the chemotherapy and PTT of colon cancer.

Core-Shell Arginine-Containing Chitosan Microparticles for Enhanced Transcorneal Permeation of Drugs.

Chitosan oligosaccharide (C) was functionalized with l-arginine (A) and short hydrocarbon chains (C8) to design an amphiphilic copolymer, henceforth CAC8, leading to microparticles (MPs) consisting of an arginine-decorated hydrophilic shell and inner hydrophobic domains allowing the encapsulation of high amount hydrophobic drugs such as sorafenib tosylate (>10% w/w). l-arginine side chains were selected in order to impart the final MPs enhanced transcorneal penetration properties, thus overcoming the typical biological barriers which hamper the absorption of drugs upon topical ocular administration. The mucoadhesive properties and drug release profile of the CAC8 MPs (CAC8-MPs) were studied, showing that CAC8-MPs can strongly interact with mucin, and thus gradually release their payload in situ to potentially improve the bioavailability of the drug after topical administration. In vitro transcorneal studies also showed that CAC8-MPs are endowed with effective permeation enhancer ability combined with negligible toxicity.

SPIONs embedded in polyamino acid nanogels to synergistically treat tumor microenvironment and breast cancer cells.

The extremely complex tumor microenvironment (TME) in humans is the major responsible for the therapeutic failure in cancer nanomedicine. A new concept of disease-driven nanomedicine, henceforth named "Theranomics", which attempts to target cancer cells and TME on the whole, represents an attractive alternative. Herein, a nanomedicine able to co-deliver doxorubicin and a tumor suppressive proteolytic protein such as collagenase-2 was developed. We successfully obtained superparamagnetic nanogels (SPIONs/Doco@Col) via the intermolecular azide-alkyne Huisgen cycloaddition. We demonstrated that a local ECM degradation and remodeling in solid tumors by means of collagenase-2 could enhance tumor penetration of nanomedicines and the in situ sustained release of the drug payload throughout 3-D tumor spheroids up to the core (parenchyma), thus enabling a synergistic and efficient anticancer effect toward highly invasive breast tumors. We illustrate that SPIONs/Doxo@Col is also capable of reducing the invasivity of cancer cells.

Branched High Molecular Weight Glycopolypeptide With Broad-Spectrum Antimicrobial Activity for the Treatment of Biofilm Related Infections.

There are few therapeutic options to simultaneously tackle Staphylococcus aureus and Pseudomonas aeruginosa, two of the most relevant nosocomial and antibiotic-resistant pathogens responsible for implant, catheters and wound severe infections. The design and synthesis of polymers with inherent antimicrobial activity have gained increasing attention as a safe strategy to treat multi-drug-resistant microbes. Here, we tested the activity of a new polymeric derivative with glycopolypeptide architecture (PAA-VC) bearing l-arginine, vancomycin, and colistin as side chains acting against multiple targets, which give rise to a broad spectrum antimicrobial activity favorably combining specific and nonspecific perturbation of the bacterial membrane. PAA-VC has been tested against planktonic and established biofilms of reference strains S. aureus ATCC 25923 and P. aeruginosa ATCC 15442 and susceptible or antibiotic resistant clinical isolates of the above-mentioned microorganisms. MIC values observed for the conjugate (48-190 and 95-190 nM for P. aeruginosa and S. aureus strains, respectively) showed higher efficacy if compared with the free vancomycin (MICs within 1.07-4.28 µM) and colistin (MICs within 0.63-1.33 µM). Additionally, being highly biocompatible (IC50 > 1000, 430, and 250 µg mL-1 for PAA-VC, vancomycin and colistin respectively) high-dosage can be adopted for the eradication of infections in patients. This positively influences the anti-biofilm activity of the conjugate leading to a quasi-total eradication of established clinically relevant biofilms (inhibition >90% at 500 µg mL-1). We believe that the in vitro presented data, especially the activity against established biofilms of two relevant pathogens, the high biocompatibility and the good mucoadhesion properties, would allow the use of PAA-VC as promising candidate to successfully address emerging infections.