Recent advances in light-triggered cancer immunotherapy.

Light-triggered phototherapies, such as photodynamic therapy (PDT) and photothermal therapy (PTT), have shown strong therapeutic efficacy with minimal invasiveness and systemic toxicity, offering opportunities for tumor-specific therapies. Phototherapies not only induce direct tumor cell killing, but also trigger anti-tumor immune responses by releasing various immune-stimulating factors. In recent years, conventional phototherapies have been combined with cancer immunotherapy as synergistic therapeutic modalities to eradicate cancer by exploiting the innate and adaptive immunity. These combined photoimmunotherapies have demonstrated excellent therapeutic efficacy in preventing tumor recurrence and metastasis compared to phototherapy alone. This review covers recent advancements in combined photoimmunotherapy, including photoimmunotherapy (PIT), PDT-combined immunotherapy, and PTT-combined immunotherapy, along with their underlying anti-tumor immune response mechanisms. In addition, the challenges and future research directions for light-triggered cancer immunotherapy are discussed.

Silica-Based Platform Decorated with Conjugated Polymer Dots and Prussian Blue for Improved Photodynamic Cancer Therapy.

To advance cancer treatment, we have developed a novel composite material consisting of conjugated polymer dots (CPDs) and Prussian blue (PB) particles, which were immobilized on, and encapsulated within, silica particles, respectively. The CPDs functioned as both a photosensitizer and a photodynamic agent, and the PB acted as a photothermal agent. The silica platform provided a biocompatible matrix that brought the two components into close proximity. Under laser irradiation, the fluorescence from the CPDs in the composite material enabled cell imaging and was subsequently converted to thermal energy by PB. This efficient energy transfer was accomplished because of the spectral overlap between the emission of donor CPDs and the absorbance of acceptor PB. The increase in local temperature in the cells resulted in a significant increase in the amount of reactive oxygen species (ROS) generated by CPDs, in which their independent use did not produce sufficient ROS for cancer cell treatment. To assess the impact of the enhanced ROS generation by the composite material, we conducted experiments using cancer cells under 532 nm laser irradiation. The results showed that with the increase in local temperature, the generated ROS increased by 30% compared with the control, which did not contain PB. When the silica-based composite material was positioned at the periphery of the tumor for 120 h, it led to a much slower tumor growth than other materials tested. By using a CPD-based photodynamic therapy platform, a new simplified approach to designing and preparing cancer treatments could be achieved, which included photothermal PB-assisted enhanced ROS generation using a single laser. This advancement opens up an exciting new opportunity for effective cancer treatment.

Topical methylene blue nanoformulation for the photodynamic therapy of acne vulgaris.

Acne vulgaris is a common skin disease caused by multifactorial reasons involving excessive sebum secretion and inflammation by Cutibacterium acnes (C. acnes). Various conventional therapies are available for the treatment of acne vulgaris; however, topical photodynamic therapy (PDT) has attracted much attention because of its great potential for sebum-reducing, anti-inflammatory, and antimicrobial activities. Although 5-aminolevulinic acid (ALA) has been broadly used as a photosensitizer for topical PDT, it has several limitations such as long incubation time, pain, and post-inflammatory hyperpigmentation. Here, we report a biocompatible nanoformulation consisting of methylene blue and salicylic acid (MBSD), as a potent PDT and acne therapeutics, enclosed within oleic acid. Photoactivated MBSD showed antimicrobial activity against C. acnes along with long-term stability. When 24 patients with acne were treated with MBSD and light irradiation 5 times at 1-week intervals, MBSD-based PDT exhibited a remarkable reduction in acne lesions and sebum production. In addition, the therapeutic procedure was painless and safe, without any adverse events. Therefore, MBSD is a promising topical PDT agent for biocompatible, safe, and effective acne treatment.

Metal complexation-mediated stable and biocompatible nanoformulation of clinically approved near-infrared absorber for improved tumor targeting and photonic theranostics.

Indocyanine green (ICG) is a clinically approved dye that has shown great promise as a phototheranostic material with fluorescent, photoacoustic and photothermal responses in the near-infrared region. However, it has certain limitations, such as poor photostability and non-specific binding to serum proteins, subjected to rapid clearance and decreased theranostic efficacy in vivo. This study reports stable and biocompatible nanoparticles of ICG (ICG-Fe NPs) where ICG is electrostatically complexed with an endogenously abundant metal ion (Fe3+) and subsequently nanoformulated with a clinically approved polymer surfactant, Pluronic F127. Under near-infrared laser irradiation, ICG-Fe NPs were found to be more effective for photothermal temperature elevation than free ICG molecules owing to the improved photostability. In addition, ICG-Fe NPs showed the markedly enhanced tumor targeting and visualization with photoacoustic/fluorescent signaling upon intravenous injection, attributed to the stable metal complexation that prevents ICG-Fe NPs from releasing free ICG before tumor targeting. Under dual-modal imaging guidance, ICG-Fe NPs could successfully potentiate photothermal therapy of cancer by applying near-infrared laser irradiation, holding potential as a promising nanomedicine composed of all biocompatible ingredients for clinically relevant phototheranostics.

Synthesis of Caffeoyl-Prolyl-Histidyl-Xaa Derivatives and Evaluation of Their Activities and Stability upon Long-Term Storage.

Antioxidants play a critical role in the treatment of degenerative diseases and delaying the aging of dermal tissue. Caffeic acid (CA) is a representative example of the antioxidants found in plants. However, CA is unsuitable for long-term storage because of its poor stability under ambient conditions. Caffeoyl-Pro-His-NH2 (CA-Pro-His-NH2, CA-PH) exhibits the highest antioxidant activity, free radical scavenging and lipid peroxidation inhibition activity among the histidine-containing CA-conjugated dipeptides reported to date. The addition of short peptides to CA, such as Pro-His, is assumed to synergistically enhance its antioxidative activity. In this study, several caffeoyl-prolyl-histidyl-Xaa-NH2 derivatives were synthesized and their antioxidative activities evaluated. CA-Pro-His-Asn-NH2 showed enhanced antioxidative activity and higher structural stability than CA-PH, even after long-term storage. CA-Pro-His-Asn-NH2 was stable for 3 months, its stability being evaluated by observing the changes in its NMR spectra. Moreover, the solid-phase synthetic strategy used to prepare these CA-Pro-His-Xaa-NH2 derivatives was optimized for large-scale production. We envision that CA-Pro-His-Xaa-NH2 derivatives can be used as potent dermal therapeutic agents and useful cosmetic ingredients.

Graphene oxide film guided skeletal muscle differentiation.

Engineered muscle tissues can be used for the regeneration or substitution of irreversibly damaged or diseased muscles. Recently, graphene oxide (GO) has been shown to improve the adsorption of biomolecules through its biocompatibility and intrinsic π-π interactions. The possibility of producing various GO modifications may also provide additional functionality as substrates for cell culture. In particular, substrates fabricated from pristine GO have been shown to improve cellular functions and influence stem cell differentiation. In this study, we fabricated tunable GO substrates with various physical and chemical properties and demonstrated the ability of the substrate to support myogenic differentiation. Higher cellular adhesion affinity with unique microfilament anchorage was observed for GO substrates with increased GO concentrations. In addition, amino acid (AA)-conjugated GO (GO-AA) substrates were fabricated to modify GO chemical properties and study the effects of chemically modified GO substrates on myogenic differentiation. Our findings demonstrate that minor tuning of GO significantly influences myogenic differentiation.

Template-Assisted Plasmonic Nanogap Shells for Highly Enhanced Detection of Cancer Biomarkers.

We present a template-assisted method for synthesizing nanogap shell structures for biomolecular detections based on surface-enhanced Raman scattering. The interior nanogap-containing a silver shell structure, referred to as a silver nanogap shell (Ag NGS), was fabricated on silver nanoparticles (Ag NPs)-coated silica, by adsorbing small aromatic thiol molecules on the Ag NPs. The Ag NGSs showed a high enhancement factor and good signal uniformity, using 785-nm excitation. We performed in vitro immunoassays using a prostate-specific antigen as a model cancer biomarker with a detection limit of 2 pg/mL. To demonstrate the versatility of Ag NGS nanoprobes, extracellular duplex surface-enhanced Raman scattering (SERS) imaging was also performed to evaluate the co-expression of cancer biomarkers, human epidermal growth factor-2 (HER2) and epidermal growth factor receptor (EGFR), in a non-small cell lung cancer cell line (H522). Developing highly sensitive Ag NGS nanoprobes that enable multiplex biomolecular detection and imaging can open up new possibilities for point-of-care diagnostics and provide appropriate treatment options and prognosis.

Modulation of oligonucleotide-binding dynamics on WS2 nanosheet interfaces for detection of Alzheimer's disease biomarkers.

Non-covalent adsorption and desorption of oligonucleotides on two-dimensional nanosheets are widely employed to design nanobiosensors for the rapid optical detection of targets. A precise control over the weak interactions between nanosheet interfaces and oligonucleotides is crucial for a high-sensing performance. Herein, the interface of ultrathin WS2 nanosheets used as a fluorescence quencher was engineered by four different dextran polymers in an aqueous solution to control the adsorption kinetics and thermodynamics of the DNA probe. The WS2 nanosheets, functionalized by the carboxyl group-bearing dextran (CM-dex-WS2) or the trimethylammonium-modified dextran (TMA-dex-WS2), exhibited 3.6-fold faster adsorption rates of the fluorescein-labeled DNA probe (FAM-DNA), which led to the effective fluorescence quenching of FAM, compared to the nanosheets functionalized with pristine dextran (dex-WS2) or the hydrophobic phenoxy groups-bearing dextran (PhO-dex-WS2). Isothermal titration calorimetry measurements showed that the adsorption strength of FAM-DNA for CM-dex-WS2 was one order of magnitude greater than its hybridization energy for a target microRNA (miR-29a) that is well-known as an Alzheimer's disease (AD) biomarker, leading to the unfavorable desorption of the DNA probe from the surface. In contrast, TMA-dex-WS2 exhibited the proper adsorption strength of FAM-DNA, which was lower than its hybridization energy for miR-29a, leading to its favorable desorption from the nanosheet surface along with the noticeable restoration of the quenched fluorescence after its hybridization with miR-29a. Finally, the interface modulation of WS2 nanosheets allowed the selective and sensitive recognition of miR-29a against non-complementary RNA and single base-mismatched RNA in human serum via increases in target-specific fluorescence.

Ultrathin WO3 Nanosheets Converted from Metallic WS2 Sheets by Spontaneous Formation and Deposition of PdO Nanoclusters for Visible Light-Driven C-C Coupling Reactions.

It is not facile to obtain ultrathin two-dimensional (2D) WO3 nanosheets through the exfoliation of their bulk counterpart in solution due to strong covalent interaction between interlayers. In addition, they require additional functionalization with cocatalysts to expand their applicability in photocatalytic organic reactions owing to their insufficient conduction band edge position. Here, we report a chemical approach for the simultaneous production and functionalization of ultrathin 2D WO3 nanosheets through the direct conversion of metallic WS2 nanosheets, accomplished by the spontaneous formation and deposition of PdO nanoclusters on the nanosheet surface in H2O. When chemically exfoliated metallic WS2 nanosheets were simply mixed with K2PdCl4 in H2O under mild conditions (50 °C, 1 h), they were converted to semiconducting WO3 nanosheets on which PdO nanoclusters of a uniform size (∼3 nm) were spontaneously formed, leading to the production of PdO-functionalized ultrathin WO3 (PdO@WO3) nanohybrids. The conversion yield of WO3 nanosheets from metallic WS2 nanosheets increased with increasing coverage of PdO nanoclusters on the nanosheet surface. In addition, the conversion of WO3 nanosheets induced by PdO nanocluster formation was effective only in H2O but not in organic solvents, such as N-methylpyrrolidone and acetonitrile. A mechanical study suggests that the chemisorption of hydrated Pd precursors on the chalcogens of metallic WS2 nanosheets leads to their facile oxidation by water molecules, producing WO3 nanosheets covered with PdO nanoclusters. The as-prepared PdO@WO3 nanosheets exhibited excellent photocatalytic activity and recyclability in Suzuki cross-coupling reactions of various aryl halides under visible light irradiation.

Reaction Kinetics-Mediated Control over Silver Nanogap Shells as Surface-Enhanced Raman Scattering Nanoprobes for Detection of Alzheimer's Disease Biomarkers.

It is very challenging to accurately quantify the amounts of amyloid peptides Aß40 and Aß42, which are Alzheimer's disease (AD) biomarkers, in blood owing to their low levels. This has driven the development of sensitive and noninvasive sensing methods for the early diagnosis of AD. Here, an approach for the synthesis of Ag nanogap shells (AgNGSs) is reported as surface-enhanced Raman scattering (SERS) colloidal nanoprobes for the sensitive, selective, and multiplexed detection of Aß40 and Aß42 in blood. Raman label chemicals used for SERS signal generation modulate the reaction rate for AgNGSs production through the formation of an Ag-thiolate lamella structure, enabling the control of nanogaps at one nanometer resolution. The AgNGSs embedded with the Raman label chemicals emit their unique SERS signals with a huge intensity enhancement of up to 107 and long-term stability. The AgNGS nanoprobes, conjugated with an antibody specific to Aß40 or Aß42, are able to detect these AD biomarkers in a multiplexed manner in human serum based on the AgNGS SERS signals. Detection is possible for amounts as low as 0.25 pg mL-1 . The AgNGS nanoprobe-based sandwich assay has a detection dynamic range two orders of magnitude wider than that of a conventional enzyme-linked immunosorbent assay.

2D transition metal dichalcogenides with glucan multivalency for antibody-free pathogen recognition.

The ability to control the dimensions and properties of nanomaterials is fundamental to the creation of new functions and improvement of their performances in the applications of interest. Herein, we report a strategy based on glucan multivalent interactions for the simultaneous exfoliation and functionalization of two-dimensional transition metal dichalcogenides (TMDs) in an aqueous solution. The multivalent hydrogen bonding of dextran with bulk TMDs (WS2, WSe2, and MoSe2) in liquid exfoliation effectively produces TMD monolayers with binding multivalency for pathogenic bacteria. Density functional theory simulation reveals that the multivalent hydrogen bonding between dextran and TMD monolayers is very strong and thermodynamically favored (ΔEb = -0.52 eV). The resulting dextran/TMD hybrids (dex-TMDs) exhibit a stronger affinity (Kd = 11 nM) to Escherichia coli O157:H7 (E. coli) than E. coli-specific antibodies and aptamers. The dex-TMDs can effectively detect a single copy of E. coli based on their Raman signal.

Fluorescent 2D WS2 Nanosheets Bearing Chemical Affinity Elements for the Recognition of Glycated Hemoglobin.

It is required to exfoliate and functionalize 2D transition metal dichalcogenides (TMDs) in an aqueous solution for biological and medical applications. Herein, the approach for the simultaneous exfoliation and functionalization of 2D WS2 nanosheets using boronic acid-modified poly(vinyl alcohol) (B-PVA) in an aqueous solution is reported, and the B-PVA-functionalized WS2 nanosheets (B-PVA-WS2 ) are exploited as a fluorescent biosensor for the detection of glycated hemoglobin, HbA1c. The synthetic B-PVA polymer facilitates the exfoliation and functionalization of WS2 nanosheets from the bulk counterpart in the aqueous solution via a pulsed sonication process, resulting in fluorescent B-PVA-WS2 nanohybrids with a specific recognition of HbA1c. The fluorescence of the B-PVA-WS2 is quenched in the presence of HbA1c, whereas PVA-functionalized WS2 (PVA-WS2 ), not bearing boronic acid as a recognition moiety, shows no fluorescence changes upon the addition of the target. The B-PVA-WS2 is able to selectively detect HbA1c at the concentration as low as 3.3 × 10-8 m based on its specific fluorescence quenching.

ß-Lactoglobulin Peptide Fragments Conjugated with Caffeic Acid Displaying Dual Activities for Tyrosinase Inhibition and Antioxidant Effect.

The regulation of tyrosinase activity and reactive oxygen species is of great importance for the prevention of dermatological disorders in the fields of medicine and cosmetics. Herein, we report a strategy based on solid-phase peptide chemistry for the synthesis of ß-lactoglobulin peptide fragment/caffeic acid (CA) conjugates (CA-Peps) with dual activities of tyrosinase inhibition and antioxidation. The purity of the prepared conjugates, CA-MHIR, CA-HIRL, and CA-HIR, significantly increased to 99%, as acetonide-protected CA was employed in solid-phase coupling reactions on Rink amide resins. The tyrosinase inhibitory activities of all CA-Pep derivatives were higher than the activity of kojic acid, and CA-MHIR exhibited the highest tyrosinase inhibition activity (IC50 = 47.9 µM). Moreover, CA-Pep derivatives displayed significantly enhanced antioxidant activities in the peroxidation of linoleic acid as compared to the pristine peptide fragments. All CA-Pep derivatives showed no cytotoxicity against B16-F1 melanoma cells.

Adjustable Intermolecular Interactions Allowing 2D Transition Metal Dichalcogenides with Prolonged Scavenging Activity for Reactive Oxygen Species.

There is an increasing demand for control over the dimensions and functions of transition metal dichalcogenides (TMDs) in aqueous solution toward biological and medical applications. Herein, an approach for the exfoliation and functionalization of TMDs in water via modulation of the hydrophobic interaction between poly(ε-caprolactone)-b-poly(ethylene glycol) (PCL-b-PEG) and the basal planes of TMDs is reported. Decreasing the hydrophobic PCL length of PCL-b-PEG from 5000 g mol-1 (PCL5000 ) to 460 g mol-1 (PCL460 ) significantly increases the exfoliation efficiency of TMD nanosheets because the polymer-TMD hydrophobic interaction becomes dominant over the polymer-polymer interaction. The TMD nanosheets exfoliated by PCL460 -b-PEG5000 (460-WS2 , 460-WSe2 , 460-MoS2 , and 460-MoSe2 ) show excellent and prolonged scavenging activity for reactive oxygen species (ROS), but each type of TMD displays a different scavenging tendency against hydroxyl, superoxide, and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radicals. A mechanistic study based on electron paramagnetic resonance spectroscopy and density functional theory simulations suggests that radical-mediated oxidation of TMDs and hydrogen transfer from the oxidized TMDs to radicals are crucial steps for ROS scavenging by TMD nanosheets. As-prepared 460-TMDs are able to effectively scavenge ROS in HaCaT human keratinocytes, and also exhibit excellent biocompatibility.

Ultrasensitive NIR-SERRS Probes with Multiplexed Ratiometric Quantification for In Vivo Antibody Leads Validation.

Immunotargeting ability of antibodies may show significant difference between in vitro and in vivo. To select antibody leads with high affinity and specificity, it is necessary to perform in vivo validation of antibody candidates following in vitro antibody screening. Herein, a robust in vivo validation of anti-tetraspanin-8 antibody candidates against human colon cancer using ratiometric quantification method is reported. The validation is performed on a single mouse and analyzed by multiplexed surface-enhanced Raman scattering using ultrasensitive and near infrared (NIR)-active surface-enhanced resonance Raman scattering nanoprobes (NIR-SERRS dots). The NIR-SERRS dots are composed of NIR-active labels and Au/Ag hollow-shell assembled silica nanospheres. A 93% of NIR-SERRS dots is detectable at a single-particle level and signal intensity is 100-fold stronger than that from nonresonant molecule-labeled spherical Au NPs (80 nm). The result of SERRS-based antibody validation is comparable to that of the conventional method using single-photon-emission computed tomography. The NIR-SERRS-based strategy is an alternate validation method which provides cost-effective and accurate multiplexing measurements for antibody-based drug development.

Proteolytic disassembly of peptide-mediated graphene oxide assemblies for turn-on fluorescence sensing of proteases.

Molecule-induced assembly of nanomaterials can alter their unique chemical and physical properties, which can be a promising approach for sensing. Herein, we demonstrate an optical 'turn-on' biosensor for the detection of matrix metalloproteinase-2 (MMP-2), fabricated by means of a peptide-induced assembly of fluorescent graphene oxide (GO). Functionalization of GO with a peptide substrate for MMP-2 bearing a thiol group leads to its self-assembly via disulfide bonding, accompanied by self-quenching of GO's strong fluorescence. This peptide-induced GO assembly is then disassembled by proteolytic cleavage in the presence of MMP-2, thereby restoring the level of self-quenched GO fluorescence. With this approach, we are able to detect MMP-2 and to investigate the kinetic parameters of MMP-2 activity. The GO-peptide assembly is successfully applied to the selective and sensitive detection of MMP-2 secreted by living cells, human hepatocytes HepG2, at a concentration of 2 ng mL(-1).

Double-Layer Magnetic Nanoparticle-Embedded Silica Particles for Efficient Bio-Separation.

Superparamagnetic Fe3O4 nanoparticles (NPs) based nanomaterials have been exploited in various biotechnology fields including biomolecule separation. However, slow accumulation of Fe3O4 NPs by magnets may limit broad applications of Fe3O4 NP-based nanomaterials. In this study, we report fabrication of Fe3O4 NPs double-layered silica nanoparticles (DL MNPs) with a silica core and highly packed Fe3O4 NPs layers. The DL MNPs had a superparamagnetic property and efficient accumulation kinetics under an external magnetic field. Moreover, the magnetic field-exposed DL MNPs show quantitative accumulation, whereas Fe3O4 NPs single-layered silica nanoparticles (SL MNPs) and silica-coated Fe3O4 NPs produced a saturated plateau under full recovery of the NPs. DL MNPs are promising nanomaterials with great potential to separate and analyze biomolecules.

Direct identification of on-bead peptides using surface-enhanced Raman spectroscopic barcoding system for high-throughput bioanalysis.

Recently, preparation and screening of compound libraries remain one of the most challenging tasks in drug discovery, biomarker detection, and biomolecular profiling processes. So far, several distinct encoding/decoding methods such as chemical encoding, graphical encoding, and optical encoding have been reported to identify those libraries. In this paper, a simple and efficient surface-enhanced Raman spectroscopic (SERS) barcoding method using highly sensitive SERS nanoparticles (SERS ID) is presented. The 44 kinds of SERS IDs were able to generate simple codes and could possibly generate more than one million kinds of codes by incorporating combinations of different SERS IDs. The barcoding method exhibited high stability and reliability under bioassay conditions. The SERS ID encoding based screening platform can identify the peptide ligand on the bead and also quantify its binding affinity for specific protein. We believe that our SERS barcoding technology is a promising method in the screening of one-bead-one-compound (OBOC) libraries for drug discovery.