UV Absorption Peak Research Articles

An ultra-sensitive colorimetric detection of Ag ions based on etching AuNP@MnO2 nanoparticles with glutathione by using dark field optical microscopy

Abstract Although colorimetric methods have been developed for the detection of silver ions (Ag+) based on gold nanoparticles aggregation induced by formation cytosine-Ag+-cytosine complexes or high salt centration with dark field microscopy (DFM). However, this state is usually unstable, resulting in the poor accuracy and repeatability of analytical methods. Herein, we have constructed an assay of Ag+ based on MnO2-coated gold nanoparticle (AuNP@MnO2). MnO2 shell can be reduced into Mn2+ by glutathione (GSH). The maximum absorption peak of AuNP@MnO2 significantly changes from 528 nm to 572 nm. Simultaneously, the color of a single nanoparticle becomes from yellow to green under DFM. However, in the presence of Ag+, the etching process of MnO2 is inhibited because of coordination between GSH toward Ag+. The maximum UV absorption peak of AuNP@MnO2 is basically unchanged. The linear equation for Ag+ detection is obtained in the range from 1.0 pM to 5.0 nM with R2 = 0.983 by using DFM. According to 3σ/k rule (where σ is the standard deviation of five blank samples and k is the slope of regression line), the limit of detection (LOD) is calculated to be 0.39 pM. Furthermore, this approach can be applied to detect Ag+ in real sample, showing the good potential for environmental monitoring and water quality control.

Oxygen vacancies mediated cooperative magnetism in ZnO nanocrystals: A d0 ferromagnetic case study

This article reports on the oxygen vacancies and defects induced cooperative magnetism of 28nm (as prepared) and 74nm (annealed) sized nanocrystals of ZnO synthesized through sol- gel auto-combustion route. UV–Vis–NIR optical absorption and photoluminescence (PL) spectroscopic measurements showed marginal red shifting in the band gap energy and characteristic blue shift in the UV absorption peak position with the size reduction of ZnO nanocrystallites. PL analysis revealed that 28nm sized ZnO nanocrystals have higher number of oxygen vacancies and lower interstitial defects in comparison to 74nm (annealed) nanocrystals of ZnO. Both the sample display oxygen vacancy and defect mediated ferromagnetic behaviour at 300K but 28nm ZnO nanocrystals are better ferromagnetic in comparison to annealed ZnO nanocrystals. The annealed ZnO nanocrystals also showed considerable diamagnetic character. High field (±7 Tesla) magnetization measurements down to 5K and PL analysis establish presence, inter-conversion of oxygen vacancies and valence fluctuations in neutral, mono and divalent oxygen vacancies. The monovalent oxygen and zinc vacancies play important role in the mediation of d0 type cooperative magnetism in the ZnO nanocrystals.

Fabrication of Plasmon-Active Polymer-Nanoparticle Composites for Biosensing Applications

Polymer-nanoparticle composites find relevance in various fields ranging from optoelectronics to the biomedical sciences. Various efforts have been made to devise fabrication strategies that are simple, robust,and reproducible. Herein, we demonstrate a universal strategy to fabricate plasmon-active polymer-nanoparticle composites, exemplified by the incorporation of gold nanoparticles (AuNPs) into a triethylene glycol dimethacrylate (TEGDMA) polymer scaffold. The TEGDMA scaffold was synthesized on a planar glass support substrate via surface-initiated atomic transfer radical polymerization, followed by the immersion of the TEGDMA-coated glass substrate in a solution of AuNPs prepared via conventional wet-chemical synthesis. This led to the strong attachment of AuNPs to the TEGDMA nanolobes, which was confirmed by the UV absorption peak at 527 nm, due to localized surface plasmon resonance of AuNPs. More importantly, the nanolobe architecture facilitates nanoparticle trapping while allowing molecular access to the nanoparticle surface. This enabled us to further functionalize the incorporated AuNPs with thrombin binding aptamer and utilize the biofunctionalized polymer-nanoparticle composite as a thrombin sensor. The synergistic combination of metallic nanoparticles acting as a sensing module with a nonfouling polymer matrix acting both as a nonrigid scaffold and to screen biomolecules allowed the detection of thrombin with good sensitivity down to 0.01 ng/mL with a linear range over three orders of magnitude. Our work paves the way for the fabrication of reliable biomolecular sensors based on the polymer brush-nanoparticle architecture.

Gold nanoparticles induced apoptosis via oxidative stress and mitochondrial dysfunctions in MCF‐7 breast cancer cells

Green synthesis of functionalized gold nanoparticles has been considered to be more biocompatible and has gained much attention in recent years. The eco‐friendly synthesis, long half‐life of drugs, low cost, and nontoxicity make them an appealing potential option for the biomedical field. The leaf aqueous extract of 10 different plants, namely,Araucaria heterophylla(Ah),Lagerstroemia indica(Li),Combretum indicum(Ci),Melia azedarach(Ma),Muntingia calabura(Mc),Hygrophila auriculata(Ha),Rivina humilis(Rh),Callistemon lanceolatus(Cl),Pterygota alata(Pa), andVateria indica(Vi) was used for the synthesis of gold nanoparticles (AuNPs). Among them, six plants supported the synthesis of stable AuNPs. The generation of ruby red from pale yellow color proved AuNPs synthesis and which was further confirmed by the absorption peak in UV–Vis spectroscopy. Enhanced antioxidant activity was found with Pa–AuNPs compared with other phytosynthesized AuNPs. Pa–AuNPs were thus characterized by HR‐TEM, EDX, XRD, and FTIR. Pa–AuNPs exhibited potent dose‐dependent anticancer efficacy and an effective dose of IC50mediated apoptosis and necrosis in MCF‐7 breast cancer cells. Pa–AuNPs significantly enhanced the generation of ROS, in effect inducing mitochondrial membrane sensitization to trigger the cascade of apoptosis. The research highlights the effectiveness of AuNPs on cancer cells in vitro and, in turn, a progressive step toward novel biomedical applications. These findings indicate that phytosynthesized AuNPs may be an enticing anti‐cancer strategy for breast cancer without eliciting toxicity to normal cells.

A graft copolymer composed of continuously linked carbon dioxide units and poly(vinyl alcohol)

No true CO2-based graft copolymer has been reported so far. Such a copolymer is synthesized via condensation reaction between an oligomer of CO2 and a well-defined poly(vinyl alcohol). The structure of the product is characterized. Both UV and fluorescence absorption peaks of the product are quite different from those of its precursor. A characteristic peak appears at 1755 cm−1 on the FTIR spectrum of the product, which is attributed to the incorporation of the oligomer moieties. Two glass transitions happen when the product is subjected to heating, which reflects it contains two polymeric chains. The results indicate that a true CO2-based graft copolymer is obtained.

Proton conducting behavior of a microporous metal-organic framework assisted by ligand isomerization

A microporous Tm-MOF {[Tm2L2(ox)(H2O)2]·4H2O}n (Tm-MOF, L ​= ​2-(pyridin-4-yl)-2H-imidazole-4, 5-dicarboxylate dianion; ox ​= ​oxalate dianion) with hydrogen bonds between the guest water molecules and host framework has been obtained. The CV and AC impendence studies suggested there was remarkable proton conducting behavior within Tm-MOF crystals, which was influenced by external voltage. The proton conducting mechanism was explored through dynamic simulation calculation. It was suggested that proton transferred between L ligand and water molecules through hydrogen bonds. And L ligand can isomerize to excited state stimulated by external voltage, which was essential and ensured the continuity of proton transfer. This simulated proton conduction process was verified by the fact that the low proton conductivity at 0 ​V vs. Ag-AgCl increased dramatically while open-circuit voltage increased to 1.6 ​V vs. Ag-AgCl. The UV absorption peak red shifting under higher voltage and the Ea value of 0.22eV lower than 0.4eV also confirmed the result of dynamic simulation.

The Influence of Hydrotalcite Intercalated with Benzoate on UV Stability of Acrylic Coating

It is important to realize that benzoate was intercalated into hydrotalcite (HTC-Bz) by the co-precipitation method. In this case, acrylic coating with 0.5 wt% HTC-Bz was deposited on carbon steel using the spin coating method. Next, the HTC-Bz structure was characterized by Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). In fact, an ultraviolet vision spectroscopy (UV-Vis) was used to determine the benzoate content in HTC-Bz, and the UV absorption ability of HTC-Bz. Using electrochemical techniques, water contact angle measurement, and thermal-gravimetric analysis, we compared the protective properties before and after QUV test, hydrophobicity and the thermal stability of acrylic coating containing HTC-Bz. The obtained results showed that HTC-Bz with a plate-like structure was successfully synthesized; benzoate was intercalated into the interlayer of hydrotalcite with a concentration of 28 wt%. Additionally, it was noted that HTC-Bz has an UV absorption peak at 225 nm. In conclusion, the addition of HTC-Bz enhanced the UV stability, hydrophobicity and the thermal stability of acrylic coating.

Electrochemical sensor for detecting dopamine using graphene quantum dots incorporated with multiwall carbon nanotubes

A ratiometric electrochemical biosensor was developed for dopamine detection based on the incorporation of graphene quantum dots (GQDs) with acid-functionalized multiwall carbon nanotubes (MWCNTs) on a glassy carbon electrode (GCE) surface. The GQDs@MWCNTs/GCE nanocomposite was characterized by XRD, SEM, TEM, AFM, XPS, and electrochemical techniques. The UV absorbance peak of GQDs was located at 235 nm, and the average size of the GQDs was 1–5 nm. The electrochemical responses indicated that the proposed sensor exhibited good electrocatalytic activity toward the oxidation of dopamine and spiked dopamine, over a dynamic linear range of 0.25–250 μM, with low detection limits of 95 nM and 110 nM (S/N = 3), respectively. In addition, the developed sensor interacted selectively with dopamine rather than other molecules was investigated using an amperometric technique. The developed sensor exhibited excellent reproducibility, selectivity, and sensitivity.

Biosynthesis of gold nanoparticles using Vetex negundo and evaluation of pro-apoptotic effect on human gastric cancer cell lines

Gastric cancer (GC) is mainly widespread gastrointestinal malignancy,which reports for 8% of overallcases in carcinogenesis and 10% of yearly fatality, is 4thprimary cause of cancer associated death global. The plan of the present research was to develop ethanolic extract of Vitex negundo-loaded gold nanoparticles (VN-AuNPs) and to appraise the various characteristic methods likes UV–vis spectroscopy, SAED, FTIR, XRD and HR-TEM. Additionally, the anticancer effect of VN-AuNPs on AGS cells were analysed by cell viability, apoptotic morphological changes by TUNEL, AO/EtBr and Hoechst staining, alterations of mitochondrial membrane potential (MMP) and production reactive oxygen species (ROS). Moreover, the status of apoptosis gene such as caspase-3, Bcl-2, Bcl-XL, Bax and caspase-9 expressions was analysed by using western and RT-PCR techniques. Synthesized AuNPs established by UV absorption peak of the highest at 538 and crystal nature of AuNPs was additionallyverifiedwith SAED and XRD. TEM images were illustrates size and morphological division of NPs. FTIR examinationscompletedalkene, carbodiimide and aliphatic primary amines of biomolecules werepresent in synthesized VN-AuNPs. Additionally, AuNPs were stimulatedapoptosis throughthe cytotoxicity effect,changes of MMP, generation of ROS, nuclear and apoptotic morphological alterationsvia TUNEL, AO/EtBr and Hoechst assay. Furthermore, molecular mechanisms also provoked apoptosis through modulating pro (caspase-3, Bax, Bid, caspase-9) and anti-apoptotic (Bcl-2 and Bcl-XL) mediators by western blotting and gene expression in AGS cells. This production of AuNPs from VN was eco-friendly, large-scaled up and easy.

Carbon dots as fluorescent nanoprobe for the determination of N-acetyl-β-d-glucosaminidase activity

Carbon dots (CDs) were synthesized from p-aminophenol and ethylenediamine via one-step under mild condition and used as a sensitive fluorescent nanoprobe for the activity determination of N-acetyl-β-d-glucosaminidase (NAG). In this assay, p-nitrophenol was in situ produced from p-nitrophenyl-β-D-N-acetyl-glucosaminide, which was exclusively hydrolyzed by NAG. The UV absorption peak of p-nitrophenol (maximum at 400 nm) overlapped the excitation peak of CDs with maximum wavelength at 415 nm, which caused the fluorescence decline of CDs based on inner filter effect. The activity of NAG was determined by the fluorescence changes. The assay is highly sensitive to NAG with a low detection limit of 0.75 U L−1 (K = 3) and showed a good linear relationship in the range from 1 to 45 U L−1. This CDs nanoprobe was successfully applied for the determination of NAG activity in human serum and urine samples.

A comparison between observed and DFT calculations on structure of 5-(4-chlorophenyl)-2-amino-1,3,4-thiadiazole

The crystal and molecular structure of 5-(4-chlorophenyl)-2-amino-1,3,4-thiadiazole 3 was reported, which was characterized by various spectroscopic techniques (FT-IR, NMR and HRMS) and single-crystal X-ray diffraction. The crystal structure 3 (C8H6ClN3S) crystallized in the orthorhombic space group Pna21 and the unit cell consisted of 8 asymmetric molecules. The unit cell parameters were a = 11.2027(2) Å, b = 7.6705(2) Å, c = 21.2166(6) Å, α = β = γ = 90°, V = 1823.15(8) Å3, Z = 8. In addition, the structural geometry (bond lengths, bond angles, and torsion angles), the electronic properties of mono and dimeric forms of compound 3 were calculated by using the density functional theory (DFT) method at B3LYP level 6-31+ G(d,p), 6-31++ G(d,p) and 6-311+ G(d,p) basis sets in ground state. A good correlation was found (R2 = 0.998) between the observed and theoretical vibrational frequencies. Frontier molecular orbitals (HOMO and LUMO) and Molecular Electrostatic Potential map of the compound was produced by using the optimized structures. The NBO analysis was suggested that the molecular system contains N-H…N hydrogen bonding, strong conjugative interactions and the molecule become more polarized owing to the movement of π-electron cloud from donor to acceptor. The calculated structural and geometrical results were in good rational agreement with the experimental X-ray crystal structure data of 1,3,4-thiadiazol-2-amine, 3. The compound 3 exhibited n→π* UV absorption peak of UV cutoff edge, and great magnitude of the first-order hyperpolarizability was observed. The obtained results suggest that compound 3 could have potential application as NLO material. Therefore, this study provides valuable insight experimentally and theoretically, for designing new chemical entities to meet the demands of specific applications.

Properties and Extraction of Crude Pectin Esterase from Potato (Solanum Tuberosum)

In order to study the enzymatic properties of potato esterase, the crude enzyme of potato esterase was extracted with phosphate buffer solution, and the extraction conditions were optimized. The optimal condition is: the optimal condition for phosphate buffer solution pH 7.0, water bath time for 30 min, extraction temperature 35°C, and solid-liquid ratio 1:4 (g/mL). The property analysis showed that the potato esterase extracted from phosphate buffer solution was not a single esterase, but a kind of esterase isozyme. At 273nm and 325nm, the potato esterase crude enzyme had two characteristics uv absorption peak, its isoelectric point was near pI 4.4, and its molecular weight was roughly distributed at 16.4, 20.866, 22.73 and 40.286 KDa. In 40 °C ∼ 45 °C, under the condition of pH 7.0, better able to maintain its activity, and seven kinds of metal ions are inhibitory effect to it. This study provides a theoretical basis for further understanding the enzymatic characteristics of potato esterase and its application in pesticide residue detection.

Preparation and characterization of invert ZnO–B2O3 glasses and its shielding behavior towards gamma irradiation

Binary zinc borate glasses with invert compositions (50–75 mol % ZnO) were prepared by melting and annealing technique. The glasses were collectively characterized by measuring and identifying their structural building groups through FTIR spectroscopy and their optical transparency beside also their thermal expansion parameters. FTIR spectra reveal compact vibrational bands within the mid region 400-1700 cm−1 reflecting both triangular and tetrahedral borate groups beside the sharing of ZnO as either modifier oxide or as B–O–Zn linkages and possibly ZnO4 groups. The optical absorption measurements reveal that the studied undoped ZnO–B2O3 glasses show distinct UV absorption extending from 200 to 370 nm with three peaks and these UV absorption peaks are related to unavoidable trace iron (Fe3+) impurities contaminated within the chemicals used for the preparation of the zinc borate glasses. The optical absorption spectra after gamma irradiation with a dose of 5 Mrad reveal the maintenance of the UV spectra identified before irradiation with the appearance of a minor curvature at 510 nm in the spectra of two samples and disappeared at high ZnO contents. Such optical spectral result after irradiated refers to suggested shielding effect towards gamma irradiation with high ZnO content in the studied invert compositions. Both the dilatometric softening temperatures and density data show obvious increase with the first increase of ZnO content up to 70% and then reveal constancy. This behavior is correlated with the mode of housing Zn2+ ions in the network structure which is assumed to form some ZnO4 groups at high percent of ZnO giving compactness to the network of such glasses.

Efficient clean-up of waters contaminated with diazinon pesticide using photo-decomposition of peroxymonosulfate by ZnO decorated on a magnetic core/shell structure

In the present study, ZnO nanoparticles were anchored on a magnetic core/shell structure (SiO2@Fe3O4) to perpetrate ZnO@SiO2@Fe3O4 and then coupled with UV light as a heterogeneous nanocatalyst for activating peroxymonosulfate (PMS) into diazinon (DZ) degradation. Several techniques like XRD (X-ray diffraction), BET (Brunaeur, Emmett and Teller), TEM (Transmission electron microscope), FESEM (Field emission-scanning electron microscope) coupled with EDS (Energy Dispersive X-ray Spectrometer), PL (photoluminescence), VSM (Vibrating Sample Magnetometer) and UV–vis diffuse reflectance spectroscopy (DRS) were applied for identification of catalyst features. A possible mechanism for PMS activation and DZ degradation was proposed in details. The effect of solution pH, various concentrations of catalyst, PMS and DZ, quenching agents, different chemical oxidants and co-existing anions was assessed as operating factors to determine the optimum conditions. PMS decomposed effectively in coupling with ZnO@SiO2@Fe3O4 and UV. At optimal conditions, over 95 and 56% of DZ and TOC were removed during 60 min reaction, respectively. The complete degradation of DZ was confirmed using its absorption peak in UV–vis spectra analysis over 60 min treatment. A wide variety of free radicals was identified during quenching tests. HO• and h+ played a pivotal role in the degradation process of DZ. Decreasing the degradation efficiency in the presence of anions was as Cl− > CO32− > NO3− > PO43− > SO42− > HCO3−. A negligible amount of leaching Fe (<0.2 mg/L) was found for ZnO@SiO2@Fe3O4, indicating that the catalyst possesses a high stability in oxidation systems. In addition, a significant potential was achieved in reusing of catalyst within five consecutive runs. In conclusion, ZnO@SiO2@Fe3O4/PMS/UV hybrid system can be utilized as a promising advanced oxidation process into efficient degradation of pesticides, thanks to easy recovery, high catalytic activity, co-production of different reactive species and high durability and recyclability potential.

Physicochemical characterization of a novel cadmium-binding protein from rice grain endosperm

In this work, rice ultrafiltration albumin (RUA) and rice cadmium-binding protein (RCBP) were separated and purified from rice albumin (RA) in rice grain endosperm using ultrafiltration and ion-exchange chromatography (IEC). Physicochemical properties of RCBP were investigated, including cadmium content, molecular mass, ultraviolet absorption (UV) characteristics, amino acid composition, and secondary structure. The results showed that a novel cadmium-binding protein with the UV absorption peaks of 225 nm and 275 nm was purified from rice grain endosperm, and its molecular mass was determined as 13514 Da. RCBP had the highest glutamic acid content (18.31 g/100 g protein), followed by cysteine (11.45 g/100 g protein), as well as aromatic amino acids (tyrosine and phenylalanine) and histidine contents were 2.35 g/100 g protein and 1.76 g/100 g protein, respectively. In addition, the highest α-helix content (39.49%) was presented among secondary structures of RCBP, followed by random coiling (23.48%), and β-sheet and β-turn was 19.54% and 17.58%, respectively. Compared with RUA, cadmium (2.38 μg g−1) and cysteine contents of RCBP were increased by 2.66 and 5.26 times, whereas aromatic amino acids and lysine contents decreased by 46.10% and 40.97%, respectively. Moreover, the contents of α-helix and β-sheet increased significantly. Take together these results suggested that cadmium in RCBP may bind to cysteine and RCBP could be an atypical cadmium metallothionein (Cd-MT) in rice grain endosperm.

The antioxidant and antimicrobial activities of different phenolic acids grafted onto chitosan

Four phenolic acid-grafted-chitosan conjugates were prepared with different phenolic acids including gallic acid (GLA), caffeic acid (CA), gentisate acid (GTA) and sinapic acid (SA), and their characteristics were analyzed. Furthermore, the antioxidant and antimicrobial activities of conjugates were compared to screen out the optimal conjugates. The characterization analysis showed that the UV absorption peaks of CA-g-CS were stronger than that of GLA-g-CS, indicating a higher substitution degree. In addition, the substitution degree and antioxidant activity of caffeic acid-grafted-chitosan (CA-g-CS) and gallic acid-grafted-chitosan (GLA-g-CS) had significantly (p < 0.05) higher than CS and other two conjugates. However, CA-g-CS demonstrated stronger bacteriostatic ability, of which the minimum inhibitory concentrations (MICs) against Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis and Staphylococcus aureus were lower, and the inhibitory zones were larger than GLA-g-CS. In summary, the present findings will provide a theoretical basis for the expanding of CS application in food processing and preservation.

Potential benefits of polysaccharides derived from marine alga Ulva lactuca against hepatotoxicity and nephrotoxicity induced by thiacloprid, an insecticide pollutant.

The present study aimed to evaluate the potential protective and antioxidant effect of polysaccharides (PS) extracted from Ulva lactuca against thiacloprid (THC) induced nephrotoxicity and hepatotoxicity. The antioxidant capacity of PS was tested in vitro using ABTS radical scavenging activity and plasmid DNA cleavage assays andin vivo on adult male rats treated for 30 days. Animals were allocated into four groups: control; THC (22.5 mg/kg); THC (22.5 mg/kg) + PS1 (100 mg/kg diet); and THC (22.5 mg/kg) + PS2 (200 mg/kg diet). The structural features of PS were determined by Fourier transformed infrared (FT-IR), UV absorption peak detection, high performance liquid chromatography (HPLC) and gel permeation chromatography, and also functional properties were investigated. Overall, results indicated that THC increased significantly malondialdehyde, advanced oxidation protein products, glutathione levels, which is correlated with severe histological and plasmatic biochemical injuries in both liver and kidney tissues. However, cotreatment PS induced a significant protective and healing affects against the nephrotoxicity and hepatotoxcity induced by THC.

Photoprotective and Antigenotoxic Effects of the Flavonoids Apigenin, Naringenin and Pinocembrin.

This work evaluated the photoprotective and antigenotoxic effects against ultraviolet B (UVB) radiation of flavonoid compounds apigenin, naringenin and pinocembrin. The photoprotective efficacy of these compounds was estimated using in vitro photoprotection indices, and the antigenotoxicity against UVB radiation was evaluated using the SOS chromotest and an enzymatic (proteinase K/T4 endonuclease V enzyme) comet assay in UV-treated Escherichia coli and human (HEK-293) cells, respectively. Naringenin and pinocembrin showed maximum UV-absorption peak in UVC and UVB zones, while apigenin showed UV-absorption capability from UVC to UVA range. These compounds acted as UV filters reducing UV-induced genotoxicity, both in bacteria and in human cells. The enzymatic comet assay resulted highly sensitive for detection of UVB-induced DNA damage in HEK-293 cells. In this work, the photoprotective potential of these flavonoids was widely discussed.

Experimental Study of Rutile Crystalline Phase Titania Nanoparticles via Chemical Route

TiO2 nanoparticles have been demanded in many applications. Sol-gel chemical process is one of the easiest ways and possesses credentials to optimize optical, electrical and structural properties of the materials during the synthesis process. In this work, we present the synthesis and characterization of TiO2 nanoparticles. X-ray diffraction pattern and Raman study showed the rutile phase peaks. UV-Vis spectroscopy analysis showed the UV absorption peak at 392 nm corresponds to the band gap value 3.03 eV. The polycrystalline nature of the prepared nanoparticles is confirmed by the transmission scanning microscopy (TEM) measurement.

Combination of CuS and g-C3N4 QDs on upconversion nanoparticles for targeted photothermal and photodynamic cancer therapy

Combined therapy with multimodal therapeutic agents based on nanomaterials has been shown as a promising approach to cancer treatment. In this report, a highly efficient multifunctional anti-cancer nanocomposite was fabricated by assembling a photothermal agent (CuS nanoparticles) and a photodynamic agent (g-C3N4 quantum dots) on upconversion nanoparticles (UCNPs) after mesoporous silica coating. Then, the surface modification of the obtained nanocomposite (abbreviated as CUSCs) with polyethylene glycol (PEG) and folic acid (FA) endows the final sample (denoted as CUSCs-PEG-FA) with an excellent cancer cell targeting effect and biocompatibility. In this nanoplatform, CuS nanoparticles are an inorganic substance with low toxicity and high photothermal conversion efficiency. g-C3N4 QDs have excellent biocompatibility and are beneficial for cellular uptake due to their small size. UCNPs can be excited by near-infrared (NIR) light to produce ultraviolet and visible (UV–vis) light emission, which overlaps with the UV absorption peak of high fluorescence g-C3N4 quantum dots (QDs). Therefore, when the nanocomposite is excited by 808 nm NIR light, a synergistic treatment effect will be presented. Since the wavelengths absorbed by the chosen photothermal agent and the photosensitizer are different, sufficient utilization of energy can be achieved. Combining photothermal therapy (high photothermal conversion efficiency of 27.4%) and photodynamic therapy can inhibit cancer more effectively compared to any monotherapy. Moreover, as a result of the inherent performance ability of the doped rare earth ions, excellent applicability for computed tomography (CT), upconversion luminescence (UCL) and magnetic resonance imaging (MRI) has been achieved.