Ultrastable graphene isolated Au Ag nanoalloy for SERS biosensing and photothermal therapy of bacterial infection

Plasmonic metal nanomaterials with intrinsic surface–enhanced Raman scattering(SERS)and photothermal properties,especially AuAg nanoalloys with both the outstanding merits of Au and Ag nanocrystals,show huge application prospects in bacterial theranostics.However,the direct exposure of AuAg nanoalloys in external conditions probably cause undesirable reactions and poisonous metal ion leakage during SERS detection and photothermal antibacterial therapy process,which severely hinder bacterial theranostics applications.Herein,we report an ultrastable graphene–isolated AuAg nanoalloy(GAA)with AuAg core confined in few–layer graphitic shell as a versatile platform for bacterial detection and therapy.The encapsulation of graphene ensures the good stability of AuAg core,that its superior SERS and photothermal properties are therefore further guaranteed.GAA is used for SERS detection of two vital bacterial biomarkers(including corrosive cyanide and pyocyanin),exhibiting good SERS quantitative and multiplexing ability.GAA is further used for photothermal antibacterial therapy application,and ultrahigh antibacterial efficacies for both Gram–negative Escherichia coli and Gram–positive Staphylococcus aureus are achieved under 808 nm laser irradiation.This work proposes a valuable method to develop robust bacterial theranostic platform.

A Magnetocatalytic Propelled Cobalt-Platinum@Graphene Navigator for Enhanced Tumor Penetration and Theranostics

Complex biological environments and multiple physiological barriers significantly impede efficient accumulation and penetration of nanomaterials within tumor tissue for therapy.In situ energy conversion of nanomotors features autonomous movements and improves cancer treatment.However,one of the key challenges is to prepare nanomotors with an adequately small size,good biocompatibility,and precise positioning.Herein,we demonstrate a simple,ultrasmall,versatile,and real-time motion guidance strategy for magnetocatalytic CoPt@graphene navigators(MCGNs)that can enable highly efficient propulsion in the presence of H_(2)O_(2) or magnetic actuation.MCGNs act as highly diffusive delivery vehicles to promote tumor tissue targeting,and the amount of drug in the tumor was three times than without navigation.By engaging movements powered through in situ energy conversion,MCGNs gain considerable propulsion to penetrate a cell’s membrane and enhance intracellular delivery.

Versatile graphitic nanozymes for magneto actuated cascade reaction-enhanced treatment of S.mutans biofilms

Pathogenic oral biofilms especially acid-producing ones cause a variety of oral diseases such as dental caries.Given that bacteria are embedded within the biofilms matrix to prevent the penetration of therapeutic drugs,people have explored the applications of nanoparticles to treat oral diseases.However,current nanoparticle-mediated eradication has not achieved the precise treatment of biofilms,and the stabilities of nanoparticles go on strike because of acidic environment leading to poor therapeutic effectiveness.Herein,we design an integrated nanozyme,CoPt@graphene@glucose oxidase(CoPt@G@GOx),which has cascade reaction activity with two-step process.Hydrogen peroxide(H_(2)O_(2))produced through the glucose oxidation by GOx serves as the substrate for peroxidase-mimic CoPt@G to produce highly toxic hydroxyl radical under acidic environment.Compared to the simple mixture of GOx and CoPt@G,CoPt@G@GOx shows around fourfold catalytic effect enhancement.Meanwhile,CoPt@G@GOx can precisely target the location of the biofilms,which ensures the minimal impact on normal softtissues.Relying on the advantage of the magneto-actuated cascade catalytic activity,CoPt@G@GOx reveals a superior antibacterial ability in the Streptococcus mutans biofilms model.Thus,our results provide an easy and effective method to exploit bifunctional nanozyme as a novel topical agent to prevent the prevalent biofilm-induced oral disease.

Hydrogen-Bonding-Induced H-Aggregation of Charge-Transfer Complexes for Ultra-Efficient Second Near-Infrared Region Photothermal Conversion

Aggregation plays a critical role in modulating the photophysical process of organicmolecules.However,the rational control of the construction of a functionoriented stacking mode for efficient photothermal(PT)conversion in the second near-infrared region(NIR-II;1000-1700 nm)remains a challenge.Herein,an H-aggregation of 3,3′,5,5′-Tetramethylbenzidine(TMB)-TMB dication(TMB++)complexes in linear agarose(H-TTC/LAG)with narrowed band gap(0.96 eV)was fabricated through intermolecular hydrogenbonding interactions between the amino groups of TTC and the peripheral hydroxyl groups of LAG.Charge-transfer mechanism and H-aggregation ensured NIR-Ⅱ absorption of the complex at>1400 nm.The H-aggregation also promoted a non-radiation relaxation pathway and improved the thermal stability of TTC,which together favored the constructed H-TTC/LAG with ultra-efficient PT conversion that increased rapidly to 140℃ in 15 s under the NIR-Ⅱ laser(1064 nm,1.0 W cm^(−2))irradiation.Such a unique H-TTC/LAG with good biocompatibility was used to demonstrate a superior PT therapy via high-efficie ncy tumor growth inhibition in mouse mammary carcinoma(4T1)the BALB/c mice tumor-bearing xenografts.This is the first established H-aggregation of charge-transfer complexes in a noncovalent system,which not only provides a new strategy to develop ultra-efficient NIR-Ⅱ PT materials but also paves the way for constructing functional materials with aggregates of charge-transfer complexes.