Simultaneous enhancement of photothermal stability and gene delivery efficacy of gold nanorods using polyelectrolytes

Metal-based nanoparticle in cancer treatment: lessons learned and challenges

Cancer, being one of the deadliest diseases, poses significant challenges despite the existence of traditional treatment approaches. This has led to a growing demand for innovative pharmaceutical agents that specifically target cancer cells for effective treatment. In recent years, the use of metal nanoparticles (NPs) as a promising alternative to conventional therapies has gained prominence in cancer research. Metal NPs exhibit unique properties that hold tremendous potential for various applications in cancer treatment. Studies have demonstrated that certain metals possess inherent or acquired anticancer capabilities through their surfaces. These properties make metal NPs an attractive focus for therapeutic development. In this review, we will investigate the applicability of several distinct classes of metal NPs for tumor targeting in cancer treatment. These classes may include gold, silver, iron oxide, and other metals with unique properties that can be exploited for therapeutic purposes. Additionally, we will provide a comprehensive summary of the risk factors associated with the therapeutic application of metal NPs. Understanding and addressing these factors will be crucial for successful clinical translation and to mitigate any potential challenges or failures in the translation of metal NP-based therapies. By exploring the therapeutic potential of metal NPs and identifying the associated risk factors, this review aims to contribute to the advancement of cancer treatment strategies. The anticipated outcome of this review is to provide valuable insights and pave the way for the advancement of effective and targeted therapies utilizing metal NPs specifically for cancer patients.

Bioactive nanomaterials kickstart early repair processes and potentiate temporally modulated healing of healthy and diabetic wounds

Slow-healing and chronic wounds represent a major global economic and medical burden, and there is significant unmet need for novel therapies which act to both accelerate wound closure and enhance biomechanical recovery of the skin. Here, we report a new approach in which bioactives that augment early stages of wound healing can kickstart and engender effective wound closure in healthy and diabetic, obese animals, and set the stage for subsequent tissue repair processes. We demonstrate that a nanomaterial dressing made of silk fibroin and gold nanorods (GNR) stimulates a pro-neutrophilic, innate immune, and controlled inflammatory wound transcriptomic response. Further, Silk-GNR, lasered into the wound bed, in combination with exogeneous histamine, accelerates early-stage processes in tissue repair leading to effective wound closure. Silk-GNR and histamine enhanced biomechanical recovery of skin, increased transient neoangiogenesis, myofibroblast activation, epithelial-to-mesenchymal transition (EMT) of keratinocytes and a pro-resolving neutrophilic immune response, which are hitherto unknown activities for these bioactives. Predictive and temporally coordinated delivery of growth factor nanoparticles that modulate later stages of tissue repair further accelerated wound closure in healthy and diabetic, obese animals. Our approach of kickstarting healing by delivering the "right bioactive at the right time" stimulates a multifactorial, pro-reparative response by augmenting endogenous healing and immunoregulatory mechanisms and highlights new targets to promote tissue repair.

Gold nanobipyramids-based laser-activated sealants for effective skin sealing and repair

Anisotropic gold nanostructures have gained increased attention for biomedical applications because of their remarkable optical properties. An emerging type of gold nanostructure-gold nanobipyramids (AuNBP)-has been shown to exhibit superior absorption properties compared to conventionally used gold nanoparticles, which makes them attractive for photothermal applications. We generated a high-shape-purity dispersion of AuNBP using a seed-mediated method and embedded them as photothermal conversion agents in a silk fibroin matrix to investigate their efficacy in photothermal sealing of incisional wounds in immunocompetent mice. These AuNBP-doped laser-activated sealants, or AuNBP-LASE were able to absorb near-infrared laser energy and convert it to heat, thereby inducing transient hyperthermia in the wound and the surrounding tissue. This photothermal conversion facilitated rapid sealing of the skin tissue by the AuNBP-LASE, which resulted in faster functional recovery of skin barrier function compared to nylon sutures at the early stages of repair. Further, the biomechanical properties of the healing skin closed with AuNBP-LASE those of intact skin more rapidly compared to incisions approximated with sutures. Histology studies indicated higher penetration of the LASE within the volume of the incision in skin tissue, lower scab formation, and a similar epidermal gap compared to conventional suturing. These results demonstrate that AuNBP-LASEs can be effective as wound approximation devices for photothermal sealing.

Thermal Effect during Laser-Induced Plasmonic Heating of Polyelectrolyte-Coated Gold Nanorods in Well Plates

We examined the generation and transfer of heat when laser irradiation is applied to water containing a suspension of gold nanorods coated with different polyelectrolytes. The ubiquitous well plate was used as the geometry for these studies. The predictions of a finite element model were compared to experimental measurements. It is found that relatively high fluences must be applied in order to generate biologically relevant changes in temperature. This is due to the significant lateral heat transfer from the sides of the well, which strongly limits the temperature that can be achieved. A 650 mW continuous-wave (CW) laser, with a wavelength that is similar to the longitudinal plasmon resonance peak of the gold nanorods, can deliver heat with an overall efficiency of up to 3%. This is double the efficiency achievable without the nanorods. An increase in temperature of up to 15 °C can be achieved, which is suitable for the induction of cell death by hyperthermia. The nature of the polymer coating on the surface of the gold nanorods is found to have a small effect.

Gold nanorods/tetrahedral DNA composites for chemo-photothermal therapy

Combination therapy is extensively developed for cancer treatment in recent years due to its high efficiency. Herein, we constructed a nanocomposite based on gold nanorods (GNRs) and drug-loaded tetrahedral DNA nanostructures (TDN) for chemo-photothermal combinational therapy. Anti-tumor drug doxorubicin (DOX) was loaded via the insertion within GC base pairs of TDN. The aptamer AS1411 was attached to the apex of TDN (ATDN) to target tumor cells. The DOX-loaded DNA tetrahedron (ATDN-DOX) was compressed by the GNRs coated with PEI (GNRs@ATDN-DOX) to realize the photothermal function and lysosome escape. GNRs under the illumination of 808 nm infrared laser showed high photothermal conversion and stability due to the protection of PEI layer. The drug-loading capacity of ATDN-DOX was as high as 314 DOX molecules in per ATDN. The positive charge of PEI in GNRs@ATDN-DOX nanocomposites was utilized to achieve excellent cell penetration and induce proton sponge effect for lysosomal escape. The nanocomposites presented HeLa and 4T1 cells targeting and resulted in efficient anticancer activity.

Nanoparticle-assisted, image-guided laser interstitial thermal therapy for cancer treatment

Laser interstitial thermal therapy (LITT) guided by magnetic resonance imaging (MRI) is a new treatment option for patients with brain and non-central nervous system (non-CNS) tumors. MRI guidance allows for precise placement of optical fiber in the tumor, while MR thermometry provides real-time monitoring and assessment of thermal doses during the procedure. Despite promising clinical results, LITT complications relating to brain tumor procedures, such as hemorrhage, edema, seizures, and thermal injury to nearby healthy tissues, remain a significant concern. To address these complications, nanoparticles offer unique prospects for precise interstitial hyperthermia applications that increase heat transport within the tumor while reducing thermal impacts on neighboring healthy tissues. Furthermore, nanoparticles permit the co-delivery of therapeutic compounds that not only synergize with LITT, but can also improve overall effectiveness and safety. In addition, efficient heat-generating nanoparticles with unique optical properties can enhance LITT treatments through improved real-time imaging and thermal sensing. This review will focus on (1) types of inorganic and organic nanoparticles for LITT; (2) in vitro, in silico, and ex vivo studies that investigate nanoparticles' effect on light-tissue interactions; and (3) the role of nanoparticle formulations in advancing clinically relevant image-guided technologies for LITT. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease Implantable Materials and Surgical Technologies > Nanoscale Tools and Techniques in Surgery.

Characterization of Gold Nanorods Conjugated with Synthetic Glycopolymers Using an Analytical Approach Based on spICP-SFMS and EAF4-MALS

A new comprehensive analytical approach based on single-particle inductively coupled plasma-sector field mass spectrometry (spICP-SFMS) and electrical asymmetric-flow field-flow-fractionation combined with multi-angle light scattering detection (EAF4-MALS) has been examined for the characterization of galactosamine-terminated poly(N-hydroxyethyl acrylamide)-coated gold nanorods (GNRs) in two different degrees of polymerization (DP) by tuning the feed ratio (short: DP 35; long: DP 60). spICP-SFMS provided information on the particle number concentration, size and size distribution of the GNRs, and was found to be useful as an orthogonal method for fast characterization of GNRs. Glycoconjugated GNRs were separated and characterized via EAF4-MALS in terms of their size and charge and compared to the bare GNRs. In contrast to spICP-SFMS, EAF4-MALS was also able of providing an estimate of the thickness of the glycopolymer coating on the GNRs surface.

Improvements in Gold Nanorod Biocompatibility with Sodium Dodecyl Sulfate Stabilization

Due to their well-defined plasmonic properties, gold nanorods (GNRs) can be fabricated with optimal light absorption in the near-infrared region of the electromagnetic spectrum, which make them suitable for cancer-related theranostic applications. However, their controversial safety profile, as a result of surfactant stabilization during synthesis, limits their clinical translation. We report a facile method to improve GNR biocompatibility through the presence of sodium dodecyl sulfate (SDS). GNRs (120 × 40 nm) were synthesized through a seed-mediated approach, using cetyltrimethylammonium bromide (CTAB) as a cationic surfactant to direct the growth of nanorods and stabilize the particles. Post-synthesis, SDS was used as an exchange ligand to modify the net surface charge of the particles from positive to negative while maintaining rod stability in an aqueous environment. GNR cytotoxic effects, as well as the mechanisms of their cellular uptake, were examined in two different cancer cell lines, Lewis lung carcinoma (LLC) and HeLa cells. We not only found a significant dose-dependent effect of GNR treatment on cell viability but also a time-dependent effect of GNR surfactant charge on cytotoxicity over the two cell lines. Our results promote a better understanding of how we can mediate the undesired consequences of GNR synthesis byproducts when exposed to a living organism, which so far has limited GNR use in cancer theranostics.

Multifunctional Gold Nanorod for Therapeutic Applications and Pharmaceutical Delivery Considering Cellular Metabolic Responses, Oxidative Stress and Cellular Longevity

Multifunctional gold nanorods (GNR) have drawn growing interest in biomedical fields because of their excellent biocompatibility, ease of alteration, and special optical properties. The great advantage of using GNR in medicine is their application to Photothermal therapy (PPTT), which is possible thanks to their ability to turn luminous energy into heat to cause cellular hyperthermia. For this purpose, the relevant articles between 1988 and 2020 were searched in databases such as John Wiley, Free paper, Scopus, Science Direct, and Springer to obtain the latest findings on multifunctional gold nanorods for therapeutic applications and pharmaceutical delivery. In this article, we review recent progress in diagnostic and therapeutic applications of multifunctional GNR, highlighting new information about their toxicity to various cellular categories, oxidative stress, cellular longevity, and their metabolic effects, such as the effect on the energy cycles and genetic structures. The methods for the synthesis and functionalization of GNR were surveyed. This review includes new information about GNR toxicity to various cellular categories and their metabolic effects.

Toxicity of gold nanorods on Ceriodaphnia dubia and Danio rerio after sub-lethal exposure and recovery

Gold nanorods (AuNRs) are rod-shaped nanoparticles (NPs) with special optical properties that allow their application in several areas including photothermal therapy, diagnosis, drug and gene delivery, cellular imaging, and biosensors. Their high potential for many applications increases the possibility of release in aquatic environments, which can cause risks to organisms. In this study, we evaluated toxic effects of AuNRs on cladoceran and fish (Ceriodaphnia dubia and Danio rerio) and their recovery after post-exposure periods. The EC₅₀ of 0.03 mg L^-1 was found for C. dubia in the acute exposure. There was a significant decrease in the number of neonates produced and in the filtration rate of C. dubia after sub-lethal exposure to AuNRs. The toxic mechanism of these NPs to cladocerans was attributed to increases in the reactive oxygen species (ROS) generation. After 4 h of recovery in clean medium, C. dubia were able to reestablish the filtration rate. Enzymatic biomarkers for D. rerio showed significant increases in the activity of superoxide dismutase, catalase, and lipid peroxidation after sub-lethal exposure to AuNRs. These biomarkers were recovered after 168 h in clean water. These results are pivotal on the comprehension of AuNR toxicity to aquatic organisms and are useful in assessing this novel nanomaterial impacts on aquatic biota.

Evaluating Phospholipid-Functionalized Gold Nanorods for In Vivo Applications

Gold nanorods (AuNRs) have attracted a great deal of attention due to their potential for use in a wide range of biomedical applications. However, their production typically requires the use of the relatively toxic cationic surfactant cetyltrimethylammonium bromide (CTAB) leading to continued demand for protocols to detoxify them for in vivo applications. In this study, a robust and facile protocol for the displacement of CTAB from the surface of AuNRs using phospholipids is presented. After the displacement, CTAB is not detectable by NMR spectroscopy, surface-enhanced Raman spectroscopy, or using pH-dependent ζ-potential measurements. The phospholipid functionalized AuNRs demonstrated superior stability and biocompatibility (IC₅₀  > 200 µg mL^-1 ) compared to both CTAB and polyelectrolyte functionalized AuNRs and are well tolerated in vivo. Furthermore, they have high near-infrared (NIR) absorbance and produce large amounts of heat under NIR illumination, hence such particles are well suited for plasmonic medical applications.

Laser-induced optothermal response of gold nanoparticles: From a physical viewpoint to cancer treatment application

Gold nanoparticles (GNPs)-based photothermal therapy (PTT) is a promising minimally invasive thermal therapy for the treatment of focal malignancies. Although GNPs-based PTT has been known for over two decades and GNPs possess unique properties as therapeutic agents, the delivery of a safe and effective therapy is still an open question. This review aims at providing relevant and recent information on the usage of GNPs in combination with the laser to treat cancers, pointing out the practical aspects that bear on the therapy outcome. Emphasis is given to the assessment of the GNPs' properties and the physical mechanisms underlying the laser-induced heat generation in GNPs-loaded tissues. The main techniques available for temperature measurement and the current theoretical simulation approaches predicting the therapeutic outcome are reviewed. Topical challenges in delivering safe thermal dosage are also presented with the aim to discuss the state-of-the-art and the future perspective in the field of GNPs-mediated PTT.

Photostability of Contrast Agents for Photoacoustics: The Case of Gold Nanorods

Plasmonic particles as gold nanorods have emerged as powerful contrast agents for critical applications as the photoacoustic imaging and photothermal ablation of cancer. However, their unique efficiency of photothermal conversion may turn into a practical disadvantage, and expose them to the risk of overheating and irreversible photodamage. Here, we outline the main ideas behind the technology of photoacoustic imaging and the use of relevant contrast agents, with a main focus on gold nanorods. We delve into the processes of premelting and reshaping of gold nanorods under illumination with optical pulses of a typical duration in the order of few ns, and we present different approaches to mitigate this issue. We undertake a retrospective classification of such approaches according to their underlying, often implicit, principles as: constraining the initial shape; or speeding up their thermal coupling to the environment by lowering their interfacial thermal resistance; or redistributing the input energy among more particles. We discuss advantages, disadvantages and contexts of practical interest where one solution may be more appropriate than the other.

Gold Nanoparticles for Vectorization of Nucleic Acids for Cancer Therapeutics

Cancer remains a complex medical challenge and one of the leading causes of death worldwide. Nanomedicines have been proposed as innovative platforms to tackle these complex diseases, where the combination of several treatment strategies might enhance therapy success. Among these nanomedicines, nanoparticle mediated delivery of nucleic acids has been put forward as key instrument to modulate gene expression, be it targeted gene silencing, interference RNA mechanisms and/or gene edition. These novel delivery systems have strongly relied on nanoparticles and, in particular, gold nanoparticles (AuNPs) have paved the way for efficient delivery systems due to the possibility to fine-tune their size, shape and surface properties, coupled to the ease of functionalization with different biomolecules. Herein, we shall address the different molecular tools for modulation of expression of oncogenes and tumor suppressor genes and discuss the state-of-the-art of AuNP functionalization for nucleic acid delivery both in vitro and in vivo models. Furthermore, we shall highlight the clinical applications of these spherical AuNP based conjugates for gene delivery, current challenges, and future perspectives in nanomedicine.

Stimuli-responsive nanoparticle-assisted immunotherapy: a new weapon against solid tumours

The interplay between photo-thermal therapy and immunotherapy allows the realization of new nanotechnology-based cancer treatments for solid tumors.

Photothermal effects of NaYF4:Yb,Er@PE3@Fe3O4 superparamagnetic nanoprobes in the treatment of melanoma

Objective: The study aimed to synthesize superparamagnetic NaYF₄:Yb,Er@PE₃@Fe₃O₄ upconversion nanoprobes and to study their photothermal effects for the treatment of malignant melanoma.

Methods: Morphological characteristics of the synthesized nanoprobes were examined by scanning electron microscopy. Their biocompatibility and biodistribution profiles were assessed through blood routine/biochemistry tests and the inductively coupled plasma/optical emission spectrometry-based analysis of tissue metal elements. Their photothermal conversion efficiency and their potential as contrast agents for upconversion luminescence (UCL)/magnetic resonance imaging (MRI) dual-modal imaging were tested. Efficacy in photothermal therapy, which was achieved by combining nanoprobes with near-infrared (NIR) irradiation, was evaluated in both A375 cell line and BALB/c mice models. The underlying mechanisms were interrogated by molecular approaches including the MTT assay, flow cytometry, semiquantitative PCR, western blot, and immunohistochemistry.

Results: 1) Our synthesized NaYF₄:Yb,Er@PE₃@Fe₃O₄ nanoprobes exhibited a uniform cubic morphology with a diameter of ~50 nm. Subcutaneous administration led to no severe, long-lasting adverse effects in mice, possibly due to complete removal of these nanomaterials within one month. 2) Our nanoprobes possessed superior photothermal conversion efficiency and strong contrasting effects during UCL/MRI dual-modal imaging, corroborating their applications in imaging-guided photothermal therapy. 3) Combinatorial treatment of these nanoprobes with NIR irradiation induced profound apoptosis/necrosis in A375 cells. Similarly, the same treatment modality led to strong therapeutic effects in BALB/c mice implanted with A375 tumor xenografts. Mechanistic studies suggested an involvement of heat shock protein 70 in mediating the observed antitumor effects of our nanoprobes.

Conclusion: Our study describes a convenient method to synthesize a new type of superparamagnetic upconversion nanoprobes, which possess high biocompatibility and can be used in imaging-guided photothermal therapy for the treatment of malignant melanoma. Importantly, our findings will promote clinical applications of NaYF₄:Yb,Er@PE₃@Fe₃O₄ as novel theranostic agents in treating melanoma and many other tumors.

Light-Activated Tissue-Integrating Sutures as Surgical Nanodevices

Sutures are typically the primary means of soft tissue repair in surgery and trauma. Despite their widespread use, sutures do not result in immediate sealing of approximated tissues, which can result in bacterial infection and leakage. Nonabsorbable sutures and staples can be traumatic to tissue, and the trauma can be exacerbated by their subsequent removal. Use of cyanoacrylate glues is limited because of their brittleness and toxicity. In this work, laser-activated tissue-integrating sutures (LATIS) are described as novel nanodevices for soft tissue approximation and repair. Incorporation of gold nanorods within fibers generated from collagen result in LATIS fibers which demonstrate robust photothermal responses following irradiation with near infrared laser light. Compared to conventional sutures, LATIS fibers result in greater biomechanical recovery of incised skin in a mouse model of skin closure after spine surgeries. Histopathology analyses show improved repair of the epidermal gap in skin, which indicate faster tissue recovery using LATIS. The studies indicate that LATIS-facilitated approximation of skin in live mice synergizes the benefits of conventional suturing and laser-activated tissue integration, resulting in new approaches for faster sealing, tissue repair, and healing.

A health concern regarding the protein corona, aggregation and disaggregation

Nanoparticle (NP)-protein complexes exhibit the "correct identity" of NP in biological media. Therefore, protein-NP interactions should be closely explored to understand and modulate the nature of NPs in medical implementations. This review focuses mainly on the physicochemical parameters such as dimension, surface chemistry, morphology of NPs, and influence of pH on the formation of protein corona and conformational changes of adsorbed proteins by different kinds of techniques. Also, the impact of protein corona on the colloidal stability of NPs is discussed. Uncontrolled protein attachment on NPs may bring unwanted impacts such as protein denaturation and aggregation. In contrast, controlled protein adsorption by optimal concentration, size, pH, and surface modification of NPs may result in potential implementation of NPs as therapeutic agents especially for disaggregation of amyloid fibrils. Also, the effect of NPs-protein corona on reducing the cytotoxicity and clinical implications such as drug delivery, cancer therapy, imaging and diagnosis will be discussed. Validated correlative physicochemical parameters for NP-protein corona formation frequently derived from protein corona fingerprints of NPs which are more valid than the parameters obtained only on the base of NP features. This review may provide useful information regarding the potency as well as the adverse effects of NPs to predict their behavior in vivo.

Polypyrrole-coated phase-change liquid perfluorocarbon nanoparticles for the visualized photothermal-chemotherapy of breast cancer

A theranostic nanoplatform (DTX/PFH@PPy-FA) for multi-modal imaging-guided photothermal-chemotherapy has been constructed. Lipid-perfluorohexane (PFH) nanodroplet loaded with docetaxel (DTX) was coated with a polypyrrole (PPy) shell. Then the folic acid (FA) molecule with active tumor-targeting function was modified on the surface of PPy shell. Due to the good photothermal conversion performance, PPy shell can raise the temperature under the near infrared laser irradiation, which not only produces photothermal effect to kill tumor cells, but also promotes liquid-gas phase change of PFH, and produces ultrasound imaging effect. The results of photothermal experiment and imaging experiment confirmed that the obtained DTX/PFH@PPy-FA possessed good photothermal, photoacoustic imaging and ultrasound imaging effects in vitro and in vivo. The results of in vitro cell experiments showed that DTX/PFH@PPy-FA had a active targeting ability to tumor cells, and its photothermal-chemotherapy synergistically inhibited the proliferation of tumor cells. In vivo study on 4T1-bearing BALB/c mice indicated that the photothermal-chemotherapy of DTX/PFH@PPy-FA not only effectively inhibited the growth of 4T1 breast cancer, but also inhibited lung metastasis. This multifunctional nanoparticle is expected to become a new nanoplatform for the visualized photothermal-chemotherapy of cancer. STATEMENT OF SIGNIFICANCE: In this work, we presented a multi-modal imaging-guided photothermal-chemotherapy theranostic nanoplatform (DTX/PFH@PPy-FA) for visualized treatment of breast cancer. The docetaxel (DTX) loaded perfluorohexane (PFH) nanodroplets (DTX/PFH@SPC) were firstly prepared and then coated with polypyrrole shell (PPy). Then, PEGylated folic acid was covalently modified to obtain the folate-targeted multifunctional nanoparticle (DTX/PFH@PPy-FA). Due to the good photothermal conversion performance, PPy shell can raise the temperature under the near infrared laser irradiation, which not only produces photothermal effect to kill tumor cells, but also promotes liquid-gas phase change of PFH, and produces good ultrasound imaging effect. The PPy shell also imparts photoacoustic imaging characteristics to the nanoparticles. Experimental results show that our prepared DTX/PFH@PPy-FA possesses folic acid-mediated tumor targeting ability, ultrasound and photoacoustic imaging, and photothermal-chemotherapy synergistic effect. This multi-functional nanoparticle is expected to become a new platform for the visualized photothermal-chemotherapy of breast cancer.

Concurrent photothermal therapy and photodynamic therapy for cutaneous squamous cell carcinoma by gold nanoclusters under a single NIR laser irradiation

The concurrent photothermal and photodynamic therapy of cutaneous squamous cell carcinoma by a single drug of Au₂₅(Capt)₁₈nanoclusters is demonstrated, together with a preliminary immune response study conducted under a single NIR laser irradiation.

Counterion coupled (COCO) gemini surfactant capped Ag/Au alloy and core–shell nanoparticles for cancer therapy

In this work hybrid silver (Ag)–gold (Au) nanoparticles (NPs) with different sizes and compositions were synthesized and applied for anticancer evaluations and which is effectively involved in cancer cell apoptosis through DNA damage.

Bioreducible Poly(Amino Ethers) Based mTOR siRNA Delivery for Lung Cancer

PURPOSE

Lung cancer is one of the leading causes of deaths in the United States, but currently available therapies for lung cancer are associated with reduced efficacy and adverse side effects. Small interfering RNA (siRNA) can knock down the expression of specific genes and result in therapeutic efficacy in lung cancer. Recently, mTOR siRNA has been shown to induce apoptosis in NSCLC cell lines but its use is limited due to poor stability in biological conditions.

METHODS

In this study, we modified an aminoglyocisde-derived cationic poly (amino-ether) by introducing a thiol group using Traut's reagent to generate a bio-reducible modified-poly (amino-ether) (mPAE). The mPAE polymer was used to encapsulate mTOR siRNA by nanoprecipitation method, resulting in the formation of stable and bio-reducible nanoparticles (NPs) which possessed an average diameter of 114 nm and a surface charge of approximately +27 mV.

RESULTS

The mTOR siRNA showed increased release from the mTS-mPAE NPs in the presence of 10 mM glutathione (GSH). The polymeric mTS-mPAE-NPs were also capable of efficient gene knockdown (60 and 64%) in A549 and H460 lung cancer cells, respectively without significant cytotoxicity at 30 μg/ml concentrations. The NPs also showed time-dependent cellular uptake for up to 24 h as determined using flow cytometry. Delivery of the siRNA using these NPs also resulted in significant inhibition of A549 and H460 cell proliferation in vitro, respectively.

CONCLUSIONS

The results demonstrate that the mPAE polymer based NPs show strong potential for siRNA delivery to lung cancer cells. It is anticipated that future modification can help improve the efficacy of nucleic acid delivery, leading to higher inhibition of lung cancer growth in vitro and in vivo.

Tightly bound polyelectrolytes enhance enzyme proteolysis and destroy amyloid aggregates

The use of polyelectrolytes is a prospective approach to form nanocomplexes to transport different compounds including proteins. In many cases, the bound protein should be digested after delivery to the target. In the present work, we studied proteolysis of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in the complexes with polyelectrolytes. We have found polyanions to enhance the proteolytic degradation of GAPDH by proteinase K and thermolysin. This effect seems to be caused by destabilization of the protein structure. However, this destabilization is reversible since the release of the enzyme from the complexes with polymers (even tightly bound with the protein such as sulfated polymers and supercharged pyridinium polycations) was accompanied by partial or complete reactivation of GAPDH, depending on the polymers and conditions. Finally, we observed that complexation with sulfated polymers enhances the proteolytic degradation of prion fibrils by proteinase K. The obtained results can be useful for treatment of pathologies associated with amyloid aggregation.

Compact Plasmonic Blackbody for Cancer Theranosis in the Near-Infrared II Window

We have developed a class of blackbody materials, i. e., hyperbranched Au plasmonic blackbodies (AuPBs), of compact sizes (<50 nm). The AuPBs were prepared in a seedless and surfactant-free approach based on the use of mussel-inspired dopamine. Strong intraparticle plasmonic coupling among branches in close proximity leads to intense and uniform broadband absorption across 400-1350 nm. The blackbody absorption imparts the compact AuPB with a superior photothermal efficiency of >80% and closely matched photothermal activity in the first near-infrared (NIR-I) and the second near-infrared (NIR-II) spectral windows, making it a rare broadband theranostic probe for integrated photoacoustic imaging and photothermal therapy (PTT). Our comparative study, using the same probe, has demonstrated that the improved PTT outcome of NIR-II over NIR-I primarily results from its higher maximum permission exposure (MPE) rather than the deeper tissue penetration favored by longer wavelengths. The compact plasmonic broadband nanoabsorbers with tailored surface properties hold potential for a wide spectrum of light-mediated applications.

Facile preparation of biocompatible Ti2O3 nanoparticles for second near-infrared window photothermal therapy

NIR-II photothermal therapy (PTT) agents of Ti₂O₃ nanoparticles have been developed.

Non-viral Gene Delivery

Although viral vectors comprise the majority of gene delivery vectors, their various safety, production, and other practical concerns have left a research gap to be addressed. The non-viral vector space encompasses a growing variety of physical and chemical methods capable of gene delivery into the nuclei of target cells. Major physical methods described in this chapter are microinjection, electroporation, and ballistic injection, magnetofection, sonoporation, optical transfection, and localized hyperthermia. Major chemical methods described in this chapter are lipofection, polyfection, gold complexation, and carbon-based methods. Combination approaches to improve transfection efficiency or reduce immunological response have shown great promise in expanding the scope of non-viral gene delivery.

Stable and Biocompatible Mushroom β-Glucan Modified Gold Nanorods for Cancer Photothermal Therapy

Naturally occurring β-glucans have been widely regarded as a natural source for functional foods and pharmaceuticals due to their immunomodulatory property and antitumor activity. However, physicochemically stable and biocompatible β-glucans are rarely explored as a carrier for nanomaterials to overcome the problems of aggregation and nanotoxicity. Here, we developed highly stable and biocompatible mushroom β-glucan coated gold nanorods (AuNR-Glu) for cancer photothermal therapy by integrating Pleurotus tuber-regium sclerotial β-glucan (Glu) and plasmonic gold nanorods (AuNRs) possessing photothermal property in the second near-infrared (NIR-II) window. AuNR-Glu showed high colloidal stability in various biological media, even in simulated gastric fluid. Moreover, AuNR-Glu had low cytotoxicity and high photothermal stability, which are excellent characteristics for photothermal agents for cancer therapy. In vitro experiments showed that AuNR-Glu nanohybrid was effective against MCF-7 (only 4.5 ± 0.9% viability) at a low dose of 20 μg/mL under NIR-II at a safe laser power density (0.75 W/cm²). Natural mushroom β-glucans are potential functional polymers that can be used to fabricate nanohybrids for biomedical applications.

Multifunctional gold nanorods and docetaxel-encapsulated liposomes for combined thermo- and chemotherapy

Personalized and precise nanomedicines are highly demanded for today’s medical needs. Liposomes are ideal candidates for the construction of multifunctional drug delivery systems. In this study, a liposome was used to improve the clinical issues of docetaxel (Doc), a potent antimitotic chemotherapy for prostate cancer (PC). RLT, a low-density lipoprotein receptor (LDLR)-binding peptide, and PEG were conjugated to the liposomes, and gold nanorods (GNRs) were also incorporated into the liposomes. The GNRs/Doc-liposome-RLT (GNRs/DocL-R) was tested in PC-3 cells and in PC-3 tumor-bearing nude mice. Results showed that GNRs/DocL-R possessed a diameter approximately 163.15±1.83 nm and a zeta potential approximately −32.8±2.16 mV. GNRs/DocL-R showed enhanced intracellular entrance, increased accumulation in the implanted tumor region, and the highest tumor inhibition in vitro and in vivo. Therefore, the multifunctional GNRs/DocL-R was a potential cancer treatment via combined chemo- and thermotherapy.

Surface chemistry for cytosolic gene delivery and photothermal transgene expression by gold nanorods

Light-inducible gene regulation has great potential for remote and noninvasive control of the fate and function of target cells. One method to achieve such control is delivery of heat shock protein (HSP) promoter-driven protein expression vectors and photothermal heaters into the cells, followed by activation by illumination. In this study, we show that gold nanorods (AuNRs) functionalized with two conventional lipids, oleate and 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), are capable of efficient transfection and quick photoactivation of the HSP promoter. Use of our AuNRs (DOTAP-AuNRs) was comparable to Lipofectamine 2000 in terms of transfection efficiency, while lower in cytotoxicity. Subsequent near-infrared laser (NIR) illumination of the cells transfected by DOTAP-AuNRs for 10 s induced time- and site-specific transgene expression without significant phototoxicity, to a degree similar to that of heating the entire culture dish for 30 min. Our mechanistic studies suggest that efficient transfection and quick photoactivation of the HSP promoter (HSP70b’) are due to the promoted endosomal escape of DOTAP-AuNRs. We propose a novel protocol for NIR-inducible, site-directed gene expression using an unprecedented complex of the three conventional components capable of both transfection and photothermal heating.

Gold nanocages decorated biocompatible amine functionalized graphene as an efficient dopamine sensor platform

Nanocomposite of gold nanocages and chemically modified graphene oxide (GNCs/CMG) was synthesized in N,N-dimethylformamide (DMF) for sensitive detection of dopamine (DA). DA is widely spread in central nervous system which can regulates essential body functions like movement and emotional behaviour. In this regard sensitive and fast detection of DA level in human body is still challenging considering its interference with other biomolecules in biological samples. CMG was synthesized through amine modification of graphene oxide (GO) with DMF at relatively high temperature followed by attachment of GNCs, fabricated using a galvanic replacement between silver nanocubes and HAuCl₄ solution in the DMF. X-ray diffraction (XRD) pattern of GNCs/CMG nanocomposite revealed high crystallization of GNCs attached to the graphene nanosheets and microscopic images revealed relatively uniform decoration of GNCs on the surface of CMG. Nanocomposite modified glassy carbon electrode (GNCs/CMG/GCE) was used to investigate the electrochemical behaviour of DA with cyclic voltammetry and amperometry techniques. The linear range for dopamine was between 0.1 and 80μM with a low detection limit of 0.02μM. Furthermore, GNCs/CMG/GCE exhibited satisfying reproducibility, long-term stability and high selectivity for DA detection in large amount of ascorbic acid with good results for determination in human serum samples.

Gadolinium oxysulfide-coated gold nanorods with improved stability and dual-modal magnetic resonance/photoacoustic imaging contrast enhancement for cancer theranostics

Gold nanorods (GNRs) are emerging as a promising nanoplatform for cancer theranostics because of their unique optical properties. However, they still suffer from many limitations, such as high cytotoxicity, low thermodynamic and biological stability, and a tedious process for integrating other imaging modalities, for further practical biomedical applications. In this work, a strategy by one-step coating of Gd₂O₂S around GNRs is reported to address these limitations of GNRs. After the coating of the Gd₂O₂S shell, the as-fabricated Gd₂O₂S coated GNRs (GNRs@Gd₂O₂S) show enhanced biocompatibility and photostability, and tunable localized surface plasmon resonance. The strong absorption in the near-infrared region renders GNRs@Gd₂O₂S outstanding photoacoustic imaging and photothermal therapy capabilities. Moreover, owing to the T₁ shortening ability of Gd₂O₂S, the GNRs@Gd₂O₂S also show an excellent T₁ MRI contrast performance. The GNRs@Gd₂O₂S thus can serve as a versatile nanoplatform for cancer theranostics combining dual-modal imaging and photothermal therapy.

Enhancing the photothermal stability and photothermal efficacy of AuNRs and AuNTs by grafting with Ru(ii) complexes

In this paper, we found that the ruthenium complex-functionalized AuNRs (AuNRs@Ru) and AuNTs (AuNTs@Ru) exhibited better photothermal stability and higher photothermal efficiency than AuNRs and AuNTs.In vivotumor model studies showed that AuNRs@Ru and AuNRs@Ru were effective for the photothermal destruction of tumors.

A hyperspectral method to assay the microphysiological fates of nanomaterials in histological samples

Nanoparticles are used extensively as biomedical imaging probes and potential therapeutic agents. As new particles are developed and tested in vivo, it is critical to characterize their biodistribution profiles. We demonstrate a new method that uses adaptive algorithms for the analysis of hyperspectral dark-field images to study the interactions between tissues and administered nanoparticles. This non-destructive technique quantitatively identifies particles in ex vivo tissue sections and enables detailed observations of accumulation patterns arising from organ-specific clearance mechanisms, particle size, and the molecular specificity of nanoparticle surface coatings. Unlike nanoparticle uptake studies with electron microscopy, this method is tractable for imaging large fields of view. Adaptive hyperspectral image analysis achieves excellent detection sensitivity and specificity and is capable of identifying single nanoparticles. Using this method, we collected the first data on the sub-organ distribution of several types of gold nanoparticles in mice and observed localization patterns in tumors.

DOI:http://dx.doi.org/10.7554/eLife.16352.001

Metallic elements like gold and silver can be made into particles that are one thousand times smaller than the width of a human hair. Researchers can create these “nanoparticles” in different sizes and shapes that exhibit unique properties. For example, gold can be made into rod-shaped particles that interact with infrared light. Other nanoparticles can be loaded with drug molecules and designed to bind to cancer cells. As a result, nanoparticles have been explored for use in a variety of biomedical imaging and therapy applications. However, we must fully understand how the nanoparticles bind to the cancer cells and how the body tolerates these nanoparticles before they can be used in humans.

Experiments that explore where nanoparticles accumulate in the body are typically called biodistribution studies. However, current techniques for studying biodistribution cannot simultaneously measure the uptake of particles into organs and reveal the fine structures inside the organs that interact with the particles.

SoRelle, Liba et al. aimed to address this problem by developing a new biodistribution technique called HSM-AD (short for hyperspectral microscopy with adaptive detection). This new technique combines a relatively recent method called hyperspectral dark-field microscopy, which can identify nanoparticles from their unique optical signatures, with versatile computer algorithms to detect nanoparticles.

HSM-AD is more sensitive than previously developed biodistribution techniques, and SoRelle, Liba et al. used it to produce highly detailed maps of nanoparticle uptake patterns in the organs of mice. These maps provide new insights into how cells and tissues in the body handle different nanoparticles. Moreover, HSM-AD was able to distinguish nanoparticles with unique shapes by their distinct optical signatures. Further experiments show that HSM-AD can reveal interactions between human tumor cells and nanoparticles specifically designed to target those cells.

HSM-AD will be a useful resource for researchers studying the effect of nanoparticles on the human body. Future studies will use this technique to explore which nanoparticles have the potential to be developed for medical uses.

DOI:http://dx.doi.org/10.7554/eLife.16352.002

Lysosome–mitochondria-mediated apoptosis specifically evoked in cancer cells induced by gold nanorods

Aim: The main aim of this article is to explain the apoptosis mechanisms of cancer cells specifically triggered by gold nanorods (GNRs). Materials & methods: GNRs were synthesized and optimized, the lysosome damage, cathepsin D, mitochondrial membrane potential, caspase-9, cleaved caspase-9, caspase-3 and intracellular GNRs location related to apoptosis was systematically evaluated. Results: GNRs specifically induce cancer cell apoptosis while posing a negligible impact on normal cells. After incubation with GNRs, the lysosomal permeability in cancer cells as indicated by cathepsin D was markedly higher than that in normal cells and resulted in an obvious decrease in mitochondrial membrane potential. Western blot analysis further confirmed that apoptosis occurred through caspase-9 and caspase-3 activation following mitochondrial damage. Transmission electron microscope images showed that GNRs did not appear in most of the damaged mitochondria but mainly accumulated in lysosomes. Conclusion: These findings indicated that GNR-induced apoptosis specifically in cancer cells by affecting lysosomes and mitochondria.

A new bifunctional hybrid nanostructure as an active platform for photothermal therapy and MR imaging

As a bi-functional cancer treatment agent, a new hybrid nanostructure is presented which can be used for photothermal therapy by exposure to one order of magnitude lower laser powers compared to similar nanostructures in addition to substantial enhancment in magnetic resonance imaging (MRI) contrast. This gold-iron oxide hybrid nanostructure (GIHN) is synthesized by a cost-effective and high yield water-based approach. The GIHN is sheilded by PEG. Therefore, it shows high hemo and biocompatibility and more than six month stability. Alongside earlier nanostructures, the heat generation rate of GIHN is compareable with surfactnat-capped gold nanorods (GNRs). Two reasons are behind this enhancement: Firstly the distance between GNRs and SPIONs is adjusted in a way that the surface plasmon resonance of the new nanostructure is similar to bare GNRs and secondly the fraction of GNRs is raised in the hybrid nanostructure. GIHN is then applied as a photothermal agent using laser irradiation with power as low as 0.5 W.cm(-2) and only 32% of human breast adenocarcinoma cells could survive. The GIHN also acts as a dose-dependent transvers relaxation time (T2) MRI contrast agent. The results show that the GINH can be considered as a good candidate for multimodal photothermal therapy and MRI.

Efficient, robust surface functionalization and stabilization of gold nanorods with quaternary ammonium-containing ionomers as multidentate macromolecular ligands

Quaternary ammonium-containing ionomers are a novel class of multidentate macromolecular surface ligands for efficient functionalization and stabilization of gold nanorods.

Biofunctionalization of Large Gold Nanorods Realizes Ultrahigh-Sensitivity Optical Imaging Agents

Gold nanorods (GNRs, ∼ 50 × 15 nm) have been used ubiquitously in biomedicine for their optical properties, and many methods of GNR biofunctionalization have been described. Recently, the synthesis of larger-than-usual GNRs (LGNRs, ∼ 100 × 30 nm) has been demonstrated. However, LGNRs have not been biofunctionalized and therefore remain absent from biomedical literature to date. Here we report the successful biofunctionalization of LGNRs, which produces highly stable particles that exhibit a narrow spectral peak (FWHM ∼100 nm). We further demonstrated that functionalized LGNRs can be used as highly sensitive scattering contrast agents by detecting individual LGNRs in clear liquids. Owing to their increased optical cross sections, we found that LGNRs exhibited up to 32-fold greater backscattering than conventional GNRs. We leveraged these enhanced optical properties to detect LGNRs in the vasculature of live tumor-bearing mice. With LGNR contrast enhancement, we were able to visualize tumor blood vessels at depths that were otherwise undetectable. We expect that the particles reported herein will enable immediate sensitivity improvements in a wide array of biomedical imaging and sensing techniques that rely on conventional GNRs.

Tumor-targeted and pH-controlled delivery of doxorubicin using gold nanorods for lung cancer therapy

Background

In lung cancer, the efficacy of conventional chemotherapy is limited due to poor drug accumulation in tumors and nonspecific cytotoxicity. Resolving these issues will increase therapeutic efficacy.

Methods

GNR-Dox-Tf-NPs (gold nanorod-doxorubicin-transferrin-nanoparticles) were prepared by different chemical approaches. The efficacy of these nanoparticles was carried out by cell viability in lung cancer and primary coronary artery smooth muscle cells. The receptor-mediated endocytosis studies were done with human transferrin and desferrioxamine preincubation. The GNR-Dox-Tf nanoparticles induced apoptosis, and DNA damage studies were done by Western blot, H2AX foci, and comet assay.

Results

We developed and tested a gold nanorod-based multifunctional nanoparticle system (GNR-Dox-Tf-NP) that carries Dox conjugated to a pH-sensitive linker and is targeted to the transferrin receptor overexpressed in human lung cancer (A549, HCC827) cells. GNR-Dox-Tf-NP underwent physicochemical characterization, specificity assays, tumor uptake studies, and hyperspectral imaging. Biological studies demonstrated that transferrin receptor-mediated uptake of the GNR-Dox-Tf-NP by A549 and HCC827 cells produced increased DNA damage, apoptosis, and cell killing compared with nontargeted GNR-Dox-NP. GNR-Dox-Tf-NP-mediated cytotoxicity was greater (48% A549, 46% HCC827) than GNR-Dox-NP-mediated cytotoxicity (36% A549, 39% HCC827). Further, GNR-Dox-Tf-NP markedly reduced cytotoxicity in normal human coronary artery smooth muscle cells compared with free Dox.

Conclusion

Thus, GNR-Dox-Tf nanoparticles can selectively target and deliver Dox to lung tumor cells and alleviate free Dox-mediated toxicity to normal cells.

A near-infrared light-controlled system for reversible presentation of bioactive ligands using polypeptide-engineered functionalized gold nanorods

A near-infrared light-controlled hybrid platform with polypeptide-engineered functionalized gold nanorods has been designed for reversible presentation of the immobilized ligands to cell surface receptors on the engineered materials.