Paper-based genetic assays with bioconjugated gold nanorods and an automated readout pipeline.

Paper-based biosensors featuring immunoconjugated gold nanoparticles have gained extraordinary momentum in recent times as the platform of choice in key cases of field applications, including the so-called rapid antigen tests for SARS-CoV-2. Here, we propose a revision of this format, one that may leverage on the most recent advances in materials science and data processing. In particular, we target an amplifiable DNA rather than a protein analyte, and we replace gold nanospheres with anisotropic nanorods, which are intrinsically brighter by a factor of ~ 10, and multiplexable. By comparison with a gold-standard method for dot-blot readout with digoxigenin, we show that gold nanorods entail much faster and easier processing, at the cost of a higher limit of detection (from below 1 to 10 ppm in the case of plasmid DNA containing a target transgene, in our current setup). In addition, we test a complete workflow to acquire and process photographs of dot-blot membranes with custom-made hardware and regression tools, as a strategy to gain more analytical sensitivity and potential for quantification. A leave-one-out approach for training and validation with as few as 36 sample instances already improves the limit of detection reached by the naked eye by a factor around 2. Taken together, we conjecture that the synergistic combination of new materials and innovative tools for data processing may bring the analytical sensitivity of paper-based biosensors to approach the level of lab-grade molecular tests.

A bionic shuttle carrying multi-modular particles and holding tumor-tropic features.

The systemic delivery of composite nanoparticles remains an outstanding challenge in cancer nanomedicine, and the principal reason is a complex interplay of biological barriers. In this regard, adaptive cell transfer may represent an alternative solution to circumvent these barriers down to the tumor microenvironment. Here, tumor-tropic macrophages are proposed as a tool to draw and vehiculate modular nanoparticles integrating magnetic and plasmonic components. The end result is a bionic shuttle that exhibits a plasmonic band within the so-called therapeutic window arising from as much as 40 pg Au per cell, magnetization in the order of 150 pemu per cell, and more than 90% of the pristine viability and chemotactic activity of its biological component, until at least two days of preparation. Its synergistic combination of plasmonic, magnetic and tumor-tropic functions is assessed in vitro for applications as magnetic guidance or sorting, with a propulsion around 4 µm s-1 for a magnetic gradient of 0.8 T m-1, the optical hyperthermia of cancer, with stability of photothermal conversion to temperatures exceeding 50∘C, and the photoacoustic imaging of cancer under realistic conditions. These results collectively suggest that a bionic design may be a promising roadmap to reconcile the efforts for multifunctionality and targeted delivery, which are both key goals in nanomedicine.

Hybrid organosilicon/polyol phantom for photoacoustic imaging.

The rapid development of hardware and software for photoacoustic technologies is urging the establishment of dedicated tools for standardization and performance assessment. In particular, the fabrication of anatomical phantoms for photoacoustic imaging remains an open question, as current solutions have not yet gained unanimous support. Here, we propose that a hybrid material made of a water-in-oil emulsion of glycerol and polydimethylsiloxane may represent a versatile platform to host a broad taxonomy of hydrophobic and hydrophilic dyes and recapitulate the optical and acoustic features of bio tissue. For a full optical parameterization, we refer to Wróbel, et al. [ Biomed. Opt. Express7, 2088 (2016)], where this material was first presented for optical imaging. Instead, here, we complete the picture and find that its speed of sound and acoustic attenuation resemble those of pure polydimethylsiloxane, i.e. respectively 1150 ± 30 m/s and 3.5 ± 0.4 dB/(MHz·cm). We demonstrate its use under a commercial B-mode scanner and a home-made A-mode stage for photoacoustic analysis to retrieve the ground-truth encoded in a multilayer architecture containing indocyanine green, plasmonic particles and red blood cells. Finally, we verify the stability of its acoustic, optical and geometric features over a time span of three months.

1064-nm-resonant gold nanorods for photoacoustic theranostics within permissible exposure limits.

Therapeutic and diagnostic methods based on photomechanical effects are attracting much current attention in contexts as oncology, cardiology and vascular surgery, for such applications as photoacoustic imaging or microsurgery. Their underlying mechanism is the generation of ultrasound or cavitation from the interaction of short optical pulses with endogenous dyes or targeted contrast agents. Among the latter, gold nanorods are outstanding candidates, but their use has mainly been reported for photoacoustic imaging and photothermal treatments. Conversely, much less is still known about their value as a precision tool for photomechanical manipulations, such as to impart local damage with high spatial resolution through the expansion and collapse of microbubbles. Here, we address the feasibility of gold nanorods exhibiting a distribution of surface plasmon resonances between about 900 to above 1100 nm as a contrast agent for photoacoustic theranostics. After testing their cytotoxicity and cellular uptake, we discuss their photostability and use to mediate cavitation and the photomechanical destruction of targeted cells. We find that the choice of a plasmonic band peaking around 1064 nm is key to enhance the translational potential of this approach. With respect to the standard alternative of 800 nm, at 1064 nm, relevant regulations on optical exposure are less restrictive and the photonic technology is more mature.

First Proof-of-Principle of Inorganic Lead Halide Perovskites Deposition by Magnetron-Sputtering.

The present work reports the application of RF-magnetron sputtering technique to realize CsPbBr 3 70 nm thick films on glass substrate by means of a one-step procedure. The obtained films show highly uniform surface morphology and homogeneous thickness as evidenced by AFM and SEM investigations. XRD measurements demonstrate the presence of two phases: a dominant orthorhombic CsPbBr 3 and a subordinate CsPb 2 Br 5 . Finally, XPS data reveals surface bromine depletion respect to the stoichiometrical CsPbBr 3 composition, nevertheless photoluminescence spectroscopy results confirm the formation of a highly luminescent film. These preliminary results demonstrate that our approach could be of great relevance for easy fabrication of large area perovskite thin films. Future developments, based on this approach, may include the realization of multijunction solar cells and multicolor light emitting devices.

Polylysine as a functional biopolymer to couple gold nanorods to tumor-tropic cells.

BACKGROUND: The delivery of plasmonic particles, such as gold nanorods, to the tumor microenvironment has attracted much interest in biomedical optics for topical applications as the photoacoustic imaging and photothermal ablation of cancer. However, the systemic injection of free particles still crashes into a complexity of biological barriers, such as the reticuloendothelial system, that prevent their efficient biodistribution. In this context, the notion to exploit the inherent features of tumor-tropic cells for the creation of a Trojan horse is emerging as a plausible alternative. RESULTS: We report on a convenient approach to load cationic gold nanorods into murine macrophages that exhibit chemotactic sensitivity to track gradients of inflammatory stimuli. In particular, we compare a new model of poly-L-lysine-coated particles against two alternatives of cationic moieties that we have presented elsewhere, i.e. a small quaternary ammonium compound and an arginine-rich cell-penetrating peptide. Murine macrophages that are exposed to poly-L-lysine-coated gold nanorods at a dosage of 400 µM Au for 24 h undertake efficient uptake, i.e. around 3 pg Au per cell, retain the majority of their cargo until 24 h post-treatment and maintain around 90% of their pristine viability, chemotactic and pro-inflammatory functions. CONCLUSIONS: With respect to previous models of cationic coatings, poly-L-lysine is a competitive solution for the preparation of biological vehicles of gold nanorods, especially for applications that may require longer life span of the Trojan horse, say in the order of 24 h. This biopolymer combines the cost-effectiveness of small molecules and biocompatibility and efficiency of natural peptides and thus holds potential for translational developments.

A multifunctional organosilica cross-linker for the bio-conjugation of gold nanorods.

We report on the use of organosilica shells to couple gold nanorods to functional peptides and modulate their physiochemical and biological profiles. In particular, we focus on the case of cell penetrating peptides, which are used to load tumor-tropic macrophages and implement an innovative drug delivery system for photothermal and photoacoustic applications. The presence of organosilica exerts subtle effects on multiple parameters of the particles, including their size, shape, electrokinetic potential, photostability, kinetics of endocytic uptake and cytotoxicity, which are investigated by the interplay of colorimetric methods and digital holographic microscopy. As a rule of thumb, as the thickness of organosilica increases from none to ∼30nm, we find an improvement of the photophysical performances at the expense of a deterioration of the biological parameters. Therefore, detailed engineering of the particles for a certain application will require a careful trade-off between photophysical and biological specifications.

Polymer Nanoparticles as Smart Carriers for the Enhanced Release of Therapeutic Agents to the CNS.

BACKGROUND: The brain is the most protected organ in the human body; its protective shield, relying on a complex system of cells, proteins and transporters, prevents potentially harmful substances from entering the brain from the bloodstream but, on the other hand, it also stops drugs administered via the systemic route. To improve the efficacy of pharmacological treatments, targeted drug delivery by means of polymer nanoparticles is a challenging but, at the same time, efficient strategy. METHODS: Thanks to a highly multidisciplinary approach, several ways to overcome the brain protection have provided effective solutions to treat a large number of diseases. Important advances in polymer science, together with the development of novel techniques for nanocarrier preparation, and the discovery of novel targeting ligands and molecules, allow a fine-tuning of size, shape, chemicophysical properties and surface chemistry of functional particulate systems; it enables the improvement of the therapeutic performances for several drugs, also toward districts that are difficult to be treated, such as the brain. CONCLUSION: This review focuses on the great strides made from scientists and doctors in the development of polymer nano-sized drug delivery systems for brain diseases. Even though the optimal nanocarrier was not yet discovered, important advances were made to strive for safer, performant and successful systems, with the expectation to find soon better solutions to cure some still untreatable pathologies.

Preparation and Photoacoustic Analysis of Cellular Vehicles Containing Gold Nanorods.

Gold nanorods are attractive for a range of biomedical applications, such as the photothermal ablation and the photoacoustic imaging of cancer, thanks to their intense optical absorbance in the near-infrared window, low cytotoxicity and potential to home into tumors. However, their delivery to tumors still remains an issue. An innovative approach consists of the exploitation of the tropism of tumor-associated macrophages that may be loaded with gold nanorods in vitro. Here, we describe the preparation and the photoacoustic inspection of cellular vehicles containing gold nanorods. PEGylated gold nanorods are modified with quaternary ammonium compounds, in order to achieve a cationic profile. On contact with murine macrophages in ordinary Petri dishes, these particles are found to undergo massive uptake into endocytic vesicles. Then these cells are embedded in biopolymeric hydrogels, which are used to verify that the stability of photoacoustic conversion of the particles is retained in their inclusion into cellular vehicles. We are confident that these results may provide new inspiration for the development of novel strategies to deliver plasmonic particles to tumors.

Metal and motion artifacts by cone beam computed tomography (CBCT) in dental and maxillofacial study.

OBJECTIVES: This study aimed at evaluating incidence/degree of metal/motion artifacts and CT-dose-index in oral/maxillofacial examinations using Cone-Beam-CT. METHODS: Interferences caused by metal and motion artifacts were evaluated in 500 patients aged from 6 to 81 years, in dental arches, maxillofacial and splanchocranium Cone-Beam-CT exams. The interferences was divided into four progressive degrees (G0-G3) related to the possibility to answer the clinical query. The parameters considered were field-of-view, scan time, patient's age, and anatomical area. Furthermore volumetric CT-dose-index was measured. RESULTS: In the presence of metal artifacts the clinical query was always answered (G3 = 0). No artifacts (G0) were found in all cases when metal was beyond 5 cm from interest site and in 18.4% when metal was inside this distance. Beam hardening and photon starvation due to implants, restoration and orthodontic therapies achieved 56.2% G1 and 25.4% G2. Motion artifacts were more frequent in under ten (31.5%) and over sixty (82.2%), and in mandible analysis (inferior arch 59.5%, both arches 47.3%). Moreover, their incidence and intensity were influenced by scan time (49.1% at 36 s) but not by field-of-view. Mean volumetric CT-dose-index of all patients was mGy 9.11 (mGy 3.62, 5.78, 8.89, and 13.07 at 18, 24, 26, and 36 s, respectively). CONCLUSIONS: In our series Cone-Beam-CT diagnostic evaluation was never inhibited by metal artifacts and only in 1.9% of the cases by motion artifacts, always with a very low CT-dose-index.

Polyfunctional recognition of pyridinedicarboxylate anions with macrocyclic polyamine receptors containing heteroaromatic groups.

The interaction of the biologically relevant anions deriving from the six pyridinedicarboxylic acids (H2PDC) with two macrocyclic receptors containing a pentamine chain and a bipyridine (1) or a phenanthroline (2) moiety, as well as with the aliphatic analogue [21]aneN7 (3), was studied by means of spectroscopic methods (UV-vis, NMR) and potentiometric titrations affording the stability constants of the adducts formed. All three receptors form stable complexes with the substrates thanks to the formation of several salt bridges and hydrogen bond contacts, as observed in the crystal structure of the H8[3(2,6-PDC)4] x H2O x 0.5 EtOH solid compound. Additional pi-stacking interactions between the aromatic moieties of substrates and receptors enhance the stability of complexes with 1 and 2. Compounds 1 and 2 show a marked selectivity toward 2,6-pyridinedicarboxylate anions. In particular, 1 is able to perform a very efficient recognition of these species in the presence of 2 and 3. Molecular modeling calculations suggested that such recognition ability of 1 can be ascribed to a superior structural and electrostatic complementarity with the substrate compared to 2 and 3.