Conjugated Polymer Loaded Nanospheres with Surface Functionalization for Simultaneous Discrimination of Different Live Cancer Cells under Single Wavelength Excitation

Different Surface Interactions between Fluorescent Conjugated Polymers and Biological Targets

Fluorescent conjugated polymers (CPs) have attracted considerable interest in biosensing owing to their high fluorescence, tunable bandgap, and good biocompatibility. Aiming at acquiring the desired optical responses of CPs for bioapplications, it is essential that the CPs bind to biological targets with high efficacy and affinity. However, the efficient binding of CPs is largely driven by their effective interaction with target surfaces. In this Review, we will focus on the different surface interactions that pervade between CPs and biological targets. The multiple surface interactions can lead to changes in spatial conformation and distribution of CPs, which manifest alterable optical properties of CPs based on accumulation of target-directed CPs, Förster resonance energy transfer mechanism, and metal-enhanced fluorescence mechanism. Then, we display diverse bioapplications applying CPs-based surface interactions, such as cell imaging, imaging-guided detection, and photodynamic therapy. Finally, the challenges and future developments to control the efficient attachment of CPs to biological targets are discussed. We expect that the understanding of surface interactions between CPs and biological targets benefits the CPs-based system design and expands their applications in biological detections and therapies.

Near-Infrared Light Regulation of Tumor PI3K/Akt Signaling Pathway for Enhancing Cancer Cell Apoptosis through Conjugated Polymer Nanoparticles

Calmodulin (CaM), as a calcium binding protein involved in the signal pathways of many life activities such as cell proliferation and apoptosis, can be regulated with the near-infrared (NIR) light-based photothermal conversion. Here, we build a conjugated polymer nanoparticle (CPNs-C) by assembling polypyrrole dione and dipalmitoyl phosphatidylethanolamine-polyethylene glycol-maleimide with a calmodulin antibody modified on the surface, which is NIR light-responsive for photothermally inducing apoptosis of cancer cells. Under near-infrared light irradiation, protein kinase B (Akt) and phosphatidylinositol 3-kinase, which bind to CaM, reduce the degree of phosphorylation due to the photothermal effect of CPNs-C, thus inhibiting the recruitment of Akt on the cell membrane. Therefore, the phosphorylation of GSK-3β downstream of the signaling pathway is reduced, and the phosphorylation of FoxO3a is enhanced, which can promote apoptosis of cancer cells. Compared with the photothermal effect of traditional CPNs, CPNs-C exhibits higher efficiency to regulate signaling pathways to promote cancer cells toward apoptosis. This strategy of utilizing NIR light to regulate the tumor apoptotic signaling pathway provides an effective way to enhance cancer cell apoptosis with high efficiency.

Ultrasensitive Simultaneous Detection of Multiplex Disease-Related Nucleic Acids Using Double-Enhanced Surface-Enhanced Raman Scattering Nanosensors

Developing ultrasensitive probes holds great significance for simultaneous detection of multiplexed cancer-associated nucleic acids. Bimetallic nanoparticles containing silver may be exploited as nanoprobes for disease detection, which can produce stable and strong surface-enhanced Raman scattering (SERS) signals. However, it remains extremely challenging that such SERS nanoprobes are directly synthesized. Herein gold-silver nanosnowmen, grown via a DNA-mediated approach and attached to thiol-containing Raman dyes, are successfully synthesized. Stable SERS-enhanced gold substrates are also prepared and used as the enriching containers, where the capture DNAs are tethered to sense the target genes jointly enhanced by the SERS nanoprobes in a sandwich hybridization assay. This means detection of the target gene can obtain a limit of detection close to 0.839 fM. Such double-enhanced SERS nanosensors are further employed to simultaneously detect the three types of prostate carcinoma-related genes with high sensitivity and specificity, which meanwhile exhibit robust capacity of resisting disturbance in practical samples. Simultaneous and multiplexed detection of cancer-related genes may provide further biomedical applications with new opportunity.

Affibody molecules for molecular imaging and targeted drug delivery in the management of breast cancer

Breast cancer is one of the leading reasons for the morbidity and mortality of cancer related death globally. The modern therapies are basically the combination of the breast-preserving surgeries or ablation with or without node biopsy or destroying the carcinoma cells adjuvant with chemotherapy, radiotherapy, hormonal or biological therapies depending upon the nature of the receptor of the cancerous cells, nature of the lymph node, as well as the tendency of the recurrence. For decade's carcinoma management suffered by the limitation of imagining, targeting and penetrability problem associated with management and cure of this deadly disease leads to unwanted chemo-toxicity and side effects. Alike other antibody mimetics, affibodies are designed with the combinatorial protein engineering approaches which are small and robust protein scaffolds retaining the favorable folding and stability. Affibody is one of the significantly important tools for imaging and diagnosis of the affinity specific over expressed proteins in the breast cancer management. The review summarizes the various affibody strategies uses in the management of breast cancer.

Ultrasmall Conjugated Polymer Nanoparticles with High Specificity for Targeted Cancer Cell Imaging

Fluorescent and biocompatible organic nanoparticles have attracted great interest in cancer detection and imaging, but the nonspecific cellular uptake has limited the detection specificity and sensitivity. Herein, the authors report the ultrasmall conjugated polymer nanoparticles (CPNs) with bright far-red/near-infrared emission for targeted cancer imaging with high specificity. The sizes of the ultrasmall CPNs are around 6 nm (CPN6), while large CPNs show sizes around 30 nm (CPN30). Moreover, CPN6 exhibits largely improved fluorescence quantum yield (η) of 41% than CPN30 (25%). Benefiting from the ultrasmall size, bare CPN6 shows largely suppressed nonspecific cellular uptake as compared to CPN30, while cyclic arginine-glycine-aspartic acid (cRGD) functionalized CPN6 (cRGD-CPN6) possesses excellent selectivity toward αvβ3 integrin overexpressed MDA-MB-231 cells over other cells in cell mixtures. The faster body clearance of CPN6 over CPN30 indicates its greater potentials as a noninvasive nanoprobe for in vivo and practical applications.

Multiplexed photoluminescent sensors: towards improved disease diagnostics

This tutorial review highlights the development of multiplexed photoluminescent sensors which can simultaneously detect multiple and diverse biomarkers that exist in a homogenous solution or a single cell, accelerating the progress towards precise disease diagnostics.

Multifunctional Conjugated Polymer Nanoparticles for Image-Guided Photodynamic and Photothermal Therapy

A multifunctional theranostic platform based on conjugated polymer nanoparticles (CPNs) with tumor targeting, fluorescence detection, photodynamic therapy (PDT), and photothermal therapy (PTT) is developed for effective cancer imaging and therapy. Two conjugated polymers, poly[9,9-bis(2-(2-(2-methoxyethoxy)ethoxy)-ethyl)fluorenyldivinylene]-alt-4,7-(2,1,3-benzothiadiazole) with bright red emission and photosensitizing ability and poly[(4,4,9,9-tetrakis(4-(octyloxy)phenyl)-4,9-dihydro-s-indacenol-dithiophene-2,7-diyl)-alt-co-4,9-bis(thiophen-2-yl)-6,7-bis(4-(hexyloxy)phenyl)-thiadiazolo-quinoxaline] with strong near-infrared absorption and excellent photothermal conversion ability are co-loaded into one single CPN via encapsulation approach using lipid-polyethylene glycol as the matrix. The obtained co-loaded CPNs show sizes of around 30 nm with a high singlet oxygen quantum yield of 60.4% and an effective photothermal conversion efficiency of 47.6%. The CPN surface is further decorated with anti-HER2 affibody, which bestows the resultant anti-HER2-CPNs superior selectivity toward tumor cells with HER2 overexpression both in vitro and in vivo. Under light irradiation, the PDT and PTT show synergistic therapeutic efficacy, which provides new opportunities for the development of multifunctional biocompatible organic materials in cancer therapy.

Photoswitchable Emission Color Change in Nanodots Containing Conjugated Polymer and Photochrome

A simple approach for the preparation of conjugated polymer (CP)-based fluorescent nanodots containing photochrome (dithienylethene, DTE) is reported. The CP in the nanodots was designed to exhibit dual emissions of blue and green. The photochromic, fluorescent, composite nanodots (PNDs) were able to tune the emission color from green to blue using selective energy transfer from the CP to DTE under ultraviolet (UV) irradiation. The UV-irradiation-induced ring closure of the DTE within the PNDs provided a spectral overlap between the green emission of the CP and the absorption of DTE, leading to quenching of the green emission and, concomitantly, maintaining of the blue emission. The photoswitchable fluorescent PNDs with high on-off green fluorescence contrast were successfully applied in a living zebrafish imaging. Our design strategy provided a versatile tool for constructing a special photomodulated color-changeable nanostructure in bioimaging.

Biosensors for breast cancer diagnosis: A review of bioreceptors, biotransducers and signal amplification strategies

Breast cancer is highly prevalent in females and accounts for second highest number of deaths, worldwide. Cumbersome, expensive and time consuming detection techniques presently available for detection of breast cancer potentiates the need for development of novel, specific and ultrasensitive devices. Biosensors are the promising and selective detection devices which hold immense potential as point of care (POC) tools. Present review comprehensively scrutinizes various breast cancer biosensors developed so far and their technical evaluation with respect to efficiency and potency of selected bioreceptors and biotransducers. Use of glycoproteins, DNA biomarkers, micro-RNA, circulatory tumor cells (CTC) and some potential biomarkers are introduced briefly. The review also discusses various strategies used in signal amplification such as nanomaterials, redox mediators, p19 protein, duplex specific nucleases (DSN) and redox cycling.

Semiconducting polymer nanoparticles as photoacoustic molecular imaging probes

As an emerging class of optical nanomaterials, semiconducting polymer nanoparticles (SPNs) are highly photostable, optically active and versatile in chemistry; these properties make them attractive as molecular imaging agents to enable imaging of biological events and functionalities at multiple scales. More recently, a variety of SPNs have been found to exhibit high photoacoustic properties, and further empowered photoacoustic imaging for contrast enhanced in vivo molecular imaging. Target-sensitive components can be incorporated in the SPNs to create activatable imaging probes to sense and monitor the target dynamics in living objects. Intrinsically biophotonic and biocompatible, SPNs can be further engineered for multimodal imaging and for real-time imaging of drug delivery. WIREs Nanomed Nanobiotechnol 2017, 9:e1418. doi: 10.1002/wnan.1418 For further resources related to this article, please visit the WIREs website.

Tuning the emission properties of a fluorescent polymer using a polymer microarray approach – identification of an optothermo responsive polymer

Fluorescent polymer microarrays were prepared using inkjet printing and screened. The fluorescence intensity was found to be tunable by temperature change when the dye was immobilized in identified thermo-responsive polymer beads.

An electrochemical immunosensor for detection of a breast cancer biomarker based on antiHER2-iron oxide nanoparticle bioconjugates

A label free immunosensor was designed for ultra-detection of human epidermal growth factor receptor 2 (HER2) in real samples using a differential pulse voltammetry (DPV) method. In a separate process, antiHER2 antibodies were attached to iron oxide nanoparticles (Fe3O4 NPs) to form stable bioconjugates which were later laid over the gold electrode surface. In this way, by the advantage of their long terminals, the bioconjugates provided the most possible space for the immuno-reaction between biomolecules. Under optimal conditions, the immunosensor was responsive to HER2 concentrations over the ranges of 0.01-10 ng mL(-1) and 10-100 ng mL(-1) linearly and benefited from a satisfactory detection limit as low as 0.995 pg mL(-1) and a favorable sensitivity as sharp as 5.921 μA mL ng(-1). The reliability of the method in clinical analysis was proved by successful quantization of HER2 levels in serum samples obtained from patients. Furthermore, the precision and the stability of the method were evaluated and verified to be acceptable in immunoassay studies.

Polymer-encapsulated organic nanoparticles for fluorescence and photoacoustic imaging

Polymer encapsulated organic nanoparticles have recently attracted increasing attention in the biomedical field because of their unique optical properties, easy fabrication and outstanding performance as imaging and therapeutic agents. Of particular importance is the polymer encapsulated nanoparticles containing conjugated polymers (CP) or fluorogens with aggregation induced emission (AIE) characteristics as the core, which have shown significant advantages in terms of tunable brightness, superb photo- and physical stability, good biocompatibility, potential biodegradability and facile surface functionalization. In this review, we summarize the latest advances in the development of polymer encapsulated CP and AIE fluorogen nanoparticles, including preparation methods, material design and matrix selection, nanoparticle fabrication and surface functionalization for fluorescence and photoacoustic imaging. We also discuss their specific applications in cell labeling, targeted in vitro and in vivo imaging, blood vessel imaging, cell tracing, inflammation monitoring and molecular imaging. We specially focus on strategies to fine-tune the nanoparticle property (e.g. size and fluorescence quantum yield) through precise engineering of the organic cores and careful selection of polymer matrices. The review also highlights the merits and limitations of these nanoparticles as well as strategies used to overcome the limitations. The challenges and perspectives for the future development of polymer encapsulated organic nanoparticles are also discussed.

Molecular photoacoustic imaging of breast cancer using an actively targeted conjugated polymer

Conjugated polymers (CPs) are upcoming optical contrast agents in view of their unique optical properties and versatile synthetic chemistry. Biofunctionalization of these polymer-based nanoparticles enables molecular imaging of biological processes. In this work, we propose the concept of using a biofunctionalized CP for noninvasive photoacoustic (PA) molecular imaging of breast cancer. In particular, after verifying the PA activity of a CP nanoparticle (CP dots) in phantoms and the targeting efficacy of a folate-functionalized version of the same (folate-CP dots) in vitro, we systemically administered the probe into a folate receptor-positive (FR+ve) MCF-7 breast cancer xenograft model to demonstrate the possible application of folate-CP dots for imaging FR+ve breast cancers in comparison to CP dots with no folate moieties. We observed a strong PA signal at the tumor site of folate-CP dots-administered mice as early as 1 hour after administration as a result of the active targeting of the folate-CP dots to the FR+ve tumor cells but a weak PA signal at the tumor site of CP-dots-administered mice as a result of the passive accumulation of the probe by enhanced permeability and retention effect. We also observed that folate-CP dots produced ~4-fold enhancement in the PA signal in the tumor, when compared to CP dots. These observations demonstrate the great potential of this active-targeting CP to be used as a contrast agent for molecular PA diagnostic imaging in various biomedical applications.

Conjugated polymer dots-on-electrospun fibers as a fluorescent nanofibrous sensor for nerve gas stimulant

A novel chemical warfare agent sensor based on conjugated polymer dots (CPdots) immobilized on the surface of poly(vinyl alcohol) (PVA)-silica nanofibers was prepared with a dots-on-fibers (DoF) hybrid nanostructure via simple electrospinning and subsequent immobilization processes. We synthesized a polyquinoxaline (PQ)-based CP as a highly emissive sensing probe and employed PVA-silica as a host polymer for the elctrospun fibers. It was demonstrated that the CPdots and amine-functionalized electrospun PVA-silica nanofibers interacted via an electrostatic interaction, which was stable under prolonged mechanical force. Because the CPdots were located on the surface of the nanofibers, the highly emissive properties of the CPdots could be maintained and even enhanced, leading to a sensitive turn-off detection protocol for chemical warfare agents. The prepared fluorescent DoF hybrid was quenched in the presence of a chemical warfare agent simulant, due to the electron transfer between the quinoxaline group in the polymer and the organophosphorous simulant. The detection time was almost instantaneous, and a very low limit of detection was observed (∼1.25 × 10(-6) M) with selectivity over other organophosphorous compounds. The DoF hybrid nanomaterial can be developed as a rapid, practical, portable, and stable chemical warfare agent-detecting system and, moreover, can find further applications in other sensing systems simply by changing the probe dots immobilized on the surface of nanofibers.

Fluorene-based macromolecular nanostructures and nanomaterials for organic (opto)electronics

Nanotechnology not only opens up the realm of nanoelectronics and nanophotonics, but also upgrades organic thin-film electronics and optoelectronics. In this review, we introduce polymer semiconductors and plastic electronics briefly, followed by various top-down and bottom-up nano approaches to organic electronics. Subsequently, we highlight the progress in polyfluorene-based nanoparticles and nanowires (nanofibres), their tunable optoelectronic properties as well as their applications in polymer light-emitting devices, solar cells, field-effect transistors, photodetectors, lasers, optical waveguides and others. Finally, an outlook is given with regard to four-element complex devices via organic nanotechnology and molecular manufacturing that will spread to areas such as organic mechatronics in the framework of robotic-directed science and technology.

Conjugated polymer amplified far-red/near-infrared fluorescence from nanoparticles with aggregation-induced emission characteristics for targeted in vivo imaging

Fluorescence-amplified far-red/near-infrared (FR/NIR) nanoparticles (NPs) are synthesized by co-encapsulation of conjugated polymer donor (poly[9,9-bis(2-(2-(2-methoxyethoxy)ethoxy)ethyl)fluorenyldivinylene]; PFV) and a fluorogen acceptor (2-(2,6-bis((E)-4-(phenyl(4'-(1,2,2-triphenylvinyl)-[1,1'-biphenyl]-4-yl)amino)styryl)-4H-pyran-4-ylidene)malononitrile; TPE-TPA-DCM) with aggregation-induced emission (AIE) characteristics using biocompatible bovine serum albumin (BSA) as the encapsulation matrix. The good spectral overlap and close proximity between PFV and TPE-TPA-DCM in BSA NPs result in a 5.3-fold amplified TPE-TPA-DCM emission signal via fluorescence resonance energy transfer (FRET). The obtained PFV/TPE-TPA-DCM co-loaded BSA NPs are spherical in shape with a large Stokes shift of ∼223 nm and low cytotoxicity. The BSA matrix allows further functionalization with arginine-glycine-aspartic acid (RGD) peptide to yield fluorescent probes for specific recognition of integrin receptor-overexpressed cancer cells. The advantage of PFV amplified FR/NIR signal from TPE-TPA-DCM is further demonstrated in cellular and in vivo imaging using HT-29 colon cancer cells and a murine hepatoma H22 tumor-bearing mouse model, respectively. The high FR/NIR fluorescence and specific cancer targeting ability by RGD surface functionalization make the PFV/TPE-TPA-DCM co-loaded BSA-RGD NPs a unique FR/NIR fluorescent probe for cellular imaging and in vivo tumor diagnosis in a high contrast and selective manner.

Ultrasensitive and selective electrochemical diagnosis of breast cancer based on a hydrazine-Au nanoparticle-aptamer bioconjugate

Human epidermal growth factor receptor 2 (HER2) and HER2-overexpressing breast cancer cells were detected using an electrochemical immunosensor combined with hydrazine and aptamer-conjugated gold nanoparticles (AuNPs). The sensor probe was fabricated by covalently immobilizing anti-HER2 onto a nanocomposite layer that was composed of self-assembled 2,5-bis(2-thienyl)-1H-pyrrole-1-(p-benzoic acid) (DPB) on AuNPs. The hydrazine-AuNP-aptamer bioconjugate, where the hydrazine reductant was directly attached onto AuNPs to avoid the nonspecific deposition of silver on the sensor surface, was designed and used to reduce silver ion for signal amplification selectively. The silver-stained target cells were visualized easily by the bare eye and an optical microscope, and the cells were quantitatively analyzed using stripping voltammetry. The parameters affecting the analytical response were optimized. The proposed sensor was capable of differentiating between HER2-positive breast cancer cells and HER2-negative cells. This method exhibited an excellent diagnosis method for the ultrasensitive detection of SK-BR-3 breast cancer cells in human serum samples with a detection limit of 26 cells/mL.

Detection of circulating cancer cells using electrocatalytic gold nanoparticles

A rapid cancer cell detection and quantification assay, based on the electrocatalytic properties of gold nanoparticles towards the hydrogen evolution reaction, is described. The selective labeling of cancer cells is performed in suspension, allowing a fast interaction between the gold nanoparticle labels and the target proteins expressed at the cell membrane. The subsequent electrochemical detection is accomplished with small volumes of sample and user-friendly equipment through a simple electrochemical method that generates a fast electrochemical response used for the quantification of nanoparticle-labeled cancer cells. The system establishes a selective cell-detection assay capable of detecting 4 × 10(3) cancer cells in suspension that can be extended to several other cells detection scenarios.

Simple monitoring of cancer cells using nanoparticles

Here we present a new strategy for a simple and fast detection of cancer circulating cells (CTCs) using nanoparticles. The human colon adenocarcinoma cell line (Caco2) was chosen as a model CTC. Similarly to other adenocarcinomas, colon adenocarcinoma cells have a strong expression of EpCAM, and for this reason this glycoprotein was used as the capture target. We combine the capturing capability of anti-EpCAM functionalized magnetic beads (MBs) and the specific labeling through antibody-modified gold nanoparticles (AuNPs), with the sensitivity of the AuNPs-electrocatalyzed hydrogen evolution reaction (HER) detection technique. The fully optimized process was used for the electrochemical detection of Caco2 cells in the presence of monocytes (THP-1), other circulating cells that could interfere in real blood samples. Therefore we obtained a novel and simple in situ-like sensing format that we applied for the rapid quantification of AuNPs-labeled CTCs in the presence of other human cells.

Conjugated polymer and gold nanoparticle co-loaded PLGA nanocomposites with eccentric internal nanostructure for dual-modal targeted cellular imaging

Herein is reported the one-step synthesis of an integrated nanocomposite with eccentrically loaded 5 nm gold nanoparticles (Au NPs) and conjugated polymer of poly[9,9-bis(6'-N,N,N-trimethylammonium)hexyl)fluorenyldivinylene-alt-4,7-(2,1,3,- benzothiadiazole) dibromide] (PFVBT). The nanocomposite is generated with surface-functionalized folic acid groups due to the matrix polymer of PLGA-PEG(2000) -folate used for encapsulation. The nanocomposite shows far-red fluorescence from PFVBT and scattering signal from Au NPs. Although Au NPs have been widely reported to quench the fluorescence of conjugated polymers, the PFVBT fluorescence is well maintained in the nanocomposite due to the eccentric location of Au NPs. The folic acid groups at the nanocomposite surface favor its cellular uptake by MCF-7 breast cancer cells, which have overexpressed folate receptors on the cell membranes. In conjugation with its low cytotoxicity, the folic-acid-functionalized nanocomposite has been successfully utilized for fluorescence and dark-field dual-modal targeted cellular imaging.

Aptamer-based polymerase chain reaction for ultrasensitive cell detection

A new system was developed for sensitive and selective detection of tumor cells taking advantage of cell-attached aptamers amplified by PCR and output signals amplified by cationic conjugated polymers.

Cell delivery of therapeutic nanoparticles

Nanomedicine seeks to manufacture drugs and other biologically relevant molecules that are packaged into nanoscale systems for improved delivery. This includes known drugs, proteins, enzymes, and antibodies that have limited clinical efficacy based on delivery, circulating half-lives, or toxicity profiles. The <100 nm nanoscale physical properties afford them a unique biologic potential for biomedical applications. Hence they are attractive systems for treatment of cancer, heart and lung, blood, inflammatory, and infectious diseases. Proposed clinical applications include tissue regeneration, cochlear and retinal implants, cartilage and joint repair, skin regeneration, antimicrobial therapy, correction of metabolic disorders, and targeted drug delivery to diseased sites including the central nervous system. The potential for cell and immune side effects has necessitated new methods for determining formulation toxicities. To realize the potential of nanomedicine from the bench to the patient bedside, our laboratories have embarked on developing cell-based carriage of drug nanoparticles to improve clinical outcomes in infectious and degenerative diseases. The past half decade has seen the development and use of cells of mononuclear phagocyte lineage, including dendritic cells, monocytes, and macrophages, as Trojan horses for carriage of anti-inflammatory and anti-infective medicines. The promise of this new technology and the perils in translating it for clinical use are developed and discussed in this chapter.