Upconversion nanoparticle-based fluorescence resonance energy transfer sensing of programmed death ligand 1 using sandwich epitope-imprinted polymers.

Programmed death ligand 1 (PD-L1) has been shown to suppress the anti-tumor immune response of some lung cancer patients, and thus PD-L1 expression may be a valuable predictor of the efficacy of anti-PD-1/PD-L1 monoclonal therapy in such patients. In this work, a sandwich approach to fluorescence resonance energy transfer (FRET) was used with green-emitting Yb3+/Ho3+-doped upconversion nanoparticles (UCNPs) and a rhodamine-conjugated conductive polymer as donor and acceptor, respectively. Yb3+/Ho3+-doped UCNPs were synthesized and then coated with poly(ethylene-co-vinyl alcohol), pEVAL, imprinted with PD-L1 peptide. Epitope-imprinted composite nanoparticles were characterized by dynamic light scattering, superconducting quantum interference magnetometry, and atomic force microscopy. Poly(triphenylamine rhodamine-3-acetic acid-co-3,4-ethoxylenedioxythiophene)s copolymers (p(TPAR-co-EDOT)) were imprinted with various epitopes of PD-L1 by in situ electrochemical polymerization. The epitope-imprinted polymer-coated electrodes were then characterized by scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Finally, the sandwich sensing of various PD-L1 concentrations with peptide-imprinted p(TPAR-co-EDOT)-coated substrate and UCNP-containing magnetic peptide-imprinted pEVAL nanoparticles by FRET was conducted to measure the concentration of PD-L1 in A549 lung cancer cell lysate.

Photoelectrochemical biosensor based on SiW12@CdS quantum dots for the highly sensitive detection of HPV 16 DNA.

A highly sensitive biosensor for detecting HPV 16 DNA was prepared based on Keggin-type polyoxometalate (SiW12)-grafted CdS quantum dots (SiW12@CdS QDs) and colloidal gold nanoparticles (Au NPs), which exhibited remarkable selectivity and sensitivity upon target DNA detection because of its excellent photoelectrochemical (PEC) response. Here, an enhanced photoelectronic response ability was achieved with the strong association of SiW12@CdS QDs by polyoxometalate modification, which was developed through a convenient hydrothermal process. Furthermore, on Au NP-modified indium tin oxide slides, a multiple-site tripodal DNA walker sensing platform coupled with T7 exonuclease was successfully fabricated with SiW12@CdS QDs/NP DNA as a probe for detecting HPV 16 DNA. Due to the remarkable conductivity of Au NPs, the photosensitivity of the as-prepared biosensor was improved in an I3-/I- solution and avoided the use of other regents toxic to living organisms. Finally, under optimized conditions, the as-prepared biosensor protocol demonstrated wide linear ranges (15-130 nM), with a limit of detection of 0.8 nM and high selectivity, stability, and reproducibility. Moreover, the proposed PEC biosensor platform offers a reliable pathway for detecting other biological molecules with nano-functional materials.

Embedded Upconversion Nanoparticles in Magnetic Molecularly Imprinted Polymers for Photodynamic Therapy of Hepatocellular Carcinoma.

In this work, high-temperature pyrolysis was used to prepare both the core and shell of lantha-nide-doped UCNPs with lithium yttrium tetrafluoride (LiYF4) to enhance the green luminescence. Merocyanine 540 (MC540)-grafted magnetic nanoparticles were incorporated in the PD-L1 pep-tide-imprinted poly(ethylene-co-vinyl alcohol) particles, which were formed by precipitation in a non-solvent. UCNPs in the non-solvent bath were thus entrapped in the imprinted particles to generate composite nanoparticles for the targeting and photodynamic therapy of PD-L1 in tumor cells. Finally, the in vitro cytotoxicity of the nanoparticles in HepG2 human liver cancer cells was evaluated with the continuous administration of MC540/MNPs@MIPs/UCNPs under irradiation by an NIR laser. To understand the delivery of the UCNP-embedded molecularly imprinted pol-ymers, the intrinsic and extrinsic pathways were also investigated.

Thermal annealing study of the mid-infrared aluminum nitride on insulator (AlNOI) photonics platform.

Aluminum nitride on insulator (AlNOI) photonics platform has great potential for mid-infrared applications thanks to the large transparency window, piezoelectric property, and second-order nonlinearity of AlN. However, the deployment of AlNOI platform might be hindered by the high propagation loss. We perform thermal annealing study and demonstrate significant loss improvement in the mid-infrared AlNOI photonics platform. After thermal annealing at 400°C for 2 hours in ambient gas environment, the propagation loss is reduced by half. Bend loss and taper coupling loss are also investigated. The performance of multimode interferometer, directional coupler, and add/drop filter are improved in terms of insertion loss, quality factor, and extinction ratio. Fourier-transform infrared spectroscopy, Raman spectroscopy, and X-ray diffraction spectroscopy suggest the loss improvement is mainly attributed to the reduction of extinction coefficient in the silicon dioxide cladding. Apart from loss improvement, appropriate thermal annealing also helps in reducing thin film stress.

Diagnosing ovarian cancer by identifying SCC-antigen on a multiwalled carbon nanotube-modified dielectrode sensor.

Ovarian cancer starts in the ovaries in its earlier stages and then spreads to the pelvis, uterus, and abdominal region. The success of an ovarian cancer treatment depends on the stage of the cancer and the diagnostic system. Squamous cell carcinoma antigen (SCC-Ag) is one of the most efficient cancer biomarkers, and elevated levels of SCC-Ag in ovarian cancer cells have been used to identify ovarian cancer. Carbon is a potential material for biosensing applications due to its thermal, electrical, and physical properties. Multiwalled carbon nanotubes (MWCNTs) are carbon-based materials that can be used here to detect SCC-Ag. Anti-SCC-Ag antibody was immobilized on the amine-modified MWCNT dielectric sensing surface to detect SCC-Ag. The uniformity of the surface structure was measured with a 3D nanoprofiler, and the results confirmed the detection of SCC-Ag at ∼80 pM. The specific detection of SCC-Ag was confirmed with two control proteins (factor IX and human serum albumin), and the system did not show biofouling. This experimental set-up with MWCNTs a dielectric sensing surface can lead to the detection of ovarian cancer in its initial stages.

Aluminum nitride on insulator (AlNOI) platform for mid-infrared photonics.

We report an aluminum nitride on insulator platform for mid-infrared (MIR) photonics applications beyond 3 µm. Propagation loss and bending loss are studied, while functional devices such as directional couplers, multimode interferometers, and add/drop filters are demonstrated with high performance. The complementary metal-oxide-semiconductor-compatible aluminum nitride offers advantages ranging from a large transparency window, high thermal and chemical resistance, to piezoelectric tunability and three-dimensional integration capability. This platform can have synergy with other photonics platforms to enable novel applications for sensing and thermal imaging in MIR.

All-Dielectric Surface-Enhanced Infrared Absorption-Based Gas Sensor Using Guided Resonance.

The surface-enhanced infrared absorption (SEIRA) technique has been focusing on the metallic resonator structures for decades, exploring different approaches to enhance sensitivity. Although the high enhancement is achieved, the dissipative loss and strong heating are the intrinsic drawbacks of metals. Recently, the dielectric platform has emerged as a promising alternative. In this work, we report a guided resonance-based all-dielectric photonic crystal slab as the platform for SEIRA. The guided resonance-induced enhancement in the effective path length and electric field, together with gas enrichment polymer coating, leads to a detection limit of 20 ppm in carbon dioxide (CO2) sensing. This work explores the feasibility to apply low loss all-dielectric structures as a surface enhancement method in the transmission mode.

Fabrication, stability and efficacy of dual-component antimicrobial nanoemulsions: essential oil (thyme oil) and cationic surfactant (lauric arginate).

The influence of a cationic surfactant (lauric arginate, LAE) on the physical properties and antimicrobial efficacy of thyme oil nanoemulsions was investigated. Nanoemulsions prepared from pure thyme oil were highly unstable due to Ostwald ripening, but they could be stabilized by adding a ripening inhibitor (corn oil) to the oil phase prior to homogenisation. The loading capacity and antimicrobial efficacy of thyme oil nanoemulsions were significantly increased by adding LAE. In the absence of LAE, at least 60 wt% corn oil had to be added to the lipid phase to inhibit Ostwald ripening; but in the presence of 0.1 wt% LAE, only 30 wt% corn oil was needed. LAE addition substantially increased the antimicrobial efficacy of the thyme oil nanoemulsions: 200 µg/ml thyme oil was needed to inhibit growth of a spoilage yeast (Zygosaccharomyces bailii) if LAE was added, whereas ⩾ 400 µg/ml was needed in the absence of LAE.

Optimization of orange oil nanoemulsion formation by isothermal low-energy methods: influence of the oil phase, surfactant, and temperature.

Nanoemulsions are particularly suitable as a platform in the development of delivery systems for lipophilic functional agents. This study shows that transparent orange oil nanoemulsions can be fabricated using an isothermal low-energy method (spontaneous emulsification), which offers the advantage of fabricating flavor oil delivery systems using rapid and simple processing operations. Orange oil nanoemulsions were formed spontaneously by titration of a mixture of orange oil, carrier oil [medium-chain triglyceride (MCT)], and non-ionic surfactant (Tween) into an aqueous solution (5 mM citrate buffer at pH 3.5) with continuous stirring. The oil/emulsion ratio content was kept constant (10 wt %), while the surfactant/emulsion ratio (SER) was varied (2.5-20 wt %). Oil-phase composition (orange oil/MCT ratio), SER, and surfactant type all had an appreciable effect on nanoemulsion formation and stability. Transparent nanoemulsions could be formed under certain conditions: 20% surfactant (Tween 40, 60, or 80) and 10% oil phase (4-6% orange oil + 6-4% MCT). Surfactant type and oil-phase composition also affected the thermal stability of the nanoemulsions. Most of the nanoemulsions broke down after thermal cycling (from 20 to 90 °C and back to 20 °C); however, one system remained transparent after thermal cycling: 20% Tween 80, 5% orange oil, and 5% MCT. The mean droplet size of these nanoemulsions increased over time, but the droplet growth rate was reduced appreciably after dilution. These results have important implications for the design and utilization of nanoemulsions as delivery systems in the food and other industries.

Physical properties and antimicrobial efficacy of thyme oil nanoemulsions: influence of ripening inhibitors.

Thyme oil-in-water nanoemulsions (pH 3.5) were prepared as potential antimicrobial delivery systems. The nanoemulsions were highly unstable to droplet growth and phase separation, which was attributed to Ostwald ripening due to the relatively high water solubility of thyme oil. Ostwald ripening could be inhibited by mixing thyme oil with a water-insoluble ripening inhibitor (≥60 wt % corn oil or ≥50 wt % MCT in the lipid phase) before homogenization, yielding nanoemulsions with good physical stability. Physically stable thyme oil nanoemulsions were examined for their antimicrobial activities against an acid-resistant spoilage yeast, Zygosaccharomyces bailii (ZB). Oil phase composition (ripening inhibitor type and concentration) had an appreciable influence on the antimicrobial activity of the thyme oil nanoemulsions. In general, increasing the ripening inhibitor levels in the lipid phase reduced the antimicrobial efficacy of nanoemulsions. For example, for nanoemulsions containing 60 wt % corn oil in the lipid phase, the minimum inhibitory concentration (MIC) of thyme oil to inhibit ZB growth was 375 µg/mL, while for nanoemulsions containing 90 wt % corn oil in the lipid phase, even 6000 µg/mL thyme oil could not inhibit ZB growth. This effect is also dependent on ripening inhibitor types: at the same concentration in the lipid phase, MCT decreased the antimicrobial efficacy of thyme oil more than corn oil. For instance, when the level of ripening inhibitor in the lipid phase was 70 wt %, the MICs of thyme oil for nanoemulsions containing corn oil and MCT were 750 and 3000 µg/mL, respectively. The results of this study have important implications for the design and utilization of nanoemulsions as antimicrobial delivery systems in the food and other industries.

Influence of surfactant charge on antimicrobial efficacy of surfactant-stabilized thyme oil nanoemulsions.

Thyme oil-in-water nanoemulsions stabilized by a nonionic surfactant (Tween 80, T80) were prepared as potential antimicrobial delivery systems (pH 4). The nanoemulsions were highly unstable to droplet growth and phase separation, which was attributed to Ostwald ripening due to the relatively high water solubility of thyme oil. Ostwald ripening could be inhibited by incorporating ≥75% of corn oil (a hydrophobic material with a low water solubility) into the nanoemulsion droplets. The electrical characteristics of the droplets in the nanoemulsions were varied by incorporating ionic surfactants with different charges after homogenization: a cationic surfactant (lauric arginate, LAE) or an anionic surfactant (sodium dodecyl sulfate, SDS). The antifungal activity of nanoemulsions containing positive, negative, or neutral thymol droplets was then conducted against four strains of acid-resistant spoilage yeasts: Zygosaccharomyces bailli, Saccharomyces cerevisiae, Brettanomyces bruxellensis, and Brettanomyces naardenensis. The antifungal properties of the three surfactants (T80, LAE, SDS) were also tested in the absence of thymol droplets. Both ionic surfactants showed strong antifungal activity in the absence of thymol droplets, but no antimicrobial activity in their presence. This effect was attributed to partitioning of the antimicrobial surfactant molecules between the oil droplet and microbial surfaces, thereby reducing the effective concentration of active surfactants available to act as antimicrobials. This study shows oil droplets may decrease the efficacy of surfactant-based antimicrobials, which has important consequences for formulating effective antimicrobial agents for utilization in emulsion-based food and beverage products.