An ex vivo animal model to study the effect of transverse mechanical loading on skeletal muscle.

In many populations like wheelchair and prosthetic users, the soft tissue is subject to excessive or repetitive loading, making it prone to Deep Tissue Injury (DTI). To study the skeletal muscle response to physical stress, numerous in vitro and in vivo models exist. Yet, accuracy, variability, and ethical considerations pose significant trade-offs.

A universal polymer shell-isolated nanoparticle (SHIN) design for single particle spectro-electrochemical SERS sensing using different core shapes.

Shell-isolated nanoparticles (SHINs) have attracted increasing interest for non-interfering plasmonic enhanced sensing in fields such as materials science, biosensing, and in various electrochemical systems. The metallic core of these nanoparticles is isolated from the surrounding environment preventing direct contact or chemical interaction with the metal surface, while still being close enough to enable localized surface plasmon enhancement of the Raman scattering signal from the analyte. This concept forms the basis of the shell isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) technique.

Stimulated Raman scattering microscopy with spectral phasor analysis: applications in assessing drug-cell interactions.

Statins have displayed significant, although heterogeneous, anti-tumour activity in breast cancer disease progression and recurrence. They offer promise as a class of drugs, normally used for cardiovascular disease control, that could have a significant impact on the treatment of cancer. Understanding their mode of action and accurately assessing their efficacy on live cancer cells is an important and significant challenge.

Design of Functional Coassembling Organic-Inorganic Hydrogels for Hierarchical Mineralization and Neovascularization.

Synthetic nanostructured materials incorporating both organic and inorganic components offer a unique, powerful, and versatile class of materials for widespread applications due to the distinct, yet complementary, nature of the intrinsic properties of the different constituents. We report a supramolecular system based on synthetic nanoclay (Laponite, ) and peptide amphiphiles (PAs, ) rationally designed to coassemble into nanostructured hydrogels with high structural integrity and a spectrum of bioactivities. Spectroscopic and scattering techniques and molecular dynamic simulation approaches were harnessed to confirm that nanofibers electrostatically adsorbed and conformed to the surface of nanodisks.

Phenotypic analysis of extracellular vesicles: a review on the applications of fluorescence.

Extracellular vesicles (EVs) have numerous potential applications in the field of healthcare and diagnostics, and research into their biological functions is rapidly increasing. Mainly because of their small size and heterogeneity, there are significant challenges associated with their analysis and despite overt evidence of the potential of EVs in clinical diagnostic practice, guidelines for analytical procedures have not yet been properly established. Here, we present an overview of the main methods for studying the properties of EVs based on the principles of fluorescence.

Covalent co-assembly between resilin-like polypeptide and peptide amphiphile into hydrogels with controlled nanostructure and improved mechanical properties.

Covalent co-assembly holds great promise for the fabrication of hydrogels with controllable nanostructure, versatile chemical composition, and enhanced mechanical properties given its relative simplicity, high efficiency, and bond stability. This report describes our approach to designing functional multicomponent hydrogels based on photo-induced chemical interactions between an acrylamide-functionalized resilin-like polypeptide (RLP) and a peptide amphiphile (PA). Circular dichroism (CD) spectroscopy, electron microscopy, and amplitude sweep rheology were used to demonstrate that the co-assembled hydrogel systems acquired distinct structural conformations, tunable nanostructures, and enhanced elasticity in a PA concentration-dependent manner.

Detection and quantification of warfarin in pharmaceutical dosage form and in spiked human plasma using surface enhanced Raman scattering.

Analytical approaches for the quantitation of warfarin in plasma are high in demand. In this study, a novel surface enhanced Raman scattering (SERS) technique for the quantification of the widely used anticoagulant warfarin sodium in pharmaceutical dosage form and in spiked human plasma was developed. The colloidal-based SERS measurements were carefully optimized considering the laser wavelength, the type of metal nanoparticles, their surface functionalization and concentration as well as the time required for warfarin to associate with the metal surface.

3D bioprinting of mature bacterial biofilms for antimicrobial resistance drug testing.

The potential to bioprint and study 3D bacterial biofilm constructs could have great clinical significance at a time when antimicrobial resistance is rising to dangerously high levels worldwide. In this study, clinically relevant bacterial species including Escherichia coli, Staphylococcus aureus (MSSA), Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa were 3D bioprinted using a double-crosslinked alginate bioink to form mature bacteria biofilms, characterized by confocal laser scanning microscopy (CLSM) and fluorescent staining. Solid and porous bacteria-laden constructs were reproducibly bioprinted with thicknesses ranging from 0.

Stability-indicating micellar enhanced spectro-fluorometric determination of Daclatasvir in its tablet and spiked human plasma.

A fast, simple and sensitive micellar enhanced spectrofluorimetric method is performed for the determination of Daclatasvir dihydrochloride (DAC) in its pharmaceutical dosage form and in spiked human plasma. The fluorescence intensity (FI) was measured at 367 nm after excitation at 300 nm. In aqueous solution, the FI of DAC was greatly enhanced by >110% in the presence of sodium dodecyl sulphate (SDS).

Optimized polydopamine coating and DNA conjugation onto gold nanorods for single nanoparticle bioaffinity measurements.

Gold nanorods (NRs) have attracted a great deal of interest for a variety of biomedical and sensing applications. However, developing robust methods for biofunctionalizing NRs has continued to be challenging, especially for NR-DNA conjugates. This is due to the presence of cetyltrimethylammonium bromide (CTAB), which plays an essential role in controlling the anisotropic particle growth.

Tandem Femto- and Nanomolar Analysis of Two Protein Biomarkers in Plasma on a Single Mixed Antibody Monolayer Surface Using Surface Plasmon Resonance.

The multiplexed detection of protein biomarkers in plasma present over a range of clinically relevant concentrations continues to be difficult for surface-based bioaffinity detection platforms such as surface plasmon resonance (SPR). As well as nonspecific adsorption, challenges include quantitative comparison between targets whose concentrations differ by orders of magnitude, regenerating SPR chips after plasma exposure, and the two- or four-channel limitation of many commercial SPR instruments limiting sample throughput. In this article, we explore an approach where two protein biomarkers alpha-1 antitrypsin (AAT) and Tau 381 are detected in tandem within a single SPR channel at micromolar and femtomolar concentrations, respectively.

Light-Triggered Inactivation of Enzymes with Photothermal Nanoheaters.

A universal method for inactivating enzymes on demand is introduced, which involves irradiating nanorod-bound enzymes with near-infrared light. The subsequent generation of plasmonic heat denatures the enzymes selectively without damaging other proteins or cell membranes present in the same solution.

Real-time assessment of nanoparticle-mediated antigen delivery and cell response.

Nanomaterials are increasingly being developed for applications in biotechnology, including the delivery of therapeutic drugs and of vaccine antigens. However, there is a lack of screening systems that can rapidly assess the dynamics of nanoparticle uptake and their consequential effects on cells. Established in vitro approaches are often carried out on a single time point, rely on time-consuming bulk measurements and are based primarily on populations of cell lines.

Femtomolar Detection of Tau Proteins in Undiluted Plasma Using Surface Plasmon Resonance.

The ability to directly detect Tau protein and other neurodegenerative biomarkers in human plasma at clinically relevant concentrations continues to be a significant hurdle for the establishment of diagnostic tests for Alzheimer's disease (AD). In this article, we introduce a new DNA aptamer/antibody sandwich assay pairing and apply it for the detection of human Tau 381 in undiluted plasma at concentrations as low as 10 fM. This was achieved on a multichannel surface plasmon resonance (SPR) platform with the challenge of working in plasma overcome through the development of a tailored mixed monolayer surface chemistry.

Dual nanoparticle amplified surface plasmon resonance detection of thrombin at subattomolar concentrations.

A novel dual nanoparticle amplification approach is introduced for the enhanced surface plasmon resonance (SPR) detection of a target protein at subattomolar concentrations. Thrombin was used as a model target protein as part of a sandwich assay involving an antithrombin (anti-Th) modified SPR chip surface and a thrombin specific DNA aptamer (Th-aptamer) whose sequence also includes a polyadenine (A30) tail. Dual nanoparticle (NP) enhancement was achieved with the controlled hybridization adsorption of first polythymine-NP conjugates (T20-NPs) followed by polyadenine-NPs (A30-NPs).

Nanopropulsion by biocatalytic self-assembly.

A number of organisms and organelles are capable of self-propulsion at the micro- and nanoscales. Production of simple man-made mimics of biological transportation systems may prove relevant to achieving movement in artificial cells and nano/micronscale robotics that may be of biological and nanotechnological importance. We demonstrate the propulsion of particles based on catalytically controlled molecular self-assembly and fiber formation at the particle surface.

Universal surface-enhanced Raman tags: individual nanorods for measurements from the visible to the infrared (514-1064 nm).

Surface-enhanced Raman scattering (SERS) is a promising imaging modality for use in a variety of multiplexed tracking and sensing applications in biological environments. However, the uniform production of SERS nanoparticle tags with high yield and brightness still remains a significant challenge. Here, we describe an approach based on the controlled coadsorption of multiple dye species onto gold nanorods to create tags that can be detected across a much wider range of excitation wavelengths (514-1064 nm) compared to conventional approaches that typically focus on a single wavelength.

Ultrasensitive and ultrawide range detection of a cardiac biomarker on a surface plasmon resonance platform.

One of the main challenges in the development of new analytical platforms for ultrasensitive bioaffinity detection is jointly achieving a wide dynamic range in target analyte concentration, especially for approaches that rely on multistep processes as a part of the signal amplification mechanism. In this paper, a new surface-based sandwich assay is introduced for the direct detection of B-type natriuretic peptide (BNP), an important biomarker for cardiac failure, at concentrations ranging from 1 aM to 500 nM. This was achieved using nanoparticle-enhanced surface plasmon resonance (SPR) where a DNA aptamer is immobilized on a chemically modified gold surface in conjunction with the specific adsorption of antiBNP coated gold nanocubes in the presence of the biomarker target.

Stabilized gold nanorod-dye conjugates with controlled resonance coupling create bright surface-enhanced resonance Raman nanotags.

The preparation and characterization of stable and non-aggregated colloidal suspensions of gold nanorod-molecular dye complexes which exhibit very bright surface-enhanced resonance Raman scattering (SERRS) signals is described. A systematic study was performed where both the localized surface plasmon resonance (LSPR) of the nanorod and the molecular resonance of dyes adsorbed onto the rod surface were selectively tuned with respect to the laser excitation wavelengths. Resonance coupling was found to be a significant factor in the overall SERRS enhancement.

Synthesis and NIR optical properties of hollow gold nanospheres with LSPR greater than one micrometer.

Optical analysis in the near infrared region is of significant biological importance due to better tissue penetration and reduced autofluorescence. In this work, an improved synthesis of hollow gold nanospheres (HGNs), which provides a tunable localized surface plasmon resonance (LSPR) from 610 nm up to 1320 nm, is demonstrated. The scattering properties of these nanoparticles are shown using surface enhanced Raman scattering (SERS) at 1064 nm excitation wavelength and are compared to citrate reduced gold and silver nanoparticles of similar physical sizes and surface properties.

Highly sensitive electrochemical detection of proteins using aptamer-coated gold nanoparticles and surface enzyme reactions.

A novel electrochemical detection methodology is described for the femtomolar detection of proteins which utilizes both DNA aptamer-functionalized nanoparticles and a surface enzymatic reaction. Immunoglobulin E (IgE) was used as a model protein biomarker, which possesses two distinct epitopes for antibody (anti-IgE) and DNA aptamer binding. A surface sandwich assay format was utilized involving the specific adsorption of IgE onto a gold electrode surface that was pre-modified with a monolayer of aptamer-nanoparticle conjugates followed by the specific interaction of alkaline phosphatase (ALP) conjugated anti-IgE.

Nanoparticle-enhanced surface plasmon resonance detection of proteins at attomolar concentrations: comparing different nanoparticle shapes and sizes.

The application of biofunctionalized nanoparticles possessing various shapes and sizes for the enhanced surface plasmon resonance (SPR) detection of a protein biomarker at attomolar concentrations is described. Three different gold nanoparticle shapes (cubic cages, rods and quasi-spherical) with each possessing at least one dimension in the 40-50 nm range were systematically compared. Each nanoparticle (NP) was covalently functionalized with an antibody (anti-thrombin) and used as part of a sandwich assay in conjunction with a Au SPR chip modified with a DNA-aptamer probe specific to thrombin.

Mapping Localized Surface Plasmons within Silver Nanocubes Using Cathodoluminescence Hyperspectral Imaging.

Localized surface plasmons within silver nanocubes less than 50 nm in size were investigated using high-resolution cathodoluminescence hyperspectral imaging. Multivariate statistical analysis of the multidimensional luminescence data set allows both the identification of distinct spectral features in the emission and the mapping of their spatial distribution. These results show a 490-nm peak emitted from the cube faces, with shorter-wavelength luminescence coming from the vertices and edges; this provides direct experimental confirmation of theoretical predictions.

Controlled side-by-side assembly of gold nanorods and dye molecules into polymer-wrapped SERRS-active clusters.

The controlled side-by-side assembly of gold nanorods in solution together with Raman reporter dye molecules to create small SERRS-active clusters stabilised by a surrounding polymer layer is demonstrated. This promising new class of nanotags offers several advantages over spherical nanoparticles for bioimaging and is of potential importance for a wide range of plasmon-enhanced spectroscopies and can also serve as building blocks for more complex solution-phase nanostructures.

Dynamic Imaging Analysis of SERS-Active Nanoparticle Clusters in Suspension.

A novel wide-field approach for the real-time Surface Enhanced Raman Scattering (SERS) imaging of multiple silver nanoparticle clusters suspended in solution is described. This method enables direct correlation of the SERS activity of a single nanoparticle aggregate and its size through measurement of the cluster diffusion coefficient and can also be performed in a high-throughput basis. As a first demonstration, we investigate the salt-induced aggregation of silver nanoparticles in the presence of a reporter tag molecule, which has a high affinity for the nanoparticle surface.