Electrospining: Preparation and antibacterial properties of MPN@Zein-PpIX membrane

Background

Bacterial infection has become one of the most serious health problems in the world. It can induce many diseases such as pneumonia, meningitis, sepsis, cholera, skin ulcers and gastric cancer. In particular, wounds are more susceptible to bacterial infections due to the loss of skin protection. So far, antibiotics have been the first choice for treating bacterial infections. However, long-term and excessive use of antibiotics may cause serious side effects. Therefore, it is imperative to develop more efficient antibacterial materials in a non-antibiotic way.

The main point of this paper

Photothermal therapy (PTT):

PTT uses photothermal agents to convert near-infrared radiation (NIR) into heat, killing bacteria by destroying cell membranes or inactivating essential enzymes and proteins. PTT has the advantages of high efficiency, good controllability, and limited drug resistance

Photodynamic therapy (PDT):

PDT is a process that can cause bacterial cell death in the presence of light energy of appropriate wavelengths. PDT relies on the participation of photosensitizers (PSs), which are irradiated with lasers of specific wavelengths to put PSs in a singlet excited state, producing reactive singlet oxygen (1O2), which causes irreversible damage to the main components of bacteria and leads to bacterial death

Limitations of PDT and PTT:

PDT requires oxygen, and many bacterial infections occur in hypoxic environments, which means that the effect of PDT is weakened in low-oxygen environments. The thermal effect produced by PTT has low specificity for bacterial reactions, and the penetration of lasers of specific wavelengths into tissues limits its therapeutic effect

Combined application of PDT and PTT:

In order to overcome the disadvantages of using PDT or PTT alone, researchers have explored the combination of PDT and PTT. Protoporphyrin IX (PpIX) is a widely used PS that can produce significant photodynamic effects under the irradiation of a light source with a wavelength of 620-630 nm

Preparation of MPN@Zein-PpIX membrane and its antibacterial properties:

The researchers fixed PpIX on zein by electrospinning technology and prepared an in situ adherent fiber membrane (zein-PpIX) to improve the biocompatibility of PpIX. Zein has good biodegradability, biocompatibility and non-toxicity, and has unique film-forming properties. A metal polyphenol network (MPN) was constructed on the Zein-PpIX fiber membrane. MPN acts as a photothermal agent in the photothermal effect, converting near-infrared light energy into thermal energy and killing bacteria through thermal damage

Characteristics of MPN@Zein-PpIX membrane:

The MPN@Zein-PpIX membrane combines the advantages of PDT and PTT. PpIX produces singlet oxygen and MPN produces significant thermal effects under light of different wavelengths. The two work together to exert antibacterial effects, with high antibacterial properties and good biocompatibility, ensuring the great potential of MPN@Zein-PpIX membrane as an antibacterial material in clinical applications

Preparation of MPN@Zein-PpIX photothermal and photodynamic antibacterial membrane by electrospinning and its properties

Preparation method:

By electrospinning technology, protoporphyrin IX (PpIX) was introduced into zein to form a modified zein fiber structure, and finally a metal polyphenol network (MPN) coating was introduced on the fiber surface to form an MPN@Zein-PpIX membrane.

Photothermal and photodynamic properties:

The MPN@Zein-PpIX membrane exhibited good singlet oxygen generation ability and excellent photothermal conversion efficiency.

Antibacterial activity:

The antibacterial activity of the MPN@Zein-PpIX membrane was evaluated by in vitro agar plate counting method, and it was found that it exhibited good antibacterial ability in vitro due to the combination of photothermal and photodynamic properties.

Biocompatibility and adhesion:

PpIX was fixed on zein by electrospinning technology, and the prepared fiber membrane (Zein-PpIX) improved the biocompatibility of PpIX.

The MPN coating made the membrane surface more hydrophilic and enhanced the adhesion ability of the membrane to biological tissues.

Application potential:

MPN@Zein-PpIX membrane provides a new idea for the combination of photodynamic therapy (PDT) and photothermal therapy (PTT) and shows great potential in the field of antibacterial applications.

Summarize

This study proposed a membrane MPN@Zein-PpIX that combines PDT and PTT as antimicrobial agents. The photosensitizer PpIX is combined with the photothermal converter MPN, and the synthesis method is very simple. Under light of different wavelengths, the membrane exhibits good singlet oxygen production and in vitro photothermal conversion capabilities. Due to the combined effects of PDT and PTT, in vitro antibacterial experiments showed that the MPN@Zein-PpIX membrane has excellent antibacterial effects on planktonic bacteria. In addition, in vitro cytotoxicity experiments proved that the MPN@Zein-PpIX membrane has good biosafety and is expected to be used as an efficient antibacterial dressing.