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Breast cancer is a serious threat to the health of women all over the world. The precise diagnosis and treatment of breast cancer are of great importance to control the development of breast cancer as well as to improve survival rates of the patients. Nowadays, polypeptides are widely applied in breast cancer-related research, benefiting from lower immunogenicity, better biodegradability, higher penetration, and easier synthesis and modification. In this review, we have summarized recent applications of functional polypeptides in the detection and imaging of breast cancer, in which polypeptides work not only as a recognition element and signal source for detecting and imaging breast tumours, but also a building block and a therapeutic drug to assist image-guided treatment of breast cancer.

The delivery of mRNA to manipulate protein expression has attracted widespread attention, since that mRNA overcomes the problem of infection and mutation risks in transgenes and can work as drugs for the treatment of diseases. Although there are currently some vehicles that deliver mRNA into cells, they have not yet reached a good balance in terms of expression efficiency and biocompatibility. Here, a DNA nano-hydrogel system for mRNA delivery is developed. The nano-hydrogel is all composed of DNA except the target mRNA, so it has superior biocompatibility compared with those chemical vehicles. In parallel, the nano-hydrogel can be compacted into a nanosphere under the crosslinking by well-designed "X"-shaped DNA scaffolds and DNA linkers, facilitating the delivery into cells through endocytosis. In addition, smart intracellular release of the mRNA is achieved by incorporating a pH-responsive i-motif structure into the nano-hydrogel. Thus, taking the efficient delivery and release together, mRNA can be translated into the corresponding protein with a high efficiency, which is comparable to that of the commercial liposome but with a much better biocompatibility. Due to the excellent biocompatibility and efficiency, this nano-hydrogel system is expected to become a competitive alternative for delivering functional mRNA in vivo.

An antibacterial and biodegradable composite hydrogel dressing integrated with microspheres is developed for drug delivery and wound healing. The mechanism of gelation is attributed to the Schiff-base reaction between aldehyde and amino groups of oxidized alginate (OAlg) and carboxymethyl chitosan (CMCS). To enhance antibacterial and mechanical properties, tetracycline hydrochloride (TH) loaded gelatin microspheres (GMs) were fabricated by an emulsion cross-linking method, followed by integrating into the OAlg-CMCS hydrogel to produce a composite gel dressing. In vitro gelation time, swelling, degradation, compressive modulus and rheological properties of the gel dressing were investigated as the function of microsphere ratios. With increasing ratios of microspheres from 10 to 40mg/mL, the composite dressing manifested shorter gelation time and lower swelling ratios, as well as higher mechanical strength. Comparing to other formulations, the gel dressing with 30mg/mL microspheres showed more suitable stabilities and mechanical properties for wound healing. Also, in vitro drug release results showed that the loaded TH could be sustained release from the composite gel dressing by contrast with pure hydrogels and microspheres. Furthermore, powerful bacteria growth inhibition effects against Escherichia coli and Staphylococcus aureus suggested that the composite gel dressing, especially the one with 30mg/mL GMs containing TH, has a promising future in treatment of bacterial infection.

In this work, we propose a novel concept and a proof-of-concept strategy for the fabrication of a pH-based immunoassay platform with a certain degree of universality and scalability to make it adaptable for different application scenarios. The immunoreactions for the target detection are converted to pH changes through an engineered and optimized isothermal nucleic acid amplification, named exponential amplification reaction (EXPAR). Thus, a variety of well-developed methods for pH analysis, e.g. pH indicators, pH-strips and pH meters, can be applied for immunoassay directly. Here, we show that this proof-of-concept strategy is applicable for both macromolecular and micromolecular antigens by adopting human platelet-derived growth factor-BB (PDGF-BB) and chloramphenicol (CAP) as the model targets, respectively. The detection can be achieved using a colorimetric pH indicator after a 15 min reaction of the immuno-triggered isothermal nucleic acid amplification. In addition, compared with the traditional enzyme-linked immunosorbent assay (ELISA), the performance of our strategy, especially the detection limits, is improved to varying degrees for different targets, making the strategy a promising alternative for diverse application scenarios of immunoassay.

As a bifunctional enzyme, T4 polynucleotide kinase phosphatase (T4 PNKP) catalyzes the phosphorylation of 5′-hydroxyl, and also removes the terminal 3′-phosphate group. This is closely related to the restructuring, replication, and damage repair of nucleic acid. In this paper, we describe a new method for the sensitive detection of T4 PNKP activity based on the isothermal EXPonential amplification reaction (EXPAR). T4 PNKP can be linearly assayed in the range from 0.001 to 0.01 U mL−1 with a detection limit of 7.9 × 10−4 U mL−1. Moreover, the method exhibits high specificity and sensitivity and can be applied in the enzyme analysis of complex serum samples. In view of its simplicity and moderate experimental conditions, the method may suitable for use in a commercial kit for the analysis of T4 PNKP activity.

In this work, a cationic polymer, N-alkylated poly (4-vinylpyridine) was applied for the surface functionalization of nanodiamond (ND). The facile route not only settled the problems of agglomeration and poor dispersion stability of ND but also rendered the nanomaterial antibacterial property. Chemical modification of the particles was confirmed by FT-IR spectroscopy and 1HNMR, and the cationic polymer contents were determined by TGA studies. The particle diameters and dispersity of functionalized NDs were investigated by TEM and DLS measurements. It was found that extremely tight core aggregates (100–200 nm) were broken into tiny nanoparticles (20–30 nm) through functionalization with NPVP-propyl or NPVP-hexyl, which gave stable and homogeneous functionalized ND particles in colloidal solution. The antibacterial tests against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) showed that the cationic polymer-modified ND exerted certain antibacterial activity. The FE-SEM images indicated that NPVP-hexyl-ND particles were attached to the cell wall surface of E. coli, which subsequently led to the formation of nanoscale holes on cell membrane and eventually the serious destruction of cell wall. We suspected that the interaction of NPVP-hexyl-ND with bacteria may come from the electrostatic interactions, the intermolecular and surface forces between functionalized nanoparticles and cell membranes, which may damage the outer membranes of bacteria and result in cell death.

To meet the progressive requirements for bone regeneration purpose, injectable hydrogels have attracted increasing attention in tissue regeneration and local drug delivery applications. In this study, we report a facile method to prepare injectable and degradable polysaccharide-based hydrogels doubly integrated with hydroxyapatite (HAp) nanoparticles and calcium carbonate microspheres (CMs) under physiological condition. The mechanism of cross-linking is attributed to the Schiff-base reaction between amino and aldehyde groups of carboxymethyl chitosan (CMCS) and oxidized alginate (OAlg), respectively. Synchronously, tetracycline hydrochloride (TH) loaded CMs were fabricated by the precipitation reaction with an average diameter of 6.62 μm. To enhance bioactive and mechanical properties, nano-HAp and CMs containing TH were encapsulated into the polysaccharide-based hydrogel to form injectable gel scaffolds for imitation of bone niche. The gelation time, morphology, mechanical properties, swelling ratio and in vitro degradation of the gel scaffolds could be controlled by varying HAp and CMs contents. Moreover, the composite gel scaffolds had good sustained drug release and antibacterial properties, as confirmed by drugs release calculation and antibacterial evaluation. In addition, the gel scaffolds were found to be self-healing due to dynamic equilibrium of the Schiff-base linkages. These results suggested that the prepared composite gel scaffolds hold great potential for drug delivery and regeneration of irregular bone defects.

Nanostructured biopolymer hydrogels have great potential in the field of drug delivery and regenerative medicine. In this work, a nano-fibrous (NF) biopolymer hydrogel was developed for cell growth factors (GFs) delivery and in vitro osteogenesis. The nano-fibrous hydrogel was produced via biological conjugation of streptavidin functionalized hyaluronic acid (HA-Streptavidin) and biotin terminated star-shaped poly(ethylene glycol) (PEG-Biotin). In the present work, in vitro gelation, mechanical properties, degradation and equilibrium swelling of the NF hydrogel were examined. The potential application of this NF gel scaffold in bone tissue engineering was confirmed by encapsulation behavior of osteoblasts. Osteoblasts seeded directly in NF gel scaffold containing cell growth factor, e.g. bone morphogenetic protein 2 (BMP-2), was to mimic the in vivo microenvironment in which cells interface biomaterials and interact with BMP-2. In combination with BMP-2, the NF hydrogel exhibited beneficial effects on osteoblast activity and differentiation, which suggested a promising future for local treatment of pathologies involving bone loss.