Biomimetic channels based on carbon nanotubes (CNTs) with fast and selective transport have attractive applications in many fields. In this work, a remarkable and modulated enhancement in the ion transport rate through CNTs is facilitated by means of lipid decoration, by a factor of up to 20 times. A type of CNT membrane is firstly prepared, composed of well aligned multi-wall carbon nanotubes with an inner size of ∼10 nm. An inter-diffusion method is used to efficiently incorporate lipids within the CNTs. It is found that the lipid phase state as well as the surface property of the tubes' inner walls corporately determine the assembly behavior, such as location and stability of lipids, which further influence the ion transport rate through the tubes. For example, the incorporation and self-assembly of liquid-phase DOPC and polymerized Diyne-PC within the tubes induces an enhancement in steady ion transport rate through CNTs by a factor of 5 and 20 times, respectively. In contrast, the gel-phase DPPC prefers to stay at tube tips, which increases the ion transport rate during the initial stage only. This work provides a practical guide to regulate the ion transport behaviors through CNTs for versatile applications.

The quick response of magnetic nanoparticles (MNPs) to an external field provides a unique way for cellular manipulation in a remote and non-contact mode. In this work, we demonstrate the modulation of cellular behaviors including orientation and migration based on internalized Fe3O4 nanoparticles in a particle-concentration dependent manner. After being treated with MNPs at low concentrations (e.g. 0.277 μg mL−1), the internalized particles separately distributed around the nuclei, and somewhat influenced the orientation of the cells along the direction of the external magnetic field. In contrast, when the concentration of MNPs was high enough (e.g. 2.770 μg mL−1), the particles formed clusters within the cells and moved towards the edges of the cell in the direction of the magnetic field, leading to an obvious morphological change and subsequently a directed migration of the cells. This result shows a facile way to manipulate cell behaviors with excellent biocompatibility and its potential application in the biomedical field such as in tissue engineering.

Biomembrane transformations are closely related to many biological processes including endo/exocytosis and the cellular response to the local physical environment. In this work, we investigated the transformation between lipid membranes and lipid vesicles/tubes modulated by the solid substrate of graphene oxide (GO) aggregates under laser irradiation. We firstly fabricate a novel type of lipid@GO composite consisting of micrometer-sized GO aggregates surrounded by lamellar lipid membranes. Upon laser irradiation, lipid protrusion occurs and leads to the formation of vesicles adsorbed on the GO aggregate surface, with an average size as 0.43 times of the radius of GO aggregate. Both the location and the dynamic formation process of vesicles can be modulated. The arising of vesicles prefers to occur at edges of the GO planes rather than on surface of individual GO sheets within the GO aggregate. Furthermore, at a reduced laser power density, the lipid protrusion mainly grows to tubes instead of vesicles. Such transformations from lipid membrane to vesicles and tubes is ascribed to the reduction of GO to reduced-GO (rGO) under laser irradiation, probably along with the release of gases leading to the deformation of lipid membrane surrounding the GO surface.

Regenerated Bombyx mori (B. mori) silk fibroin is a type of widely used biomaterial. The β-sheet structure of it after methanol treatment provides water-insolubility and mechanical stability while on the other side leads to a hydrophobic surface which is less preferred by biological systems. In this work we prepare a novel type of nanoconfined silk fibroin film with a thickness below 100 nm. The film has a flat while hydrophobic surface because of its β-sheet structure due to the z-direction confinement during formation. Different types of lipid monolayers, DOPC, DPPC and MO, are assembled on the silk film surface. The lipid coating, especially the DPPC membrane, provides a much smoother and more hydrophilic surface due to the gel phase tails of the lipids, in comparison with the DOPC and MO ones which are in a liquid phase and have a much stronger interfacial association between silk film surface and lipid tails. Such a lipid coating preserves the biocompatibility and cellular affinity of the silk film which promises potential applications as surface coatings for materials for biological use.

A type of photo- and thermo-responsive composite microsphere composed of reduced graphene oxide nanoparticles and poly(N-isopropylacrylamide) (rGO@pNIPAM) is successfully fabricated by a facile solution mixing method. Due to the high optical absorbance and thermal conduction of rGO, the composite microspheres are endowed with the new property of photo-response, in addition to the intrinsic thermally sensitive property of pNIPAM. This new ability undoubtedly enlarges the scope of applications of the microgel spheres. Furthermore, through controlling the rGO content in the composite, the photo- and thermo-sensitivity of the composite can be effectively modulated. That is, with a lower rGO content (≤32% by weight), the composite microspheres perform only thermally induced changes, such as volume contraction (by ∼45% in diameter) and drug release, when crossing the lower critical solution temperature of pNIPAM. With a higher rGO content (∼47.5%), both temperature and light irradiation can trigger changes in the composite. However, when the rGO content is increased to around 64.5%, the thermo-responsivity of the composite disappears, and the spheres exhibit only photo-induced drug release. With a further increase in rGO content, the environmentally responsive ability of the microspheres vanishes.

It is increasingly recognized that the investigation of the rotational motion of geometric nanoparticles in the cellular internalization process is significant to understand certain fundamental cellular activities, such as endocytosis. However, the mechanism of rotation of geometric nanoparticles in the internalization process is still largely unknown. Here, we investigate the rotational dynamics of geometric nanoparticles when they adhere onto or are wrapped by lipid membranes, by using dissipative particle dynamics. A variety of rotational modes of the nanoparticles are observed, which are closely related to the complicated competition in the internalization process. We find that the breaking of geometric symmetry of a nanoparticle is important for the occurrence of particle rotation, while its effect can be changed by the orientation of the nanoparticles and the affinity between the ligands and the receptors. Importantly, it is found by our simulations that the rotational mode even determines the possible perturbation of the geometric nanoparticle to the membrane and the configuration between the nanoparticle and lipid membrane in the internalization process. These results provide a new strategy and also provide pivotal insight for the design of nanoparticles as advanced drug-delivery vectors to cells.

Environmentally responsive materials are attractive for advance biomedicine applications such as controlled drug delivery and gene therapies. Recently, we have introduced the fabrication of a novel type of stimuli-sensitive lipogel composite consisting of poly(N-isopropylacrylamide) (pNIPAM) microgel particles and lipids. In this study, we demonstrated the temperature-triggered drug release behavior and the tunable drug loading and release capacities of the lipogel. At room temperature (22 °C), no calcein was released from the lipogel over time. At body temperature (37 °C), the release process was significantly promoted; lipids in the lipogel acted as drug holders on the pNIPAM scaffold carrier and prolonged the calcein release process from 10 min to 2 h. Furthermore, the loading and release of calcein could be effectively controlled by modulating the relative amount of lipids incorporated in the lipogel, which can be realized by the salt-induced lipid release of the lipogel.

Cellular uptake of materials plays a key role in their biomedical applications. In this work, based on the cell-mimic giant unilamellar vesicles (GUVs) and a novel type of microscale materials consisting of stimuli-responsive poly(N-isopropylacrylamide) microgel particles and the incorporated lipids, the influence of particle surface chemistry, including hydrophobic/hydrophilic property and lipid decorations, on the adsorption and consequent internalization of particles into GUVs was investigated. It is found that the decoration of particle surface with lipids facilitates the adsorption of particles on GUV membrane. After that, the hydrophobic property of particle surface further triggers the internalization of particles into GUVs. These results demonstrate the importance of surface properties of particles on their interactions with lipid membranes and are helpful to the understanding of cellular uptake mechanism.

The molecular-level interactions of an antimicrobial peptide melittin with supported membrane were studied by the combination of dissipative quartz crystal microbalance (QCM-D) experiments and computer simulations. We found the response behavior of lipids upon peptide adsorption greatly influence their interactions. The perturbance and reorientation of the lipid in liquid phase facilitate the insertion of melittin in a trans-membrane way, but in solid phase, asymmetrical membrane disruption happens. Apart from the lipid state, the local peptide-to-lipid ratio also affects the insertion capacity of melittin. When the local peptide number density is high, adjacent peptides can cooperatively penetrate into the membrane. This observation explains the occurrence of the conventional “carpet” mechanism.

•A type of plasmonic Ag@Si chips composing of Si supported Ag film was fabricated.•The chips show viable integration into fluorescent immunoassays for enhancement.•The chips show up to 57 times enhancement at 800 nm in fluorescence protein assay.•The chips show up to 4.1 times fluorescence enhancement for cell and tissue imaging.Metal-enhanced fluorescence shows great potential for improving the sensitivity of fluoroscopy, which has been widely used in protein and nucleic acid detection for biosensor and bioassay applications. In comparison with the traditional glass-supported metal nanoparticles (MNPs), the introduction of a silicon substrate has been shown to provide an increased surface-enhanced Raman scattering (SERS) effect due to the coupling between the MNPs and the semiconducting silicon substrate. In this work, we further study the fluorescence-enhanced effect of the silicon-supported silver-island (Ag@Si) plasmonic chips. In particular, we investigate their practical application of improving the traditional immunoassay such as the biotin-streptavidin-based protein assay and the protein-/nucleic acid-labeled cell and tissue samples. The protein assay shows a wavelength-dependent enhancement effect of the Ag@Si chip, with an enhancement factor ranging from 1.2 (at 532 nm) to 57.3 (at 800 nm). Moreover, for the protein- and nucleic acid-labeled cell and tissue samples, the Ag@Si chip provides a fluorescence enhancement factor of 3.0–4.1 (at 800 nm) and a significant improvement in the signal/background ratio for the microscopy images. Such a ready accommodation of the fluorescence-enhanced effect for the immunoassay samples with simple manipulations indicates broad potential for applications of the Ag@Si chip not only in biological studies but also in the clinical field.

A type of photo- and thermo-responsive composite microsphere composed of reduced graphene oxide nanoparticles and poly(N-isopropylacrylamide) (rGO@pNIPAM) is successfully fabricated by a facile solution mixing method. Due to the high optical absorbance and thermal conduction of rGO, the composite microspheres are endowed with the new property of photo-response, in addition to the intrinsic thermally sensitive property of pNIPAM. This new ability undoubtedly enlarges the scope of applications of the microgel spheres. Furthermore, through controlling the rGO content in the composite, the photo- and thermo-sensitivity of the composite can be effectively modulated. That is, with a lower rGO content (≤32% by weight), the composite microspheres perform only thermally induced changes, such as volume contraction (by ∼45% in diameter) and drug release, when crossing the lower critical solution temperature of pNIPAM. With a higher rGO content (∼47.5%), both temperature and light irradiation can trigger changes in the composite. However, when the rGO content is increased to around 64.5%, the thermo-responsivity of the composite disappears, and the spheres exhibit only photo-induced drug release. With a further increase in rGO content, the environmentally responsive ability of the microspheres vanishes.

The quick response of magnetic nanoparticles (MNPs) to an external field provides a unique way for cellular manipulation in a remote and non-contact mode. In this work, we demonstrate the modulation of cellular behaviors including orientation and migration based on internalized Fe3O4 nanoparticles in a particle-concentration dependent manner. After being treated with MNPs at low concentrations (e.g. 0.277 μg mL−1), the internalized particles separately distributed around the nuclei, and somewhat influenced the orientation of the cells along the direction of the external magnetic field. In contrast, when the concentration of MNPs was high enough (e.g. 2.770 μg mL−1), the particles formed clusters within the cells and moved towards the edges of the cell in the direction of the magnetic field, leading to an obvious morphological change and subsequently a directed migration of the cells. This result shows a facile way to manipulate cell behaviors with excellent biocompatibility and its potential application in the biomedical field such as in tissue engineering.