Nanoparticles for multiplex diagnostics and imaging

Three-Dimensional Imaging of Bioinspired Lipidic Mesophases Using Multicolored Light-Emitting Carbon Nanodots

Recent progress in the design of carbon nanostructures exhibiting strong multiphoton-excited emission opens new pathways to explore the self-organization of lipids found in living organisms. Phospholipid-based lyotropic myelin figures (MFs) are promising materials as simplified models of biomembranes due to their structural resemblance to a multilamellar sheath insulating the axon. This study demonstrates the possibility of selective labeling of MFs by strongly emitting multicolor phloroglucinol-derived carbon nanodots (PG CNDs). Such dopants are efficiently excited by visible and near-infrared light; therefore, one- and two-photon fluorescence microscopies are incorporated to gain 3D insights into the MFs. Combining nondestructive fluorescence microscopy and spectroscopy techniques along with polarized light microscopy gives details on the stability and morphology of lipidic mesophases. Our findings suggest that PG CNDs can be a viable and simple alternative to conventional fluorescent lipid stains to image biologically relevant phospholipid-based structures.

Recent Update Roles of Magnetic Nanoparticles in Circulating Tumor Cell (CTC)/Non-CTC Separation

Metastasis of cancer is a major cause of death worldwide. Circulating tumor cells (CTCs) are important in the metastatic process of cancer. CTCs are able to circulate in the bloodstream. Therefore, they can be used as biomarkers of metastasis. However, CTCs are rare when compared to a large number of blood cells in the blood. Many CTC detection methods have been developed to increase CTC detection efficiency. Magnetic nanoparticles (MNPs) have attracted immense attention owing to their potential medical applications. They are particularly appealing as a tool for cell separation. Because of their unique properties, MNPs are of considerable interest for the enrichment of CTCs through CTC or non-CTC separation. Herein, we review recent developments in the application of MNPs to separate CTCs or non-CTCs in samples containing CTCs. This review provides information on new approaches that can be used to detect CTCs in blood samples. The combination of MNPs with other particles for magnetic-based cell separation for CTC detection is discussed. Furthermore, different approaches for synthesizing MNPs are included in this review.

Robust Carbonated Structural Color Barcodes with Ultralow Ontology Fluorescence as Biomimic Culture Platform

Photonic crystal (PC) barcodes are a new type of spectrum-encoding microcarriers used in multiplex high-throughput bioassays, such as broad analysis of biomarkers for clinical diagnosis, gene expression, and cell culture. Unfortunately, most of these existing PC barcodes suffered from undesired features, including difficult spectrum-signal acquisition, weak mechanical strength, and high ontology fluorescence, which limited their development to real applications. To address these limitations, we report a new type of structural color-encoded PC barcodes. The barcodes are fabricated by the assembly of monodisperse polydopamine- (PDA-) coated silica (PDA@SiO2) nanoparticles using a droplet-based microfluidic technique and followed by pyrolysis of PDA@SiO2 (C@SiO2) barcodes. Because of the templated carbonization of adhesive PDA, the prepared C@SiO2 PC beads were endowed with simultaneous easy-to-identify structural color, high mechanical strength, and ultralow ontology fluorescence. We demonstrated that the structural colored C@SiO2 barcodes not only maintained a high structural stability and good biocompatibility during the coculturing with fibroblasts and tumor cells capture but also achieved an enhanced fluorescent-reading signal-to-noise ratio in the fluorescence-reading detection. These features make the C@SiO2 PC barcodes versatile for expansive application in fluorescence-reading-based multibioassays.

Dual-color graphene quantum dots and carbon nanoparticles biosensing platform combined with Exonuclease III-assisted signal amplification for simultaneous detection of multiple DNA targets

Sensitive and simultaneous detection of multiple biomarkers such as target DNA or proteins using biocompatible materials with good analysis performance remains an important challenge. Herein, we successfully developed a signal "off-on" highly sensitive multiplex detection platform based on the combination of dual-color graphene quantum dots (blue GQDs and green GQDs) modified DNA probes with carbon nanoparticles (CNPs), which is a cheap, effective nonfluorescent quencher to simultaneously quench the fluorescence of both GQDs-DNA probes. The Exo III-assisted sequence-independent target recycling and signal amplification strategy was integrated into this sensing platform, which endows it with high sensitivity towards the multiplex detection of targets DNA. The detection limits of 6.6 pM for HIV and 9.5 pM for HBV were achieved respectively, which is about 60-fold lower than that of traditional unamplified homogeneous fluorescent assay methods. Our proposed multiplex detecting platform is advantageous in both respective and simultaneous detection of multiple targets and can also discriminate perfectly matched targets from mismatched targets in both PBS buffer and 1% human serum samples, demonstrating its potential to be a reliable strategy for highly sensitive simultaneous detection of multiple target genes in practical diagnosis applications.

Molecular phenotyping and image-guided surgical treatment of melanoma using spectrally distinct ultrasmall core-shell silica nanoparticles

Accurate detection and quantification of metastases in regional lymph nodes remain a vital prognostic predictor for cancer staging and clinical outcomes. As intratumoral heterogeneity poses a major hurdle to effective treatment planning, more reliable image-guided, cancer-targeted optical multiplexing tools are critically needed in the operative suite. For sentinel lymph node mapping indications, accurately interrogating distinct molecular signatures on cancer cells in vivo with differential levels of sensitivity and specificity remains largely unexplored. To address these challenges and demonstrate sensitivity to detecting micrometastases, we developed batches of spectrally distinct 6-nm near-infrared fluorescent core-shell silica nanoparticles, each batch surface-functionalized with different melanoma targeting ligands. Along with PET imaging, particles accurately detected and molecularly phenotyped cancerous nodes in a spontaneous melanoma miniswine model using image-guided multiplexing tools. Information afforded from these tools offers the potential to not only improve the accuracy of targeted disease removal and patient safety, but to transform surgical decision-making for oncological patients.

Multicolor Cocktail for Breast Cancer Multiplex Phenotype Targeting and Diagnosis Using Bioorthogonal Surface-Enhanced Raman Scattering Nanoprobes

Early precise diagnosis of cancers is crucial to realize more effective therapeutic interventions with minimal toxic effects. Cancer phenotypes may also alter greatly among patients and within individuals over the therapeutic process. The identification and characterization of specific biomarkers expressed on tumor cells are in high demand for diagnosis and treatment, but they are still a challenge. Herein, we designed three new bioorthogonal surface-enhanced Raman scattering (SERS) nanoprobes and successfully applied the cocktail of them for MDA-MB-231 and MCF-7 breast cancer multiplex phenotype detection. The SERS nanoprobes containing Raman reporters with diynl, azide, or cyano moieties demonstrated apparent Raman shift peaks in 2205, 2120, and 2230 cm-1, respectively, in the biologically Raman-silent region. Three target ligands, including oligonucleotide aptamer (AS1411), arginine-glycine-aspatic acid (RGD) peptide, and homing cell adhesion molecule antibody (anti-CD44), were separately conjugated to the nanoprobes for active recognition capability. The cocktail of the nanoprobes manifested minimal cytotoxicity and simultaneously multiplex phenotype imaging of MDA-MB-231 and MCF-7 cells. Quantitative measurement of cellular uptake by inductively coupled plasma mass spectrometry (ICPMS) verified that MDA-MB-231 cells harbored a much higher expression level of CD44 receptor than MCF-7 cells. For in vivo SERS detection, Raman shift peaks of 2120, 2205, and 2230 cm-1 in the micro-tumor were clearly observed, representing the existence of three specific biomarkers of nucleolin, integrin αvβ3, and CD44 reporter, which could be used for early cancer phenotype identification. The biodistribution results indicated that target ligand modified nanoprobes exhibited much more accumulation in tumors than those nanoprobes without target ligands. The multicolor cocktail of bioorthogonal SERS nanoprobes offers an attractive and insightful strategy for early cancer multiplex phenotype targeting and diagnosis in vivo that is noninvasive and has low cross-talk, unique spectral-molecular signature, high sensitivity, and negligible background interference.

Correlation of surface-enhanced Raman scattering (SERS) with the surface density of gold nanoparticles: evaluation of the critical number of SERS tags for a detectable signal

The use of plasmonic nanotags based on the surface-enhanced Raman scattering (SERS) effect is highly promising for several applications in analytical chemistry, biotechnological assays and nanomedicine. To this end, a crucial parameter is the minimum number of SERS tags that allows for the collection of intense Raman signals under real operating conditions. Here, SERS Au nanotags (AuNTs) based on clustered gold nanoparticles are deposited on a substrate and analyzed in the same region using Raman spectroscopy and transmission electron microscopy. In this way, the Raman spectra and the surface density of the SERS tags are correlated directly, showing that 1 tag/µm² is enough to generate an intense signal above the noise level at 633 nm with an excitation power of only 0.65 mW and an acquisition time of just 1 s with a 50× objective. The AuNT density can be even lower than 1 tag/µm² when the acquisition time is extended to 10 s, but must be increased to 3 tags/µm² when a 20× objective is employed under the same excitation conditions. In addition, in order to observe a linear response, it was found that 10 SERS AuNTs inside the probed area are required. These findings indicate that a better signal-to-noise ratio requires high-magnification optics, while linearity versus tag number can be improved by using low-magnification optics or a high tag density. In general the suitability of plasmonic SERS labels for ultrasensitive analytical and biomedical applications is evident.

Robust, Highly Visible, and Facile Bioconjugation Colloidal Crystal Beads for Bioassay

High mechanical strength, highly visible, and admirable grafting molecular ability is the key challenge for colloidal photonic crystal (CPC) barcode beads in multiplex analysis fields. To achieve this goal, we proposed self-adhesion particles, polydopamine-coated SiO₂ nanoparticles (PDA@SiO₂), to construct CPC barcode beads by droplet-based microfluidic approach. Because of the adhesion, broad absorption of light, and "active" functional groups of PDA, the beads are endowed with high robustness, visibility, and excellent biomolecule immobilization. Ultrasonic treatment and compression experiments demonstrated that PDA@SiO₂ CPC barcode beads have a high mechanical strength. Color analysis illustrated that PDA@SiO₂ CPC beads exhibited a high visibility in color. The verification of fluorescent-tagged biomolecule conjugation together with the antigen detection stated that PDA@SiO₂ CPC beads are capable of immobilizing biomolecule by covalent binding. With a sandwich format, the beads were applied to analyze the tumor makers including alpha fetal protein, carcinoembryonic antigen, and prostate specific antigen from practical clinical serum. The proposed suspension arrays using PDA@SiO₂ CPC beads as a barcode showed acceptable accuracy and detection reproducibility.

Boronate affinity molecularly imprinted inverse opal particles for multiple label-free bioassays

Boronate affinity molecularly imprinted inverse opal particles were developed for the multiplex label-free detection of glycoproteins with high sensitivity and specificity.

Mathematical Model for Biomolecular Quantification Using Large-Area Surface-Enhanced Raman Spectroscopy Mapping

Surface-enhanced Raman spectroscopy (SERS) based on nanostructured platforms is a promising technique for quantitative and highly sensitive detection of biomolecules in the field of analytical biochemistry. Here, we report a mathematical model to predict experimental SERS signal (or hotspot) intensity distributions of target molecules on receptor-functionalized nanopillar substrates for biomolecular quantification. We demonstrate that by utilizing only a small set of empirically determined parameters, our general theoretical framework agrees with the experimental data particularly well in the picomolar concentration regimes. This developed model may be generally used for biomolecular quantification using Raman mapping on SERS substrates with planar geometries, in which the hotspots are approximated as electromagnetic enhancement fields generated by closely spaced dimers. Lastly, we also show that the detection limit of a specific target molecule, TAMRA-labeled vasopressin, approaches the single molecule level, thus opening up an exciting new chapter in the field of SERS quantification.

Au@pNIPAM SERRS Tags for Multiplex Immunophenotyping Cellular Receptors and Imaging Tumor Cells

Detection technologies employing optically encoded particles have gained much interest toward clinical diagnostics and drug discovery, but the portfolio of available systems is still limited. The fabrication and characterization of highly stable surface-enhanced resonance Raman scattering (SERRS)-encoded colloids for the identification and imaging of proteins expressed in cells are reported. These plasmonic nanostructures are made of gold octahedra coated with poly(N-isopropylacrylamide) microgels and can be readily encoded with Raman active dyes while retaining high colloidal stability in biofluids. A layer-by-layer polyelectrolyte coating is used to seal the outer surface of the encoded particles and to provide a reactive surface for covalent conjugation with antibodies. The targeted multiplexing capabilities of the SERRS tags are demonstrated by the simultaneous detection and imaging of three tumor-associated surface biomarkers: epidermal growth factor receptor (EGFR), epithelial cell adhesion molecule (EpCAM), and homing cell adhesion molecule (CD44) by SERRS spectroscopy. The plasmonic microgels are able to discriminate tumor A431 (EGFR+/EpCAM+/CD44+) and nontumor 3T3 2.2 (EGFR-/EpCAM-/CD44+) cells while cocultured in vitro.

Multiplexed DNA detection using a gold nanorod-based fluorescence resonance energy transfer technique

A fluorescence resonance energy transfer method for multiplex detection DNA based on gold nanorods had been successfully constructed. This method is simple, easy to operate, good selectivity, no requirement to label the probe molecule and can analyze simultaneously multiple targets of DNA in one sample. The limit of detection for the 18-mer, 27-mer and 30-mer targets is 0.72, 1.0 and 0.43 nM at a signal-to-noise ratio of 3. The recoveries of three targets were 96.57-98.07%, 99.12-100.04% and 97.29-99.93%, respectively. The results show that the method can be used to analyze a clinical sample or a biological sample; it also can be used to develop new probes for rapid, sensitive and highly selective multiplex detection of analytes in real samples.

Microfluidic synthesis of barcode particles for multiplex assays

The increasing use of high-throughput assays in biomedical applications, including drug discovery and clinical diagnostics, demands effective strategies for multiplexing. One promising strategy is the use of barcode particles that encode information about their specific compositions and enable simple identification. Various encoding mechanisms, including spectroscopic, graphical, electronic, and physical encoding, have been proposed for the provision of sufficient identification codes for the barcode particles. These particles are synthesized in various ways. Microfluidics is an effective approach that has created exciting avenues of scientific research in barcode particle synthesis. The resultant particles have found important application in the detection of multiple biological species as they have properties of high flexibility, fast reaction times, less reagent consumption, and good repeatability. In this paper, research progress in the microfluidic synthesis of barcode particles for multiplex assays is discussed. After introducing the general developing strategies of the barcode particles, the focus is on studies of microfluidics, including their design, fabrication, and application in the generation of barcode particles. Applications of the achieved barcode particles in multiplex assays will be described and emphasized. The prospects for future development of these barcode particles are also presented.

Plant pathogen nanodiagnostic techniques: forthcoming changes?

Plant diseases are among the major factors limiting crop productivity. A first step towards managing a plant disease under greenhouse and field conditions is to correctly identify the pathogen. Current technologies, such as quantitative polymerase chain reaction (Q-PCR), require a relatively large amount of target tissue and rely on multiple assays to accurately identify distinct plant pathogens. The common disadvantage of the traditional diagnostic methods is that they are time consuming and lack high sensitivity. Consequently, developing low-cost methods to improve the accuracy and rapidity of plant pathogens diagnosis is needed. Nanotechnology, nano particles and quantum dots (QDs) have emerged as essential tools for fast detection of a particular biological marker with extreme accuracy. Biosensor, QDs, nanostructured platforms, nanoimaging and nanopore DNA sequencing tools have the potential to raise sensitivity, specificity and speed of the pathogen detection, facilitate high-throughput analysis, and to be used for high-quality monitoring and crop protection. Furthermore, nanodiagnostic kit equipment can easily and quickly detect potential serious plant pathogens, allowing experts to help farmers in the prevention of epidemic diseases. The current review deals with the application of nanotechnology for quicker, more cost-effective and precise diagnostic procedures of plant diseases. Such an accurate technology may help to design a proper integrated disease management system which may modify crop environments to adversely affect crop pathogens.

Dye-doped silica nanoparticles as luminescent organized systems for nanomedicine

This review summarizes developments and applications of luminescent dye doped silica nanoparticles as versatile organized systems for nanomedicine.

A rapid method for the assessment of the surface group density of carboxylic acid-functionalized polystyrene microparticles

Particle-based assays are becoming versatile analytical tools due to their cost-effectiveness, speed, straightforward and diverse functionalization chemistries, especially when polystyrene particles are used. The introduction of functional groups (-COOH, -NH2, etc.) to the surface of such polystyrene particles promotes their application in bioanalytics. However, the traditional method to determine the amount of surface carboxylate groups is conductivity titration, which is usually time- and resources-consuming and discontinuous. Here, we synthesized polystyrene microparticles with different contents of carboxylate groups, and then investigated a simpler and potentially continuous approach to determine the amount of surface carboxylate groups by Zeta potential measurements. The results were compared to the traditional titration method and to actual coupling efficiencies of the functionalized particles with a model oligonucleotide probe as determined by flow cytometry. All quantification methods revealed good agreement.

Synthesis, characterization, and directional binding of anisotropic biohybrid microparticles for multiplexed biosensing

Anisotropic microarchitectures with different physicochemical properties have been developed as advanced materials for challenging industrial and biomedical applications including switchable displays, multiplexed biosensors and bioassays, spatially-controlled drug delivery systems, and tissue engineering scaffolds. In this study, anisotropic biohybrid microparticles (MPs) spatio-selectively conjugated with two different antibodies (Abs) are first developed for fluorescence-based, multiplexed sensing of biological molecules. Poly(acrylamide-co-acrylic acid) is chemically modified with maleimide- or acetylene groups to introduce different targeting biological moieties into each compartment of anisotropic MPs. Modified polymer solutions containing two different fluorescent dyes are separately used for electrohydrodynamic co-jetting with side-by-side needle geometry. The anisotropic MPs are chemically stabilized by thermal imidization, followed by bioconjugation of two different sets of polyclonal Abs with two individual compartments via maleimide-thiol coupling reaction and Huisgen 1,3-dipolar cycloaddition. Finally, two compartments of the anisotropic biohybrid MPs are spatio-selectively associated with the respective monoclonal Ab-immobilized substrate in the presence of the antigen by sandwich-type immunocomplex formation, resulting in their ordered orientation due to the spatio-specific molecular interaction, as confirmed by confocal laser scanning microscopy. In conclusion, anisotropic biohybrid MPs capable of directional binding have great potential as a new fluorescence-based multiplexing biosensing system.

A microfluidic concentration-gradient droplet array generator for the production of multi-color nanoparticles

A microfluidic concentration-gradient droplet array generator (CDrAG) with parallel multi-channels and multi-layers was developed with 64 outlet channels producing 33 droplet gradient concentrations. A droplet production rate of 5 × 10(4) min(-1) was obtained, and the RSD value of droplet diameters in 64 groups is 5.5% (n = 64). Using the concentration gradient droplet array as parallel microreactors, 33 Au/Ag ratio nanoparticles were synthesized. The absorption spectra of the Au/Ag nanoparticles shifted from the spectrum of pure gold to one of pure silver. This demonstrates the CDrAG platform's promising potential to produce specific nanoparticle barcodes for high-throughput screening in chemistry, biology and a broad range of life science applications.

Photoexcitation of tumor-targeted corroles induces singlet oxygen-mediated augmentation of cytotoxicity

The tumor-targeted corrole particle, HerGa, displays preferential toxicity to tumors in vivo and can be tracked via fluorescence for simultaneous detection, imaging, and treatment. We have recently uncovered an additional feature of HerGa in that its cytotoxicity is enhanced by light irradiation. In the present study, we have elucidated the cellular mechanisms for HerGa photoexcitation-mediated cell damage using fluorescence optical imaging. In particular, we found that light irradiation of HerGa produces singlet oxygen, causing mitochondrial damage and cytochrome c release, thus promoting apoptotic cell death. An understanding of the mechanisms of cell death induced by HerGa, particularly under conditions of light-mediated excitation, may direct future efforts in further customizing this nanoparticle for additional therapeutic applications and enhanced potency.

Synthesis and interfacing of biocompatible iron oxide nanoparticles through the ferroxidase activity of Helicobacter Pylori ferritin

Ferritin is an iron storage protein that is often used to coat metallic nanoparticles, such as iron oxide nanoparticles (IONPs). However, the synthesis and biocompatibility of ferritin-coated IONPs remain unclear. Therefore, this study reports the synthesis of a ferritin gene cloned and expressed from Helicobacter pylori (HPFn). The ferroxidase activity of the synthase HPFn was used for the de novo synthesis of HPFn-coated IONPs under mild conditions. Gel filtration chromatography and transmission electron microscopy analyses demonstrated that the core-shell structure of both the 5.0 nm IONP nanocore and the 12.4 nm HPFn shell were correctly assembled. The cellular uptake of mouse macrophage cells (RAW 264.7 cells) has shown that only a few HPFn-coated IONPs (3%) were taken up after 24 h of incubation. This study compares the biocompatibility of HPFn-coated IONPs, superparamagnetic iron oxide nanoparticles (SPIOs) and ferric salt (ferric ammonium citrate) in respect to cell growth inhibition, reactive oxygen species generation and pro-inflammatory cytokine TNF-α release. Assessment results showed that the responses elicited by HPFn-coated IONPs were similar to those elicited by SPIO treatment but milder than those elicited by ferric salt treatment. This accounts for the notion that ferritin-coated IONPs are biocompatible iron agents. These findings show that the ferroxidase activity of ferritin can be used to synthesize biocompatible IONPs. The favorable properties of HPFn-coated IONPs suggest that they can be used as a non-macrophage contrast agent through further surface conjugation.

Microfluidics-mediated isothermal detection of enzyme activity at the single molecule level

Conventional analysis of enzymatic activity, often carried out on pools of cells, is blind to heterogeneity in the population. Here, we combine microfluidics with a previously developed isothermal rolling circle amplification-based assay to investigate multiple enzymatic activities in down to single cells. This microfluidics-meditated assay performs at very high sensitivity in picoliter incubators with small quantities of biological materials. Furthermore, we demonstrate the assay's capability of multiplexed detection of at least three enzyme activities at the single molecule level.

Development of a stable dual functional coating with low non-specific protein adsorption and high sensitivity for new superparamagnetic nanospheres

To overcome major challenges of non-specific protein adsorption on nanoparticles for nanosensing and nanodiagnosis, an efficient method for robust chemical modification was developed to achieve excellent specific biorecognition and long-term stability in complex biomedia. This method is demonstrated by a highly specific and sensitive immunoassay (IA), using superparamagnetic nanospheres (NSs) with high magnetite content. The non-specific protein adsorption on the NSs was suppressed dramatically when modified with dual functional poly(carboxybetaine methacrylate) (polyCBMA) via surface-initiated atom transfer radical polymerization (SI-ATRP) and chemically grafted with antibodies of the β subunit of human chorionic gonadotrop (anti-β-hCG). The response to hCG of IA NSs with polyCBMA coatings was highly consistent in either phosphate-buffered saline (PBS) or 50% fetal bovine serum (FBS), which is far less variable than the response of the IA NSs without polyCBMA coatings. After all, a very robust platform for IA NSs with excellent specific biorecognition was obtained. It is expected that this method for nanoparticle modification could be widely used in ultrasensitive nanosensing and nanodiagnosis in the future.

Insulin-binding aptamer-conjugated graphene oxide for insulin detection

This paper describes a simple and sensitive aptamer/graphene oxide (GO) based assay for insulin detection. GO can protect DNA from nuclease cleavage, but aptamers can be detached from the GO surface by specific target binding. This exposes the aptamers to enzymatic cleavage and releases the target for a new cycle. Cycling of targets leads to significant signal amplification and low LOD.

Polyethylenimine-conjugated gold nanoparticles: Gene transfer potential and low toxicity in the cornea

This study examined the gene transfer efficiency and toxicity of 2-kDa polyethylenimine conjugated to gold nanoparticles (PEI2-GNPs) in the human cornea in vitro and rabbit cornea in vivo. PEI2-GNPs with nitrogen-to-phosphorus ratios of up to 180 exhibited significant transgene delivery in the human cornea without altering the viability or phenotype of these cells. Similarly, PEI2-GNPs applied to corneal tissues collected after 12 hours, 72 hours, or 7 days exhibited appreciable gold uptake throughout the rabbit stroma with gradual clearance of GNPs over time. Transmission electron microscopy detected GNPs in the keratocytes and the extracellular matrix of the rabbit corneas. Additionally, slit-lamp biomicroscopy in live animals even 7 days after topical PEI2-GNP application to the cornea detected no inflammation, redness, or edema in rabbit eyes in vivo, with only moderate cell death and immune reactions. These results suggest that PEI2-GNPs are safe for the cornea and can potentially be useful for corneal gene therapy in vivo.

FROM THE CLINICAL EDITOR

This study examined the gene transfer efficiency and toxicity of 2-kDa polyethylenimine conjugated to gold nanoparticles in the human cornea in vitro and rabbit cornea in vivo. The results suggest that PEI2-GNPs are safe for the cornea and can potentially be useful for corneal gene therapy in vivo.

Advances in transfusion medicine in the first decade of the 21st century: Advances in miniaturized technologies

Several miniaturized high throughput technologies have been developed in the last decade, primarily to study genomic structures and gene expression patterns under various conditions. At the same time, the microarrays, biosensors, integrated microfluidic lab-on-a-chip devices, next generation sequencing or digital PCR are gradually finding their diagnostic applications, although their suitability for specialised diagnostic fields has still to be assessed. In this review we discuss the potential applications of the new technologies to blood testing.

Nanoparticles as contrast agents for in-vivo bioimaging: current status and future perspectives

Nanoparticle-based contrast agents are quickly becoming valuable and potentially transformative tools for enhancing medical diagnostics for a wide range of in-vivo imaging modalities. Compared with conventional molecular-scale contrast agents, nanoparticles (NPs) promise improved abilities for in-vivo detection and potentially enhanced targeting efficiencies through longer engineered circulation times, designed clearance pathways, and multimeric binding capacities. However, NP contrast agents are not without issues. Difficulties in minimizing batch-to-batch variations and problems with identifying and characterizing key physicochemical properties that define the in-vivo fate and transport of NPs are significant barriers to the introduction of new NP materials as clinical contrast agents. This manuscript reviews the development and application of nanoparticles and their future potential to advance current and emerging clinical bioimaging techniques. A focus is placed on the application of solid, phase-separated materials, for example metals and metal oxides, and their specific application as contrast agents for in-vivo near-infrared fluorescence (NIRF) imaging, magnetic resonance imaging (MRI), positron emission tomography (PET), computed tomography (CT), ultrasound (US), and photoacoustic imaging (PAI). Clinical and preclinical applications of NPs are identified for a broad spectrum of imaging applications, with commentaries on the future promise of these materials. Emerging technologies, for example multifunctional and theranostic NPs, and their potential for clinical advances are also discussed.

Detection of blood-transmissible agents: can screening be miniaturized?

Transfusion safety relating to blood-transmissible agents is a major public health concern, particularly when faced with the continuing emergence of new infectious agents. These include new viruses appearing alongside other known reemerging viruses (West Nile virus, Chikungunya) as well as new strains of bacteria and parasites (Plasmodium falciparum, Trypanosoma cruzi) and finally pathologic prion protein (variant Creutzfeldt-Jakob disease). Genomic mutations of known viruses (hepatitis B virus, hepatitis C virus, human immunodeficiency virus) can also be at the origin of variants susceptible to escaping detection by diagnostic tests. New technologies that would allow the simultaneous detection of several blood-transmissible agents are now needed for the development and improvement of screening strategies. DNA microarrays have been developed for use in immunohematology laboratories for blood group genotyping. Their application in the detection of infectious agents, however, has been hindered by additional technological hurdles. For instance, the variability among and within genomes of interest complicate target amplification and multiplex analysis. Advances in biosensor technologies based on alternative detection strategies have offered new perspectives on pathogen detection; however, whether they are adaptable to diagnostic applications testing biologic fluids is under debate. Elsewhere, current nanotechnologies now offer new tools to improve the sample preparation, target capture, and detection steps. Second-generation devices combining micro- and nanotechnologies have brought us one step closer to the potential development of innovative and multiplexed approaches applicable to the screening of blood for transmissible agents.

Real-time imaging of bacteria in living mice using a fluorescent dye

A novel technique developed in the laboratories of Bradley D. Smith and David Piwnica-Worms for imaging bacterial infections in intact living nude mice using a novel fluorescent dye, a conjugate of a NIR carbocyanine dye and two zinc(II) dipicolylamine units, allows relatively deep imaging of bacterial infection in real time. The behavior of the mice indicated good tolerance of the probe. The probe's water-octanol partition coefficient calculated by Hansch and Leo's procedure demonstrates that it is slightly lipophilic and therefore could enter mouse cells. Extant values of the physicochemical and spectroscopic parameters relevant to practical use are tabulated.

Using aptamer-conjugated fluorescence resonance energy transfer nanoparticles for multiplexed cancer cell monitoring

To facilitate the selection of effective therapeutic pathways and improve clinical outcomes, sensitive and simultaneous diagnosis of multiple trace biomarkers or cancer cells from complex living samples is particularly critical in the early stages of tumor development. To achieve this, we have combined the selectivity and affinity of aptamers with the spectroscopic advantages of fluorescence resonance energy transfer (FRET) nanoparticles (NPs). This has produced an aptamer-conjugated FRET NP assay that performs simultaneous multiplexed monitoring of cancer cells with the desired degree of sensitivity and selectivity. First, by changing the doping ratio of three different dyes, the FRET-mediated emission signatures could be tuned such that the nanoparticles would exhibit multiple colors upon excitation with a single wavelength. These FRET nanoparticles were then modified by a few aptamers specific for different cancer cell lines, in this case, T-cell leukemia and B-cell lymphoma. As a result, simultaneous and sensitive detection of multiple cancer cell targets was achieved. Therefore, our aptamer-conjugated FRET NPs are highly promising for potential applications in the sensitive monitoring of multiple cancer cells for biomedical research and medical diagnostics.

Automated oligonucleotide solid-phase synthesis on nanosized silica particles using nano-on-micro assembled particle supports

This article describes an original strategy to enable solid-phase oligodeoxyribonucleotide (ODN) synthesis on nanosized silica particles. It consists of the reversible immobilization of silica nanoparticles (NPs) on micrometric silica beads. The resulting assemblies, called nano-on-micro (NOM) systems, are well adapted to ODN synthesis in an automated instrument. First, NPs are derivatized with OH functions. For NOM assembly preparation, these functions react with the silanols of the microbeads under specific experimental conditions. Furthermore, OH groups allow ODN synthesis on the nanoparticles via phosphoramidite chemistry. The stability of the NOM assemblies during ODN solid-phase synthesis is confirmed by scanning and transmission electron microscopy (SEM and TEM, respectively), together with dynamic light scattering analyses. Then, the release of ODN-functionalized nanoparticles is performed under mild conditions (1% NH(4)OH in water, 1 h, 60 degrees C). Our technique provides silica nanoparticles well functionalized with oligonucleotides, as demonstrated by hybridization experiments conducted with the cDNA target.

High-strength metal nanomagnets for diagnostics and medicine: carbon shells allow long-term stability and reliable linker chemistry

The rapidly growing applications of nanomagnets in magnetic drug delivery and separation in clinical diagnostics require strong and reliable magnetic vehicles. Strength conveys rapid processing, high delivery/targeting yield and rapid results when used in clinics. Reliability enables recycling of nanomagnets, regulatory-conforming drug formulations and efficient use of (expensive) antibodies in diagnostics, combined with reduced leaching (reagent loss). The present work illustrates how metal-based nanomagnets provide a two-three-times stronger magnetic particle than conventional magnetite-based materials. Ligands, antibodies or drugs can be anchored to such carbon/metal core/shell nanomagnets over covalent, hydrolysis-resistant carbon-carbon bonds. This linker chemistry resists strong acids, sterilization and prolonged storage or aggressive treatment. As dispersions, functional nanomagnets rapidly scan liquids/tissue by Brownian diffusion, capture/deliver/react at a target and are efficiently recollected after use. Metal iron-based, carbon-coated nanomagnets consist of particularly well-accepted materials and now open stable nanomagnets to a broad range of fascinating separation problems in biomedical research.