A cure may be on the way for skin diseases with the creation of the world's first nanoneedle that can deliver healthy genes directly into the affected skin cells and repair them. The research at City University spells hope for people for whom treatment alleviates the symptoms but does not cure the condition, researchers say. The needle is made of diamond, the planet's hardest natural material, with a tip just 135 nanometres in diameter, more than 5,000 times thinner than a human hair. Ten million nanometres equals 1cm. The needle can penetrate a cell membrane without killing the cell, said Dr Chen Xianfeng, an assistant professor in the department of physics and material science who first came up with the idea of nanoneedles in 2011. "Unlike traditional medical treatment that treats only the symptoms but not the cause, our nanoneedle can be used to fix the diseased skin cells directly by delivering the correct genes to them," Chen said. The researchers hope to treat psoriasis - which causes dry red patches on the skin and may increase the risk of stroke - and melasma, which refers to dark patches on the face and is common in pregnant women. In its study, Chen's team arranged up to a million needles on a 1 sq cm plate and used them on a nerve cell known as the neuron. A plate of nanoneedles delivered genes into 40 per cent of the neurons in 10 minutes, while conventional treatments took several hours to change only 5 per cent of the cells, the team found. Its application to skin diseases would be very simple, Chen said. "We just need to coat the needle tip with [healthy genes] or put the medicine directly onto the skin, then press the needle against the affected area," he said. Chen said he believed the needle could also help to cure skin cancer. In the study, the medicine-coated needle was found to increase the efficacy of anticancer drugs significantly if it was injected directly into cancer cells. If put into mass production, a 1 sq cm plate of nanoneedles would be priced at about HK$20, said Lee Chun-sing, CityU chair professor of materials science. The team lowered the cost by using silicon for the plate and laboratory-created diamonds. It will have to wait perhaps three years to start clinical trials because of a lack of funding.