Bandages sense infections, change color, treat infection

In what reads like science fiction, a new study published in the journal ACS Central Science reports the development of bandages that detect the presence of bacteria in wounds and change color, depending on whether they are drug-sensitive or drug-resistant. This is an important step in helping patients recover better. There are also bandages for specific uses, like orthopedic bandage, and fixation bandage.


Drug resistance – the problem


Drug resistance is among the greatest threats to worldwide health. If bacterial infections could be sensed early enough to treat them before they take a hold on the patient, it would help avoid serious infections. And if the bacteria resist the antibiotic, being able to detect this would be crucial in switching drugs to arrest the infection before it spreads.
At present, the methods of detecting antibiotic resistance are expensive, require professional expertise, and take too much time. Moreover, using antibiotics for infections that are resistant to them promotes even more drug resistance.


Colorimetric methods to the rescue


The new study describes a way of doing just this, based on a color-changing material. Described as “a portable paper-based band-aid (PBA)”, it is a colorimetric way of sensing and treating sensitive bacterial infections while signaling the presence of drug-resistant bacteria as well.

Early detection of infection in this study exploits the microenvironment of bacterial growth, which includes an acidic pH, various toxins and enzymes. Acidity is an easy way to track the presence of pathogenic bacteria because it is due to their breakdown of glucose. Drug resistance, on the other hand, depends on the presence of the beta-lactamase and similar enzymes. The presence of beta-lactamase is a widely used indicator of bacterial antibiotic resistance because it denotes resistance to the extremely common beta-lactam antibiotics.


Once drug resistance has been identified, photodynamic therapy and other similar treatments have been adopted to increase the level of reactive oxygen species (ROS). These molecules act on multiple cell targets associated with drug resistance, including the bacterial cell wall, nucleic acids, and proteins. A careful use of this strategy is necessary since ROS attack healthy cells and bacteria indiscriminately.

The innovation


The need of the hour is a portable, cheap and accurate device to detect and overcome antibiotic resistance. Paper-based platforms, including biosensors and sterilization paper, have stolen the limelight in this regard because of multiple advantages: low cost, sustainability, safety, and ease of adjustment. The current study focuses on a paper-based bandage device to detect and treat infection selectively after sensing antibiotic resistance.

The basis of the bandage is colorimetry. And tapes and plasters are also needed. It contains bromyothymol B that is green at first but becomes yellow on encountering acids that are found in the microenvironment of a bacterial infection. In this situation, the material releases an antibiotic, ampicillin, loaded on nanoparticles and coated with the sugar chitosan that attracts bacteria due to their negative charge. When the nanoparticles come into contact with the acid environment, they release the drug. If the bacteria are sensitive to this drug, they will be killed. If otherwise, they secrete beta-lactamase to inactivate the drug. This enzyme acts on the yellow molecule nitrocefin to turn it red.
If the bandage for first aid becomes red, the researchers will pass light through the bandage, which stimulates the production of reactive oxygen species from a metallo-organic compound called PCN-224, built on a porphyrin base, and which has high photodynamic properties, releasing a flood of ROS in response to light. These inhibit or weaken the bacteria, increasing their susceptibility to the drug. Thus, the tubular bandage has been proved to accelerate wound healing in mice after introducing both drug-sensitive and drug-resistant bacteria into the wounds.

HOW TO CARE FOR RAW OPEN SKIN WOUNDS?

All raw wounds will heal if there is enough blood supply to the area, and if the raw tissues are not allowed to “dry and die.” Open raw wounds will heal with proper care even if there is exposed fat, bone, tendon, muscle, or joint. Red is raw; pink is healed. If the wound is red, it has lost the waterproof barrier of skin and it is an open or raw wound that oozes liquid as our bodies are 80% water. The most important part of the care of raw wounds is to keep them clean and greasy so the tissues do not dry and die. Wounds all over the body can be treated in this manner. Below, we illustrate 4 typical case examples where we use this approach in complex wounds of the foot, hand, fingertips,2 and face with exposed bone, cartilage, joints, and tendons. In some cases, if there are deep, open, caved in wounds, we add a vacuum assisted wound dressing to accelerate flattening the cave.

What Kind of Operation Bandage Do We Need for Wounds?


Dressings do not need to be sterile, just clean.6 Sterile dressings are expensive and unnecessary. Coban tape off the roll is a good clean dressing that can be directly applied over grease on fingers and leg wounds.2 Panty liners, sanitary napkins, and diapers out of the package are another good source of clean inexpensive dressings.7 Every day, the old dressing is removed and the patient gets in the shower to let clean water run over the wound. After the shower, grease is applied thickly to a clean bandage. That is placed on the wound to pad it, protect it, and keep it moist until tomorrow