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